Abstract. 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.
Impacts of hypoxia on the structure and processes in pelagic communities (zooplankton, macro-invertebrates and fish)
W. Ekau,H. Auel,H. Pörtner,D. Gilbert
Published 2009 in Biogeosciences
ABSTRACT
PUBLICATION RECORD
- Publication year
2009
- Venue
Biogeosciences
- Publication date
2009-05-19
- Fields of study
Biology, Environmental Science
- Identifiers
- External record
- Source metadata
Semantic Scholar
CITATION MAP
EXTRACTION MAP
CLAIMS
CONCEPTS
- baltic sea
A semi-enclosed sea used here as one of the contrasting case systems.
- benguela current
A coastal upwelling system used here as the second contrasting case system.
- dissolved oxygen
The concentration of oxygen in the water column, reported in this paper as an environmental condition in mL O2 L-1.
Aliases: DO
- ecosystem functioning and services
The combined ecosystem processes and resulting services discussed for the two example systems.
Aliases: ecosystem functioning, ecosystem services
- hypoxia
A low-oxygen condition in aquatic waters that limits or stresses pelagic organisms.
- nektonic species
Actively swimming pelagic animals that can move away from unfavorable oxygen conditions.
Aliases: nekton
- oxygen minimum zone
A water-column layer with persistently very low oxygen that organisms may need to traverse or avoid.
Aliases: OMZ
- pelagic communities
Open-water assemblages of zooplankton, macro-invertebrates, and fish discussed in relation to oxygen availability.
Aliases: pelagic realm communities
- planktonic organisms
Drifting pelagic organisms that can mainly respond to low oxygen by shifting depth position.
Aliases: plankton
- vertical migration strategies
Depth-changing movement patterns used to use, pass through, or cope with low-oxygen layers.
Aliases: vertical migrations