On the relationship between ecology and phytoplankton composition in a karstic spring (Çepni, Bolu)

The phytoplankton assemblages and their relationship to physico-chemical environmental variables were studied in Akkaya spring, a limnocrene type of karstic spring pool, for 14 months from May 2003 to July 2004. A total of 63 taxa, belonging to Bacillariophyta (62%), Chlorophyta (29%), Cyanophyta (3%), Pyrrophyta (3%), Euglenophyta (2%), and Chrysophyta (2%), were found. According to CCA analysis, three environmental variables (conductivity, calcium, and sulphate) had the greatest influence on species composition. Based on their seasonal occurrence, most of the species found closer to the center of CCA diagram had cosmopolitan characteristics, while members of the genus Spirogyra were found together in the fall season. Similar seasonal patterns were also recorded in three other crustacean taxa including Cladocera ( Daphnia sp.), Copepoda ( Cyclops sp.), and Ostracoda ( Fabaeformiscandona fabaeformis). Overall, the first two axes of CCA explained 97% of the relationship between species composition and environmental variables. This result was also supported by UPGMA analysis, where three main groups were clustered based on their binary data and ecological preferences. Although physico-chemical characteristics of the pool changed in the following months, after building of a concrete wall around the pool in October 2003, the long-term effect of such changes are not known at the moment.