Zooplankton dynamics in a gypsum karst lake and interrelation with the abiotic environment

Abstract

Zooplankton species composition and abundance variation was studied in Lake Amvrakia, which is a deep, temperate, gypsum karst lake situated in the western Greece. The two year survey of zooplankton revealed 33 species (23 rotifers, five cladocerans, four copepods and one mollusc larva). The mean integrated abundance of the total zooplankton ranged between 83.6 and 442.7 ind. L −1 , with the higher density to be recorded in the surface 0-20 m layer. Small numbers of specimens of almost all species were found also in the hypoxic or anoxic hypolimnion. Copepods and especially the calanoid Eudiaptomus drieschi dominated the zooplankton community throughout the sampling period, followed by Dreissena polymorpha larvae, rotifers and cladocerans. Seasonal succession among the cladocerans and the most abundant rotifer species was observed. The concentration of chlorophyll-a was the most important factor for the variation of total zooplankton, as well as for the rotifers' community. Dissolved oxygen affected copepods and cladocerans, water level correlated mainly with the molluscs larvae of D. polymorpha, while temperature influenced the variation of several rotifers, the cladoceran Diaphanosoma orghidani and the mollusc larvae. Negative correlation of conductivity with the cladoceran Daphnia cucullata and the copepods E. drieschi and Macrocyclops albidus was found. The differences in species composition found in Lake Amvrakia in comparison to the nearby lakes are probably ought to the geographical isolation and perhaps to its particular chemistry (e.g., elevated conductivity).

Zooplankton community dynamics and environmental factors in Lake Ozeros (Greece)

“…The eutrophic character of the lake is the result of the increased concentrations of TP and low transparency. The seasonal TP variation was similar with that of other lakes in the area, such as Trichonis (Doulka, 2010) and Amvrakia (Chalkia et al, 2012a), although the concentration values were higher. Given the presence of human activities around the lake and especially small livestock facilities like pigfarms, it is assumed that the high load of TP was possibly the result of the washout of wastes from these industries, although it could also be attributed to fertilizers from agricultural cultivations, or mineral run-off.…”

“…Lower water transparency observed mainly in the winter was probably due to increased precipitation and sediment runoff from torrents on the western banks of the lake. The chl-a concentration and seasonal variation was similar to the nearby mesotrophic Lake Amvrakia (Chalkia et al, 2012a). On the vertical axis, the distribution of DO was uniform in the water column and the high concentration values recorded during the cold months is the result of increased oxygen solubility at lower temperatures.…”

“…This study resulted in 21 new records of zooplankton species, which have been recorded as residents in other natural and artificial lakes of western Greece, such as Trichonis (Doulka & Kehayias, 2008), Stratos Reservoir and Amvrakia (Chalkia et al, 2012a). The absence of Brachionus sp.…”

“…The values of the diversity index, as well as its seasonal variation reveal another similarity among Lake Ozeros and the nearby lakes Trichonis (Doulka, 2010) and Amvrakia (Chalkia et al, 2012a). Taking into account that increased zooplankton diversity could indicate the internal stability of an aquatic ecosystem (Michaloudi et al, 1997), communities structured in this manner are generally characteristic of stable environments (Ferrara et al, 2002.…”

Spring rotifer community structure in the Alcantara River (Sicily, Italy), using different mesh size nets: relation to environmental factors

“…Its spatial and temporal patterns are of crucial importance for understanding ecosystem functioning because it can affect its processes and stability, and it can constitute a quickly response to major shifts in environmental conditions (Suikkanen et al, 2007;Zhou et al, 2009). In fact, changes in zooplankton abundance and diversity provide important indications of environmental alteration or disturbance (Chalkia et al, 2012).…”