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| Titel |
Phytoplankton primary production in the world's estuarine-coastal ecosystems |
| VerfasserIn |
J. E. Cloern, S. Q. Foster, A. E. Kleckner |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1726-4170
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| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 11, no. 9 ; Nr. 11, no. 9 (2014-05-07), S.2477-2501 |
| Datensatznummer |
250117395
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| Publikation (Nr.) |
 copernicus.org/bg-11-2477-2014.pdf |
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| Zusammenfassung |
Estuaries are biogeochemical hot spots because they receive large inputs of
nutrients and organic carbon from land and oceans to support high rates of
metabolism and primary production. We synthesize published rates of annual
phytoplankton primary production (APPP) in marine ecosystems influenced by
connectivity to land – estuaries, bays, lagoons, fjords and inland seas.
Review of the scientific literature produced a compilation of 1148 values of
APPP derived from monthly incubation assays to measure carbon assimilation or
oxygen production. The median value of median APPP measurements in 131
ecosystems is 185 and the mean is 252 g C m−2 yr−1, but the
range is large: from −105 (net pelagic production in the Scheldt Estuary)
to 1890 g C m−2 yr−1 (net phytoplankton production in Tamagawa
Estuary). APPP varies up to 10-fold within ecosystems and 5-fold from year to
year (but we only found eight APPP series longer than a decade so our
knowledge of decadal-scale variability is limited). We use studies of
individual places to build a conceptual model that integrates the mechanisms
generating this large variability: nutrient supply, light limitation by
turbidity, grazing by consumers, and physical processes (river inflow, ocean
exchange, and inputs of heat, light and wind energy). We consider method as
another source of variability because the compilation includes values derived
from widely differing protocols. A simulation model shows that different
methods reported in the literature can yield up to 3-fold variability
depending on incubation protocols and methods for integrating measured rates
over time and depth.
Although attempts have been made to upscale measures of estuarine-coastal
APPP, the empirical record is inadequate for yielding reliable global
estimates. The record is deficient in three ways. First, it is highly biased
by the large number of measurements made in northern Europe (particularly the
Baltic region) and North America. Of the 1148 reported values of APPP, 958
come from sites between 30 and 60° N; we found only 36
for sites south of 20° N. Second, of the 131 ecosystems where APPP
has been reported, 37% are based on measurements at only one location
during 1 year. The accuracy of these values is unknown but probably low,
given the large interannual and spatial variability within ecosystems.
Finally, global assessments are confounded by measurements that are not
intercomparable because they were made with different methods.
Phytoplankton primary production along the continental margins is tightly
linked to variability of water quality, biogeochemical processes including
ocean–atmosphere CO2 exchange, and production at higher trophic levels
including species we harvest as food. The empirical record has deficiencies
that preclude reliable global assessment of this key Earth system process. We
face two grand challenges to resolve these deficiencies: (1) organize and
fund an international effort to use a common method and measure APPP
regularly across a network of coastal sites that are globally representative
and sustained over time, and (2) integrate data into a unifying model to
explain the wide range of variability across ecosystems and to project
responses of APPP to regional manifestations of global change as it continues
to unfold. |
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