Abstract

Coastal eutrophication due to excessive anthropogenic nutrient loading is a major threat worldwide, and especially in estuaries and semi-enclosed waterbodies, like the brackish Baltic Sea. In addition, coastal waters may become darker (coastal darkening) due to increased input of colored compounds from terrestrial run-off and sediment resuspension. Still, the effects of darkening on coastal food web responses to eutrophication are unknown. In a mesocosm experiment with benthic and pelagic habitats, we manipulated nutrient loading, presence of fish and light availability to disentangle bottom-up and top-down control of eutrophication symptoms in ambient and darkened waters. Overall, we found higher pelagic Chlorophyll a concentrations (a proxy of algal biomass) with darkening and with nutrient enrichment in both clear and dark waters. Albeit fish had a strong impact on zooplankton and zoobenthos, they had no cascading effect on algae. We conclude that coastal darkening due to changes in land use and climate change can pose an additional challenge concerning the recovery of coastal waters from eutrophication.

Published in

Limnology and Oceanography
2023, Volume: 68, number: 3, pages: 678-691
Publisher: WILEY

SLU Authors

• Garnier, Aurélie

  • Department of Aquatic Resources (SLU Aqua), Swedish University of Agricultural Sciences
    

• Östman, Örjan

  • Department of Aquatic Resources (SLU Aqua), Swedish University of Agricultural Sciences
    

• Bell, Olivia

  • Department of Aquatic Resources (SLU Aqua), Swedish University of Agricultural Sciences
    

• Huss, Magnus

  • Department of Aquatic Resources (SLU Aqua), Swedish University of Agricultural Sciences
    

UKÄ Subject classification

Oceanography, Hydrology, Water Resources


Publication identifier

DOI: https://doi.org/10.1002/lno.12302

Permanent link to this page (URI)

https://res.slu.se/id/publ/121435