Macrobentic organisms and physicochemical variables of Bafa Lake

The study was carried out to investigate the number of individuals and the changes in biomass values belonging to macro-benthic invertebrate groups and the dominant species within each group at ten selected stations from Bafa Lake between August-September 2010. In order to determine the relationship between the distribution of benthic fauna and environmental variables, temperature, salinity, conductivity, pH, dissolved oxygen, nutrients, chlorophyll-a, total suspended solids and carbon content of the sediment were measured. In the lake which is characterized by seasonal salinity variations, the values ranged between 13,1 and 14,3 psu in the summer period.A positive correlation was found between the total number of individuals of macro-benthic organisms with salinity and between total biomass with temperature. In the study period, Bafa Lake showed hypertrophic condition in terms of average total phosphate values. However, considering the average chlorophyll-a values, the Lake can be evaluated as mesotrophic and according to the average secchi disk depth, the lake showed eutrophic conditions.In the lake, the individuals belonging to seven groups such as Anthozoa, Polychaeta, Oligochaeta, Bivalvia, Gastropoda, Crustacea and Insecta were encountered. At all stations, Bivalvia and Chironomidae were dominant groups either number of individuals or biomass. Considering the value of biomass and number of individuals, high correlations were obtained between Chironomidae and Oligochaeta groups. Bivalvia which had the highest dominance in the groups was only contributed by Mytilaster marioni. This group was followed by Ecrobia ventrosa (Gastropoda). Crustacea and Anthozoa had the lowest dominance in the determined groups.According to the results of grain-size analysis, the sand ratio increased through the eastern part of the lake. The total biomass and abundance values showed a negative correlation with the organic carbon content of the sediments.It is concluded that the increase in pollution sources that flow into the system from different points have an impact on the lake ecosystem as well as the seasonal changes in salinity values.