Direct and Indirect Impacts of Fish on Crustacean Zooplankton in Experimental Mesocosms
Irina Feniova,
Ekaterina Sakharova,
Maciej Karpowicz,
Michail I. Gladyshev,
Nadezhda N. Sushchik,
Piotr Dawidowicz,
Zoya Gorelysheva,
Andrzej Górniak,
Yaroslav Stroinov,
Andrew Dzialowski
Affiliations
Irina Feniova
Institute of Ecology and Evolution, Russian Academy of Sciences, Leninsky Prospect 33, Moscow 119071, Russia
Ekaterina Sakharova
Papanin Institute for Biology of Inland Waters, Russian Academy of Sciences, Borok 152742, Russia
Maciej Karpowicz
Department of Hydrobiology, Institute of Biology, University of Białystok, Ciołkowskiego 1J, 15-245 Białystok, Poland
Michail I. Gladyshev
Institute of Biophysics of Federal Research Centre, Krasnoyarsk Science Centre of Siberian Branch of Russian Academy of Sciences, Akademgorodok, Krasnoyarsk 660036, Russia
Nadezhda N. Sushchik
Institute of Biophysics of Federal Research Centre, Krasnoyarsk Science Centre of Siberian Branch of Russian Academy of Sciences, Akademgorodok, Krasnoyarsk 660036, Russia
Piotr Dawidowicz
Department of Hydrobiology, Faculty of Biology, Biological and Chemical Research Center, University of Warsaw, Zwirki i Wigury 101, 02-089 Warsaw, Poland
Zoya Gorelysheva
The Scientific and Practical Center for Bioresources, National Academy of Sciences of Belarus, Minsk 220072, Republic of Belarus
Andrzej Górniak
Department of Hydrobiology, Institute of Biology, University of Białystok, Ciołkowskiego 1J, 15-245 Białystok, Poland
Yaroslav Stroinov
Papanin Institute for Biology of Inland Waters, Russian Academy of Sciences, Borok 152742, Russia
Andrew Dzialowski
Department of Integrative Biology, Oklahoma State University, Stillwater, OK 74078, USA
Understanding the factors that regulate phytoplankton and zooplankton is an important goal of aquatic ecologists; however, much remains unknown because of complex interactions between phytoplankton, zooplankton, and fish. Zooplankton, in particular cladocerans, can be regulated by bottom−up factors either via food quantity or food quality in terms of polyunsaturated fatty acids (PUFA) or phosphorus (P) contents in phytoplankton. Fish can recycle nutrients and in turn change the PUFA and P contents of algal resources, thus modifying bottom−up regulation. Furthermore, fish can change phytoplankton structure through consumption of cladocerans which selectively graze phytoplankton. We conducted a mesocosm (300 L) experiment to determine how trophic state and fish affected crustacean dynamics. The mesocosms were filled with water containing natural plankton from the eutrophic Lake Jorzec and mesotrophic Lake Majcz (Northeastern Poland), and we manipulated fish presence/absence. We also conducted a complementary life-table experiment to determine how trophic state and fish nonconsumptively affected demographic parameters of the dominant cladocerans in the mesocosms. Small and large cladoceran species responded differently to food quantity and quality. Small-bodied Ceriodaphnia were regulated mainly by resource concentrations (i.e., food quantity), while large species were limited by PUFAs (i.e., food quality). Fish likely increased food quality in terms of PUFA, primarily eicosapentaenoic acids (EPA), thus providing conditions for more successful development of Daphnia than in the fish-free treatments. Phosphorus in the seston was likely limiting for zooplankton. However, food quality in terms of phosphorus was likely less important than PUFA because zooplankton can accumulate nutrients in their body.
