Modelling effects of nutrients and hypoxia on Lake Erie's central basin foodweb

Authors

  • Hongyan Zhang Eureka Aquatic Research LLC, Ann Arbor, MI 48108, USA
  • Doran M. Mason National Oceanic and Atmospheric Administration, Great Lakes Environmental Research Laboratory, Ann Arbor, MI 48108, USA
  • Edward S. Rutherford National Oceanic and Atmospheric Administration, Great Lakes Environmental Research Laboratory, Ann Arbor, MI 48108, USA
  • Marten A. Koops Great Lakes Laboratory for Fisheries and Aquatic Sciences, Fisheries and Oceans Canada, Burlington, ON L7S 1A1
  • Timothy B. Johnson Aquatic Research and Monitoring Section, Ontario Ministry of Natural Resources and Forestry, Peterborough, ON K9J 7B8, Canada
  • Ann Marie Gorman Division of Wildlife, Ohio Department of Natural Resources, Fairport Harbor, OH 44077
  • Mark Rowe National Oceanic and Atmospheric Administration, Great Lakes Environmental Research Laboratory, Ann Arbor, MI 48108, USA
  • Xinhua Zhu Freshwater Institute and Arctic Aquatic Research Division, Fisheries and Oceans Canada, Winnipeg, MB R3T 2N6, Canada
  • Monir Hossain Great Lakes Laboratory for Fisheries and Aquatic Sciences, Fisheries and Oceans Canada, Burlington, ON L7S 1A1
  • H. Andrew Cook Lake Erie Management Unit, Ontario Ministry of Natural Resources and Forestry, Wheatley, ON N0P 2P0, Canada

Keywords:

Ecopath with Ecosim model, eutrophication, water quality, fish production

Abstract

Hypoxia (dissolved oxygen <2 mg l-1) has long been a prevalent feature of the central basin of Lake Erie. Studies of the sublethal impacts of hypoxia on fishes have focused on individual species feeding rates, behavior and spatial distributions over short time periods, but the long-term effects on the fish community and its foodweb are poorly known. Sublethal effects of hypoxia on fish include: interrupting their vertical migration, displacing them from bottom habitats either up into the water column or away from the hypoxic zones, altering predator-prey relationships by segregation or aggregation of predators and their prey, and increasing fishing mortality by concentrating fish at the edge of hypoxic zones. We used the Ecopath with Ecosim foodweb model to investigate the singular and combined effects of nutrient concentration and hypoxia on the foodweb structure in Lake Erie's central basin. Our model tracked predator-prey interactions and population biomass of 33 model groups. We balanced the model in Ecopath and calibrated it against biomass time series data from 1996 up to 2020. Model simulations were run with varied nutrients (from 20 to 220% of the previous nutrient loading target level) and hypoxia (none, average summer value from 1996 to 2017, historical high) as forcing variables on the foodweb. Model results suggested that nutrients had positive, non-linear effects on foodweb biomass, while hypoxia decreased biomass of benthos, benthivorous fishes, and some omnivores, but increased biomass of plankton and planktivorous fishes. Nutrient effects were greater than hypoxia effects on the foodweb. Results of the foodweb model analysis may inform water quality and fisheries management strategies for Lake Erie's central basin.

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Published

2023-07-01

Issue

Vol. 26 No. 3 (2023): Key role of modelling techniques in the conservation and management of diverse freshwater ecosystems: Models from North America, Africa and India

Section

Research article

License

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