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Can salinity trigger cascade effects on streams? A mesocosm approach.
Miguel Cañedo-Argüelles1, Miquel Sala2, Gabriela Peixoto2
1BETA Technology Centre, Aquatic Ecology Group, University of Vic - Central University of Catalonia, Spain; Freshwater Ecology and Management (F.E.M.) Research Group, Departament d'Ecologia, Universitat Barcelona, Diagonal, 643, 08028 Barcelona, Catalonia, Spain.
The Science of the Total Environment
|March 31, 2015
Summary
Increased river salinity stresses aquatic predators, impacting food webs. Future water scarcity may worsen these effects, requiring careful ecosystem management.
Area of Science:
- Ecology
- Environmental Science
- Aquatic Biology
Background:
- Human activities increase river salinity, a problem exacerbated by water scarcity.
- Sub-lethal salinity effects on stream invertebrates, particularly predation efficiency, are poorly understood.
- Changes in predation can trigger trophic cascades affecting herbivore populations and algal biomass.
Purpose of the Study:
- To evaluate the cascade effects of increased salinity on a stream food web.
- To investigate how salinity impacts predation efficiency and invertebrate communities.
- To assess the combined effects of predation and salinity using biomarkers and community data.
Main Methods:
- Utilized a stream mesocosm to simulate river conditions.
- Applied salt treatments and introduced predators to assess impacts.
- Analyzed aquatic invertebrate abundance, richness, community composition, and chlorophyll a concentrations.
- Employed biomarkers to evaluate predator stress levels.
Main Results:
- Both predation and salt treatments affected invertebrate abundance, richness, and community composition.
- Predators reduced herbivore abundance and richness, leading to higher chlorophyll a.
- Salt treatment significantly reduced taxa richness in gravel beds.
- Salt addition stressed predators, indicated by biomarker responses.
- Observed trends of increased Tanytarsini abundance and decreased chlorophyll a with salt and predators were not significant.
Conclusions:
- Salt addition significantly stressed the predator Dina lineata.
- Longer exposure times may be needed to observe significant cascading effects of salinity.
- Salinization's potential cascade effects must be considered in the context of water scarcity and its impact on river ecosystems.
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