The role of submerged macrophytes in stabilising water clarity and the migration pattern of dominant zooplankton in Lake Eymir, Turkey

Sillah, Mohamed
In this study, samplings within macrophyte beds and open water stations to determine the role of submerged macrophytes in stabilising water clarity and the migration pattern of dominant zooplankton from different habitats in Lake Eymir were carried out. The concentrations of nutrients and suspended solids (SS) were lower within the macrophyte beds than in the open water, while the water clarity was higher within the macrophyte beds than in the open water. The macrophyte beds stabilised the water clarity by absorbing the excess nutrients and reducing SS concentration. Grazing probably had little effect on water clarity, as chlorophyll-a concentration was higher in the macrophyte beds than in the open water. Arctodiaptomus bacillifer the dominant species undertook diel horizontal migration between the macrophyte beds and the open water station, while no diel changes were observed at the reed belt and at the macrophyte edge. The open water station was thermally stratified and the difference between daytime and nighttime density was significant at the hypolimnion but insignificant at the epilimnion. This indicated that A. bacillifer displaced vertically but this displacement did not cross uithe thermocline contrary to the common diel vertical migration pattern observed in other studies. Fish predation pressure was observed as the main inducing factor for DHM and DVM. The macrophytes beds served as daytime refuge while the low oxygen concentration in the hypolimnion served as physical refuge from fish predators. The lack of vertical displacement above the thermocline could be related to the adequate food supply in the hypolimnion.


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Citation Formats
M. Sillah, “The role of submerged macrophytes in stabilising water clarity and the migration pattern of dominant zooplankton in Lake Eymir, Turkey,” M.S. - Master of Science, Middle East Technical University, 2002.