Abstract

Eutrophication and cyanobacterial blooms have severely affected many freshwater ecosystems. We studied the effects of filter-feeding fish and bivalves on algal populations using a mesocosm experiment and long-term monitoring data from Lake Taihu (China). The mesocosm study, comprised of a two-way factorial design with the clam Corbicula fluminea and the fish Aristichthys nobilis at three biomass levels, resulted in lower chlorophyll a (Chl a) in high fish treatments, but no significant differences in the low and medium fish treatments. Chl a also decreased with an increase in clam biomass in the high fish treatments. Moreover, filter-feeding fish resulted in a decrease in algal sizes (e.g., the colony size of Microcystis aeruginosa was inversely related to fish biomass) which likely increased the filter-feeding efficiency of bivalves. Biomass of filter-feeding fish was found to be a key factor driving the synergistic effects of filter-feeding fish and bivalves in waters dominated by Microcystis colonies. Long-term monitoring revealed increasing trends in Chl a concentration, total fish catch per unit effort (TF-CPUE), and filter-feeding fish (FF-CPUE), and slightly decreasing trends in bivalve biomass and nitrogen to phosphorus ratios (N:P) from 2006 to 2016. Bivalve biomass and N:P were negatively correlated with Chl a, while FF-CPUE was not significantly related to Chl a. The current filter-feeding fish biomass in Lake Taihu is estimated to be too low to drive synergistic algal control effects together with bivalves. Furthermore, the lack of filter feeders in Lake Taihu may lead to top-down control by predators that cannot counteract the bottom-up effects of nutrients on phytoplankton. Collectively, these long-term monitoring and experimental data support the combined use filter-feeding fish and bivalves for managing cyanobacteria blooms in Lake Taihu.

Keywords

Manipulation; Top-down effect; Bottom-up effect; Eutrophication; Lake Taihu

Published in

Water Research
2023, Volume: 245, article number: 120579
Publisher: PERGAMON-ELSEVIER SCIENCE LTD

SLU Authors

• Zhang, You

  • Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences
    
  • Chinese Academy of Sciences

• Johnson, Richard

  • Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences
    

Sustainable Development Goals

Ensure availability and sustainable management of water and sanitation for all
Conserve and sustainably use the oceans, seas and marine resources for sustainable development


UKÄ Subject classification

Oceanography, Hydrology, Water Resources
Fish and Aquacultural Science


Publication identifier

DOI: https://doi.org/10.1016/j.watres.2023.120579

Permanent link to this page (URI)

https://res.slu.se/id/publ/126650