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Palynological and Paleontological Records of Changes From Glacial-Stage (Mis 2) Oxygenated Brackish to Postglacial Hypoxic and Periodically Dysoxic Conditions in the Marmara Sea, Türki̇ye

Authors:

Abstract

The Marmara Sea is a crucial gateway for water exchange with the inland Black Sea through the Strait of Bosphorus and with the Aegean and the Mediterranean Seas through the Strait of Dardanelles in the south. A wide-ranging literature review was made of the complex paleoceanographic history for the Marmara Sea Gateway, based on disparate geomorphological, geochemical, palynological and paleontological records from sediment cores on a millennial time-scale. In this manuscript, we review the characteristics of a wide variety of organisms that live in the Marmara Sea today and contribute to fossil floras and faunas that along with pollen and spores provide archives of past environmental and oceanographic changes. Macrobiota leave a patchy or incomplete record, and some calcareous and siliceous micro-organisms are absent in cold, low salinity water or high bottom water acidity. Hence, we focus on palynological studies for a wide range of organic-walled non-pollen palynomorphs (NPPs) from the Marmara Gateway, using re-calibrated age models for five cores based on 24 radiocarbon dates. Tgradient. We use two high-resolution piston cores (M02-88P and M02-89P) from the İmralı Basin to document vegetation and paleo-ceanographic changes on a scale of ~15–30 yr cm-1 from the end of MIS 3 to ~10 yr cm-1 for MIS 1 and recent times when human impacts clearly prevail over natural sea level and global climate events. The new data confirm that the MIS 3 to 17.5 cal ka interval was characterized by vegetation indicating local refugia with >600 mm annual rainfall, and enough warmth to support Castanea forest. The Marmara basin was occupied by the Propontis Lake, which was more saline and/or more oligotrophic than the contemporary Neoeuxine Lake in the Black Sea basin or the Caspian Sea. The sparse lake dinocyst assemblages are most similar to the MIS 2–5a dinocyst flora of Gulf of Corinth, Greece . There may have been sea-ice formation on the lake during winter months and we report for the first time, presence of ostracods, and the eggs or egg capsules of herring and trout fish parasites that may have marked a stressed fish population. The entire Propontis Lake interval is marked by a prevalence of parasitic chytrid and saprophytic biota (cf. Multiplicisphaeridium) that may reflect the low dinoflagellate population. After the Last Glacial Maximum at ~20 cal ka, the Propontis Lake remained low (~ –100 m) except during meltwater discharge event(s) but the flooding left little trace in the lake biota. Climate was cold and dry, and primary production remained low but new ostracod remains appear in the NPP fraction for the first time, and there are traces of Ammonia spp. benthic foraminifera. A major series of oceanographic changes began at ~13.8 cal ka when rising Aegean Sea waters entered the Marmara basin, affecting its full salinification in less than ~700 yr and triggering more eutrophic conditions, sapropel development, and immigration of calcareous marine phyto- and zoo-plankton. There was a decrease in freshwater Pediastrum coenobia, concurrent with the appearance of benthic foraminiferal linings and planktonic foraminiferal tests, increased dinoflagellate cyst concentrations including the Paratethyan relict Spiniferites cruciformis and other Pannonian Basin Spiniferites species, such as Spiniferites maisensis. From ~13.5–12.9 cal ka, there was a rapid increase in pollen concentration, but reduced arboreal pollen and greatly increased Artemisia sage brush pollen that clearly marks the Younger Dryas cold interval 12.9 to 11.7 cal ka region-wide. Increases of oak and other thermophilous tree taxa mark the early interglacial Greenlandian Age and the start of the Holocene thermal optimum that terminated around the time of the Meghalayan 4.2 cal ka drought event, recorded here for the first time. There is a succession of freshwater algae: the glacial stage chorophyte Pediastrum is followed by the desmid Staurastrum volans around 11 cal ka, ending with the more eurythermal, bloom-forming chlorophyte Botryococcus at ~10.5 cal ka, pointing to progressive eutrophication of the Marmara Sea surface waters. The thermal optimum is marked by higher amounts and greater diversity of dinoflagellate cysts that can generate harmful algal blooms, but their abundances decline abruptly at 3 cal ka for uncertain reasons that may include climate cooling before the industrial age and recent climate warming.
CHAPTER 2
PALYNOLOGICAL AND PALEONTOLOGICAL
RECORDS OF CHANGES FROM GLACIAL-STAGE
(MIS 2) OXYGENATED BRACKISH TO
POSTGLACIAL HYPOXIC AND PERIODICALLY
DYSOXIC CONDITIONS IN THE

Petra J. MUDIE1*, Richard N. HISCOTT2, Ali E. AKSU2
1Natural Resources Canada, Geological Survey of Canada-Atlantic, Dartmouth, Canada, B2A 4A2
E-mail: PMudie@nrcan.gc.ca
2Memorial University of Newfoundland, Department of Earth Sciences, St. John’s, NL, Canada A1B 3X5
E-mail: rhiscott@mun.ca; aaksu@mun.ca
DOI: 10.26650/B/xxxxx.2024.xxx.002
Abstract
The Marmara Sea is a crucial gateway for water exchange with the inland Black Sea through the Strait of
Bosphorus in the north, and with the Aegean and the Mediterranean Seas through the Strait of Dardanelles in the
south. A wide-ranging literature review was made of the complex paleoceanographic history for the Marmara Sea
Gateway, based on disparate geomorphological, geochemical, palynological and paleontological records from
sediment cores on a millennial time-scale. These earlier studies fail to record rapid climate changes during MIS 2
glacial conditions of oxygenated, low salinity water or transformation to periodically dysoxic conditions during the
warm interglacial MIS 1. Variability in calibration of dating methods has also contributed to uncertainty in inter-core
correlation of biozones. In this manuscript, we review the characteristics of a wide variety of organisms that live in
the Marmara Sea today and contribute to fossil floras and faunas that along with pollen and spores provide archives
of past environmental and oceanographic changes. Macrobiota leave a patchy or incomplete record, and some
calcareous and siliceous micro-organisms are absent in cold, low salinity water or high bottom water acidity. Hence,
we focus here on palynological studies that use updated information on a wide range of organic-walled non-pollen
palynomorphs (NPPs) from the Marmara Gateway to avoid these shortcomings. The studies also use re-calibrated
age models for five cores based on 24 radiocarbon dates including one at the Y2 tephra level. To assist interpretation,
we present new surface sample data for a suite of NPPs that is qualitatively calibrated to a salinity and oxygen
         
vegetation and paleoceanographic changes on a scale of ~15–30 yr cm-1 from the end of MIS 3 to ~10 yr cm-1 for
MIS 1 and recent times when human impacts clearly prevail over natural sea level and global climate events. The
new palynological data confirm that the MIS 3 to 17.5 cal ka interval was characterized by vegetation indicating
local refugia with >600 mm annual rainfall, and enough warmth to support Castanea forest. The Marmara basin was
ECOLOGICAL CHANGES IN THE SEA OF MARMARA
PALYNOLOGICAL AND PALEONTOLOGICAL RECORDS OF CHANGES FROM GLACIAL-STAGE (MIS 2)...
114
occupied by the Propontis Lake, which was more saline and/or more oligotrophic than the contemporary Neoeuxine
Lake in the Black Sea basin or the Caspian Sea. The sparse lake dinocyst assemblages are most similar to the MIS
2–5a dinocyst flora of Gulf of Corinth, Greece, where there were intermittent marine connections and disconnection
over almost one million years. There may have been sea-ice formation on the lake during winter months and we
report for the first time, presence of ostracods, and the eggs or egg capsules of herring and trout fish parasites that
may have marked a stressed fish population. The entire Propontis Lake interval is notably marked by a prevalence
of parasitic chytrid and saprophytic biota (cf. Multiplicisphaeridium) that may reflect the low dinoflagellate
population. After the Last Glacial Maximum at ~20 cal ka, the Propontis Lake remained low (~ –100 m) except
during meltwater discharge event(s) which raised the Neoeuxine Lake to overspill and increase the Propontis Lake
level to ~ –65 m elevation so it overflowed through the Strait of Dardanelles into the Aegean Sea, although the
flooding left little trace in the lake biota. Climate was cold and dry, and primary production remained low. However,
notable amounts of Crustacean resting eggs and ostracod remains appear in the NPP fraction for the first time, and
there are trace numbers of Ammonia spp. benthic foraminifera. A major series of oceanographic changes began at
~13.8 cal ka when rising Aegean Sea waters entered the Marmara basin, affecting its full salinification in less than
~700 yr and triggering more eutrophic conditions, sapropel development, and immigration of calcareous marine
phyto- and zoo-plankton. There was a decrease in freshwater Pediastrum coenobia, concurrent with the appearance
of benthic foraminiferal linings and planktonic foraminiferal tests, increased dinoflagellate cyst concentrations
including the Paratethyan relict Spiniferites cruciformis and other Pannonian Basin Spiniferites species, such as
Spiniferites maisensis. From ~13.5–12.9 cal ka, there was a rapid increase in pollen concentration, but reduced
arboreal pollen and greatly increased Artemisia sage brush pollen that clearly marks the Younger Dryas cold interval
12.9 to 11.7 cal ka region-wide. Increases of oak and other thermophilous tree taxa mark the early interglacial
Greenlandian Age and the start of the Holocene thermal optimum that terminated around the time of the Meghalayan
4.2 cal ka drought event, recorded here for the first time. There is a succession of freshwater algae: the glacial stage
chorophyte Pediastrum is followed by the desmid Staurastrum volans around 11 cal ka, ending with the more
eurythermal, bloom-forming chlorophyte Botryococcus at ~10.5 cal ka, pointing to progressive eutrophication of the
Marmara Sea surface waters. The thermal optimum is marked by higher amounts and greater diversity of
dinoflagellate cysts that can generate harmful algal blooms, but their abundances decline abruptly at 3 cal ka for
uncertain reasons that may include climate cooling before the industrial age and recent climate warming.
Keywords: Paleoceanography, Dinoflagellate Cysts, Pollen and Spores, Non-Pollen Palynomorphs, Bosphorus,
Dardanelles, Eustacy
115Petra J. MUDIE, Richard N. HISCOTT, Ali E. AKSU

Marmara is the smallest (~220 km × ~70 km) sea in the world, with a surface area of 11,500
km2; it is situated between the Black Sea and the Aegean Sea (Fig. 1). It is a crucial gateway for
water exchange between the inland Black Sea and the Aegean Sea (the northeastern prolongation
of the Mediterranean Sea) through the Strait of Bosphorus in the north, and via the Strait of

straits, it is referred to as the Marmara Sea Gateway because of its role in the transport of
watermasses from the Mediterranean Sea to the Black Sea, and in the export of floodwater from
the Black Sea and the Caspian Sea to the Mediterranean Sea during the Pleistocene (Fig. 1).








PALYNOLOGICAL AND PALEONTOLOGICAL RECORDS OF CHANGES FROM GLACIAL-STAGE (MIS 2)...
116
These water exchanges took place across two narrow and shallow natural channels, the
Straits of Dardanelles in the southwest and Bosphorus in the northeast, which are often
collectively referred to as “the Turkish Straits”. The Marmara Sea Gateway also constitutes
a critical “biological corridor” for many species migrating between the Black Sea and the
Aegean Sea. This corridor has been used by vessels en route to eastern Europe since at least the
time of the Greek explorers ca. 2,700 years ago (King, 2004, p. 26). Paleoceanographic studies
show that the early trading was accompanied by two-way dispersal of coccolithophorids
and dinoflagellates (Jones, 1994; Marret et al., 2009; Shumilovskikh et al., 2016). In recent
decades, these heavily transited waterways have been polluted by international vessel traffic,
oil spills, bilge water discharges, and solid waste disposals. The ship hulls and ballast water
discharges are sources of invasive species that have triggered a trophic cascade in the Black
Sea (Mee et al., 2005), and potentially threaten the dwindling fish stocks in the Marmara
Sea (Ulman et al., 2020). The small size of the Marmara Sea magnifies the impact of large


to increased occurrences of red tides and other harmful algal blooms (HABs) as documented

events (locally called “sea snot”) are also periodically produced by widespread plankton
blooms dominated by diatoms, the dinoflagellate Gonyaulax fragilis, and the coccolithophorid
Emiliana huxleyi. The organic mucilage covers the sea surface, then sinks to accumulate on

Marmara Sea were covered by the gooey viscous “sea snot” formed in response to large-scale
eutrophication associated mainly with untreated municipal wastewater. The unsightly viscous
organic matter furthermore smothered and killed filter-feeding benthos when the sticky mats
and entrapped organic matter fell to the seabed.
As a framework for planning the restoration of the Marmara Sea marine environment,
it is useful to examine the evidence for ecological changes as preserved in sedimentary
archives representing the past 7,000 years of continuous interconnection between the Aegean
and Black Seas. There is also need to determine the conditions that may have preceded the
restoration of full marine conditions after the basin was isolated from both the Black and
Aegean Seas during the Late Glacial interval of lowered sea level, referred to as the Propontis
Lake. Previous studies of these geological archives are mostly from low-resolution (multi-
centennial) palynological records of natural and anthropogenic changes in regional vegetation
(Mudie et al., 2002a; Caner and Algan, 2002; Cordova et al., 2009; Valsecchi et al., 2012),
117Petra J. MUDIE, Richard N. HISCOTT, Ali E. AKSU
and in plankton or benthos that produce organic-walled resting spores (dinoflagellate cysts,
tintinnids, and copepods) or chitinous remains (copepod and ostracod carapace linings,
nematodes, turbellarian egg capsules, and benthic foraminiferal linings). Other paleontological
data mainly come from calcareous planktonic and benthic foraminifera, coccolithophorids,
ostracod carapaces, and mollucs, and from siliceous diatom valves or sponge remains (Nazik,
2001; Aksu et al., 2002a; Kaminski et al., 2002; Kubanç, 2005; McHugh et al., 2008; Vidal

 
al. (2016) described some aspects of these geological changes in their review of the Late
Quaternary paleoecological and paleoclimatic evolution of the Marmara Sea. In this chapter
we provide, for the first time, information on the late MIS 3 to Last Glacial Maximum (LGM)
conditions and elaborate on the timing and nature of the paleoceanographic changes that took
place since the LGM using new higher resolution data for the Holocene, Pleniglacial and Late
Glacial intervals. As background to these new data, we first present a summary of past large-
scale changes as reviewed by Aksu and Hiscott (2022; Table 1; Fig. 2).
Table 1. Key hydrographic events in Marmara Sea through Marine Isotopic Stage (MIS) 2 and
MIS 1. Base-level configurations relate to numbered sketches in Figure 2. Ages are calibrated
(cal) to astronomical years, in thousands of years before present (ka), using the Marine20
calibration curve (Heaton et al., 2020).
   
29 End of MIS 3, start of MIS 2: Global sea level is low (~ –110 m), well
below the f loor of Strait of Dardanelles; Mar mara Sea basin is landlocke d,
separate from the Neoeuxine Lake in the Black Sea basin, and forming
the stagnant evaporative and brackish Propontis Lake with water levels
85 – 100 m lower than today.
1
24 -18 LGM: Evaporation and isolation from the Aegean and Black Seas result
in lowering of the Propontis Lake level to at least –85 m, long enough to
create a prominent terrace at that depth.
1
17.2 -15.7 MIS 2: Meltwater from the Scandinavian ice sheet transits the Turkish
Straits System, building the lower delta at the Bosphorus exit, and filling the
Propontis Lake sufficiently that lacustrine water spills over the Dardanelles
sill (then at ~ –75 m), into the Aegean Sea that remained at ~ –110 m.
2
15.7-13.8 Late MIS 2: Renewed evaporation and isolation from the Aegean and
Black Seas lower the Propontis Lake level to –85 m to –100 m with
southern shelf-edge deltas recording this lowstand.
1
13.8 Early MIS 1: Initial entry of saline water through the Strait of Dardanelles
due to post-g lacial rise of the Aegean S ea; in ~100 year s this entry i ncreased
the base level of the former Propontis Lake from below –85 m to ~ –70 m.
3
13.8-13.2 Density-driven intrusion of Mediterranean water and upward/outward
expulsion of fresher lacustrine water created water-column stratif ication
with dysoxic deep basins, initiating M1 sapropel accumulation. By
~13.2 cal ka euryhaline molluscs could thrive in shallow waters,
indicating nearly complete replacement of the Propontis Lake water by
Mediterranean water.
4
PALYNOLOGICAL AND PALEONTOLOGICAL RECORDS OF CHANGES FROM GLACIAL-STAGE (MIS 2)...
118
13. 2 -11.1 Marmara Sea was now a semi-isolated embayment of the Aegean Sea;
algal-serpulid-molluscan bioherms colonised newly inundated shelves
although weak deep-water circulation maintained dysoxic conditions and
M1 sapropel accumulation.
4
11.1-10.2 MIS 1 meltwater event: renewed Neoeuxine Lake outflow created a
climbing delta lobe at the Bosphorus exit, establishing water-column
stratification conducive to sapropel accumulation in Marmara basins;
elsewhere, very fine sand and mud were supplied largely f rom the Kocasu
River debouching into the southern Marmara Sea.
5
10.2 -8 Early Holocene: Marmara Sea saline water advanced northward along the
floor of the Strait of Bosphorus as a ‘salt wedge’, reaching its northern
end to initiate two-way exchange with brackish surface waters exiting the
Neoeuxine Lake/Black Sea. This first major entry of seawater into the
Black Sea at ~ 9.5 cal ka preceded steady two-way flow at ~ 8 cal ka, and
successful colonisation by euryhaline fauna at ~ 7.5 cal ka.
6
8-6.5 Gradual reduction in deep-water stagnation in the Marmara Sea as
northeastward advection of oxygenated Mediterranean water continued,
leading to the end of M1 sapropel deposition. Moder n base level was
reached at ~7 cal ka, after which the present hypoxic estuarine marine
conditions were established.
6
In this chapter, we highlight the importance of marine palynology records using
dinoflagellate cysts and other organic-walled non-pollen palynomorphs (NPPs), in addition

et al. (2016). Other fossil groups, including coccoliths, foraminifera and ostracods, which
help to illuminate environmental changes over the last ~30 ka are used to support conclusions
based on the palynological data.
Here, we also present new pollen and spore, dinoflagellate cyst and other NPP

one from the northern rim of the basin (core M02-89P) and the other within the basin
itself (core M02-88P). These cores have a very high sedimentation rate, thus providing
a high temporal resolution palynostratigraphy for the Late Pleistocene through Middle-
Late Holocene of the Marmara Sea. Furthermore, these new data are correlated with
paleoceanographic interpretations of other cores studied by Aksu et al. (2002a), Londeix et
al. (2009), Valsecchi et al. (2012), and Vidal et al. (2010), which allow comparisons with
older lacustrine-phase intervals that are more condensed in other cores in the region (e.g.,

119Petra J. MUDIE, Richard N. HISCOTT, Ali E. AKSU





2.1. Bathymetry
The morphology of the Marmara Sea is characterized by four deep central basins and three
intervening ridges surrounded by steep fringing slopes which are in turn surrounded by shallow

rhombohedral depressions where water depth exceeds 1100–1200 m (Fig. 3). The easternmost


PALYNOLOGICAL AND PALEONTOLOGICAL RECORDS OF CHANGES FROM GLACIAL-STAGE (MIS 2)...
120
A fifth basin outside the central zone is a shallow (~370 m deep), crescent-shaped depression


have water depths generally shallower than –600 m. The shelf edge is at water depths of –90 m
to –100 m around the Marmara Sea, and very steep slopes of 10º–30º lead to the abyssal depths
of the basins. The northern shelf is narrow (3–10 km wide), whereas an approximately 20–30
km-wide shelf occurs across the southern Marmara Sea (Fig. 3). The northern shelf consists
of eroded Tertiary bedrock overlain by a very thin veneer of Holocene sediments, whereas the
southern shelf comprises a thick succession of Miocene–Recent delta wedges (Aksu et al., 1999;
Sorlien et al., 2012; Hiscott et al., 2021).

The Marmara Sea has a water volume of 3,378 km3. The Black Sea receives a very large
volume of freshwater discharge from major European rivers (Danube, Don, Dnieper, Dniester,
Southern Bug), thus exports ~300 km3 yr-1 of brackish water to the Marmara Sea and onward into

annual discharge of the small rivers and streams entering the Marmara Sea is ~5.5 km3 yr-1, which
is ~55 times smaller than the Black Sea outflow through the Strait of Bosphorus. The present
water exchange across both straits occurs as a two-layer flow. A cooler, lower salinity (S = 17–20
psu, hereafter unitless; Menaché et al., 1985) surface layer ~20 m thick exits the Black Sea and
a warmer, higher salinity (S= 38–39) layer of Mediterranean water flows northward through the

The surface circulation in the Marmara Sea is dominated by the outflow of a low-salinity

Sea from the Bosphorus flows south–southwest as a narrow current for nearly the entire width
of the basin, but curves initially west and later northwest along the edge of the southern shelf
(Fig. 4). This current then crosses the Marmara Sea before it swings southwest towards the
Strait of Dardanelles, forming large meander loops with three weak anticyclonic gyres (Fig.

by the rate of influx of denser Mediterranean water through the Strait of Dardanelles. The
water circulation across the shallow Strait of Bosphorus (–40 to –110 m deep) and the
deeper Strait of Dardanelles (–63 to –103 m deep) mimics that across the Marmara Sea:
a surface outflowing layer of well-oxygenated, low salinity Black Sea water, and a lower
inflowing layer of oxygenated Mediterranean Sea bottom water that is progressively reduced
in dissolved oxygen from southwest to northeast in the Marmara Sea.
121Petra J. MUDIE, Richard N. HISCOTT, Ali E. AKSU
Morphology of the 






Hydrography and Oceanography for the northeast and southwest Marmara Sea shelves and the
northeast Aegean Sea shelf, placed over bathymetry extracted from EMODnet data (http://www.













and Oceanography for the shelves of Marmara Sea and the NE Aegean Sea, and authors’ data for

from EMODnet data (http://www.emodnet-hydrography.eu/) for the Aegean and Black Seas. Greater




PALYNOLOGICAL AND PALEONTOLOGICAL RECORDS OF CHANGES FROM GLACIAL-STAGE (MIS 2)...
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Residence times of lower-layer waters at ~ –500 m in the Marmara and Black Seas are
~12–19 years and ~625 years, respectively (Lee et al., 2002). In the Marmara Sea, saline water
in the deepest basins may have an average residence time of ~6–7 years (Ünlüata et al., 1990;

with summer and winter sea surface temperatures (SST) of 15–23°C and 5–9°C, respectively.
The lower water mass is consistently warm (15–20°C), denser and more saline (S=38–39),

their table 1) report the oceanographic characteristics (salinity, temperature, dissolved oxygen

Bosphorus and Dardanelles for 2010–2013.

The Late Glacial period is the time of rapid climate change during the transition from end
of the last glacial interval (MIS 2, 29–14 cal ka) to the Holocene interglacial that started at 11.7
cal ka. Changes in the depths of water flowing through the Straits of Dardanelles and Bosphorus
largely determine the Late Glacial to latest Holocene paleogeographic evolution of the Marmara
Sea, as reconstructed by Aksu and Hiscott (2022) from decades of high-resolution seismic surveys,
sedimentological and micropaleontological studies. During the Last Glacial Maximum (LGM),
ca. 24–18 cal ka, global sea level was lowered to about –110 m, resulting in isolation of the
Marmara Sea and the formation of the land-locked Propontis Lake, with a water level of ca. –85
m relative to today (Fig. 2, Configuration 1). During the early post-LGM deglaciation, ~17.2–
15.7 cal ka (Tudryn et al., 2015), meltwater from European ice-sheets drained into the similarly
isolated Neoeuxine Lake occupying the present-day Black Sea basin. The meltwater raised the
water level of the inland lake enough to spill over into the Propontis Lake (Fig. 2, Configuration
2), potentially coinciding with the accumulation of red-brown clays in the Black Sea basin from
16.35 to 15.4 cal ka (Yanchilina et al., 2019), and with the development of an elongate deltaic
lobe at the southern exit of the Strait of Bosphorus (lower Pleniglacial delta of Hiscott et al., 2002;
Aksu et al., 2016). The meltwater input caused the low salinity, well-oxygenated glacial Propontis
Lake level to rise above the sill depth of the Strait of Dardanelles (paleo-elevation ca. –75 m) and
overflow southwards into the Aegean Sea (Fig. 2, Configuration 2). Between 15.7 cal ka and 13.8
cal ka, climate changes apparently forced a large-scale evaporative drawdown in the Propontis and
Neoeuxine Lakes, causing their second isolation when base levels dropped to ca. –90 m and –110
m, respectively (Hiscott et al., 2021; Aksu et al., 2002c).
However, with rising global sea levels at the end of MIS 2, the Aegean Sea water began
to spill across the Strait of Dardanelles (Fig. 2, Configuration 3), probably rapidly salinising
123Petra J. MUDIE, Richard N. HISCOTT, Ali E. AKSU
the small Propontis post-glacial lake and initiating strong water-column stratification during

water conditions within a fully saline embayment (Fig. 2, Configuration 4) and initiating
accumulation of sapropel (>2% TOC) and sapropelic mud (1.5–2% TOC). Renewed outflow
from the Neoeuxine Lake at 11.1 cal ka re-established strong water-column stratification and
created a low salinity lid with strong outflow to the Aegean Sea (Fig. 2, Configuration 5).
Finally, during the Early Holocene at ~10.2 cal ka, a salt wedge lifted the brackish Neoeuxine
Lake outflow off the floor of the Strait of Bosphorus and established a more persistent density
underflow like the situation today (Fig. 2, Configuration 6). Supplying this saline underflow
induced effective deep circulation across the Marmara Sea basins. Gradually, enough seawater
entered the Black Sea for euryhaline marine organisms to be able to replace its lacustrine
faunas by ~7.5 cal ka. During this time the surface layer in Marmara Sea became thinner and
stratification became seasonally weaker. The most recent changes to the Marmara Sea during



areas. Anthropogenic inputs were of secondary importance until the l990s after which they

and Gulf of Gemlik (Ediger et al., 2016).

Geoscientists reconstruct past environmental conditions by quantifying and assessing
trends of various proxy variables, which may be geochemical in nature (elemental, molecular
or isotopic; obtained on bulk sediments, pore waters, or the hard parts of fossils), or may
be derived directly from quantitative or qualitative interpretation of the fossil remains. The
latter can involve species identification and inventories, community (trophic) structure,
morphological indicators of stress or other evidence of behaviour (e.g., feeding strategies,
depth and intensity of burrowing). Physical processes including the strength and orientation
of paleocurrents can be interpreted from sediment textures and bedding styles (e.g., graded
bedding, lamination).
This chapter is focused specifically on biological evidence for environmental changes,
using a range of flora and fauna living in the Marmara Sea and its precursor Propontis
Lake. We begin with an introduction to each group of organic-walled micro-organisms

and ostracods, we provide notes on their occurrence in the modern Marmara Sea region as
PALYNOLOGICAL AND PALEONTOLOGICAL RECORDS OF CHANGES FROM GLACIAL-STAGE (MIS 2)...
124
a reference point for the interpretation of past spatial distributions and temporal trends and
future studies that may allow biomolecular linkage of calcareous ostracod carapaces and their
organic linings.

Palynomorphs are organic-walled microfossils that are highly resistant to post-depositional
degradation under strongly acidic conditions, in contrast to calcareous microfossils such as
coccoliths, foraminifera and ostracods, or siliceous diatoms and glass sponges. The best known
palynomorphs are pollen and spores produced by terrestrial plants, including ferns, horsetails
and mosses. Palynomorph assemblages, however, also include remains of freshwater aquatic
algae, fungal spores, marine phytoplankton (primarily resting stages of dinoflagellates and
tintinnids). The marine palynomorph assemblages may also include various zoomorphs – most
commonly the organic linings of foraminifera and ostracods, chitinous mandibles and resting
eggs of small crustaceans, egg capsules of helminths, and neorhabdocoel worms (Matsuoka
and Ishi, 2018; Mudie et al., 2021; Matsuoka and Ando, 2021). Collectively, these non-pollen-
spore remains are referred to as Non-Pollen Palynomorphs (NPPs), as recently reviewed in a
monograph edited by Marret et al. (2021). NPPs are the focus of modern paleoenvironmental
studies using palynology to reconstruct the flora and faunas of aquatic environments in
addition to the traditional pollen and spore proxies for regional vegetation and climate change.

Pollen analysis of marine sedimentary sequences is a powerful tool for reconstructing
regional vegetation and climate changes because it allows direct correlations of climate
change over land and in the ocean, with minimum chronological uncertainty (Sanchez-Goñi
et al., 2018). The marine and terrestrial microfossils can be analysed from the same sample
so that the ocean-atmosphere paleo-data represent identical time slices. In land-locked marine
environments such as the Marmara Sea, accumulations of autochthonous terrestrial pollen and
terrestrial spores from vegetation surrounding the sea (Cordova et al., 2009; Shumilovskikh
et al., 2012; Valsecchi et al., 2012; Marinova et al., 2018) provide good records of landscape
changes (see Cordova et al., 2009, their fig. 6), as shown by the correlation between the

Sea core site M97-2G (see Fig. 3 for location). Miebach et al. (2016; their fig. 6) also discuss

sequence, the Marmara Sea cores MD-2430 (Valsecchi et al., 2012) and M94-5 (Mudie et
al., 2002a), and the Black Sea cores 22-GC3 and 25-GC (see Shumilovskikh et al., 2012,
125Petra J. MUDIE, Richard N. HISCOTT, Ali E. AKSU
2014). Valsecchi et al. (2012) relate fluctuations in percentages of pollen vegetation indices
to the stable isotopic data for Sofular Cave speleothems (Badertscher et al., 2011) and NGRIP
(Johnsen and North Greenland Ice Core Project members, 2004) records, and with trends
in global insolation since 31 cal ka. However, Miebach et al. (2016) note discrepancies

as Dansgaard-Oeschger (DO) events. These anomalies will be discussed in Section 6 of this
chapter, in light of a new high-resolution core M02-89P from the southeastern Marmara

Shumilovskikh et al. (2012, 2014).

Marmara Sea for the period from MIS 2 to MIS 1, beginning with the low-resolution study of
Ediger (1990) who reported on palynomorphs in 12 samples of Holocene sediments from the

records within Marmara Sea cores, notably the presence of a lower diversity in temperate
Mediterranean tree taxa and absence of the moisture-demanding tree Picea in the westerly
Homo
sapiens migration and early spread of agriculture, this east–west trend seems to be mirrored
on a larger scale, from the eastern Black Sea to the western Marmara Sea (Mudie et al., 2011).
Using a mixture of uncalibrated and variously (pre-2016) calibrated chronologies from

of climatic and vegetation change from the pollen-spore records for the past ca. 31,000 years.
Stage 1, the early Late Pleniglacial – Last Glacial Maximum (LGM) interval starts with
evidence of widespread Pinus and deciduous Quercus forest that declines towards the LGM
at the expense of increased Pistacia and evergreen Quercus woodland. Miebach et al. (2016)

Lake pollen records representing the area south of the present-day Marmara Sea shoreline but
pollen records from the Gemlik Bay indicate conditions warm and wet enough to support a
Castanea (sweet chestnut) refugium (Caner and Algan, 2002). These subregional differences

Holocene interval during which there is an increased presence of steppe forest pollen, and a

(Greenlandian Age) interval of climate warming and increased precipitation, starting with
appearances and increases of temperate forest trees such as Tilia, Castanea and Ulmus that
require warm, moist conditions (Mudie et al., 2004, 2007; Valsecchi et al., 2012; Roberts,
PALYNOLOGICAL AND PALEONTOLOGICAL RECORDS OF CHANGES FROM GLACIAL-STAGE (MIS 2)...
126
2012). Low-resolution cores (multi-centennial-scale) show that during and after ~7 cal ka
during the mid-Holocene Northgrippian Age (~8.2–4.2 cal ka), increases in Carpinus and
Ostrya pollen indicate generally warm and dry climatic conditions for the Marmara Sea region
(Caner and Algan, 2002; Mudie et al., 2004, 2007). Valsecchi et al. (2012) interpret short-
lived 20% decreases in deciduous forest taxa at 5.5 cal ka and 2.1 cal ka as marking abrupt
cold events and retreats of forests. From 4–1.5 ka during the Late Holocene Meghalayan Age,

southern Türkiye, including evidence of arbiculture [e.g. olives, Manna ash (Fraxinus cornus),
sweet chestnut (Castanea) and grape vines] in addition to cereals and livestock raising (Leroy,
2002; Mudie et al., 2007).

Dinoflagellates (Superphylum Alveolata, Division Dinoflagellata) are eukaryotic
microorganisms, primarily living in the photic zone above the thermocline in fully marine or
brackish seas, and second only to diatoms in productivity (Mudie et al., 2021 and references
therein). Dinoflagellates are also notorious producers of Harmful Algal Blooms (HABs),
having the largest number of potentially toxin-producing species, including seven of the
73 taxa occurring in the Marmara Sea (Balkis, 2004; Balkis et al., 2016a). The majority
of dinoflagellates are heterotrophic (58%), while others are phototrophic or mixotrophic; a
few are parasitic or symbiotic. Dinoflagellates have a complex life cycle, including motile
asexual and sexual phases, and some species produce resting cysts that may remain dormant
for decades before resuspension initiates a new algal bloom. Typically, about 14% of the
dinoflagellate taxa produce cysts; however, the cysts of a higher proportion of dinoflagellates
(36%) occur in the oxygen-poor sediments of the meromictic (layered watermasses that do
not intermix) Marmara and Black Seas (Mudie et al., 2017, 2021). The cyst ‘seed’ banks in
Marmara Sea sediment cores document past blooms and also show the potential for future
red tide production when resuspended from shallow water or by disturbance of soft bottom
sediment (Balkis et al., 2016b).

Marmara Sea and the Turkish Straits back to 1974, and they note that there has been a recent

and inter-annual variability of red tides along the Trabzon coastline (central Anatolian Black
Sea coast) caused by Diplopsalis lenticula and Gymnodinium sanguineum in summer, and
Scrippsiella trochoidea in winter. These authors note that HABs seem to be sporadic in that
region, being correlated with enrichment of NO3 and PO4 but showing no significant effect of
127Petra J. MUDIE, Richard N. HISCOTT, Ali E. AKSU
Fe, temperature or salinity. However, ongoing studies continue to find new HAB cyst taxa;

plankton tow samples from the Gulf of Erdek (Fig. 3), indicating the ongoing introduction of
potentially invasive species.
Studies of dinoflagellate cysts in surface sediments of the Marmara Sea and the adjoining

walled dinocysts are abundant throughout the region (Fig. 5) where 40 cyst taxa occur in
abundances up to 30,000 cysts/g sediment. Lesser abundances and a lower diversity of
dinocysts species are found in the Azov and Caspian Seas (Mudie et al., 2017), and Sala-
Perez et al., (2020) record an average concentration of ~11,000 cysts/mL wet sediment
and 11 taxa for the Caspian Sea. Results of a new palynological study of samples collected
along a transect of the Marmara Sea southern shelf (Fig. 5, M02-1 to -19) and other archival
surface samples show that dinocysts (Fig. 5, dark blue pie slices) dominate most of the NPP
assemblages, comprising 28% to almost 74% of the total NPP. There is a tendency for the
relative abundance of the dinocysts to increase with water depth, but concentrations are
variable and not clearly related to oxygen levels (depth) or salinity. Ciliate zooplankton (Fig.
5, light blue pie slices) appear as the second largest category of NPP (mean count per slide =
21) but they are only dominant (49%) in the surface sample M02-77 from the Black Sea shelf
off the Strait of Bosphorus.
Benthic foraminiferal linings (Fig. 5E, dark orange pie slices) are the third most abundant
NPP, with range and mean counts of 10–(17.5)–39 per slide, and a tendency to decrease
in deeper water. Allocthonous monocellular fungal spores (Fig. 5, light green pie slices),
primarily representing aerial influx from regional grasses or farmlands, are the fourth
largest category, with counts of 2–90 with an average of 16.5. Allochthonous freshwater
algae, primarily the chlorophyte Botryococcus and the acritarch Micrhystridium, sometimes
including the potentially toxic cyanophyte, Gloeotrichia, comprise the fifth category, with
counts of 2–16 with an average of 8. Arthropod remains, ostracod carapace linings and
mandibles, and turbellarian egg capsules have mean values of 4–5, while the remaining NPP,
mandibles of gastropods, small nematodes and sponge spicules have averages of less than 2
specimens per slide.
Principle component analysis of dinocysts in samples from the Marmara Sea Gateway
(Mudie et al., 2004) showed that surface assemblages are dominated by cysts of opportunistic
autotrophic gonyaulacoids, such as Lingulodinium machaerophorum (Lm), Operculodinium
centrocarpum (Oc) and Spiniferites spp. These cysts of autotrophic or mixotrophic
PALYNOLOGICAL AND PALEONTOLOGICAL RECORDS OF CHANGES FROM GLACIAL-STAGE (MIS 2)...
128
dinoflagellates distinguish the high salinity (31–38) Mediterranean watermass, whereas a
diversity of heterotrophic protoperidinioids characterises the low-salinity conditions (~4–25)
of the Marmara and Black Sea surface watermasses (Mudie et al., 2004).
 







study of dinoflagellate cysts at 25 sites along the coast of western Türkiye. They show that at
129Petra J. MUDIE, Richard N. HISCOTT, Ali E. AKSU
most sites, the opportunistic autotrophs dominate and the ratio Lm:Oc is much greater than
2.0 except at one Central Basin Marmara Sea site. Likewise, the new dinoflagellate-transect
data (Fig. 5) also indicate the typical dominance of L. machaerophorum over O. centrocarpum
but with occasional notable reversals. The reversals may reflect changes from high nutrient
inputs that favour blooms of Lingulodinium polyedrum which produces L. machaerophorum
cysts, while Protoperidinium reticulatum populations producing O. centrocarpum cysts are
more responsive to unstable oceanographic conditions than to nutrient enrichment (Kenneth
Mertens, IFREMER, personal communication February 2023). It is not clear if the switch
to autotrophic dominance reflects the increased eutrophication of the Marmara Sea over the
past ~20 years. Nonetheless, these new observations are important for interpreting large-scale
changes in the Lm:Oc ratio observed in Marmara Sea sediment records (see Section 6).

Tuberculodinium vancampoae, Spiniferites cruciformis, Stelladinium abei, Stelladinium
steinii, and S. robustum cyst types are only observed in the Marmara Sea (although S.
cruciformis is widespread in Black Sea surface sediments; Mudie et al., 2017). Selenopemphix
quanta has been identified as an indicator of industrial pollution and high primary production.

produced by autotrophic (A) dinoflagellates than by heterotrophs (H), and expressed as

found that concentrations of the heterotroph cysts Votadinium calvum and Trinovantedinium
pallidifurvum
of Gymnodinium nolleri heterotroph cysts were correlated with high levels of Pb and Cu.
Total organic carbon content was significantly positively correlated with concentrations of
the autotroph cysts Operculodinium centrocarpum.
Despite the ecological and socio-economic importance of dinoflagellates, there are
relatively few Late Pleistocene–Holocene records of dinocysts for the Marmara Sea. The
first work is by Ediger (1990) for the low-resolution Haliç (Golden Horn) estuary borehole
record but this includes only the most oxidation-resistant taxa (mostly un-named Spiniferites
sp., including a specimen of S. cruciformis that was reported as being a Hystrichokolpoma
sp. (Edinger, 1990, their plate 3, their fig. 12). Mudie et al. (2001, 2002b, 2004) showed
major shifts from low diversity (8 taxa) in Late Glacial sediments to relatively diverse cyst
assemblage composition (20 taxa) during the Holocene interglacial in gravity cores with
sub-millennial-scale records (see details in Sections 4 and 6). These shifts reflected the early
postglacial reconnection with Aegean Sea, and increased influence of Black Sea outflow after
PALYNOLOGICAL AND PALEONTOLOGICAL RECORDS OF CHANGES FROM GLACIAL-STAGE (MIS 2)...
130
ca. 11.1 cal ka. Similar changes were reported by Londeix et al. (2009) in the piston core


Basin are described in Section 6 where the first Marmara Sea higher resolution Holocene
record is presented, which allows correlation of post-glacial dinoflagellate recolonisation from
the Aegean Sea to southwestern Black Sea.

Non-pollen palynomorphs (NPP) are defined as “extra” microfossils often found in
palynology slides (Shumilovskikh et al., 2021), and the category includes the dinoflagellate
cysts (hereafter referred to as dinocysts) that dominate in marine environments, but not in
lakes or coastal ponds. The study of these extra organic-walled non-pollen palynomorphs
originated primarily with the work of Bas Van Geel in peatbogs of the Netherlands during
the 1970’s (see Marret et al., 2021 for historical overview and references). Many of these
other NPPs were formerly reported as Acritarcha (palynomorphs of unknown or uncertain
biological affinity), Solecodonta (presumed to be chitinous jaws of polychaete worms),
and as Chitinozoa or Tintinnomorpha (the latter is a term used by van Waveren for various
vase-shaped palynomorphs incorrectly thought to be fossil tintinnid loricae according to
Matsuoka and Ishii, 2018). These groups of other non-dinocyst NPPs have now become
a focus of attention in marine palynology as a result of new methods that use molecular
phylogeny and micro-Fourier Transform Infrared spectroscopy to show the macromolecular
composition of palynomorphs and obtain precise information on their taxonomy and trophic
preferences (Bogus et al., 2014; Gurdebeke, 2019 and references therein). Shumilovskikh
et al. (2021) and Mudie et al. (2021) review the taxonomic groups of NPPs and provide
illustrations of the most common taxa in freshwater and marine environments. McCarthy et
al. (2021) provide additional details for freshwater and brackish water NPPs that might be
found in coastal lakes or for the Propontis Lake paleoenvironment. A selection of the most
important non-dinocyst NPPs used in the new studies reported in Section 6 are illustrated
in Figures 6 and 7.
Previous Marmara Sea palynological studies, starting with Ediger (1990), have reported
on the presence of freshwater algal coenobia, fungal spores, and marine phytoplankton
(primarily resting stages of dinoflagellates and tintinnids), in addition to unspecified
Acritarchs associated with deltaic paleoenvironments (Mudie et al., 2002b, 2011). Ediger
(1990, his plate 3) illustrates various fungal spore types, from simple monocellular
Monoporisporites spores to multicellular Multicellaesporites, and the fungal body,
131Petra J. MUDIE, Richard N. HISCOTT, Ali E. AKSU
Microcychyridites spp. The same morphotypes are commonly found in the western Marmara
Sea transect surface samples (Fig. 5). Ediger (1990, his plate 3, his fig. 19) also shows an
insect head fragment as a scolecodont. Mudie et al. (2011, their table 1) show that Aegean
Sea and Marmara Sea surface samples include 4–10 NPP taxa in addition to dinocysts,
whereas the low salinity coastal Sapanca Lake and Black Sea surface samples have higher
numbers, up to 19 taxa. Shumilovskhikh et al. (2016) report on and illustrate the non-
dinocyst NPP in a 7,500 yr high resolution core (9 m-long) from shallow water (< 1 m)

chapter, we provide the first detailed NPP diagrams for the Marmara Sea cores, grouped
into the 12 categories outlined below.
 Acritarchs
In this paper, the acritarchs mainly include palynomorph taxa of uncertain biological
origin but thought to mostly represent the spores of planktonic green algae, primarily
freshwater Micrystridium Deflandre 1937, and Sigmopollis psilatus Piel 1971, and rarely (in
Propontis Lake sediments), Mecseckia, which is a Pannonian Sea relic. The acritarchs also
include an enigmatic apparently saprophytic palynomorph resembling Multiplicisphaeridium
(Fig. 6) which becomes the dominant taxon throughout most of the Propontis Lake interval
(see Section 6 for details). Londeix et al. (2009, their plate 5, their figs. 1–3) called this
morphologically distinct acritarch a Multiplicasphaeridium-type algal cyst, presumably
because its shape is similar to that of the dinoflagellate Cladopyxis brachiolata; however, the
brown colour, lack of thecal plates or archeopyle, and frequent embedment of the branched
tips in organic material (Fig. 6-14) do not support that assignment. Mudie et al. (2002b)
incorrectly referred to this palynomorph as an unknown cf. Tetraploa fungal spore with
branched processes.
The true biological affinity of this enigmatic acritarch is currently under investigation
(Mudie and Rochon, unpublished draft manuscript), but Figs. 6-13 to 6-16 illustrate the
similarity in color and morphology of the sub-triangular central body (thallus?) to those of
a chytrid (Order Chytridiales of the fungal class Chytridiomycetes). The morphology of cf.
Multiplicisphaeridium is very similar to that of the Late Oligocene acritarch Microsphaeridium
ancistroides (Benedek, 1972; his pl. 12 and fig. 3). Benedek notably shows this taxon in an
assemblage of NPPs including Pediastrum, a Staurastrum-like species Longerheimia aff.
longiseta and twelve other NPP morphotypes that co-occur with cf. Multiplicisphaeridium in
the Propontis Lake sediments.
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132
1-12
; 
shown. , :  spp. and Codonella spp. are
7: 8:
 spp., M02-89P, 800 cm. 9–12
Sea surface samples; 9: Castrella truncata-
base, M02-09; : 11–12:

cm; 11a M02-89P, 800
cm; : small spatulate morphotype of cf. 
: large morphotype
of cf. 


133Petra J. MUDIE, Richard N. HISCOTT, Ali E. AKSU
 
This category most commonly includes algal coenobia of the freshwater chlorophyte
Pediastrum and freshwater–brackish Botryococcus spp., and the single cells of the freshwater–
marine prasinophyte Cymatiosphaera globosa, the soil alga Concentricystes (which is still
of uncertain status according to Shumilovskikh et al., 2021), and the freshwater charophyte
desmids Cosmarium and Staurastrum. Less common are the zygospores and aplanospores of
zygnematalean freshwater filamentous algae, Spirogyra, Debarya, and very rarely, Mougeotia.
Potentially bloom-forming Cyanobacteria of terrestrial and lacustrine habitats are represented
by Gloeotrichia-type sheaths, akinetes of Anabaena and colonies of Merismopedia.

The spores, hyphae and thallus fragments (called fungal bodies) are the largest group
of classical (non-dinocyst) NPPs, including over 600 Quaternary types. They probably are
almost all markers of terrigenous sediment input because the only autochthonous marine fungi
are thin-walled chytrid-like taxa, most of which do not fossilise. Glomus-type palynomorphs
are chlamydospores of woody micorrhizal fungi produced underground and hence commonly
considered good markers of soil erosion when found in lacustrine or marine sediments.
Shumilovskikh et al. (2016, 2021) provide illustrations of various common uni- or di-cellular

of human and livestock parasites (Trichuris) and coprophilous dung fungi Coniochaeta,
Chaetomium and Sporormiella that can be proxies for raising livestock. The most common
fungal spores in the Holocene sediments are small unicellular teliospores of fungus molds or
plant parasites (smuts and rusts), including cereal crops.
 
The loricae and resting spores of the single-celled eukaryotic Tintinnids (Ciliophora,
Spirotrichea) are present in the Marmara and Black Seas (Fig. 6), sometimes in very large
quantities (see Fig. 3, station M02-77). The resting eggs (cysts) of tintinnids are part of a
group of subspherical- to vase-shaped palynomorphs called tintinnomorphs (Matsuoka and
Ando, 2021), but most of the larger vase- to cup-shaped palynomorphs formerly thought
to be tintinnid loricae are probably egg capsules of Platyhelminth worms (see subsection

of planktonic ciliates in the marine environment and that they are the main consumers of
ultra- and nano-plankton in the pelagic ecosystem. Thirty-three tintinnid species occur in the

PALYNOLOGICAL AND PALEONTOLOGICAL RECORDS OF CHANGES FROM GLACIAL-STAGE (MIS 2)...
134
proteinaceous vase-shaped loricae of tintinnids preserve in the upper sediment layer and in
the Holocene sediment of the North Atlantic Ocean, but it is uncertain that all tintinnomorphs
were preserved long after sediment burial (Mudie et al, 2021; Matsuoka and Amdo, 2021).
The loricae of the marine ciliate Hexasterias (Polyasterias) problematica are present in the
Upper Holocene sediment of the Marmara and Black Seas. The acritarchs Radiosperma and
Halodinium of Bujak (1986) recently have been shown to be cysts of Ciliophora, Order
Prorodontida (Gurdebeke et al., 2018). Matsuoka and Ishii (2018, their fig. 6) illustrate
Halodinium- and Radiosperma-type ciliate loricae associated with freshwater in surface
sediments of Osaka Bay. Similar morphotypes occur in Propontis Lake sediments of core
M02-89P (Figs. 6-7, 6-8).
 
Stable oxygen-isotope measurements of foraminiferal tests can be used to quantify past

et al., 2016). Organic linings of benthic foraminifera are an important component of marine
palynological assemblages, often second in abundance to dinocysts (Fig. 5). Unfortunately, the
organic membranes that support the formation of the calcitic tests in planktonic foraminifera
are not preserved in sediments and they are not recovered in palynological residues. Benthic
foraminifera are calcareous, arenaceous/agglutinated or organic-walled, omnivorous protists that
live on or within the surface of the seabed and have a wider salinity and dissolved oxygen tolerance
than planktonic foraminifera (Hemblen et al., 1989). When well-preserved, these test linings (Fig.
7) can be related to the dominant calcareous and arenaceous benthic foraminiferal species in
the northwestern Black Sea where the spiral linings of planispiral Ammonia and other rotalids
dominate the low-diversity assemblages (Mudie and Yanko-Hombach, 2019; Mudie et al., 2019).
The benthic foraminiferal linings in surface samples of the Marmara Sea contain relatively
few spherical Ammonia-type linings and a much greater diversity of unilocular linings, wedge-
shaped biseriate textularid-type linings, tubular Rhabdaminella-type and linear uniseriate
linings of arenaceous species such as Rheophax scottii (Figs. 7-1–7-20), some of which are
   
(2004). Previous studies of temporal changes in foraminiferal linings from the Marmara Sea

only the spherical and subspherical lining morphotypes of calcareous rotalid species. In the
new studies reported in Section 6, the occurrence of distinctive linear linings of arenaceous
species is also shown. Studies of surface samples and plankton tows show that in the Marmara
Sea, the benthic foraminiferal fauna displays much greater diversity (335 species) than the
135Petra J. MUDIE, Richard N. HISCOTT, Ali E. AKSU
planktonic fauna (6 species), with maximum richness on the southern shelf (247 species), and
with lowest diversity (<90 species) in the semi-brackish Black Sea overflow water transiting

The Marmara Sea benthic foraminiferal fauna is also much more diverse than in lower
salinity Ponto-Caspian Seas (Yanko, 2022), where there are 173 species and lower-order taxa

and Elphidiidae (Ammonia, Porosononion and Elphidium) above –150 m on the southern shelf
of the Marmara Sea. In contrast, samples from deeper water down to –350 m have assemblages
dominated by and Gyroidina. Phipps et al. (2010, their text-
fig. 3) also report the predominance of Ammonia spp. in a thin surface layer, and the common
co-occurrence with Elphidium in calcareous foraminiferal assemblages from –15 m to –50 m
water depth. However, other typical marine rotalids (Bulimina and spp., Cassidulina
carinata, and Nonionella opima) dominate at depths from –50 m to –350 m). In water deeper
than –350 m, the miliolid Spiroloculina tenuisepta, and the agglutinated nodosarid Amphicoryna
scalaris are common in Marmara seabed samples. The distinctive organic linings of the latter
species are also found in palynological samples from the same sites (Fig. 7-13).
About 40% of the Ponto–Caspian taxa are calcareous, chambered rotalids (order
Rotaliida), with approximately 25% Miliolida and 20% Lagenida; the remaining ~15%
comprise calcareous, wedge-shaped Buliminida and various agglutinated taxa (Yanko, 2022).
The same proportion (65%) of calcareous taxa (rotalids+miliolids) is represented among the
309 species recorded for the Marmara Sea surface sediments. However, there appears to be
a higher proportion of agglutinated taxa in the Marmara Sea. Frontalini et al. (2011, their
appendix B) found 50 agglutinated species in surface samples on a transect from –15 m
to –350 m water depth across the southern shelf, with Eggerelloides scaber and Rheophax
scorpiurus dominating above ca. –150 m, and with Bigenerina nodosaria and various
textulariids characterising greater water depths. Taxonomic diversity of the agglutinants in
these surface samples increases with depth to –225 m, below which agglutinant diversity
decreases in direct relation to dissolved oxygen concentrations.
PALYNOLOGICAL AND PALEONTOLOGICAL RECORDS OF CHANGES FROM GLACIAL-STAGE (MIS 2)...
136

(1 – 7
21), a
22), a nematode (), and
29). Sample numbers and water depth are shown above the
1: unknown
2

: : cf. 
7, 89:
Reophax spp.; 11: 12:
; : 
deeper water coretop M98-12; :
171819: -type
21:
22: Polychaete
 (jaw hook), M02-89P 140 cm; : large larval nematode; : M02-89P 800 cm.
),
27: 
28: Candona
29
137Petra J. MUDIE, Richard N. HISCOTT, Ali E. AKSU

(2013) found that the shallow water (0 m to –35 m depth) Ammonia-Elphidium assemblage is
linked to the amount of organic matter, river sediment discharge and Black Sea surface inflow.
From –28 m to –50 m, the assemblage dominated by Bulimina aculeata, Bolivina variabilis,
Nonionella turgida, and Bulimina elongate is related to seasonal salinity fluctuations due to
vertical mixing. The deeper water assemblage, from –36 m to –320 m, is the most diverse
(10 taxa), apparently reflecting greater environmental stability of the saline Mediterranean

dominated by miliolids, small Bolivina and  spp., Cassidulina spp. Chilostomella
mediterranensis and Melonis pompilioides characterise oxygen depleted, organic-rich
sediments. Alavi (1988) also noted a lack of textulariid taxa and common redeposition of
microfossils in cores of the deepest basin.
 Benthic ostracod remains
Ostracods, commonly called seed shrimp, are small Crustacea in the phylum Arthropoda
(Fig. 7; see details in Section 3.2.2). There is little published information on the organic
linings and chitinous mandibles of ostracod carapaces compared to the well-known use of
foraminiferal linings in palynological studies. The first report may have been for the presence
of mandibles and chitinous carapace linings in samples from Sapanca Lake and in core M05-
15 from the southwestern Black Sea shelf (Mudie et al., 2011; Linegar, 2012). The common
occurrence of these palynomorphs in the new high-resolution cores from Marmara Sea (Figs.
7-25, 7-26, 7-28, 7-29) determine their potential usefulness for paleoenvironmental studies
parallel to micropaleontological investigations using the calcareous valves and carapaces of
ostracods, e.g., Vidal et al. (2010) and Mischke et al. (2012).
 
Several Metazoans produce acid-resistant, fossilisable resting eggs, including the
Tardigrada, Rotifera, and several genera in the order Cladocera and class Copepoda of the
subphylum Crustacea (Belmonte and Rubino, 2019). Thick-walled resting eggs of copepods
are commonly recovered in palynological samples from coastal waters (Mudie et al., 2021).
However, the resting eggs of rotifers, cladocerans and tardigrades are uncommon (eight or
fewer species) in fully marine environments and only occasionally found in surface sediments
of the northwestern Black Sea although they are common in sediments of lower salinity

table 1) records only two species of tardigrades in Turkish coastal water, these being found in
PALYNOLOGICAL AND PALEONTOLOGICAL RECORDS OF CHANGES FROM GLACIAL-STAGE (MIS 2)...
138
the pre-Bosphorus waters of the Black Sea. Resting eggs of cladocerans can also be common
in the low salinity North Adriatic and Baltic Seas (Belmonte and Rubino, 2019). Moscatello
and Belmonte (2009) illustrate the thick-walled resting eggs of Calanus and Artemia and
other crustaceans from saline lakes, and several types of copepod eggs in surface sediments
of the outer Ukrainian shelf of the Black Sea are illustrated by Mudie et al. (2019). Rubino
et al. (2017) illustrate the dinoflagellate and other resting cysts of planktonic NPPs in recent
sediments of Haifa port, Israel (eastern Mediterranean) and they show how egg distributions
and viability are impacted by environmental conditions, including heavy metal distributions,
TOC and water transparency. However, there have been no previous temporal studies of resting
eggs in sediment cores of the Marmara Sea and the western and southern Turkish coasts. In the

other chitinous remains (e.g., exoskeleton segments, endopods, caudal setae and antennae)
were recorded to investigate changes in the occurrences of the NPPs during the late glacial
lacustrine and postglacial marine phase of Marmara Sea evolution.

Although commonly grouped together as “worms”, nematodes are unsegmented
roundworms in the Phylum Nematoda, while polychaetes (bristleworms) comprise the
paraphyletic class Polychaeta in the phylum Annelida, and are mostly marine segmented
worms in the phylum Annelida. Nematodes inhabit freshwater, terrestrial and marine
environments; unexpectedly, small species commonly inhabit the brine-filled interstices of
sea-ice in the Arctic Ocean. Nematodes are free-living predators or parasites of plants and
of animals (whipworms), including humans. Nematodes are represented in palynological
residues by acid-resistant remains of juvenile-stage instars (worm larvae) with chitinous walls
(Fig. 7-29) or as eggs of Trichuris and other intestinal parasites documented and illustrated by


and eight species for the Marmara Sea, most of which are fish parasites; the taxonomic
diversity of nematodes is highest in the Aegean Sea, with 20 taxa. The nematode instars found
in the palynological samples from the Marmara and Black Seas are translucent and colourless,

serpentiform morphotype (Forms 5, 6) reported by Sergeeva and Smyrnova (2020, their fig.
2) as characterising the permanent free hydrogen sulphide zone of the Black Sea, where waters

Sea have been little studied, but they record the presence of 198 polychaete species collected
139Petra J. MUDIE, Richard N. HISCOTT, Ali E. AKSU
between 2006 and 2010 at depths from 0 m to –66 m, and illustrate the mandibles and setae
of some taxa. The chitinous mandibles, hooked falciger chaetae or uncinus (Fig. 7-23) and
bristle-like setae (Fig. 6-14) of polychaete worms are occasionally present in palynological
samples from the outer Ukrainian shelf (Mudie et al., 2019) and in the new cores described
in Section 6. Mikkelsen and Virnstein (1982) provide a useful glossary and guide to the
identification of polychaete skeletons and appendages.
 
Turbellarians are flatworms that were formerly considered to comprise a class of non-
parasitic flatworms (Turbellaria) within the Phylum Platyhelminthes which mainly consists
of parasitic worms in three classes: Trematoda (flukes/parasitic flatworms), Cestoda
(hookworms) and Monogenea (fish ectoparasites). Recent molecular studies, however, show
that the non-parasitic flatworms are a polyphyletic group, and Ruggiero et al. (2015) assigned
the Turbellarians to various classes within the Subphylum Catenula of the Platyhelminthes.
Matsuoka and Ando (2021) have reviewed this taxonomy and recommended that palynologists
retain the name turbellarian rather than Rhabdoceala or tintinnomorph to indicate flatworm taxa
that produce egg capsules, primarily genera within the Umagillidae (mainly freshwater non-
parasitic rhabdocoels), Dalyelliidae (marine and freshwater rhabdocoels) and Typhloplanidae
(free-living limnoterrestrial rhabdocoels). Matsuoka and Ando (2021) also discuss the former
incorrect assignment of vase- or cup-shaped turbellarian egg capsules found in palynological
samples from freshwater to deepwater marine sediments as the loricae of tintinnida, but they
recommend retaining the term Tintinnomorphs for these palynomorphs (see Figs. 6-10–6-12).

which are parasitic on marine fishes.
 
The chitinous radula teeth of small gastropods are occasionally present in palynological

(Fig. 7-22). The modern mollusc fauna of the Marmara Sea is discussed in Section 3.3.2. The
gastropods Turricaspia caspia and Ecrobia ventrosa occur in Lake Propontis sediments (see
section 4.1).

The remains of Insecta (e.g., moth wing scales, chironomid larvae and mandibles) and
Arachnid mouthparts are occasionally recovered in the palynological samples from marine
sediment cores, e.g., as illustrated in Yanko-Hombach et al. (2013, their fig. 6) for the deltaic
PALYNOLOGICAL AND PALEONTOLOGICAL RECORDS OF CHANGES FROM GLACIAL-STAGE (MIS 2)...
140
facies of a late Neoeuxine Lake core. Similar remains are occasionally recorded in samples



Porifera in the Marmara Sea coast, from 0 m to –100 m water depth. Most sponges live in
shallow water above –25 m but two species (Thenea muricata and ) were
found at depths deeper than –100 m. The chitinous spicules of demosponges are occasionally
found in palynological residues from Transect 1 (Fig, 5C) at the shallow water site M02-8,
M02-9, and at the deepwater site M98-09. Spicules are also occasionally present in the new

and bryozoans among the epifauna of bioherms near the Strait of Dardanelles. Demosponges
are very intolerant of high suspended sediment influxes and recently were smothered by
deposition of “seasnot” in the Marmara Sea (Topçu et al., 2019). A few fragments of a colonial
Membranipora-type bryozoan were found in the palynological residue from the surface
sample M98-09 (Fig. 5) and rarely, in Holocene marine sediments of core M02-88P from

observed in the samples of the late glacial maximum interval (440–320 cm core depth, 19.2
–~18.7 cal ka) but it was not possible to determine if they were in place or reworked from
older deposits in the Propontis Lake sediments.

      
sediment cores for determining the paleoecological conditions in the Marmara Sea. In this
section, we provide background information on other microfossils and macrofossils that are
rarely or never represented as palynological remains but are important for reconstructing the
paleoceanography of the Marmara Sea Gateway as outlined in Section 4.

Coccolithophores are small (mostly <10 µm) calcareous, unicellular Protista in the Division
Haptophyta, Class Prymnesiophyceae (or Coccolithophyceae). These microorganisms are
almost exclusively marine (only one known extant freshwater species, Hymenomonas roseola)
photosynthetic phytoplankton, often occurring in large numbers in the photic zone, forming


(coccoliths) that accumulate in sediments are an important component of the marine carbon
141Petra J. MUDIE, Richard N. HISCOTT, Ali E. AKSU
cycle and the biological pump. Coccolithophores also produce dimethylsulfoniopropionate
(DMSP) which is broken down to dimethyl sulphide, an important sulphur source contributing
to backscatter of incoming radiation via cloud condensation. Hence, their recent geographic
expansion and increased abundance in response to ocean warming and eutrophication is a
focus of current research (Franklin et al., 2010; Deng et al., 2020).







in the Marmara Sea and the Turkish Straits (Anacanthoica acanthos, Calciosolenia spp.,
Calyptrosphaera spp., Coccolithus pelagicus, Emiliania huxleyi, Rhabdosphaera spp.,
Syracosphaera pulchra and Syracosphaera spp.) but only E. huxleyi and S. pulchra occur in
the cooler, less saline water of the Strait of Bosphorus. E. huxleyi is an important component
of a three-phase spring phytoplankton bloom sequence of diatoms (March), dinoflagellates

that in the Strait of Dardanelles, winter and summer blooms of E. huxleyi are interrelated
with blooms of three dinoflagellate taxa at salinities of 22.3–38.5; anomalies of salinity and
temperature combined with low phosphate and silicate levels favour the coccolithophorid
PALYNOLOGICAL AND PALEONTOLOGICAL RECORDS OF CHANGES FROM GLACIAL-STAGE (MIS 2)...
142
blooms. Furthermore, E. huxleyi is highly euryhaline and eurythermal, and it can also reach
bloom concentrations in the central Black Sea at salinities of 18–19, from which it may
overflow and bloom in the Marmara Sea, then spill out into the NE Aegean Sea. E. huxleyi
also occurs in the brackish water (S = ~11) of the Azov Sea and Caspian Sea but is absent
E. huxleyi always occur
in shallow mixed layers of maximum depth –20 m to –30 m, and high light intensities appear
to be required for their development (Tyrrell et al., 2008). This detailed information may be
used to constrain the possible environmental conditions represented by peak occurrences of
E. huxleyi in Marmara Sea sediment cores (Section 4.2).

The Ostracoda are a class of aquatic microcrustaceans in the superclass Oligostraca of
the subphylum Crustacea, phylum Arthropoda. Ostracods are typically 1 mm in size, but
adults range from 0.2 to 2.0 mm. Ostracods secrete low-Mg calcite carapaces comprising
two articulated valves which enclose the organic body (Holmes and Chivas, 2002b). The
strongly calcified carapace (or valve) is typically the only systematically identifiable part of
the ostracod that is preserved as a fossil. However, Martens and Horne (2009) reported the
occurrence of organic (chitinous) carapace linings and coverings, and these, together with
the chitinous mandibles, are recovered in acid-treated palynological preparations (Fig. 7).
Ostracods grow by moulting with nine growth stages (“instar stages”), of which the adult stage
is most commonly used for taxonomic identification. The earliest tiny and fragile juvenile
valves are generally not found in the calcareous fossil record, but the valves of the subsequent
instar stages are often found in the fine sand-size fractions, and the palynological residues
from Marmara Sea may contain valve linings up to 0.2 mm in length. Ostracods are highly
sensitive to changes in physical and chemical conditions in the aquatic environment; thus their
distribution is highly dependent on water conditions, including salinity, water depth and nature
of substrates, water chemistry, nutrient availability and temperature (Horne et al., 2002).
Salinity is the major factor controlling ostracod distribution, and ostracods are commonly
categorised into marine, brackish, and freshwater species (Athersuch et al., 1989). Dissolved
oxygen levels also influence the distribution of ostracods; some species are well adapted to
reduced-oxygen environments, yet others live in fully oxygenated environments (Whatley,
1990; Boomer et al., 2003, 2005). Because of their sensitivity to environmental parameters,
ostracods are valuable proxies for environmental and paleoenvironmental studies (Frenzel
and Boomer, 2005). Ostracods are also often used in the determination of oxygen, carbon and
strontium isotopic ratios and various geochemical studies dealing with the incorporation of
143Petra J. MUDIE, Richard N. HISCOTT, Ali E. AKSU
minor and trace elements into the low-Mg calcite lattice, but there have been few applications
to the Marmara Sea cores (Vidal et al., 2010).
Perçin-Paçal et al. (2016) report a total of 184 ostracod species in the Marmara Sea, but
the diversity in any single area is significantly less. For example, a regional study across
the littoral zone along the southern Marmara Sea revealed 35 living Ostracoda species
belonging to 19 genera dominated by Callistocythere lobiancoi, Costa edwardsii, Costa
batei, Aurila convexa, Loxoconcha rhomboidea, Xestoleberis communis, Acanthocythereis
hystrix, Aurila prasina, Urocythereis britannica, Loxoconcha stellifera, Paracytheridea
parallia and Cyprideis torosa (Kubanç, 2005). Statistical analysis showed that these species
exhibit preferred dissolved oxygen concentrations of ~9.5–11.5 mg/L, 19.5–20.5 salinities,
and 8–24ºC temperatures (Kubanç, 2005). In a similar study from the northern coastal regions
of the Marmara Sea, Kubanç et al. (2009) identified 33 species in 16 genera, including the
first indentification of live specimens of Callistocythere diffusa, Loxoconcha littoralis and
Loxoconcha pontica in the Marmara Sea surface sediments. This study further showed that
Cyprideis torosa, Xesteloberis communis, Loxoconcha rhomboidea and Paracytheridea
parallia have the strongest correlations with variations of temperature, salinity and dissolved
oxygen concentrations, respectively (Kubanç et al., 2009).
Two local studies examined the ecology of 92 living ostracod species belonging to 39
genera (Erdek Bay, Fig. 3; Perçin-Paçal and Balkis, 2012, 2015) and 112 living species

collected samples from the southwestern Marmara Sea. The total number of species was
highest in the autumn, but their abundances were lowest, compared to the spring, when
the total species number was minimal but the individual numbers were the highest. The
dominant species during all seasons were Cytheridea neapolitana, Pterigocythereis
jonesii, Costa punctatissima, Hiltermannicythere rubra, Loxoconcha rhomboidea and
Carinocythereis carinata (Perçin-Paçal and Balkis, 2015). Nazik (2001) studied ostracod
faunal composition at depths of –23 m to –71 m on the southern Marmara Sea shelf where
the salinity is in the range 34–38. Here, seven dominant species formed three distinct
assemblages: (a) an assemblage characterized by Costa edwardsii, (b) a mixed assemblage
consisting of Cytheridea neapolitana, Pterygocythereis ceratoptera, Tegmenia rugosa,
Acanthocythereis hystrix and Xestoleberis communis, and (c) an assemblage characterized
by Aurila convexa (Nazik, 2001).
Several studies have examined the temporal variations in abundance and species diversity
of ostracods at selected localities across the Marmara Sea: the southern sector of the Strait of
PALYNOLOGICAL AND PALEONTOLOGICAL RECORDS OF CHANGES FROM GLACIAL-STAGE (MIS 2)...
144
Bosphorus (Gülen et al., 
terraces (Meriç et al., 1995), and the southern sector of the Armutlu Peninsula (Fig. 3). Meriç

belonging to eight genera in the Holocene sediments of shallow (< 50 m) boreholes. The
Bosphorus Strait samples were dominated by Cyprideis torosa, Carinocythereis aff. antiquata,
Costa edwardii, Costa spp., Aurilia amygdala, Urocythereis britannica, Urocythereis spp.,
Loxoconcha granukata, Loxoconcha spp., Heterocyris incongruens, Callistocythere spp.,
Trachyleberis spp., Hemicythere spp., Cytheropteron spp., Xestoleberis spp., Paradoxtoma
spp. and Macrocypris spp.
In contrast, Perçin-Paçal et al. (2016) identified a larger number (54) of ostracod species in
surface samples from the Strait of Bosphorus. Mischke et al. (2012) found mainly valves and
carapaces of the brackish water ostracod Cyprideis torosa in a short (3.52 m) core from the

et al. (2018) identified 13 species of ostracods in two boreholes (SK-1, SK-2). These species
belong in eight genera, including four species of Ponto-Caspian origin in addition to Darwinula
stevensoni, Limnocythere inopinata, Limnocythere inopinata sevanensis, Heterocypris salina,
Candona neglecta, Candona sp., Ilyocypris bradyi, and Ilyocypris gibba. Meriç et al. (2018)
suggested that … “determination of Ponto-Caspian ostracod species, such as Amnicythere
olivia, A. striatocostata, A. stepanaitysae and Tyrrhenocythere amnicola, indicates that the
…”. To further
assist paleoecological studies for times of fresh or brackish conditions, researchers can avail
of the wealth of literature on lacustrine faunas from the Late Pleistocene and earliest Holocene
Neoeuxine Lake (today’s Black Sea) and other Ponto-Caspian basins (e.g., Boomer et al., 2005,




al., 2016), here we focus on those phyla and orders which have been described from sediment
cores and which actually or potentially experienced species turnover(s) during the transition
from lacustrine (Propontis Lake) to marine conditions. In the modern Marmara Sea, the phylum
Echinodermata is represented by two species of the Order Crinoidea, 17 species of Asteroidea,

However, only sea urchins (Echinoidea) have been described from author cores (Section 4.1),
and mostly as scattered plates giving little hope of full species identification. The geometric
145Petra J. MUDIE, Richard N. HISCOTT, Ali E. AKSU
arrangement of the attachment scars (tubercles) of spines suggests Brissopsis spp. in these cores.
Echinoids feed by grazing on surface organic matter or rasping algae from hard surfaces. They
avoid settings with fluctuating salinity and temperature and prefer salinity above ~15.
In a number of trawl collections across water depths of –33 to –298 m, the most common
Spatangus purpureus and Brissopsis lyrifera.
Both prefer sandy and silty substrates. S. purpureus is found from –18 m to –50 m in the
Aegean Sea but to below –950 m elsewhere in the Mediterranean Sea (Koukouras et al.,
2007). Brissopsis spp. is reported from –2 m to –105 m by the same authors in the Aegean Sea,
Brissopsis
lyrifera from as deep as –490 m in the Marmara Sea, but mostly from –40 m to –75 m. Sea
urchins are preyed upon by seabirds, so when single plates and fragments are found in coastal
areas (e.g., anywhere around the small Marmara Sea), they might have been scattered post-
mortem, although still contemporary with the enclosing sediments.


and carbon isotope ratios as proxies primarily for palaeosalinity changes. The bivalves and
gastropods retrieved in sediment samples and cores from the Marmara Sea and Pontic basins
belong to the Phylum Mollusca, Classes Bivalvia and Gastropoda. The classes Cephalopoda,
Polyplacophora, Caudofoveata and Scaphopoda also have representatives in the Marmara


and Büyükmeriç (2016). Molluscs live in all aquatic environments with sufficient nutrients
and dissolved oxygen although some are more tolerant of salinity variations than others (thus
euryhaline as opposed to stenohaline species that tolerate only a narrow range). Bivalves tend
to be filter feeders whereas most gastropods are heterotrophs and many have chitinous radulae
used for grazing rocks and seaweed: these radulae are recovered in palynological residues. In a


13 bivalve species and 9 gastropod species in surface sediments (0–35 cm sub-seafloor
depths) from shallow-water sites (–37 m to –42 m), and total molluscs for shelf (–61 m to
–72 m), slope (–159 m) and basinal (–371 m) sites, respectively, of 48, 14 and 8 taxa. Clearly
the greatest diversity occurs on the shelf. Bivalve species constituting more than ~5% of the
molluscan fauna on the shelf are Nucula nitidosa, Modiolula phaseolina, Myrtea spinifera,
Thyasira flexuosa, Kurtiella bidentata, Parvicardium exiguum, Kelliella miliaris and Corbula
PALYNOLOGICAL AND PALEONTOLOGICAL RECORDS OF CHANGES FROM GLACIAL-STAGE (MIS 2)...
146
gibba, and equally abundant gastropods are Bittium deshayesi and Turritella communis. For
the slope and basinal sites combined, the more common (>5%) bivalves are Nucula nucleus,
Ennucula corbuloides, Saccella commutata, Bathyarca philippiana, Similipecten smile,
Myrtea spinifera, Kelliella miliaris, Corbula gibba, Cuspidaria rostrata and Tropidomya
abbreviata accompanied by the more common gastropods Ecrobia cf. ventrosa, Turritella
communis, Odostomia tenuis, Turbonilla aff. fenestra, Roxania utriculus and Syrnola sp.
Myrtea spinifera, Corbula gibba and Turritella communis are widely present on the shelf,

bivalve and gastropod species identified by Büyükmeriç (2016) is 84, which is significantly


Twenty-eight of the bivalve species listed by Büyükmeriç (2016) and 19 of the
gastropod species are also represented in surface sediment samples collected with a Shipek

She documented a natural separation at ca. –75 m between the more common species
Bittium latreilli, Turritella communis, Nucula nucleus, Timoclea ovata and Corbula gibba
in shallower water and, in deeper water mostly below –147 m, Mytilaster lineatus, Myrtea
spinifera in addition to N. nucleus and C. gibba
analysis to characterise the measured environmental variables temperature, salinity, and
dissolved oxygen content of bottom water, sand/silt/clay ratios, and TOC. She found high
positive loadings on temperature and salinity, and a high negative loading on TOC for a
component with highest scores at –14 m to –60 m water depths and below –255 m depth in

Another environmental component has its highest negative loadings on dissolved oxygen
and sand contents, with high scores along most of Transect 1 and with consistently high
values in depths from –65 m to –250 m where August 2002 dissolved oxygen averaged
1.7 mL/L (~63 mmol/L). In a shorter Transect 4 adjacent to the southern Bosphorus exit,

2002 from ca. –30 m to –144 m depth. Over these depths, the most common molluscs
retrieved, in decreasing order of abundance, were Myrtea spinifera, C. gibba, N. nucleus,
T. ovata, Bittium reticulatum and Saccella (Nuculana) commutata.
It is instructive to compare the occurrence of molluscs in the fully saline lower watermass
of the Marmara Sea (S= 38–39) with the population in the semi-marine Black Sea (S=
19–22) which may be an analog for the early stages of reconnection of the Propontis Lake
147Petra J. MUDIE, Richard N. HISCOTT, Ali E. AKSU

(2005) analysed molluscs from sixteen stations (Transects 2 and 3 across the Black Sea
shelf west of the Bosphorus exit) from similar water depths of –23 m to –112 m as for
the Marmara Sea Transect 1. In the Marmara Sea, C. gibba, T. communis, N. nucleus, M.
spinifera and T. ovata species were common (6–32% of shells) but virtually absent in the
Black Sea samples. In contrast, a high abundance in the Black Sea, but near absence in
the Marmara Sea surface samples was recorded for Modiolula phaseolina, Parvicardium
exiguum, Abra alba, B. reticulatum, Trophonopsis muricata, Tritia pellucida (Cyclope
donovani), Mytilus galloprovincialis, Spisula subtruncata and [possibly reworked] Dreissena
polymorpha M. phaseolina, P. exiguum, A. alba are the dominant species,
accounting for 84% of the shells in the Black Sea surface samples. These differences in
species abundances do not signify that the uncommon species cannot survive in both seas

an inability to compete with better adapted competitors. Suitable substrates might also be
an issue for sessile benthos like Mytilidae (see their occurrence in Marmara Sea bioherms,
Section 3.3.3). This is evident in a study of the mollusc assemblages in sand-prone nearshore
waters (depth above –5 m) of the southwestern Marmara Sea (Bitlis et al., 2022) where
the dominant species are M. galloprovincialis (54% in spring; 75% in summer), Mytilaster
lineatus (~45% in autumn and winter), B. reticulatum, Rissoa splendida and Tricolia pullus
pullus. M. galloprovincialis mussel banks are widespread above the halocline (ca. –20 m; Fig.

Black Sea, however, communities of M. galloprovincialis are widespread to water depths of
ca. –65 m (Shurova and Gomoiu, 2006), and on the Romanian shelf, colonies dominated by
M. phaseolina cover 40% of the seabed to depths of –120 m (Begun et al., 2010).
In deeper portions of her Marmara Sea cores, Büyükmeriç (2016) retrieved rare specimens
of Dreissena, Monodacna, Theodoxus, Euxinipyrgula, Turricaspia and Clathrocaspia. These
are all brackish-water taxa and lived in the area before the 13.8 cal ka reconnection of the
Propontis Lake to the Aegean Sea. In some cases they have been eroded from the margins

Dreissena fossils are particularly well represented in pre-reconnection deposits in the
Marmara and Black Seas (e.g., Yanchilina et al., 2017) because species like D. rostriformis
live in a wide range of water depths to below –150 m, and in salinities of ~7–12 (Orlova et al.,
2005). There are several excellent sources for descriptions and photographs of Ponto-Caspian
brackish-water molluscs that the authors have recovered from the deeper parts of cores in the
PALYNOLOGICAL AND PALEONTOLOGICAL RECORDS OF CHANGES FROM GLACIAL-STAGE (MIS 2)...
148
Marmara Sea (Section 4.1). These include Gelembiuk et al. (2006), Kantor and Sysoev (2006),
Wesselingh (2007), Anistratenko (2008), Filippov and Riedel (2009), Neubauer et al. (2018)
and Wesselingh et al. (2018).

The Pteropoda are an order of subclass Heterobranchia of the class Gastropoda, of phylum
Mollusca. Pteropods are generally <1 cm in size and are specialised free-swimming, filter-
feeding exclusively marine gastropods. They mainly occupy the upper 10–200 m of the
water column, and feed on phytoplankton and zooplankton, thus are generally concentrated
in nutrient-rich waters. Most researchers assign pteropods to one of two orders: shelled
Thecosomata (“sea butterflies”) and shell-less Gymnosomata (“sea angels”) (Peijnenburg et
al., 2020). Shelled pteropods secrete their shells of aragonite, a metastable form of calcium
carbonate (CaCO
3
) which is ~50% more soluble than the chemically identical mineral calcite
(Fabry et al. 2008). As such, pteropods are known as sentinel species of ocean acidification
and they are major contributors to carbon and carbonate fluxes in the open ocean. However,
pteropods have never been reported from the Marmara Sea proper although Tunçer et al.
(2021) observed for the first time a bloom of the needle-like pteropod Creseis acicula from
the Strait of Dardanelles in 2020. C. acicula is a globally common holoplanktonic gastropod
occurring in the surface water between –10 and –100 m in open oceans to coastal waters,
within a range of surface temperatures from 10ºC to 28ºC and salinities of 30–41 (Comeau
et al. 2012). Tunçer et al. (2021) linked the Creseis acicula bloom to reduced anthropogenic
impact on marine habitats in the Strait of Dardanelles during COVID-19 lockdowns, and to
the concurrent advection of a warm Mediterranean watermass into the strait. Organic remains
of pteropods have never been reported previously in palynological residues.

Multibeam echosounder profiles acquired in 2011 show that there are extensive patches
of near circular mounds on the seabed in the funnel-shaped eastern entrance to the Strait
of Dardanelles, arranged in highly organized clusters, some with the geometry of parallel
concentric rings and others in linear or sinuous arrangements (Figs. 9, 10). These features are
referred to as ‘bioherm colonies’ by Aksu et al. (2018) who describe bioherms as “… mound-
like organic reefs and mounds built by a variety of mostly sessile marine organisms, including
corals, echinoderms, gastropods and molluscs, often associated with encrusting calcareous
red (coralline) algae and serpulid worm tubes …”. In addition to molluscs, cores in the
bioherm field recovered encrustations of coralline red algae and serpulid tubes. Coralline
149Petra J. MUDIE, Richard N. HISCOTT, Ali E. AKSU
algae belong to the Order Corallinales of the Phylum Rhodophyta. They require sunlight for
photosynthesis, but this can be very faint and irregularly available. For example, Littler and
Littler (1985) photographed and recovered living specimens from –268 m depth offshore the
Bahamas and an increasing number of species above –190 m in the same area. However, the
depth of sunlight penetration in coastal waters is less than in open-ocean settings.
      
particular Corallina officinalis, Ellisolandia elongata, Haliptilon attenuatum, Phymatolithon
lenormandii and Hydrolithon farinosum. Nodules (rhodoliths), branching fragments and living
coralline red algae of Lithothamnion corallioides and Phymattolithon calcareum are common
in the recent sediments of the southern Marmara Sea below the halocline in water depths of
–27 m to –52.5 m; Lithothamnion calcareum, L. fruticolusum and L. racemus are prominent
in shallow water (–20 to –40 m), where calcareous algal meadows, typical for Mediterranean
conditions, are reported (Ergin et al., 1991).





Rhodoliths which include serpulid worm tubes have been recovered in cores near drowned
Holocene bioherms from the southern shelf region (Aksu et al., 1999) and two examples have
been dated to 6.9 cal ka and 10.8 cal ka. Serpulid worms belong to the Family Serpulidae
of the Order Sabellida, Phylum Annelida. They are exclusively marine and encrust hard
substrates with calcium carbonate. Unlike Polychaeta which have chitinous jaws that can be
recovered in palynomorph assemblages, the serpulid worms are filter feeders and their organic
PALYNOLOGICAL AND PALEONTOLOGICAL RECORDS OF CHANGES FROM GLACIAL-STAGE (MIS 2)...
150
remains are not preserved. There is no water depth limitation. They are described from the







Serpulids also characterise Holocene bioherms, both on the southern shelf (Aksu et al.,

the sessile organisms remain elevated above the surrounding sedimented seafloor and that
the environmental conditions are favourable for their development. In 2D high-resolution
seismic reflection profiles, the bioherms and bioherm colonies appear as tightly-corrugated
reflectors which form convex-up mound-shaped units on the seafloor (Fig. 11). The top
of these units is the present-day depositional surface, whereas the base is marked by the

Strait of Dardanelles (Fig. 11). This unconformity is identified by the progressive onlap and

in Units 2 and 3 (Fig. 11). Previous studies documented that Unit 1 is Holocene in age and that

151Petra J. MUDIE, Richard N. HISCOTT, Ali E. AKSU
ocean as well as the Marmara Sea were lower than the floor of the Strait of Dardanelles (e.g.,
Hiscott and Aksu, 2002; Hiscott et al., 2007; Aksu et al., 2018, 2022). These mound-shaped
units (i.e., bioherm colonies) constitute part of the seismic stratigraphic Unit 1 (Aksu et al.,
1999, 2018, 2022; Aksu and Hiscott 2002). Elsewhere, where bioherms are absent, Unit 1
is generally characterised by a regularly reflective package of high-frequency, acoustically
strong and laterally continuous reflectors.
Grain size of grab samples shows that the surficial sediments across the bioherm mounds
   

2[size in millimetres]). This sand is nearly entirely composed
of heavily encrusted and largely fragmented carbonate bioclasts, with smaller quantities of
intact disarticulated shells (Aksu et al., 2018). In the gravel-sized fractions (coarser than

without periostracum) and broken fragments of mussel shells of the genera Modiolus and
Mytilus dominate and are abundant in the biogenic carbonate fraction of the surface sediments
(Fig. 12). Coral fragments, intact shells and fragments of the bivalves Timoclea ovata and
Clausinella brongniartii are common. Rare specimens of the gastropods Addisonia lateralis,
Calliostoma conulus and Turritella are present, along with the bivalves Arca noae and Venus
casina. The chitinous mandibles of small gastropods have been recovered in palynological
remains from Marmara and Black Sea sediments (e.g., Fig. 7-22).






PALYNOLOGICAL AND PALEONTOLOGICAL RECORDS OF CHANGES FROM GLACIAL-STAGE (MIS 2)...
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A camera-drift transect acquired over bioherm colonies in water depths of –45 to –55 m
shows the presence of three distinct habitats: bioherm mounds, inter-mound channels and the
seafloor outside of the bioherm colonies (Fig. 13; Aksu et al., 2018). The muddy featureless
seabed outside of the bioherm colonies is characterized by abundant Cnidarians, including sea
pens (Pennatula phosphorea) and occasional sea whips (Funiculina spp.). Organic remains of
these filter feeders are not preserved in palynological assemblages. In several places, large (~7
cm across) infaunal bivalves protrude from the sediment, such as Pinna rudis or juvenile Pinna
nobilis (identified solely based on size and habit, burrowed to half shell length in sediment; Aksu
et al., 2018). Burrows in sediment are abundant and fine shell debris is scattered in patches. The
coarser substrate on bioherms is mostly sparsely populated. Soft corals (Alcyonium spp.) and the
holothurian Stichopus regalis are occasionally observed (Fig. 13c), with frequent occurrences of
coralline algae (likely Lithothamnion calcareum and/or L. corallioides; Fig. 13b) which are more
abundant toward the tops of mounds. Burrowing brittle stars are present, but less common than
those observed within the inter-mound channels. Deep burrows, some inhabited by crabs, are
common in crevices between coarse particles and shell hash. Erect epifauna are sparse, represented
by a few sabellid polychete tubes (fan worms) and infrequent sponges, hydroids and bryozoans.
Closer to the tops of the bioherms, the seabed is almost entirely covered by disarticulated and
broken shells of Mytilids covered with a thin veneer of easily resuspendable silt (Fig. 13b,c).


(M14-45X), ,  spp.
and  (M14-50X),  and  (M14-46X),
 and  spp. (M14-
47X), 
153Petra J. MUDIE, Richard N. HISCOTT, Ali E. AKSU
In these regions, the benthic community seems impoverished; however, the fauna are
typical for coralligeneous habitats of the Mediterranean Sea (e.g., Bonacorsi et al., 2012).
The bioherm mounds imaged in the southwestern Marmara Sea at the throat of the Strait of
Dardanelles are ~16 m in diameter with ~21 m spacing between the crests of neighbouring
mounds (Table 2; Aksu et al., 2018).
Table 2. Summary of some bioherm statistics (adopted from Aksu et al., 2018). Irradiance values
are from CTD casts.
Var i a bl e Mean ± Standard Deviation
Crest-to-crest distance 20.6 ± 4.6 m
Surface area of bioher m mound 192.3 ± 38.0 m2
Diameter of bioherm mound 15.6 ± 2.9 m
Height of bioherm mound 112.7 ± 21.0 cm
Width of inter-mound channel 4.4 ± 0.7 m
Depth of inter-mound channel below nick point 32.9 ± 6.1 cm
Elevation of colony centre from adjacent seafloor 4.9 ± 0.9 m
Density of bioherms in a colony (%) 59.1 ± 0.9
Depth 1% irradiance, 2011 and 2014 casts –18.9 ± 3.2 m
Depth 0.01% irradiance, 2014 casts –56.3 ± 4.7 m
These bioherm mounds are developed in regions where the uppermost Unit 1 is very
thin (< 1 m thick) or absent, and older successions of Units 2 and/or 3 are exposed or nearly
exposed at the seafloor (Fig. 11), which provided a hard substrate on which bioherm growth
started. Each bioherm mound stands ~1.1 m above an encircling moat (Figs. 9, 10), while the
most interior mounds in bioherm colonies have crests ~5 m above the seafloor outside the
colony (Aksu et al., 2018). Bioherm mounds are strictly confined to seafloor depths of 30–60
m, and are distinctly absent above and below these water depths (Fig. 14).
The physical oceanographic framework of the region occupied by the bioherms and
bioherm colonies is determined using five CTD (Conductivity Temperature Depth) casts
(Fig. 14). These profiles show that the upper 15–22 m (average ~20 m) of the water column
is occupied by a watermass characterized by low salinities (22–25), high temperatures (19–
24ºC) and variable dissolved oxygen concentrations, ranging from 5.1–5.2 mL/L at stations
M11-1 and M11-2 to 5.8–6.0 mL/L at stations M14-5, M14-6 and M14-7 (Fig. 14). This
watermass is known as the Black Sea watermass, and occupies the uppermost 25–50 m of


dissolved oxygen concentrations, and a relatively stable salinity.
PALYNOLOGICAL AND PALEONTOLOGICAL RECORDS OF CHANGES FROM GLACIAL-STAGE (MIS 2)...
154









155Petra J. MUDIE, Richard N. HISCOTT, Ali E. AKSU









Below ~ –25 to –30 m, there is another watermass which is characterized by notably
high salinities (38–39), relatively low temperatures (14–18ºC) and moderate–low dissolved
oxygen concentrations (Fig. 14). This is the Mediterranean watermass, which enters the
Strait of Dardanelles and flows toward the northeast exiting the strait and plunging down
to occupy the depths of the Marmara Sea. A prominent mixing zone occurs between the
upper Black Sea and lower Mediterranean watermasses, delineated by the halocline from
–15.5 to –20.5 m, a thermocline from –14 to –21.5 m and oxycline from –13 to –23 m.
The depth of sunlight penetration in the Marmara Sea is a function of the turbidity of the
water column caused by varying concentrations of organic and inorganic optically-active
constituents either in dissolved form or in suspension. It is estimated to be similar to global
coastal waters and shelves, and that not much sunlight normally penetrates below –50 m
depth (Fig. 14; Prazeres and Renema, 2019). Phytoplankton blooms and detrital organic
PALYNOLOGICAL AND PALEONTOLOGICAL RECORDS OF CHANGES FROM GLACIAL-STAGE (MIS 2)...
156
matter (remains of zooplankton and phytoplankton), and inorganic suspended sediment
can variably diminish the amount of light available for photosynthetic activity, causing
the depth of light penetration to differ dramatically between oceanic and coastal waters
(Mascarenhas and Keck, 2018). In general, there is almost no significant light below the
‘sunlit’ or the ‘euphotic’ zone forming the upper 150–200 m of the ocean. In open ocean
waters with relatively low amounts of phytoplankton, the blue-green wavelengths penetrate
deeper in the water column. In contrast, high concentrations of both suspended particulate
(phytoplankton and sediments) and dissolved matter strongly absorb the blue-green
wavelengths in coastal waters thereby restricting the penetration of sunlight into deeper
regions. Seawater absorbs more readily the warm colours (i.e., long wavelength sunlight),
such as red and orange and scatters the cool colours (i.e., short wavelength sunlight), such
as yellow and green (Mascarenhas and Keck, 2018).
Aksu et al. (2018) concluded that (a) water depth, nutrient supply, salinity, and sunlight
level are the most critical factors that control bioherm development and growth across the
southwestern Marmara Sea at the eastern entrance of the Strait of Dardanelles; (b) the bioherm
colonies occur within a very narrow depth range of –30 to –60 m, and are notably absent
above and below these water depths; (c) the distinctive Mediterranean fauna and flora found
in these sediments demonstrate that they are restricted to the high salinity Mediterranean
water mass, immediately below the overriding, brackish Black Sea outflow; (d) the presence
of encrusting coralline red algae in all surface samples further limits bioherm development
to water depths receiving, as an estimate, at least 0.01% of surface solar irradiance; (e) in
the tightly packed colonies, space appears to be fully utilised as indicated by the pentagonal
and hexagonal geometries of the inter-mound channels – a circle is the most efficient shape
in terms of the ratio of the area to perimeter, thus the mounds progressively assume a near
circular shape as they grow above the inter-mound channels; and (f) bioherm growth started
in various parts of the Marmara Sea during the latest Pleistocene – earliest Holocene, after
~13.8 cal ka, subsequent to breaching of a sill in the Strait of Dardanelles by rising global
sealevel and replacement of the brackish watermass of the Propontis Lake by full-salinity
Mediterranean seawater (Fig. 2; Table 1).
In the western Marmara Sea, active growth might have been prevented until ~7 cal ka
because of unfavourably low salinity in surface waters, limited light for photosynthesis in
coralline algae at depth, and agitation of surface waters by waves. The paleoenvironmental
significance of bioherms in latest Pleistocene successions from the northern Marmara Sea
shelf immediately south of the exit of the Strait of Bosphorus is discussed in Section 4.7.
157Petra J. MUDIE, Richard N. HISCOTT, Ali E. AKSU


Three piston cores and two gravity cores (Figs. 3, 15; Table 3) are used in this section to
constrain the paleoceanographic evolution of the Marmara Sea and its precursor Propontis
Lake since ~30 cal ka. Archival records for a number of older cores as well as new data sets
will be used to advance understanding of the Late Quaternary history of the region.

Piston core (later labeled as Calipso core) MD01-2430 and the two gravity cores M97-
11G and M98-12G have been described before, including their faunal and floral remains and
geochemistry (Aksu et al., 2002a; Kaminski et al., 2002; Abrajano et al., 2002; Mudie et al.,

2015). All these cores were raised beyond the modern shelf edge and below the ca. –95 m
lowstand shoreline of the MIS 2 Propontis Lake. The sediment representing the lacustrine
interval younger than ~30 cal ka up to ~ 17 cal ka (phase 1 in Table1) consists of burrow-
mottled calcareous silty mud with streaks and patches of black iron monosulphide (greigite,
Dreissena polymorpha and gastropods
Turricaspia caspia and Ecrobia ventrosa, and rare bedrock pebbles.



PALYNOLOGICAL AND PALEONTOLOGICAL RECORDS OF CHANGES FROM GLACIAL-STAGE (MIS 2)...
158
 Coordinates, core lengths and water depths of cores used in this section. MD01-2430 is
from Vidal et al. (2010).
Core Latitude   
M9 7-11G 40º39.20’N 28º22.67’E 237 cm –111 m
M98 -12G 40º50.54’N 27º47.67’E 219 cm –549 m
M02-88P 4 0 º 37. 99’ N 28º50.49’E 682 cm –354 m
M02-89P 40º40.30’N 28º51.39’E 806 cm –257 m
MD 01-2430 4 0 º47. 81’ N 27º43. 51’E 290 cm –580 m
    34S
(average ~10‰, up to >40‰ at the M3/2 boundary) in core M02-89P (Roberts, 2012).

interval in core MD01-2430 is ~4%, which corresponds to carbonate content as CaCO
3
of
~10%. The contact with the overlying marine sediment tends to be sharp, and in M02-89P
there are increased numbers of small D. polymorpha shells and fragments just below this
contact (Fig. 16). The marine muds in core MD01-2430 consist of three facies (Fig. 15):
(a) dark-coloured sapropel with TOC ~2–2.5% and common millimetre-thick “pinstripe”
lamination; (b) moderately dark sapropelic mud (TOC 1.5–2%) with burrows mostly limited
to ~1 mm diameter Chondrites galleries, and (c) burrow-mottled calcareous silty mud with
scattered marine molluscs including Turritella communis, Nuclea spp., Scrobicularia plana
and Acra
contain rare echinoderm plates, tentatively identified as Brissopsis spp., and there are rare
sharp-based silt laminae (event layers) in the sapropelic mud facies. Carbonate content of
the marine sediments is similar to that of the lacustrine mud. There are two tephras in core
MD01-2430: the cryptic Avellino tephra at 468 cm core depth and the visible reddish-brown

core M02-89P at a depth of ~5.66 m (Fig. 16).

sapropel has several cross-cutting discontinuities (slip planes) and thin (<5 cm) recumbent and
flattened micro-folds. There is no indication whether the original succession might have been
thinned or even thickened (by duplication), but only thinning would be consistent with the

Basin (Fig. 17). The top of this core has an age of ~7.65 cal ka (Table 4) and a co-located gravity
core acquired in 2014 confirms that there is no younger sediment at this site (i.e., coring of M02-
89P is not responsible for the missing middle and upper Holocene). Fortunately, nearby core
159Petra J. MUDIE, Richard N. HISCOTT, Ali E. AKSU

Except for the top-truncated core M02-89P (Fig. 15, Table 4), all core tops discussed in this
chapter are assigned an age of 0 cal yr to complete the age models using the justification provided
below. By definition, the radiocarbon zero age is 1950 CE so ~50 years before collection of

~5 cm for core M02-88P. Core-top samples include the uppermost 2 cm to provide sufficient
material for various analyses, so would capture any post-1950 CE sediment. Gravity and piston
coring rarely, if ever, recovers the true sediment surface, with box coring the preferred method
to do this, as was used for the surface sediment studies along Transect 1 (Section 3.1.3). As a
result of these limitations, the described and sampled core tops might actually lack a record for
the last ~50 years and the assignment of a 0 cal yr age for the core top is a fair assumption for
development of age models. For cores M02-88P and M97-02 (Mudie et al., 2002a); however, the
distributions of Ambrosia pollen and fly ash indicate that little sediment is missing from those
coretops. Bioturbational mixing of perhaps 5–10 cm (generally at the lower end of this range)
further redistributes the youngest sediment downcore.

 spp. shells





PALYNOLOGICAL AND PALEONTOLOGICAL RECORDS OF CHANGES FROM GLACIAL-STAGE (MIS 2)...
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Age models for the five cores are based on (1) calibrated radiocarbon dates (Table 4),
(2) matching of the central total organic carbon (TOC) peak and its flanks between cores
MD01-2430, M98-12G, M02-88P and M02-89P (Fig. 18), and (3) restriction of the transition
between (a) absence of planktonic foraminifera and (b) their first arrival in the Marmara Sea
to the interval ~13.5–13.1 cal ka (Aksu and Hiscott, 2022). Planktonic foraminifera are unable
to survive in the modern Black Sea (S ~19) and have limited diversity in the modern Marmara
Sea (N = 6), so occurrences clearly would have required near-total replacement of the Late
Pleistocene brackish watermass of the Propontis Lake by inflowing seawater from the Aegean
Sea in the few centuries following first entry at ~13.8 cal ka (Table 1, configuration 3). The
radiocarbon calibrations follow procedures and reservoir corrections explained in Aksu and
Hiscott (2022) and use the Marine20 calibration curve (Heaton et al., 2020) and Oxcal4.4 and
Calib8.2 online utilities. In the case of core M97-11G, one previously published radiocarbon
date of 13.86 cal ka (Aksu and Hiscott, 2022, their table 2) is ignored in creating its age model
because this date is inconsistent with the planktonic foraminiferal evidence.
The marine unit is identical to the “Holocene mud drape” of Hiscott et al. (2021), and in
cores raised and described by the authors from the Marmara Sea since 1997. It commonly
contains molluscs Turritella communis, Corbula gibba, Mytilis galloprovincialis, Abra abra,
Nucula spp. and Spissula subtruncata – the first two species are dominant and are indicators
of dysoxic conditions (Büyükmeriç, 2016).
One radiocarbon date of 11090±25 14C yr BP on the organic carbon fraction of a bulk
13C value of the organic
13C mixing line between
    
assessed to contain 28% marine organic carbon and 72% terrestrial organic carbon. The
terrestrial fraction would not have had a zero age at the time of sedimentation, and based on
research elsewhere. We assumed that it was pre-aged in coastal areas, fluvial interfluves or

core depth and wiggle matching of TOC data with other cores (Fig. 18), the age of this sample
was estimated to be ~12,700–12,800 cal yr, for which the default reservoir age built in to the
Marine20 curve is ~550 yr (Heaton et al., 2020; Reimer et al., 2020). We therefore assumed a
local marine reservoir age of 550–100 = 450 yr for the 28% marine fraction and combined this
with pre-aging of 200 yr for the 72% terrestrial fraction. The weighted average of these age
offsets is 450×0.28+200×0.72=270 yr, and this value was subtracted from the raw radiocarbon
date before calibration using Calib8.2 and the Intcal20 curve. The result is 12,750±10 cal yr,
161Petra J. MUDIE, Richard N. HISCOTT, Ali E. AKSU

yr attached to the radiocarbon date (so 12,750±35 cal yr; Table 4).


-1






PALYNOLOGICAL AND PALEONTOLOGICAL RECORDS OF CHANGES FROM GLACIAL-STAGE (MIS 2)...
162







 Accelerator mass-spectrometer (AMS) 14
               
Calibration uses the Marine20 curve of Heaton et al. (2020) with its default reservoir correction of
R = ~400 yr for 14C dates <12000 yr BP. R for earlier times is consistent with Aksu and Hiscott
(2022, their Table 3 and their figure 8). The single exception is M02-89P, 211 cm depth, calibrated
using the IntCal20 and adjustments explained in the text.  = local departures from the global
average R. Laboratory numbers are available in Aksu and Hiscott (2022) and Vidal et al. (2010). * =
subjacent shell core M02-16P.
Core Material or
feature  C date
(yr BP) ΔR 
(cal yr) Justification
All but
-89P
Core top 0 0 Assumed modern
seafloor
MD 01-2430 Avellino tephra 161 3945±10 Sevinç et al. (2011) in

MD 01-2430 Scrobicularia
plana
200 47855 –100 4955 ±110
MD 01-2430 Scrobicularia
plana
253 8010 ±60 –10 0 8415±9 0
163Petra J. MUDIE, Richard N. HISCOTT, Ali E. AKSU
MD 01-2430 Acra spp. 337 10850±65 –100 122 85 ±145
MD 01-2430 Acra spp. 348 1105 0 ± 65 100 12535±90
MD 01-2430 Turricaspia
caspia
384 13050±70 630 13810±130
MD 01-2430 Y2 tephra top 691 18915± 40 800 220 55±110 Aksu and Hiscott
(2022) , *
MD 01-2430 Y2 tephra base 698 18915 ±40 800 2 2 055±110 Aksu and Hiscott
(2022), *
MD 01-2430 Dow nward
extrapolation
740 23185 Base of TOC data, not
the 28.9 m core
M02-88P Brissopsis spp.
(echinoderm)
43 1065±15 –100 5850
M02-88P Brissopsis spp.
(echinoderm)
240 2895±15 –100 2610 ±75
M02-88P Brissopsis spp.
(echinoderm)
365 3815±15 –100 3720±80
M02-88P Brissopsis spp.
(echinoderm)
663 5935±15 –100 6265±70
M02-88P Downward
extrapolation
682 6425 Base of core
M02-88P Upward
extrapolation
07645 Co-located gravity
core indicates no core-
top loss
M02-89P Bivalve
fragments
10 7775±15 –100 8160 ±75
M02-89P TOC match to
MD 01-2430
40 9700
M02-89P TOC match to
MD 01-2430
50 1020 0
M02-89P Bulk mud, 72%
terrigenous
211 11090±2 5 R=270 12750 ±35  –100 yr for marine
fraction
M02-89P Downward
extrapolation
249 13370 Above unconformity
M02-89P Realistic
minimum age
250 13500 Below unconfor mity,
no planktonic
foraminifera
M02-89P Bivalve
fragments
255 12 920±110 526 13770±165
M02-89P Downward
extrapolation
260 14040 Above unconformity
M02-89P Upward
extrapolation
262 16540 Below unconfor mity
M02-89P Dreissena
polymorpha
270 15005±30 235 17050 ±115
M02-89P Dreissena
polymorpha
290 160 8 30 240 18325±125
PALYNOLOGICAL AND PALEONTOLOGICAL RECORDS OF CHANGES FROM GLACIAL-STAGE (MIS 2)...
164
M02-89P Dreissena
polymorpha
290 160 8 30 240 18325±125
M02-89P Dreissena
polymorpha
450 16895 ±35 180 19260±120
M02-89P Dreissena
polymorpha
490 1757 0 ±35 125 20175±120
M02-89P Y2 tephra top 563 18915 ±40 800 22 055±110 Aksu and Hiscott
(2022), *
M02-89P Y2 tephra base 568 18915 ±40 800 22 055±110 Aksu and Hiscott
(2022), *
M02-89P Dreissena
polymorpha
740 23690 ±70 842 27 795 ±110
M02-89P Dreissena
polymorpha
800 25320 ±90 –930 296 75 ±110
M02-89P Downward
extrapolation
813 30080 Base of core
M9 7-11G Tu rri tella spp. 79 1079 0±70 –100 12180 ±150
M9 7-11G 110 13500 A ksu et al.
(2002a), estimated
arrival planktonic
foraminifera
M9 7-11G Small ‘oyster’ 174 14940±90 215 17000±155
M9 7-11G Dreissena spp. 204 15590±90 17920 ±155
M9 7-11G Downward
extrapolation
237 18930 Base of core
M98 -12G Bivalve
fragment
50 4200±100 –100 4235±15 0
M98 -12G Age of M1 peak
TOC
90 9750 Imported age from
MD01-2430 TOC
profile
M98 -12G Nuculacea spp. 130 10660 ±130 –100 11980 ± 2 30
M98 -12G Sharp base M1
sapropel
143 13400 ~130 yr gap
(lacustrine–marine
facies in M02-89P)
Age-depth curves for the five cores considered in this section (Fig. 19) show a range of
accumulation rates. The M02-89P plot has two gaps representing hiatuses. The upper gap of
~150 yr is marked by an unconformity expressed as a sharp contact between lacustrine and
marine deposits, with the marine sediment being a dark sapropelic mud with subtle parallel
laminae (Fig. 16a). The lower age gap separates radiocarbon-dated shells 15 cm apart but
different in age by ~3300 yr (Table 4), and seems to coincide with a subtle boundary at 262
cm core depth between burrowed mud with ~10% small Dreissena spp. shells above, and
similar but bivalve-free mud below. Nothing at this level suggests erosion.
165Petra J. MUDIE, Richard N. HISCOTT, Ali E. AKSU



This discontinuity might be an unconformity or a very condensed section, but the presence
        
microfolds and low-angle slip surfaces in the overlying sapropel at this core site suggest the
need for caution, because a fault in soft, bioturbated sediments without marker horizons could
have little physical expression. There are sufficient dated features in overlying and underlying
sediments to ensure reliable age assignments for the M02-89P samples, and accumulation
rates away from this discontinuity are realistic when compared with other studied cores (Fig.
19). Regardless of the uncertainty surrounding its origin (erosional or tectonic), there is a
real temporal break that interrupts the Late Pleistocene record from ~17–14 cal ka, but which
leaves the remainder of this record intact back to the MIS 3/2 transition. For simplicity, we
have decided to refer to this interval with sharp age discontinuity as a hiatus in both the text
and figures, regardless of the possibility that it might actually be the expression of a cryptic
low-angle fault. The above age models (i.e., Fig. 19) permit replotting of archival multi-proxy
data originally presented by Aksu et al. (2002a); Kaminski et al. (2002); Abrajano et al. (2002)
and Mudie et al. (2002a,b) for cores M97-11G and M98-12G (Fig. 20). This is done to provide
comparable data sets for the interpretation of the much higher resolution palynological results
presented in Section 6, particularly for core M02-88P. For selected environmentally sensitive
microflora and fauna, the previous results are reviewed below to better guide the assessment
of the new results and compensate for the hiatuses in core M02-89P.
PALYNOLOGICAL AND PALEONTOLOGICAL RECORDS OF CHANGES FROM GLACIAL-STAGE (MIS 2)...
166

The coccolith assemblages in Upper Pleistocene and Holocene sediments from the
Marmara Sea have relatively low diversity and abundance, and they are largely dominated
by Emiliania huxleyi, with minor occurrences of Syracosphaera pulchra, Coccolithus
pelagicus, and Rhabdosphaera clavigera (Figs. 21, 22; Aksu et al., 2002a). In addition to
this present-day microplankton, sediment cores contain variable but significant occurrences

are Helicopondosphaera wallichii, Helicopondosphaera selli, Helicopondosphaera
kemptaneri, Braarudosphaera bigelowii, Calcidiscus leptoporus, Geophyrocapsa oceanica,
Reticulofenestra clavigera, R. pulchra, R. sessilis, Umbilicosphaera tenuis, Helicosphaera
carteri and Reticulofenestra spp. The Marmara Sea paleo-assemblages are similar in
diversity and abundance to coccolith floras in sediment cores from the northern Aegean
Sea and eastern Mediterranean Sea (Aksu et al., 2002a and references therein). In the
Marmara Sea, the diversity of coccoliths increases upwards during the Holocene because
of the addition of seven oceanic species (C. pelagicus, C. leptoporus, R. clavigera, R.
pulchra, R. sessilis, U. tenuis, and H. carteri) to a low diversity Early Holocene flora
comprising E. huxleyi, S. pulchra, Reticulatofenestra spp. and G. oceanica. In core M98-
12G of the western Central Basin (Figs. 3, 21), the most eurythermal and euryhaline species
Emiliania huxleyi is common as early as 11.4 cal ka (120 cm core depth) but displays a
peak occurrence beginning at ~3.4 cal ka (40 cm core depth). Here the peak abundance of
dinoflagellate cysts occurs at ~10–8 cal. ka and precedes the coccolith abundance maximum

reported in Section 3.1.3.12, it might be concluded that this younger time interval marks
the onset of anomalies of salinity and temperature, together with a lowering of phosphate
and silicate levels that would favour the coccolithophorid blooms over dinoflagellates,
and correlative with the expansion into the Black Sea. However, in core M97-11G from
the southern Marmara shelf edge, the peak coccolith and dinocyst abundances coincide
during the warm mid-Holocene interval (Fig. 20). Here Emiliana huxleyi first occurs
at ~4.5 cal ka, much later than in the basinal core M98-12G although other marine
coccolithophorids (Geophyrocapsa oceanica, Helicopondosphaera wallichii, H. selli, H.
hyalina, Helicopondosphaera spp. and Reticulofenestra spp.) are sporadically present in
low abundances since ~12 ka (Fig. 22). In contrast, E. huxleyi did not invade the Black
Sea via the Strait of Bosphorus before 2730±130 cal yr (Jones, 1994) when coccolith ooze
deposition began, continuing until 1635±30 cal yr (consistent with authors’ calibrations
167Petra J. MUDIE, Richard N. HISCOTT, Ali E. AKSU
using the IntCal20 curve of Reimer et al., 2020). Jones (1994) interpreted this delayed entry
as indicating that coccolithophores transported to the Black Sea in the Marmara Sea bottom
water cannot survive in the absence of light, and attributed the eventual colonisation to the
introduction of E. huxleyi to Black Sea surface water by early Greek seafaring explorers.
The light limitation for good growth of E. huxleyi implies that this species must have
colonised the Marmara Sea during an interval without strong salinity stratification.



1813C are oxygen and


It is notable, however, that in contrast to the Black Sea, there is no coccolith ooze in the
Marmara Sea sediments, and the coccolith abundances are reduced in the interval of sapropel
M1 deposition (Fig. 21; Aksu et al. 2002a; Vidal et al., 2010).
PALYNOLOGICAL AND PALEONTOLOGICAL RECORDS OF CHANGES FROM GLACIAL-STAGE (MIS 2)...
168





The planktonic foraminiferal assemblages in both the basin and shelf cores are dominated
by the North Atlantic subpolar species T. quinqueloba, with lesser percentages of G. bulloides,
and N. pachyderma dextral and reflect the present-day temperature and salinity conditions
of the Marmara Sea (Figs. 21, 22). These species also characterise the cooler regions of the
Mediterranean Sea, where winter surface temperatures vary between 10
o
C and 16
o
C (Aksu
et al., 1995). It is noteworthy that in their comprehensive study of benthic and planktonic
