Fish-mediated plankton responses to increased temperature in subtropical aquatic mesocosm ecosystems: Implications for lake management

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  • Hu He, Chinese Acad Sci, Nanjing Institute of Geography & Limnology, CAS, Chinese Academy of Sciences, State Key Lab Lake Sci & Environm, Nanjing Inst Geog & Limnol
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  • Hui Jin, Netherlands Inst Ecol NIOO KNAW, Royal Netherlands Academy of Arts & Sciences, Netherlands Institute of Ecology (NIOO-KNAW), Dept Aquat Ecol
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  • Erik Jeppesen
  • Kuanyi Li, Sino-Danish Centre for Education and Research Beijing China, State Key Laboratory of Lake Science and Environment, Nanjing, China
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  • Zhengwen Liu, State Key Laboratory of Lake Science and Environment, Nanjing, China, Sino-Danish Centre for Education and Research Beijing China, Department of Ecology and Institute of Hydrobiology, Jinan University
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  • Yongdong Zhang, Chinese Acad Sci, Nanjing Institute of Geography & Limnology, CAS, Chinese Academy of Sciences, State Key Lab Lake Sci & Environm, Nanjing Inst Geog & Limnol

Although it is well established that climate warming can reinforce eutrophication in shallow lakes by altering top-down and bottom-up processes in the food web and biogeochemical cycling, recent studies in temperate zones have also shown that adverse effects of rising temperature are diminished in fishless systems. Whereas the removal of zooplanktivorous fish may be useful in attempts to mitigate eutrophication in temperate shallow lakes, it is uncertain whether similar mitigation might be achieved in warmer climates. We compared the responses of zooplankton and phytoplankton communities to climate warming in the presence and absence of fish (Aristichthys nobilis) in a 4-month mesocosm experiment at subtropical temperatures. We hypothesized that 1) fish and phytoplankton would benefit from warming, while zooplankton would suffer in fish-present mesocosms and 2) warming would favor zooplankton growth but reduce phytoplankton biomass in fish-absent mesocosms. Our results showed significant interacting effects of warming and fish presence on both phytoplankton and zooplankton. In mesocosms with fish, biomasses of fish and phytoplankton increased in heated treatments, while biomasses of Daphnia and total zooplankton declined. Warming reduced the proportion of large Daphnia in total zooplankton biomass, and reduced the zooplankton to phytoplankton biomass ratio, but increased the ratio of chlorophyll a to total phosphorus, indicating a relaxation of zooplankton grazing pressure on phytoplankton. Meanwhile, warming resulted in a 3-fold increase in TP concentrations in the mesocosms with fish present. The results suggest that climate warming has the potential to boost eutrophication in shallow lakes via both top-down (loss of herbivores) and bottom-up (elevated nutrient) effects. However, in the mesocosms without fish, there was no decline in large Daphnia or in total zooplankton biomass, supporting the conclusion that fish predation is the major driver of low large Daphnia abundance in warm lakes. In the fishless mesocosms, phytoplankton biomass and nutrient levels were not affected by temperature. Our study suggests that removing fish to mitigate warming effects on eutrophication may be potentially beneficial in subtropical lakes, though the rapid recruitment of fish in such lakes may present a challenge to success in the long-term. (C) 2018 Elsevier Ltd. All rights reserved.

Original languageEnglish
JournalWater Research
Volume144
Pages (from-to)304-311
Number of pages8
ISSN0043-1354
DOIs
Publication statusPublished - 1 Nov 2018

    Research areas

  • Climate warming, Fish removal, Eutrophication, Top-down control, Shallow lakes, SHALLOW LAKES, CLIMATE-CHANGE, COMMUNITY STRUCTURE, SILVER CARP, HYPOPHTHALMICHTHYS-MOLITRIX, CHLOROPHYLL RELATIONSHIPS, ZOOPLANKTON COMMUNITIES, SIZE DISTRIBUTION, EUTROPHIC LAKES, WATER

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