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Titel |
Impacts of hypoxia on the structure and processes in pelagic communities (zooplankton, macro-invertebrates and fish) |
VerfasserIn |
W. Ekau, H. Auel, H.-O. Pörtner, D. Gilbert |
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 ; 7, no. 5 ; Nr. 7, no. 5 (2010-05-21), S.1669-1699 |
Datensatznummer |
250004777
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Publikation (Nr.) |
copernicus.org/bg-7-1669-2010.pdf |
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Zusammenfassung |
Dissolved oxygen (DO) concentration in the water column is an environmental
parameter that is crucial for the successful development of many pelagic
organisms. Hypoxia tolerance and threshold values are species- and
stage-specific and can vary enormously. While some fish species may suffer
from oxygen values of less than 3 mL O2 L−1 through impacted
growth, development and behaviour, other organisms such as euphausiids may
survive DO levels as low as 0.1 mL O2 L−1. A change in the average
or the range of DO may have significant impacts on the survival of certain
species and hence on the species composition in the ecosystem with
consequent changes in trophic pathways and productivity.
Evidence for the deleterious effects of oxygen depletion on pelagic species
is scarce, particularly in terms of the effect of low oxygen on development,
recruitment and patterns of migration and distribution. While planktonic
organisms have to cope with variable DOs and exploit adaptive mechanisms,
nektonic species may avoid areas of unfavourable DO and develop adapted
migration strategies. Planktonic organisms may only be able to escape
vertically, above or beneath the Oxygen Minimum Zone (OMZ). In shallow areas
only the surface layer can serve as a refuge, but in deep waters many
organisms have developed vertical migration strategies to use, pass through
and cope with the OMZ.
This paper elucidates the role of DO for different taxa in the pelagic realm
and the consequences of low oxygen for foodweb structure and system
productivity. We describe processes in two contrasting systems, the
semi-enclosed Baltic Sea and the coastal upwelling system of the Benguela
Current to demonstrate the consequences of increasing hypoxia on ecosystem
functioning and services. |
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