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We present a summary of biomass data for 11 Plankton Functional Types (PFTs) plus phytoplankton pigment data, compiled as part of the MARine Ecosystem biomass DATa (MAREDAT) initiative. The goal of the MAREDAT initiative is to provide global gridded data products with coverage of all biological components of the global ocean ecosystem. This special issue is the first step towards achieving this. The PFTs presented here include picophytoplankton, diazotrophs, coccolithophores, Phaeocystis, diatoms, picoheterotrophs, microzooplankton, foraminifers, mesozooplankton, pteropods and macrozooplankton. All variables have been gridded onto a World Ocean Atlas (WOA) grid (1° × 1° × 33 vertical levels × monthly climatologies). The data show that (1) the global total heterotrophic biomass (2.0–6.4 Pg C) is at least as high as the total autotrophic biomass (0.5–2.6 Pg C excluding nanophytoplankton and autotrophic dinoflagellates), (2) the biomass of zooplankton calcifiers (0.9–2.3 Pg C) is substantially higher than that of coccolithophores (0.01–0.14 Pg C), (3) patchiness of biomass distribution increases with organism size, and (4) although zooplankton biomass measurements below 200 m are rare, the limited measurements available suggest that Bacteria and Archaea are not the only heterotrophs in the deep sea. More data will be needed to characterize ocean ecosystem functioning and associated biogeochemistry in the Southern Hemisphere and below 200 m. Microzooplankton database: doi:10.1594/PANGAEA.779970.
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CMYK RGB
MAREDAT: towards a world atlas of
MARine Ecosystem DATa
E. T. Buitenhuis1, M. Vogt2, R. Moriarty3, N. Bednarˇ
sek4, S. C. Doney5, K. Leblanc6, C. Le Qu´
er´
e1,
Y.-W. Luo5, C. O’Brien2, T. O’Brien7, J. Peloquin2, R. Schiebel8, and C. Swan2
1Tyndall Centre for Climate Change Research and School of Environmental Sciences,
University of East Anglia, Norwich NR4 7TJ, UK
2Environmental Physics, Institute for Biogeochemistry and Pollutant Dynamics, ETH Z¨
urich,
Universit¨
atsstrasse 16, 8092 Z¨
urich, Switzerland
3School of Earth, Atmospheric and Environmental Sciences, University of Manchester, Williamson Building,
Oxford Road, Manchester M13 9PL, UK
4NOAA Pacific Marine Environmental Laboratory, 7600 Sand Point Way NE, Seattle, WA 98115, USA
5Department of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution,
Woods Hole, Massachusetts 02543, USA
6Aix-Marseille Universit´
e, Universit´
e du Sud Toulon-Var, CNRS/INSU, IRD, MIO, UM110,
13288 Marseille, Cedex 09, France
7National Marine Fisheries Service, 1315 East–West Highway, Silver Spring, Maryland, USA
8LUNAM University, Angers University, UMR CNRS 6112 LPGN-BIAF, Laboratoire des Bio-Indicateurs
Actuels et Fossiles, 2 Boulevard Lavoisier, 49045 Angers CEDEX 01, France
Correspondence to: E. Buitenhuis (tinyurl.com/contacterik)
Received: 13 November 2012 – Published in Earth Syst. Sci. Data Discuss.: 23 November 2012
Revised: 2 May 2013 – Accepted: 15 May 2013 – Published: 12 July 2013
Abstract. We present a summary of biomass data for 11 plankton functional types (PFTs) plus phytoplankton
pigment data, compiled as part of the MARine Ecosystem biomass DATa (MAREDAT) initiative. The goal
of the MAREDAT initiative is to provide, in due course, global gridded data products with coverage of all
planktic components of the global ocean ecosystem. This special issue is the first step towards achieving this.
The PFTs presented here include picophytoplankton, diazotrophs, coccolithophores, Phaeocystis, diatoms,
picoheterotrophs, microzooplankton, foraminifers, mesozooplankton, pteropods and macrozooplankton. All
variables have been gridded onto a World Ocean Atlas (WOA) grid (1×1×33 vertical levels ×monthly cli-
matologies). The results show that abundance is much better constrained than their carbon content/elemental
composition, and coastal seas and other high productivity regions have much better coverage than the much
larger volumes where biomass is relatively low. The data show that (1) the global total heterotrophic biomass
(2.0–4.6PgC) is at least as high as the total autotrophic biomass (0.5–2.4PgC excluding nanophytoplankton
and autotrophic dinoflagellates); (2) the biomass of zooplankton calcifiers (0.03–0.67PgC) is substantially
higher than that of coccolithophores (0.001–0.03PgC); (3) patchiness of biomass distribution increases with
organism size; and (4) although zooplankton biomass measurements below 200m are rare, the limited mea-
surements available suggest that Bacteria and Archaea are not the only important heterotrophs in the deep
sea. More data will be needed to characterise ocean ecosystem functioning and associated biogeochemistry in
the Southern Hemisphere and below 200m. Future eorts to understand marine ecosystem composition and
functioning will be helped both by further archiving of historical data and future sampling at new locations.
Microzooplankton database: doi:10.1594/PANGAEA.779970
All MAREDAT databases: http://www.pangaea.de/search?&q=maredat
Published by Copernicus Publications.
228 E. T. Buitenhuis et al.: MAREDAT: towards a world atlas of MARine Ecosystem DATa
1 Introduction
The MARine Ecosystem Model Intercomparison Project
(MAREMIP) was initiated in 2007 to facilitate communica-
tion, collaboration and the sharing of data and procedures,
such as model evaluation techniques, between research
groups developing Dynamic Green Ocean Models (DGOMs;
Le Qu´
er´
e et al., 2005). DGOMs are global ocean biogeo-
chemical models that represent more than two plankton func-
tional types (PFTs), thus including more ecological inter-
actions than the unidirectional flow represented in Nutrient
Phytoplankton Zooplankton Detritus (NPZD) models. After
an exploratory phase, a kick-omeeting was held in 2009
(Le Qu´
er´
e and P´
esant, 2009). At this meeting it was decided
to collectively synthesise existing biomass concentration
measurements for the previously defined “key plankton func-
tional types that need to be simulated explicitly to capture im-
portant biogeochemical processes in the ocean” (Le Qu´
er´
e et
al., 2005). This MARine Ecosystem biomass DATa (MARE-
DAT) special issue in Earth System Science Data is the re-
sult, with 11 papers on 11 PFTs and 1 paper on HPLC-based
(high-performance liquid chromatography) phytoplankton
pigments (http://www.earth-syst-sci-data.net/special issue7.
html). There are six papers relating to autotrophic groups:
picophytoplankton (Buitenhuis et al., 2012a), diazotrophs
(Luo et al., 2012), coccolithophores (O’Brien et al., 2013),
Phaeocystis (Vogt et al., 2012), diatoms (Leblanc et al.,
2012), and HPLC-based phytoplankton pigments (Peloquin
et al., 2013). There are six papers relating to heterotrophic
groups: picoheterotrophs (Bacteria and Archaea, Buitenhuis
et al., 2012b), microzooplankton (here, we briefly reiter-
ate and correct the microzooplankton biomass database that
was recently published by Buitenhuis et al., 2010), plank-
tic foraminifers (Schiebel and Movellan, 2012), mesozoo-
plankton (Moriarty et al., 2013), pteropods (Bednarˇ
sek et al.,
2012), and macrozooplankton (Moriarty et al., 2013). By this
collaborative eort we are able to provide global databases
for 9 out of the 10 PFTs that were proposed by Le Qu´
er´
e et
al. (2005).
The missing PFT is mixed phytoplankton, which is mostly
made up of autotrophic dinoflagellates and nanophytoplank-
ton other than coccolithophores and Phaeocystis. Nanophy-
toplankton are a taxonomically diverse group of algae, in-
cluding prymnesiophytes, chlorophytes, and cryptophytes,
which are not consistently treated as a distinct group in the
literature. Where the term nanophytoplankton is used in the
literature it often includes members of PFTs that have been
included in the data products in this special issue. Therefore,
we excluded this PFT from the current collection of data,
even though nanophytoplankton represent a significant part
of the phytoplankton biomass. Demarcation issues between
nanophytoplankton and the other PFTs will need to be re-
solved before we can complete the abundance based atlas of
phytoplankton biomass. Chemotaxonomic interpretation of
the HPLC-based phytoplankton pigment database described
in this special issue (Peloquin et al., 2013) oers one pathway
toward resolving mixed phytoplankton biomass distribution.
However, the most reliable way to prevent double counting
and achieve a consistent dataset would be to measure the
biomass and cell size of all distinct phytoplankton groups in
the same samples in transects that cross all ocean basins.
A similar demarcation issue occurs for the zooplank-
ton. The sum of micro-, meso-, and macrozooplankton
should represent the total zooplankton population. How-
ever, although small foraminifers are microzooplankton, they
tend not to be included in microscopic counts. Likewise,
pteropods fall partly in both meso- and macrozooplankton
size classes. In macrozooplankton studies, the focus is usu-
ally taxon specific, at a variety of levels between phylum and
species. The sum of all relevant phyla is rarely accounted for,
making an accurate assessment of the total macrozooplank-
ton biomass dicult, and thus leading to a risk of underesti-
mation, as opposed to the risk of double counting in the case
of foraminifers and pteropods.
In addition to the 9 PFTs mentioned above, we include
data on two groups of zooplankton calcifiers, the calcite pro-
ducing planktic foraminifers (Schiebel and Movellan, 2012)
and the pteropods (Bednarˇ
sek et al., 2012), which include
both shelled aragonite-producing species and naked species.
These data should be valuable in complementing research
into phytoplankton calcifiers, i.e. coccolithophores, and in
addressing the biogeochemical cycling of calcium carbon-
ate, and thus alkalinity and atmospheric CO2. The diazotroph
dataset contains both biomass estimates and nitrogen fixation
rate data, which are useful to evaluate the ecological roles of
diazotrophs or to quantify marine nitrogen fixation (Luo et
al., 2013).
Since 1994, the World Ocean Atlas (WOA) has been syn-
thesising interpolated global gridded climatological datasets
of physical and chemical parameters (temperature, oxygen,
nutrients, etc.). Initially, these datasets were annual averages,
but increasingly they cover seasonal variations on a monthly
basis in the surface ocean. WOA provides datasets that
achieve data coverage across all grid points by interpolation.
These data products are used extensively by global ocean
modellers for initialisation and/or evaluation (e.g. Doney
et al., 2009), in combination with biogeochemical datasets
such as dissolved inorganic carbon, alkalinity, pCO2, and
DMS, which have been synthesised through initiatives like
MAREDAT (e.g. the CARINA special issue in ESSD http:
//www.earth-syst-sci-data.net/special issue2.html). The goal
of MAREDAT is to provide, in due course, similar data prod-
ucts and coverage for all planktic components of the global
ocean ecosystem, and this special issue is the first step to-
wards achieving this. For ease of use we have gridded the bi-
ological variables onto the same grid as used for the WOA
(1×1×33 vertical levels ×monthly climatologies). Be-
cause of the large seasonal variability in biological compo-
nents over most of the ocean, we have chosen to provide
monthly files from the start. At this point, there is not yet
Earth Syst. Sci. Data, 5, 227–239, 2013 www.earth-syst-sci-data.net/5/227/2013/
E. T. Buitenhuis et al.: MAREDAT: towards a world atlas of MARine Ecosystem DATa 229
Table 1. Database characteristics.
doi:10.1594/Raw data Chauvenet’s criteria Number of data Number of 10
PANGAEA. Total Excluded Standard Critical on WOA grid boxes with dataa
number outliers deviation value (zc)
Autotrophs
Picophytoplankton 777385 40946 0 0.79 4.36 10747 147
Diazotrophs 774851 3849 1b1.59b3.66b2280 110
Coccolithophores 785092 11503 1 0.92 4.03 5162 167
Phaeocystis 779101 3526 0 1.28 3.72 392 63
Diatoms 777384 91704 151 1.15 4.54 3852 158
Pigments 793246 35634 ND ND ND 10880 174
Heterotrophs
Picoheterotrophs 779142 39766 0 0.44 4.37 9284 84
Microzooplankton 779970 4282 0 0.91 3.67 2029 121
Foraminifers 777386 1057 0 1.05 3.49 745 25
Mesozooplankton 785501 153163 0 1.13 4.65 42245 458
Pteropods 777387 15134 0 1.52 4.13 7151 248
Macrozooplankton 777398 36237 32 1.93 4.29 8147 187
aOut of 539 ocean boxes.
bThe Chauvenet’s criterion for the diazotroph database was calculated separately for the dierent data sources, but here we calculate one value for the standard deviation and
zc for comparison to the other databases.
enough information to furnish filled (interpolated) datasets.
Hence, we did not interpolate the data but produced datasets
with missing values. Our aim in bringing together these data
has been to (1) stimulate research on observation-based im-
provements in our knowledge of the ecological and biogeo-
chemical functioning of the ocean and (2) provide in situ-
based data constraints for numerical models and satellite al-
gorithms that distinguish multiple plankton groups.
2 Data
Both the raw data files and the gridded files that were
compiled for the 11 PFTs and the phytoplankton pigments
are publicly available at the PANGAEA Data Publisher for
Earth and Environmental Science (http://www.pangaea.de/
search?&q=maredat) and the MAREDAT website (http://
www.maredat.info). The latter also includes a technical cor-
ner with the gridding program, QC script, etc. Each of the 12
datasets can be cited with the DOIs reported in Table 1. The
raw data include longitude, latitude, depth, date, abundance,
biomass conversion factors, biomass, references and quality
control flags. The pigment database contains pigment con-
centrations instead of abundance, biomass and biomass con-
version factors. The Phaeocystis database contains biomass
information with and without an estimate of the gelatinous
mucus surrounding colonial cells. The diazotroph database
includes biomass information based on cell counts and on
nifH gene counts. The biomass concentrations of coccol-
ithophores and foraminifers are organic carbon only, while
the pteropod biomass concentrations include both organic
and inorganic carbon. In this paper, we only use the Phaeo-
cystis biomass without mucus, and the diazotroph biomass
based on cell counts.
Furthermore, we provide a database of microzooplank-
ton distribution that was recently published by Buitenhuis et
al. (2010). Some errors in the previous version (C. Stock, per-
sonal communication, 2011) have been corrected (n=682),
and we also took this opportunity to grid this dataset in the
same way as the others (doi:10.1594/PANGAEA.779970).
2.1 Quality control by Chauvenet’s criterion
In all contributing PFT papers, Chauvenet’s criterion has
been used to exclude very high values from the gridded
databases (Glover et al., 2011). While all data had already
been quality controlled by the contributing researchers, there
was still a risk of over-representation of high values from
(1) studies that specifically targeted the occurrence/bloom of
the relevant PFT, (2) high productivity coastal sites or (3) er-
rors in the reported units. Chauvenet’s criterion assumes that
the data has a normal distribution and rejects data on the pre-
sumption that if a set of n measurements were carried out
twice, outliers would be excluded at 1/(2n) probability of
occurrence, thus preventing any bias between the outlier re-
jection in the two sets of measurements. The critical value
occurs at p=11/2n. None of the datasets had a normal
distribution, therefore Chauvenet’s criterion was performed
on log-transformed data. Log-transformation of biomass val-
ues meant the exclusion of zero values. Zero and very low
values for biomass are a true reflection of the ecology of the
oceans. Zero abundance or biomass is often treated as a lack
of measurement (i.e. represented by a blank entry rather than
a zero concentration), even though it supplies useful infor-
mation about the absence of an organism or PFT. This means
that zero values are usually under-represented, especially in
the deep sea. Therefore, a one-sided Chauvenet’s criterion
was applied to identify only the high value outliers. For the
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230 E. T. Buitenhuis et al.: MAREDAT: towards a world atlas of MARine Ecosystem DATa
smallest dataset (foraminifers, n=1057 non-zero observa-
tions) the critical value was 3.50 times the standard devia-
tion from the average, while for the largest dataset (meso-
zooplankton, n=153163) it was 4.65 times the standard de-
viation. The pigment database was subjected to a dierent
set of quality control procedures as described by Peloquin et
al. (2013).
2.2 Gridding
In order to arrive at a consistent collection of gridded data
products for all abundance based PFTs, they were all grid-
ded with the same program, and include the number of obser-
vations, average abundance, average biomass, median abun-
dance, median biomass, standard deviation of abundance,
and standard deviation of biomass, both for the total datasets
and for the non-zero observations. In some datasets, some
of this information was excluded for methodological rea-
sons: there is no abundance for mesozooplankton, and the
databases for picoheterotrophs, diatoms and mesozooplank-
ton contain no zero observations. All PFT and pigment data
were gridded on a 1×1horizontal grid, with grid box cen-
tres from 179.5W to 179.5E and 89.5S to 89.5N. The
vertical axis also follows the WOA spacing, centred on the 33
depths: 0, 10, 20, 30, 50, 75, 100, 125, 150, 200, 250, 300,
400, 500, 600, 700, 800, 900, 1000, 1100, 1200, 1300, 1400,
1500, 1750, 2000, 2500, 3000, 3500, 4000, 4500, 5000, and
5500m. The time axis uses a climatological year with 12
months. By using a climatological year we implicitly ignore
any temporal trend in the datasets, some of which span sev-
eral decades, but at the present coverage this seems justified.
2.3 Patchiness
We use the following formula as a mathematical represen-
tation of the patchiness of the horizontal distribution of the
PFTs summed over all depths:
P=1/B×(Σ((LB)2)/(n1)) (1)
where Pis patchiness, Bis mean biomass, Lis the average
within 10longitude and latitude of the individual observa-
tions B, and nis the number of observations.
3 Results
3.1 Microzooplankton biomass database
The microzooplankton biomass database contains 4044 geo-
referenced data points. The gridded database contains 2029
data points (Fig. 1, Table 1). Data from the Northern Hemi-
sphere makes up 64% of the database, data from the top
225m makes up 96% of the database, and data from the
spring and summer months makes up 63% of the data.
The average biomass is 7.0±15.3 µg C L1with a median
Figure 1. Microzooplankton biomass [µgCL1]. (A) 0–40m,
(B) 40–112.5 m, (C) 112.5–225m, (D) >225m.
of 1.8µgCL1. Biomass is considerably lower in the trop-
ics (3.4±7.5µgCL1) than in the Northern Temperate (23–
67N, 7.9±18.7µgCL1) and Southern Temperate Zones
(8.4±13.2µgCL1), and increases further towards the Arc-
tic (9.7±9.9µgCL1) and Antarctic (16.1±25.5µgCL1).
Compared to the microzooplankton database published by
Buitenhuis et al. (2010), the corrected database contains both
lower and higher values. The mean of the whole dataset has
decreased by almost a factor 3, while the median has de-
creased by 10%.
3.2 Comparison of PFT biomass concentrations
The number of data points that are available for each PFT
diers by two orders of magnitude (Table 1). The larger
databases have been built on earlier data synthesis eorts
(O’Brien et al., 2002; Vaulot et al., unpublished data; Gos-
selin et al., unpublished data). We intend to maintain this
group eort and extend the databases in future. By making
both the raw and gridded databases publicly available, we
also hope to encourage other researchers to publish extended
versions. The horizontal distribution of each PFT at selected
depths is presented in the contributing papers. Here, we com-
pare the global average vertical profiles of the 11 PFTs and
phytoplankton pigments (Fig. 2) and the zonal average sec-
tions (depth versus latitude) of the 11 PFTs in the top 200m
(Fig. 3; for the zonal average sections of pigments see fig-
ure 8 in Peloquin et al., 2013).
3.2.1 Patchiness
We calculated the horizontal patchiness of each PFT. There is
a clear increase in patchiness with organism size (Fig. 4), al-
though the relationship is dierent for autotrophs (patchiness
=2.14×log(size) +0.98, n=5, p=0.04) and heterotrophs
(log(patchiness) =0.25×log(size)0.35, n=6, p=0.04).
Earth Syst. Sci. Data, 5, 227–239, 2013 www.earth-syst-sci-data.net/5/227/2013/
E. T. Buitenhuis et al.: MAREDAT: towards a world atlas of MARine Ecosystem DATa 231
Figure 2. Depth profiles of average PFT biomass [µgCL1].
(A) Autotrophs from abundance. Black, “Pico”: picophytoplank-
ton; grey, “Diaz”: diazotrophs; blue, “Cocc”: coccolithophores;
cyan, “Phae”: Phaeocystis; brown, “Diat”: diatoms. (B) Het-
erotrophs from abundance. Black, “Bact”: picoheterotrophs; grey,
“Micr”: microzooplankton; blue crosses, “Fora”: foraminifers;
cyan, “Meso”: mesozooplankton; green, “Pter”: pteropods; brown,
“Macr”: macrozooplankton. (C) Autotrophs from pigments. Black,
“Pico”: prokaryotes from chlorophyll band zeaxanthin; blue,
“Nano”: nanophytoplankton from 19’-hexanoyloxyfucoxanthin,
19’-butanoyloxyfucoxanthin, and alloxanthin; cyan, “Peri”: di-
noflagellates from peridinin; brown, “Fuco”: diatoms from fucox-
anthin; green, “Tot”: total; dashed black: prokaryotes from sum of
abundance based diazotroph and cyanobacteria; dashed blue: sum of
abundance based biomass of coccolithophores and picoeukaryotes.
(D) Black, “NoPha”: sum of available phytoplankton without and
grey, “Phyt”: with Phaeocystis; blue, “Het”: sum of heterotrophs
without and cyan, “Hettot”: with foraminifers and pteropods; green,
“Pigm”: total phytoplankton from pigments; Brown, “Chl”: WOA
2005 chlorophyll ×model C: Chl ratio. See text for details.
This increased patchiness may reflect a change from small
K-selected organisms, which tend to form a constant back-
ground biomass, to large r-selected organisms (MacArthur
and Wilson, 1967), which go through bloom and bust cy-
cles. For the zooplankton it may in addition reflect a tendency
for larger organisms to show coordinated vertical migration
and/or swarming.
3.2.2 Autotrophic biomass
The highest phytoplankton biomass recorded in our datasets
is found for Phaeocystis (Fig. 2a). As can be seen in fig-
ure 7 of Vogt et al. (2012), there is considerable sampling
bias towards coastal waters, where dense Phaeocystis blooms
can be a regular occurrence, and under which conditions
a mix of colonial and single cells are often found. Under
non-bloom conditions, Phaeocystis is mostly found as single
cells, which cannot be distinguished from other nanophyto-
plankton with standard microscopic protocols, and therefore
such measurements of background numbers of single Phaeo-
cystis cells are almost absent from the database.
The next most abundant phytoplankton PFTs are picophy-
toplankton and diatoms (Fig. 2a), which is consistent with
accepted wisdom about the importance of these two groups.
However, dominance of picophytoplankton in the low lati-
tudes and diatoms in the temperate latitudes has been sug-
gested (Alvain et al., 2005; Uitz et al., 2006), while our
plots of zonal average biomass show very little latitudinal
dierences in these groups (Fig. 3a, e). Dominance of pico-
phytoplankton in low latitudes can be consistent with a ho-
mogenous latitudinal distribution because of the increase in
biomass from low to temperate latitudes (Fig. 3f), but for di-
atoms there is a real discrepancy. The diatom biomass profile
(Fig. 2a) has a distinct peak at 125 m. This peak is caused by
a single observation of 7210µgCL1, which was measured
in a massive accumulation of mat forming Rhizosolenia, a
feature which has been regularly observed in various olig-
otrophic environments (Shipe et al., 1999).
The average biomass of coccolithophores is surprisingly
low (Fig. 2a), though it is almost constant down to 150 m,
which is consistent with previous studies that showed the
importance of coccolithophores in the lower euphotic layer
(Cort´
es et al., 2001; Haidar and Thierstein, 2001). Coccol-
ithophore biomass is lower even than diazotroph biomass, al-
though the latter have hardly been measured at high latitudes
(Fig. 3b), where they are thought not to occur (Carpenter,
1983).
3.2.3 Comparison of autotrophic biomass with pigment
distributions
Recent syntheses suggest that virtually no pigment can be
unequivocally assigned to quantify one marine algal type
or species, since most of these pigments are shared across
multiple phytoplankton taxa (Higgins et al., 2011). For this
reason, statistical methods employing multiple pigment to
chlorophyll ratios are required to adequately resolve the
algal community composition (e.g. Mackey et al., 1996;
Van den Meersche et al., 2008). Nonetheless, a prelimi-
nary analysis of the basin-scale distribution of a few key
diagnostic pigments from the global phytoplankton pigment
database (Peloquin et al., 2013) permits a rough comparison
with some of the autotrophic biomass distributions from the
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232 E. T. Buitenhuis et al.: MAREDAT: towards a world atlas of MARine Ecosystem DATa
Figure 3. Zonal average PFT biomass [µgCL1]. (Pico) Picophy-
toplankton, (Diaz) diazotrophs, (Cocco) coccolithophores, (Phae)
Phaeocystis, (Diat) diatoms, (Chl) WOA 2005 chlorophyll ×Plank-
TOM5.3 C: Chl ratio, (Bac) picoheterotrophs, (Micro) microzoo-
plankton, (Fora) foraminifers, (Meso) mesozooplankton, (Ptero)
pteropods, and (Macro) macrozooplankton.
abundance databases. For example, zeaxanthin, roughly in-
dicative of the presence of cyanobacteria, exhibited a max-
imum concentration around the equatorial region, and is an
order of magnitude lower poleward of 50(figures 8l and 9l
in Peloquin et al., 2013). This is consistent with the biomass
data of Prochlorococcus and Synechococcus (figure 6a, b
in Buitenhuis et al., 2012a) and the observed lack of dia-
zotroph biomass at high latitudes (figure 3b, Luo et al., 2012).
In addition, divinyl chlorophyll ais a strong biomarker for
the presence of Prochlorococcus. Concentration of this pig-
ment in the subtropics occurs at slightly deeper depths in the
Southern Hemisphere than in the Northern Hemisphere (fig-
ure 9f in Peloquin et al., 2013), mirroring those patterns ob-
served in the Prochlorococcus biomass distribution (figure 6a
in Buitenhuis et al., 2012a). Fucoxanthin, a widely prevalent
pigment among diatom species, exhibits maxima at high lat-
Figure 4. Patchiness (see Sect. 2.3) as a function of log (nominal
organism size in µm). Plusses: autotrophs; crosses: heterotrophs.
itudes, particularly in the Southern Hemisphere (figures 8g
and 9g in Peloquin et al., 2013). However, Fig. 3e indicates
much less meridional variability in diatom abundance, which
further highlights the need for incorporating the complexity
of multiple pigment ratios when assessing phytoplankton dis-
tributions.
In order to also compare the depth profiles of biomass
from the abundance and pigment databases, we first use pig-
ment concentrations to calculate the contribution of dier-
ent size classes of the phytoplankton to the overall chloro-
phyll concentration using the conversion factors of Uitz et
al. (2006), and then convert chlorophyll to biomass using the
C:Chl ratios of the PlankTOM5.3 model (Buitenhuis et al.,
2013), which uses photosynthetic parameters synthesised by
Geider et al. (1997). Because the C:Chl ratio of diatoms is
about a third of the other two phytoplankton groups in the
model, we use one profile of C:Chl ratios as a function of
depth for diatoms and another profile for all other phyto-
plankton. The resulting pigment based biomass concentra-
tions for diatoms and prokaryotes agree quite well with the
abundance based biomass concentrations (Fig. 2a, c). The
pigment based biomass for nanophytoplankton is close to
the abundance based biomass of coccolithophores plus pi-
coeukaryotes. This is rather surprising given the taxonomic
diversity of larger eukaryotes that have not been included in
the biomass from abundance, and the exclusion of Phaeocys-
tis biomass. The pigment based biomass of dinoflagellates is
estimated at roughly a third of the diatom biomass.
A thorough chemotaxonomic analysis of the global pig-
ment database will reveal patterns in phytoplankton commu-
nity structure on finer scales, and potentially contribute miss-
ing information on autotrophic dinoflagellates and nanophy-
toplankton. In concert with MAREDAT biomass develop-
ment and analysis, analysis of global pigment distributions
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E. T. Buitenhuis et al.: MAREDAT: towards a world atlas of MARine Ecosystem DATa 233
Table 2. PFT characteristics.
Approximate diameter PFT biomass (µgCL1) in top 200 mbPFT global biomass
[µm] [Pg C]c
Min Max Min Max Mean Median Std Min Max
Autotrophs
Picophytoplankton 0.6 3 0 449 12.7 5.47 22.1 0.28 0.64
Diazotrophs 0.6 2000a0 676 5.5 0.03 27.4 0.008 0.12
Coccolithophores 5 20 0 83 0.4 0.05 2.4 0.001 0.03
Phaeocystis 5 2000a0 1248 28.3 2.18 96.0 0.11 0.71
Diatoms 10 200 0 4155 16.5 1.74 104.7 0.10 0.94
Heterotrophs
Picoheterotrophs 0.4 0.6 0.2 58 8.1 6.64 6.0 1.00 1.10
Microzooplankton 5 200 0 304 9.3 3.12 17.1 0.48 0.73
Foraminifers 100 1000 0 0.4 0.03 0.008 0.05 0.0009 0.002
Mesozooplankton 200 2000 0 345 6.0 2.77 10.6 0.33 0.59
Pteropods 1000 3000 0 878 2.9 0.01 25.4 0.026 0.67
Macrozooplankton 2000 10000 0 3967 9.3 0.21 67.7 0.22 1.52
aLower end of size range is for individual cells, higher end for colonies.
bCalculated from gridded databases.
cLower estimate using median depth profiles, higher estimate using mean depth profiles; see Sect. 3.2.5 for details.
will help further guide the representation of all PFTs in
ecosystem models.
3.2.4 Heterotrophs
The largest zooplankton biomass is found for macrozoo-
plankton, up to 59µgCL1at 20 m depth (Fig. 2b). Macro-
zooplankton include some species that swarm, which could
explain this sharp biomass peak, but it is also possible that
some sampling bias such as proposed for the high diatom
concentrations at 125m depth occurred at a biomass con-
centration that was not quite high enough to be excluded
by Chauvenet’s criterion. Also, as noted above, the biomass
distribution of all PFTs tends to become more patchy with
increasing organism size (Fig. 4), thus increasing the errors
around the means. The biomass of picoheterotrophs, meso-
zooplankton, microzooplankton and pteropods is fairly sim-
ilar in the top 100m, around 6µgCL1(Fig. 2b), while be-
low 100m the microzooplankton biomass is about half that
of the picoheterotrophs and mesozooplankton, and pteropod
biomass about a tenth, although there are no mesozooplank-
ton data below 500m. The biomass of planktic foraminifers
is low, 0.04 µgCL1at 10 m depth, and decreases to less than
0.01 below 300m. At present, the database of foraminifers is
limited to the Northern Hemisphere (Fig. 3i).
The numbers of observations drop dramatically below
1000m for the zooplankton. Picoheterotrophs are the only
PFT for which there are still around 100 observations at
each level down to 3000m. It is dicult to make definite
statements about the ecology of the deep sea with so lit-
tle information, but the data suggest that there are non-
negligible concentrations of zooplankton in the deep sea:
up to 6µgCL1macrozooplankton in the mesopelagic and
0.19µgCL1microzooplankton below 2750m, compared to
0.36µgL1picoheterotrophs. These biomass concentrations
are low relative to the surface biomass, but the volume of the
deep sea is much larger, suggesting that zooplankton could
make a substantial contribution to global ocean biogeochem-
ical cycles in the deep sea as well. Picoheterotrophs have re-
ceived much more attention with respect to their role in the
biogeochemical cycling of organic matter in the deep ocean,
but the ecology and biogeochemistry of the deep sea with a
significant zooplankton contribution could be quite dierent
from what we expect for a picoheterotroph-dominated deep
sea.
3.2.5 Global PFT biomass inventories
The integrated global biomass inventories of the 11 PFTs
are presented in Table 2. A low estimate was calculated by
multiplying the median biomass at each depth by the vol-
ume of water at that depth, and a high estimate by using
the mean concentrations at each depth. We vertically inter-
polated biomass between depths without observations. The
main uncertainties in the biomass estimates are the uncertain-
ties around conversion from abundance to biomass, a lack of
coverage (which is due to both lack of samples and to only
partial availability of those samples that have been taken),
and also the tendency to sample near the coast or where a
PFT is thought to occur or even bloom. Because of the latter
sampling bias, the maximum global biomass inventories are
likely to be overestimates. The conversion factors are proba-
bly the main source of uncertainty in all the datasets, while
the importance of lack of coverage or of sampling bias ap-
pear to vary between datasets, e.g. for Phaeocystis there is a
substantial sampling bias towards the coast, as noted above,
which appears to explain the high horizontally averaged pro-
file (Fig. 2a). For bacteria it was shown that a potential bias
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234 E. T. Buitenhuis et al.: MAREDAT: towards a world atlas of MARine Ecosystem DATa
towards the coast (in this case due to an observed change in
the conversion factor rather than over-representation of sam-
pling) was unimportant (Buitenhuis et al., 2012b).
We compare our phytoplankton biomass concentrations
to the WOA 2005 total chlorophyll measurements. Without
conversion to carbon, this equates to 18 to 30Tg Chl. We
calculated the total phytoplankton biomass by multiplying
the WOA 2005 chlorophyll concentration by the C: Chl ratio
profile of the PlankTOM5.3 model (Buitenhuis et al., 2013,
Fig. 2d). The sum of our phytoplankton PFT biomass inven-
tories is between 0.7 and 1.6 times the total phytoplankton
derived from WOA chlorophyll down to 250 m (Fig. 2d),
despite the fact that we did not include a large part of the
nanophytoplankton nor the autotrophic dinoflagellates. One
of the reasons for the overestimate at the surface is proba-
bly a strong sampling bias in the Phaeocystis dataset towards
high values, as suggested above. Dividing our phytoplank-
ton carbon without Phaeocystis by WOA chlorophyll results
in C:Chl ratios of between 44 and 99 down to 250m, ex-
cept at 125m where diatom biomass is unexpectedly high.
While these C:Chl ratios are reasonable, they can be quite
variable between taxonomic groups, even at a given light in-
tensity. Therefore, these C: Chl ratios do not constitute a very
stringent test, and a biomass similar to the picophytoplankton
depth profile could be added to the total global mean biomass
at any depth and still result in reasonable C: Chl ratios.
For the phytoplankton both the biomass and the number of
observations decrease rapidly below 225m (<1–3 % of the
data). For diatoms, and in particular for Phaeocystis, we sus-
pect an additional possible bias because there are a few high
values at depth, which show a considerable departure from
the expected decrease of biomass with depth. These high
concentrations below the euphotic zone are likely to be sink-
ing cells after a bloom in the upper ocean rather than viable
populations. However, recent samples from a depth range of
2000–4000 m that were taken during the Malaspina 2010 ex-
pedition confirm the ubiquitous presence of morphologically
well-preserved, living phytoplankton cells of dierent taxa
in the deep ocean (Agust´
ı et al., ASLO conference presenta-
tion, 2012). The latter results suggest the existence of a far
more ecient biological pump than previously thought, or
the presence of physiological mechanisms that preserve cells
at high pressures and low temperatures. We have integrated
Phaeocystis biomass only to 225m, and diatoms to 550m.
For the picoheterotrophs, estimating global biomass from
the depth profile seems to give reasonable results since there
are still a fair number of observations and the biomass in
the deep sea is fairly homogenous. However, the uncertainty
about abundance to biomass conversion applies to pico-
heterotrophs as well. For the mesozooplankton the biomass
has only been integrated where there was data down to
500m, and for the pteropods the biomass has only been in-
tegrated down to 1050m (with only 4 observations between
1050 and 2000m).
3.2.6 Comparison of autotrophic and heterotrophic PFT
biomass
In order to place PFT biomass in a wider context, total
heterotrophic biomass is examined in relation to total au-
totrophic biomass in the global ocean (Fig. 5a). The median
concentration for each group is considered. Lower biomass
in the autotrophic component of the ecosystem reflects the
higher turnover and metabolic costs of these small organisms
(Odum, 1971). With higher turnover and metabolic costs, a
low standing crop with high productivity can supply higher
trophic levels with the energy that is then stored in their
biomass because of lower turnover and metabolic costs. The
global biomass data for each plankton group (Fig. 5a) do
not show a blunt food pyramid as is typically found in ter-
restrial ecosystems, but instead confirm the high H:A(het-
erotroph:autotroph) ratio of around 1 (see also Fig. 2d) that
was previously found by Gasol et al. (1997).
In general, the coastal biomass concentrations are higher
than in the open ocean (Fig. 5b, c), as expected. Foraminifers
and picophytoplankton are the exceptions, with lower con-
centrations in the coastal ocean. For foraminifers this has
been reported previously (Retailleau et al., 2009). Coccol-
ithophores show a lower mean but higher median in the
coastal ocean. Judging from the standard deviation associ-
ated with many of the PFTs (Table 2, Fig. 5), caution is re-
quired not to over-interpret these data. In accordance with the
results of Gasol et al. (1997), we find that metazoan biomass
possibly increases more than phytoplankton in the coastal
ocean, but in contrast to them we find that microzooplankton
also increase at least as much as phytoplankton. The bacterial
abundance is the same in the coastal and open ocean, which is
consistent with a decrease relative to phytoplankton in Gasol
et al. (1997), but more work is needed to confirm whether the
carbon content of bacteria is higher in the coastal ocean (see
Buitenhuis et al., 2012b).
4 Discussion
At a time when we, the human species, are subjecting the
biosphere to unprecedented rates of change, we know very
little at the global scale of the baseline functioning of the
biosphere. There is a large gap between the detailed but anec-
dotal information that is available about the physiology of
individual species under particular in situ or controlled labo-
ratory conditions, and what we can say about the functioning
of the biosphere as a whole. In ocean ecosystem modelling
we have only begun to address this gap in the last decade. The
present eort at data synthesis on the global biomass distri-
bution of most of the PFTs representing the lower trophic
levels of the ocean ecosystem is the first attempt at compre-
hensively addressing this gap. It is necessarily preliminary
and raises more questions than it answers. These questions
indicate that despite the scarcity of data for most groups we
still know much more about the abundance of organisms than
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E. T. Buitenhuis et al.: MAREDAT: towards a world atlas of MARine Ecosystem DATa 235
Figure 5. Trophic pyramid of autotrophic and heterotrophic PFTs. Mean (black outline) and median (grey fill, values in brackets) biomass
(µgCL1) in the top 200 m for each of the PFTs presented in the MAREDAT special issue. Standard deviation is listed but not shown in the
graph. (a) Global ocean (for full details see Table 2, (b) coastal and (c) open ocean.
about their carbon content/elemental composition, and much
more about places where organisms are abundant than about
the much larger volumes of global ocean where biomass is
relatively low.
Information becomes even more anecdotal, and under-
standing more tenuous, when looking at time scales longer
than a few seasons. For large regions ofthe global ocean, sys-
tematic changes at an interannual scale (or longer) are largely
unknown for most PFTs. Extending our perspective to the
longer term and geological time scales, MAREDAT data may
lead to a better understanding of both environmental and cli-
mate change, and the rate of CO2increase experienced over
not only glacial-interglacial cycles but also since the begin-
ning of industrialisation. Over time intervals of millions of
years, distribution and size of planktic foraminifers (Schmidt
et al., 2004) and coccolithophores (Henderiks and Pagani,
2007) have been aected by climate change, and this might
also be true for other PFTs. The MAREDAT approach is a
step towards a more complete, qualitative and quantitative
understanding of PFTs and associated feedbacks with past
and future environmental and, in particular, climate change
at a global scale and over long intervals of time.
Currently, at least two large-scale programs are collect-
ing plankton samples that will increase our knowledge on
plankton community composition and species diversity in the
global oceans. The Tara Oceans expedition (http://oceans.
taraexpeditions.org) is collecting plankton samples from
2009 to 2013 for a depth range of 0 to 200 m, including sam-
ples from all the major ocean basins. The Malaspina 2010 ex-
pedition (http://www.expedicionmalaspina.es) completed its
journey in 2011, and collected samples from the deep oceans,
at depths down to several thousand metres (Laursen, 2011).
The latter expedition will furnish us with new data to increase
our understanding of deep ocean ecosystems, while the for-
mer will increase data coverage in the upper layers of the
ocean.
The ranges of global biomass inventories we calculated
from the profiles of median and mean biomass in several
cases span more than an order of magnitude. Despite this un-
certainty they indicate that heterotrophic PFTs are at least
as abundant as autotrophic PFTs (Table 2; Figs. 2d, 5), even
if we account for the risk of double counting foraminifers
as microzooplankton and pteropods as macrozooplankton in
the sum of the zooplankton biomass. Within the uncertainty
in the data this is in agreement with Gasol et al. (1997), who
estimated that the open ocean biomass of phytoplankton, to-
tal zooplankton and picoheterotrophs is roughly the same.
We have compared our estimates of the sum of the available
total phytoplankton biomass estimates with in situ chloro-
phyll. We find the sum of phytoplankton biomass is higher
than biomass estimated from chlorophyll. All these databases
are biased towards oversampling of the coastal ocean. The
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236 E. T. Buitenhuis et al.: MAREDAT: towards a world atlas of MARine Ecosystem DATa
coastal ocean represents 5% of the ocean area, but the phy-
toplankton biomass in the coastal ocean represents between
7 % (diazotrophs) and 34% (Phaeocystis and diatoms) of the
respective databases, while the WOA 2005 in situ chloro-
phyll represents 20% of that database. In future updates of
the databases we intend to diminish this bias by including
additional observational data and improving the cell to car-
bon conversion algorithms, in particular for those PFTs with
a large range of morphotypes and cell sizes. This will allow
a better determination of total phytoplankton biomass in the
global ocean.
Plankton are governed by physical, chemical and bio-
logical processes that occur on a vast variety of temporal
and spatial scales. This is one reason why large datasets
are needed to reliably estimate the global biomass distri-
bution of any PFT. Physical processes can drive patchiness
in PFTs on scales from millimetres to thousands of kilome-
tres (Pinel-Alloul, 1993; Folt and Burns, 1999). Over fine
scales, millimetres to tens of metres, biological processes
are often more important. For the picoheterotrophs, the esti-
mated global biomass using the median and mean concentra-
tions is very similar, indicating that the horizontal variation
in biomass makes only a small contribution to the uncertainty
in the estimated global biomass. This range does not include
the uncertainty from the respective conversion factors from
abundance to biomass. For the autotrophic PFTs, horizon-
tal variability is larger (Fig. 4), and the dierence between
the median and the mean is more than an order of magni-
tude for three PFTs (Table 2). For diazotrophs this variability
is compounded by lack of spatial coverage, but for coccol-
ithophores and pteropods there is also large variability de-
spite a better spatial coverage (Table 1, Fig. 3). For the zoo-
plankton PFTs, individual behaviour, e.g. mating, predator
avoidance and searching for food (Folt and Burns, 1999), and
variables such as food concentration, swimming behaviour
(Pinel-Alloul, 1993) and species interactions (Mackas et al.,
1985) are important examples of small-scale biological pro-
cesses that aect patchiness. Growth rates for a number of
groups within the macrozooplankton, particularly the gelati-
nous members, salps, ctenophores, cnidarians and appendic-
ularians, are higher than those of mesozooplankton cope-
pods (Hirst and Bunker, 2003). The ability of these groups
to “bloom” or swarm, through a combination of high graz-
ing rates, growth rates and life history, when food concen-
tration or other environmental factors are favourable, means
that macrozooplankton may reach high biomass concentra-
tions in areas where they amass, resulting in a spatially het-
erogeneous distribution.
We show that the patchiness of PFT biomass increases
with size. In terms of database synthesis, this means that
more data would be needed for larger organisms before we
can reliably generate interpolated datasets of biomass. In
terms of model representation, it suggests that it will be more
dicult to accurately represent individual data points, and
that it will only be possible to represent the mean state or to
build stochastic representations. It should be noted that by
using point measurements (usually representative of <1m2)
and binning these into a horizontal grid spacing of 1, there
is potential for distorting the results. On the one hand, using
gridded data means that the calculation cannot detect vari-
ations in patchiness that are smaller than 1. On the other
hand, there are not enough data points in each grid point to
obtain a true reflection of the average biomass in that grid
cell, and therefore fine scale variability could potentially be
ascribed to a larger scale. There is no indication that the latter
invalidates the increase in patchiness with size that we find,
since if it did then patchiness should be significantly higher
for smaller datasets, which is not the case (p=0.5, n=11).
In addition to the depth and coastal ocean bias already
noted for the phytoplankton, all of the heterotroph databases
also have a depth bias (62–96% of samples at <225 m) and
all but one have a coastal bias (13–28% of samples in the
coast). The exception is foraminifers (2%). In addition, 9 of
the databases show a substantial bias towards samples in the
Northern Hemisphere (64–100% of the databases). The ex-
ceptions are pigments and coccolithophores, while macro-
zooplankton show a bias towards the Southern Hemisphere
(70%). The databases also tend to show some bias towards
spring and summer (56–86% of the databases).
Qualitative information on the presence or absence of spe-
cific autotrophic groups from MAREDAT may help guide the
a priori selection of pigment ratios that is essential for quan-
tifying algal type abundance through Bayesian-type analy-
ses (Mackey et al., 1996; Van der Meersche et al., 2008).
Conversely, the biomass databases from MAREDAT will be
instrumental in evaluating those quantitative results, which
may help bridge some of the information gaps in phytoplank-
ton distributions.
In its first iteration it is dicult to judge the overall qual-
ity of the MAREDAT dataset. The data gathering eort has
been a massive success (see Table 1). The data has been qual-
ity controlled and each dataset has documented the associ-
ated uncertainties. There is consistency across the datasets in
this respect, and ensuring this consistency is one of the major
achievements of MAREDAT (see Table 1).
5 Summary
This introduction to MAREDAT and the data, results and dis-
cussion presented here represents what was at one point an
almost impossible goal for many of those involved in this
project. We are now in a position to make the first data based
estimates of global annual average biomass for 11 PFTs and
to validate biogeochemical models. PFT modelling is a rela-
tively new development in ocean biogeochemical modelling,
and global models embedded in general circulation models
(GCMs) have only been available for the last 10 yr (Au-
mont et al., 2003). Improved validation of these models will
also support climate change research, helping early detection
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E. T. Buitenhuis et al.: MAREDAT: towards a world atlas of MARine Ecosystem DATa 237
of impacts and feedbacks from current climate change, and
building better models for projections into the future.
The MAREDAT data will also be fundamental for the in-
vestigation of global plankton biogeography and ecology. In
this initial analysis, we investigate zonal and vertical patterns
of plankton biomass, their relative contribution to global
plankton biomass, and the relationship of body size with
patchiness. We find that (1) the global total heterotrophic
biomass is at least as high as the total autotrophic biomass,
(2) the biomass of zooplankton calcifiers is higher than that
of coccolithophores, (3) patchiness of biomass distribution
increases with organism size, and (4) although zooplank-
ton biomass measurements below 200m are rare, the limited
measurements available suggest that Bacteria and Archaea
are not the only heterotrophs in the deep sea. Future stud-
ies will investigate patterns of plankton diversity, ecological
niches, and habitat structure (Luo et al., 2013) and dynamics.
The MAREDAT initiative has been accepted by many
within the community as a timely, important and “enor-
mously useful” contribution to biological oceanography and
biogeochemistry. Similar eorts have been suggested to col-
lect other marine ecological data, such as phytoplankton
traits (e.g. Barton et al., 2013). The general weaknesses, e.g.
fundamental lack of open water data and lack of elemental
information for a variety of taxa, have also been recognised.
Another major weakness of the initiative was that it was not
possible to include some existing published and unpublished
datasets, either because they were not publicly available, due
to a lack of time for data retrieval, or because the response
rates of the data owners to our data call were low. However,
we have now set a precedent within the community for pub-
lishing this type of data and giving full accreditation to those
involved in gathering it. Hopefully this will encourage data
holders to contribute data in the future. The authors involved
in this special issue have agreed that datasets and documen-
tation will be updated for the next release of MAREDAT,
planned for 2015. The experience gained from this MARE-
DAT iteration and the subsequent analysis of plankton ecol-
ogy based on this data will help inform MAREDAT2015.
Overall, this special issue has brought together abundance
and biomass data for most of the PFTs in the lower trophic
levels of the ocean ecosystem, as well as a global database of
HPLC-based phytoplankton pigments. In several cases the
biomass databases represent the first of their kind to cover
all ocean basins, and in the remaining cases they are substan-
tially larger than what has been available so far. In all, we
have brought together 436887 biomass measurements in 12
databases. The gridded data products have been provided for
the ocean ecosystem modelling community. The raw data, in-
cluding references and metadata, are also publicly available
at http://www.pangaea.de/search?&q=maredat.
Acknowledgements. We thank Marie-Pierre Gosselin for
collecting the first versions of several PFT databases, funded by
EUR-OCEANS. We thank the guest editors St´
ephane Pesant and
Walker O. Smith, the ESSD editorial team Dave Carlson and
Hans Pfeienberger, and the PANGAEA team. We acknowledge
funding from the EU (to ETB, EMBRACE, contract 282672, to
COB, Greencycles, contract 238366, to RM, FAASIS, MEST-CT-
2004-514159), ETH Z¨
urich (to MV), and the National Science
Foundation (to SCD and YL, NSF-EF-0424599).
Edited by: W. Smith
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... This also suggests a possible reason why several BGC models underestimate mean global mesozooplankton biomass by a similar magnitude ( Figure S10 in Supporting Information S1) (Aumont et al., 2015;Lovato et al., 2022). In addition, mean global microzooplankton estimates from the Global-k scenario are much greater than observations by Buitenhuis et al. (2013), where biomass is estimated to have a mean of 9.3 ± 17.1 mgC m 3 and a median of 3.1 mgC m 3 . These limitations occur despite improved model skill at reproducing the magnitude and distribution of satellite-derived phytoplankton. ...
... These limitations occur despite improved model skill at reproducing the magnitude and distribution of satellite-derived phytoplankton. Local-k mean global biomass for microphytoplankton is within the range of estimates by Buitenhuis et al. (2013) (Table 3). ...
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... Yet, complex system models are inherently data-hungry, and model predictions are often limited by the available data [95]. There are several open or publicly available resources that can aid in ecosystem model development and parameterization [96][97][98], yet entire-system model-building efforts are still costly and time-consuming, as many sources of information are missing or difficult to obtain [8,99]. ...
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As the impacts of climate change continue to intensify, humans face new challenges to long-term survival. Humans will likely be battling these problems long after 2100, when many climate projections currently end. A more forward-thinking view on our science and its direction may help better prepare for the future of our species. Researchers may consider datasets the basic units of knowledge, whose preservation is arguably more important than the articles that are written about them. Storing data and code in long-term repositories offers insurance against our uncertain future. To ensure open data are useful, data must be FAIR (Findable, Accessible, Interoperable and Reusable) and be complete with all appropriate metadata. By embracing open science practices, contemporary scientists give the future of humanity the information to make better decisions, save time and other valuable resources, and increase global equity as access to information is made free. This, in turn, could enable and inspire a diversity of solutions, to the benefit of many. Imagine the collective science conducted, the models built, and the questions answered if all of the data researchers have collectively gathered were organized and immediately accessible and usable by everyone. Investing in open science today may ensure a brighter future for unborn generations.
... The abundance-based estimates rely on relatively sparse, in situ observations and must make assumptions about cellular carbon concentrations. Abundance-based estimates from Buitenhuis et al. ( 38 ) put global C phy between 500 and 2,400 Tg. Relying on previous estimates, a global census for all oceanic life on Earth ( 41 ) provides a best estimate of ~600 Tg C phy . ...
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... These approaches have been recently adapted for marine epipelagic species (Benedetti et al. 2021;Reygondeau and Beaugrand 2011;Righetti et al. 2019;Rombouts et al. 2009). However, limited efforts were made to investigate the global diversity of mesozooplankton in the entire mesopelagic ocean because the majority studies focused only on the upper mesopelagic zone (Buitenhuis et al. 2013;Drago et al. 2022). ...
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... The total zooplankton biomass of 0.5-0.53 Gt C in our simulation ( Figure 3, Table C1) is at the upper end of estimates observed by Buitenhuis et al. (2013), but within the very large uncertainty range given by Drago et al. (2022). Furthermore, the distribution of vertically integrated zooplankton biomass in UVic is similar to the vertical integral of the net zooplankton biomass of DVM 200 F1 (Figures C1a and C1b) showing large maxima in the tropical oceans and also large values in the high latitudes. ...
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Vertical migrants are a diverse group of organisms, which includes crustaceans, cephalopods and mesopelagic fishes. They play an active role in the biogeochemical cycles but are in general not included in numerical models. In this study we introduce a fully coupled Earth system model that represents vertical migration and with this resolves the key components of the mesopelagic ecosystem, namely migrating zooplankton and mesopelagic fish, including their feedbacks on biogeochemical cycles. The redistribution of nutrients in the water column by vertical migration results in a reduction of the net primary production of 14%–21%, as well as in an asymmetric response in the low oxygenated waters in the tropical Pacific (an increase in the northern and a decrease in the southern oxygen minimum zone). On a global scale, we find the active transport of carbon out of the surface layer to be equivalent to ∼25% of the total export (∼30% relative to passive sinking). In the low latitudes, migration results regionally in a reduction of the shallow export by 2%–10% and an increase of the deep carbon export by 6%–15%. In our simulations, mesopelagic fish, with a biomass of 3–3.4 Gt wet weight, have a slightly larger impact on active carbon flux than migrating zooplankton.
... compilations to reducing the gap in available size structure estimates A global compilation of particle size distribution has recently been published by Kiko et al. (2022) using the UVP5 bulk particle size distribution accessible from EcoPart. Other recent studies (e.g., Hatton et al., 2021) have also constructed global estimates of size distribution in marine organisms using indirect biomass estimates of arbitrary plankton size classes derived from satellite proxies, models, or data compilations like COPEPOD and the MARine Ecosystem biomass DATa (MAREDAT, Buitenhuis et al., 2013) without relying on direct size estimates. More recently, Atkinson et al. (2024) compiled estimates of spectral slopes measured in 41 sites, mostly located in the Atlantic Ocean and a number of lakes, displaying important characteristics relevant to studying the impact of climate change. ...
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In marine ecosystems, most physiological, ecological, or physical processes are size dependent. These include metabolic rates, the uptake of carbon and other nutrients, swimming and sinking velocities, and trophic interactions, which eventually determine the stocks of commercial species, as well as biogeochemical cycles and carbon sequestration. As such, broad-scale observations of plankton size distribution are important indicators of the general functioning and state of pelagic ecosystems under anthropogenic pressures. Here, we present the first global datasets of the Pelagic Size Structure database (PSSdb), generated from plankton imaging devices. This release includes the bulk particle normalized biovolume size spectrum (NBSS) and the bulk particle size distribution (PSD), along with their related parameters (slope, intercept, and R2) measured within the epipelagic layer (0–200 m) by three imaging sensors: the Imaging FlowCytobot (IFCB), the Underwater Vision Profiler (UVP), and benchtop scanners. Collectively, these instruments effectively image organisms and detrital material in the 7–10 000 µm size range. A total of 92 472 IFCB samples, 3068 UVP profiles, and 2411 scans passed our quality control and were standardized to produce consistent instrument-specific size spectra averaged to 1° × 1° latitude and longitude and by year and month. Our instrument-specific datasets span most major ocean basins, except for the IFCB datasets we have ingested, which were exclusively collected in northern latitudes, and cover decadal time periods (2013–2022 for IFCB, 2008–2021 for UVP, and 1996–2022 for scanners), allowing for a further assessment of the pelagic size spectrum in space and time. The datasets that constitute PSSdb's first release are available at 10.5281/zenodo.11050013. In addition, future updates to these data products can be accessed at 10.5281/zenodo.7998799.
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There are a number of hypotheses for the environmental controls on marine nitrogen fixation (NF). Most of these hypotheses have not been assessed against direct measurements on the global scale. In this study, we use ~ 500 depth-integrated field measurements of NF covering the Pacific and Atlantic Oceans to test whether the spatial variance of these measurements can be explained by the commonly hypothesized environmental controls, including measurement-based surface solar radiation, mixed layer depth, sea surface temperature, surface nitrate and phosphate concentrations, surface excess phosphate (P&ast;), atmospheric dust deposition and surface wind speed, as well as minimum dissolved oxygen in upper 500 m to identify possible subsurface denitrification zones. By conducting simple linear regression and stepwise multiple linear regression (MLR) analyses, solar radiation and/or sea surface temperature as well as subsurface dissolved oxygen are identified as the predictors explaining the most spatial variance in the observed NF data, while dust deposition and wind speed do not appear to influence the spatial patterns of NF on global scale. Our study suggests that marine NF is coupled to regional loss of fixed nitrogen induced by subsurface low oxygen concentration, with its magnitude constrained by solar radiation or temperature. By applying the MLR-derived equation, we estimate the global-integrated NF at 71 (error range 49–104) Tg N yr−1 in the open ocean, acknowledging that it could be substantially higher as the 15N2-assimilation method used by most of the field samples underestimates NF. Our conclusion suggests that marine NF will increase in the future if subsurface nitrogen-losses increase as a consequence of developing deoxygenation with the global warming, a projection that will be modulated by other factors such as warming, elevated carbon dioxide, and changes in macro- and micro-nutrient distributions. More field NF samples in the Pacific and Indian Oceans, particularly in the oxygen minimum zones, are needed to reduce uncertainties in our conclusion.
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