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An introduction to the biology and systematics of Komokiacea. Galathea Report

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Komokiacea n . superfam . (Textulariina. Foramini-1928. Lana n . gen., Baculella n . gen., and Edgertonia n . ferida. Protozoa) comprises agglutinating foramini-gen . are described . Two families. Komokiidae and fers with test consisting of a complex system of fine. Baculellidae. are erected . branching tubules of even diameter . The test wall is The group has worldwide distribution. mainly in simple. with argillaceous particles . Stercomata accu-the abyssal zone . The greatest relative abundances mulate within the tubules .
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... However, the true nature of foraminifera assemblages on Pacific abyssal plains, and the scale of their diversity, only started to become apparent as a result of research in the central North Pacific during the 1970s (Hessler, 1974). This revealed that the macrofauna is dominated by agglutinated foraminifera (Bernstein et al., 1978), many of them singlechambered monothalamids (class Monothalamea) including tubular forms and those with highly unusual test morphologies, for which Tendal and Hessler (1977) established the superfamily Komokiacea. A group of even larger monothalamids, the xenophyophores (Tendal, 1972), make a major contribution to the North Pacific megafauna (Gooday et al., 2017b;Simon-Lledó et al., 2019a), while largely undescribed sessile foraminifera are very abundant on polymetallic nodules (Veillette et al., 2007;Gooday et al., 2015). ...
... Renewed interest in seabed mining during the last two decades has generated an upsurge of research on benthic foraminifera within the CCZ (Figures 2b,c). The 1970s had seen the establishment of the Komokiacea and their recognition as an important component of the abyssal Pacific macrofauna (Tendal and Hessler, 1977), although this unusual group of what are presumed to be soft-bodied monothalamous foraminifera had been known to Russian scientists since the 1950s and a few were included in Saidova's (1975) monograph (summarized in Gooday et al., 2007). Most recent foraminiferal studies in the CCZ have included these and other delicate monothalamids. ...
... Order (Tendal and Hessler, 1977) or the North Atlantic (Shires et al., 1994), indicating wide distributions. Similarly, some of the nodule-encrusting macrofaunal morphospecies in the UK-1 and OMS areas unpublished data) are also reported from the eastern and western CCZ sites of Veillette et al. (2007). ...
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Benthic foraminiferal research in the North Pacific has a long history, with works published over a century ago providing important information about the taxonomy and distribution of morphospecies. These studies focused mainly on areas outside the Clarion-Clipperton Zone (CCZ). Our knowledge of foraminiferal faunas within the CCZ originates largely from recent baseline investigations related to likely future seabed mining of the polymetallic nodule deposits. These have revealed highly diverse assemblages of sediment-dwelling morphospecies among the meiofauna and macrofauna, as well as megafaunal xenophyophores and nodule-attached fauna. Morphological analyses have been complemented by metabarcoding studies that yielded even higher numbers of molecular species (Operational Taxonomic Units - OTUs). Monothalamids, the vast majority undescribed, constitute a substantial proportion of both morphological and molecular datasets, with multichambered agglutinated and calcareous foraminifera being less common. Their importance in this abyssal (>4,000 m depth) habitat likely reflects food limitation combined with carbonate dissolution close to and below the carbonate compensation depth. Literature records, supported in a few cases by genetic data, suggest that many morphospecies found in the CCZ have wide geographical distributions across the Pacific abyss and in other oceans. At smaller spatial scales (several 100s of kilometers) there is a general uniformity in assemblage composition. Nevertheless, many morphospecies are too rare to conclude anything about their geographical distributions. Similarly, the part played by benthic foraminifera in CCZ ecosystems is largely a matter of speculation, although their abundance across different size classes suggests that it is significant. Meiofauna-sized taxa that consume freshly-deposited organic detritus may be important in carbon cycling, particularly at the shallower, more eutrophic eastern end of the CCZ. Megafaunal xenophyophores can provide habitat structure for other organisms, potentially enhancing benthic biodiversity. Foraminifera of all sizes could be among the earliest recolonisers of disturbed or redeposited sediments. Their potential contributions in terms of both ecology and biodiversity make these protists significant members of benthic communities in the CCZ.
... Holocene; North Pacific from 180 to 7,298 m; Equatorial Pacific from 3,270 to 4,438 m; South Pacific from 3,768 to 3,804 m; East Atlantic from 610 to 5,300 m; West Atlantic from 2,200 to 2,400 m; Equatorial Atlantic from 2,610 m; Caribbean from 1,100 to 5,656 m; Western Indian Ocean from 3,960 to 4,900 m ( Loeblich & Tappan 1988); South of the Colombian Caribbean. Species Komokia multiramosa Tendal & Hessler, 1977. Catalogue number: INV FOR172, INV FOR177, INV FOR181. ...
... Gooday et al. 2007a). Family BACULELLIDAE Tendal & Hessler, 1977 Species Catena piriformis Schröder, Medioli & Scott, 1989. Catalogue number: INV FOR179. ...
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Research regarding deep-sea benthic foraminifera in the Colombian Caribbean requires further development given the complete lack of information related to the different groups that constitute associations and the ecological functions they fulfill. For this purpose, a taxonomic description of Superfamily Komokioidea was composed from macrofauna samples from between 1,215 m and 3,179 m depth, obtained during the research cruise ANH-COL 4 and COL 5 carried out in 2014. Results showed foraminifera belonging to the three families: Komokiidae, Baculellidae, and Normaninidae, inclu-ding five genera (Lana, Komokia, Ipoa, Normaninam, and Catena) and five species (Lana neglecta, Komokia multiramosa, Normanina conferta, Ipoa fragila, and Catena piriformis). This study presents knowledge regarding deep-sea Colombian Caribbean benthic foraminifera, which to date have not been recorded from this region. Their depth distribution when compared with other studies from the Atlantic and Pacific, allows the expansion of taxonomic inventories and the characterization of biodiversity within poorly explored regions.
... Nevertheless, there is growing evidence that they sometimes constitute a highly diverse component of the meiobenthos. This is particularly apparent in deep-sea habitats where monothalamids sometimes dominate meiofaunal, macrofaunal, and even megafaunal assemblages (Tendal & Hessler 1977;Goineau & Gooday 2017;Amon et al. 2016). These morphology-based results are strongly supported by recent analyses of environmental DNA samples (Lecroq et al. 2011;Lejzerowicz et al. 2014). ...
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We present new data on monothalamous (single-chambered) foraminifera from the Black Sea Crimean shelf zone between Karkinitsky Gulf in the west to the area near Kerch in the east. Within this region we recognized a total of 40 morphospecies; 8 are assigned, in some cases tentatively, to known species and another 9 to known genera, again sometimes tentatively. Twelve species (all undescribed) are reported here for the first time. The most abundant species are Psammophaga sp. (sensu Gooday et al. 2011), Goodayia rostellata Sergeeva & Anikeeva 2008 and Vellaria pellucida Gooday & Fernando 1992, each of which is evenly distributed in all studied areas. The highest species richness of monothalamous foraminifera was observed in the Yalta region. Based on a multivariate analysis of monothalamid assemblage structure and diversity indices [Shannon (H’), Margalef (D’), eveness Pielou (J’), Simpson (1-λ’) and rarefaction ES(n)], we recognized three groups of stations, corresponding to the Western, Southern and Eastern coasts of the Crimean peninsula. The monothalamid assemblages found in each of these coastal regions exhibit different structural features and are distinguished by certain characteristic species.
... Baculella globofera Hessler, 1977 See Tendal andHessler (1977) Figure S10: a, b Clusters of short, finger-like branching tubules, typically ~50 µm wide, usually ending in slightly bulbous swellings or clusters of swellings. Tubes and swellings contain discrete clumps of stercomata, often separated by more or less distinct septae that subdivide the interior into compartments. ...
... Around half of all species in our samples accumulated stercomata (waste pellets), a common feature of deep-sea monothalamids 8,29,32 . The protoplasm to body volume ratio is often low in these taxa, the protoplasm being diffuse and often obscured by masses of stercomata 9 . The stercomata may persist in dead specimens, eventually decaying into grey 'sediment' . ...
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The benthic biota of the Clarion–Clipperton Zone (CCZ, abyssal eastern equatorial Pacific) is the focus of a major research effort linked to possible future mining of polymetallic nodules. Within the framework of ABYSSLINE, a biological baseline study conducted on behalf of Seabed Resources Development Ltd. in the UK-1 exploration contract area (eastern CCZ, ~4,080 m water depth), we analysed foraminifera (testate protists), including 'live' (Rose Bengal stained) and dead tests, in 5 cores (0–1 cm layer, >150-μm fraction) recovered during separate megacorer deployments inside a 30 by 30 km seafloor area. In both categories (live and dead) we distinguished between complete and fragmented specimens. The outstanding feature of these assemblages is the overwhelming predominance of monothalamids, a group often ignored in foraminiferal studies. These single-chambered foraminifera, which include agglutinated tubes, spheres and komokiaceans, represented 79% of 3,607 complete tests, 98% of 1,798 fragments and 76% of the 416 morphospecies (live and dead combined) in our samples. Only 3.1% of monothalamid species and 9.8% of all species in the UK-1 assemblages are scientifically described and many are rare (29% singletons). Our results emphasise how little is known about foraminifera in abyssal areas that may experience major impacts from future mining activities.
... Baculella globofera Hessler, 1977 See Tendal andHessler (1977) Figure S10: a, b Clusters of short, finger-like branching tubules, typically ~50 µm wide, usually ending in slightly bulbous swellings or clusters of swellings. Tubes and swellings contain discrete clumps of stercomata, often separated by more or less distinct septae that subdivide the interior into compartments. ...
... A shift from calcareous to agglutinated foraminifera would likely impact deep-sea function (e.g., deep-sea carbon cycling) in addition to altering the biogeographical distribution of fauna (Gooday et al., 2012). Agglutinated foraminifera, particularly forms such as komokiaceans, which are a dominant faunal component in the abyssal deep sea (Tendal and Hessler, 1977), are believed to have a lower metabolic rate and to be less active in carbon processing than calcareous foraminifera (Gooday et al., 2008). ...
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The deep sea encompasses the largest ecosystems on Earth. Although poorly known, deep seafloor ecosystems provide services that are vitally important to the entire ocean and biosphere. Rising atmospheric greenhouse gases are bringing about significant changes in the environmental properties of the ocean realm in terms of water column oxygenation, temperature, pH and food supply, with concomitant impacts on deep-sea ecosystems. Projections suggest that abyssal (3000–6000 m) ocean temperatures could increase by 1°C over the next 84 years, while abyssal seafloor habitats under areas of deep-water formation may experience reductions in water column oxygen concentrations by as much as 0.03 mL L –1 by 2100. Bathyal depths (200–3000 m) worldwide will undergo the most significant reductions in pH in all oceans by the year 2100 (0.29 to 0.37 pH units). O 2 concentrations will also decline in the bathyal NE Pacific and Southern Oceans, with losses up to 3.7% or more, especially at intermediate depths. Another important environmental parameter, the flux of particulate organic matter to the seafloor, is likely to decline significantly in most oceans, most notably in the abyssal and bathyal Indian Ocean where it is predicted to decrease by 40–55% by the end of the century. Unfortunately, how these major changes will affect deep-seafloor ecosystems is, in some cases, very poorly understood. In this paper, we provide a detailed overview of the impacts of these changing environmental parameters on deep-seafloor ecosystems that will most likely be seen by 2100 in continental margin, abyssal and polar settings. We also consider how these changes may combine with other anthropogenic stressors (e.g., fishing, mineral mining, oil and gas extraction) to further impact deep-seafloor ecosystems and discuss the possible societal implications.
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Foraminifera are a major component of the abyssal meiofauna in parts of the eastern Pacific Clarion-Clipperton Zone (CCZ) designated by the International Seabed Authority for polymetallic nodule exploration. We analysed the diversity and distribution of stained (‘live’) and unstained (dead) assemblages (0–1 cm layer, >150-μm sieve fraction) in megacorer samples from 11 sites (water depths 4051–4235 m) within three 30 × 30 km ‘strata’ in the United Kingdom 1 (UK1 Strata A and B; 5 and 3 samples, respectively) and Ocean Minerals Singapore (3 samples) exploration contract areas and separated by distances of up to 28 km within a stratum and 224 km between strata. Foraminiferal assemblage density, diversity and composition at the higher taxon/morphogroup level were largely consistent between samples. Stained assemblages were dominated (>86%) by single-chambered monothalamids, mainly spheres, tubes, komokiaceans and forms that are difficult to categorise morphologically. Hormosinaceans were the most common multichambered group (∼10%), while calcareous taxa (mainly rotaliids) represented only ∼3.5% of stained tests. Dead foraminifera were more evenly distributed between monothalamids (56%) and multichambered taxa (44%). Almost all test fragments were monothalamids, mainly tubes. Morphospecies were added regularly with each new sample and totalled 580 (stained + dead, complete + fragments), of which 159 occurred in all three strata, 222 were shared between UK1 Strata A and B, 209 between UK1A and the OMS Stratum, and 193 between UK1B and the OMS Stratum. Individual strata yielded 310–411 and individual samples 132–228 putative morphospecies. The majority (550) of the 580 species were represented by intact tests of which 462 included at least some that were stained. Most of the stained (∼80%) and stained + dead (∼75%) species were monothalamids, almost all of them undescribed. Many species were rare; 146 of the 550 species with complete tests (stained + dead) were singletons and 53 doubletons. Values of Morisita's index indicated that most individual species represented by ≥ 10 complete tests had aggregated distributions. In MDS plots, all 11 samples fell within the 95% confidence limit, consistent with a general uniformity in assemblage composition. However, there was also a weak grouping of UK1A samples, while a plot of Bray-Curtis similarity against distance between samples suggests that there may be some gradual change in assemblage composition related to distance. We conclude that the foraminiferal assemblages at our eastern CCZ sites are highly diverse, dominated by undescribed monothalamids, include many rare species, and are fairly similar across the study area, but with a patchy distribution at the level of individual morphospecies.
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Fossil benthic and planktonic foraminifers play a major role in paleontology, first of all as a stratigraphic tool, but also in paleoecology, paleoclimatology, paleoceanography and paleobiogeography. Recent foraminifers are abundant and diverse in nearly all modern marine ecosystems, and although little is known about their life as organisms, they are among the most important marine animal groups (Bernstein et al., 1978; Gooday, 1986, 1988; Hemleben et al., 1989; Lipps, 1983; Murray, 1973; Tendal & Hessler, 1977; Thiel, 1975, 1983).
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