Consequences of increasing hypoxic disturbance on benthic communities and ecosystem functioning.
Anna Villnäs1, Joanna Norkko, Kaarina Lukkari
1Marine Research Centre, Finnish Environment Institute, Helsinki, Finland. anna.villnas@environment.fi
Plos One
|October 24, 2012
Summary
Artificial hypoxia in coastal sediments impairs benthic communities, altering oxygen and nutrient fluxes. The extent of this ecosystem function change depends more on the community
Area of Science:
- Marine Ecology
- Benthic Ecology
- Ecosystem Functioning
Background:
- Disturbance-induced species loss impacts ecosystem functions, but direct empirical evidence from natural settings is limited.
- Hypoxia (oxygen deficiency) is a pervasive threat to coastal and estuarine ecosystems, with known negative effects on benthic communities.
- Few studies have assessed how varying degrees of hypoxic stress in situ affect the contribution of benthic communities to ecosystem functioning.
Purpose of the Study:
- To investigate the in situ effects of experimentally induced hypoxia on sediment ecosystem functions (oxygen and nutrient fluxes).
- To evaluate how changes in benthic community structure, traits, and behavior under hypoxic stress influence ecosystem functioning.
- To determine the relative importance of hypoxia duration versus benthic community changes in altering ecosystem functions.
Main Methods:
- Artificial induction of hypoxia for varying durations (0, 3, 7, 48 days) in a subtidal sandy habitat.
- Measurement of sediment oxygen and nutrient fluxes using benthic chamber incubations.
- Quantification of benthic species richness, structure, traits, and behavioral changes (bivalve reburial rates).
Main Results:
- Hypoxia induced non-linear degradation in benthic parameters (abundance, biomass, bioturbation potential), impairing community structure and function.
- Increased hypoxia duration altered sediment oxygen consumption and enhanced effluxes of ammonium (NH4+) and dissolved silica (Si).
- Benthic community composition and disturbance-driven alterations explained more variability in ecosystem functions than hypoxia duration alone.
Conclusions:
- The level of stress on benthic habitats is critical in determining ecosystem function alterations.
- Changes in benthic community structure and traits are key drivers of altered sediment oxygen and nutrient fluxes under hypoxia.
- The relationship between biodiversity and ecosystem function in natural environments is complex and influenced by multiple factors.
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