Abstract
Effect of larvae of Astyanax altiparanae (AA), Piaractus mesopotamicus (PM), Leporinus obtusidens (LO) and Prochilodus lineatus (PL) on plankton communities and water quality were evaluated. Twenty 500 L tanks were used into a completely randomized design with five treatments and four replications, containing 350 individuals of each species per tank. One treatment control had no larvae (CT). Every six days, were collected periphyton and water to determine the concentrations of chlorophyll and total phosphorus. Plankton samples (20 mm mesh net) were taken every three days. Fish affected plankton communities, which showed lower densities of total zooplankton in AA tanks than in LO tanks. Increased density of rotifers and reduced density of copepods were found in AA, PM and PL tanks in relation to the CT. Higher density of testate amoebae was observed in AA, PM and LO tanks. As to biovolume, higher values for total plankton were registered in the CT and LO tanks compared with AA, PM and PL tanks; higher values for rotifers were observed in PL tanks than in the CT. Copepod biovolume was higher in CT and LO tanks. Biovolume of cladoceran and testate amoebae were not affected. Plankton´s chlorophyll concentration was higher in tanks with fish. Higher concentrations of dissolved oxygen were found in AA and PM tanks. It can be concluded that juveniles of these fish species differently affect the plankton community and chemical parameters of the water.
Highlights
Adult and juvenile fish influence planktonic communities in natural environments, reducingActa Scientiarum
The consumption of large filtering zooplankton reduces the impact of grazing upon phytoplankton, which in turn allow for the increase of its biomass and promote changes in the composition of this community (Milstein, Hepher, & Teltch, 1988; Qin, Madon, & Culver, 1995; Böing et al, 1998; Esteves, 1998; Matheus & Barbiere, 1999; Pegano, SaintJean, Arfi, Bouvy, & Guiral, 1999) and increase in values of total chlorophyll (Beklioglu & Moss, 1995; Qin et al, 1995)
Under the hypothesis: the eating habits of different of Brazilian native fish in early developmental stages can change / affect the quality of water and the plankton community of experimental tanks of fish farming, this study aimed to evaluate if the quality of water and the plankton community may be affected in experiments populated by larvae of Brazilian native fish
Summary
Adult and juvenile fish influence planktonic communities in natural environments, reducingActa Scientiarum. Selective visual predation by fish is an important mechanism structuring zooplankton communities (Keefe, Brewer, & Dodson, 1998), affecting the biomass, species composition and size of organisms (Guest et al, 1990; Böing, Wagner, Voigt, Deppe, & Benndorf, 1998; Milstein, Vandenberg, & Harpaz, 2006). The consumption of large filtering zooplankton reduces the impact of grazing upon phytoplankton, which in turn allow for the increase of its biomass and promote changes in the composition of this community (Milstein, Hepher, & Teltch, 1988; Qin, Madon, & Culver, 1995; Böing et al, 1998; Esteves, 1998; Matheus & Barbiere, 1999; Pegano, SaintJean, Arfi, Bouvy, & Guiral, 1999) and increase in values of total chlorophyll (Beklioglu & Moss, 1995; Qin et al, 1995). The effects of fish predation on zooplankton communities are differently expressed in lake ecosystems, which can cause changes in the diversity and density of zooplanktonic species, the composition and biomass of phytoplankton and the physical and chemical conditions of the environment
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