Valerica GÎlcĂ

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Valerica Gîlcă, I. Gîlcă

The aim of this work was to realize a sinecological analyses of a freshwater pool by analytical determination of environmental indicators (abundance, constancy, dominance) and synthetic organic indicators such as the index of ecological significance. Research has been organized in the summer of 2011, for a period of 45 days, respectively May and first half of June. For sinecological analyses the collection of plankton were made weekly, and the formolisated samples were brought to the Hydrology Laboratory of Animal Husbandry Faculty, where were made the quantitative and qualitative determinations of planktonic species in the freshwater's lake investigated. In the summer of 2011, every week they have taken water samples to determine the structure and abundance of plankton in the Bicaz Lake. Water samples taken from the basin were fixed immediately with 3% formalin solution and then were transported to the laboratory for qualitative and quantitative determinations. Processing laboratory was to their sedimentation for 21 days and centrifuging at 1500 rpm/min., for 5 minutes. Numerical assessment and species identification was made in the laboratory with a microscope HC 1, using a counting camera. After quantitative determination of planktonic organisms which belong to different systematic groups, we reporting results to the initial volume of water and determined the total density of plankton. Based on the data obtained were calculate the analytical indicators: abundance, constancy and dominance and ecological indicators of the synthetic index of ecological significance. From the Bicaz Lake investigated in summer 2011 were collected a total of 10939 phytoplankton individuals, belonging to four systematic groups with 15 taxons and a number of 6289 zooplankton individuals, enrolled in four classes with 13 taxons. After determining the structure of phytoplankton observed that the most abundant were euglenofitele followed by cianofite and diatoms, while chlorophytes were less numerous. On zooplankton structure determinations showed that the highest abundance were rotifers followed by cladocere and the least abundant being copepoda.

Key words: analyze, plankton, abundance, dominanace