engleski

Rotifers in deep vs. shallow lakes of Balkan Peninsula

Lakes and ponds increased habitat heterogeneity and, in particular, invertebrate biodiversity. Both ecosystems, peculiarly in the karst region are sensitive to diverse anthropogenic impacts reflected in an increase of nutrients, as one of the most pronounced detorioration of standing waters. Zooplankton (Rotifera, Cladocera, Copepoda) plays an important and pivotal role in the the foodwebs of both, deep and shallow waterbodies, thus are reliable indicators of the water quality, according to their traits: diversity, abundance, biomass, size and feeding structure. In this survey, rotifer traits across three types of threatened ecosystems were assessed: (i) deep karst lakes of Balkan Peninsula (Plitvice Lakes and Visovac Lake, Croatia ; Shkodra Lake, Albania ; Ohrid Lake, Macedonia) ; (ii) permanent shallow waterbodies in temperate climate (inland Croatia) and (iii) ephemeral waterbodies in Mediterranean climate (Adriatic Sea, Croatia). Overall, trends of deteriorated water quality were exhibited across studied ecosystem, reflected in decreased biodiversity, increased abundance (up to three species), decrease in the specimen’s body size and transition of feeding preferences, from algivorous to detritivorous. In deep karst lakes still prevailed large-sized algivorous rotifers (genera Synchaeta, Polyarthra, Trichocerca), however with increased trophic state small-sized detridivores overtook domination. Abundance:biomass anaylysis indicated notable deterioration particularly in Mediterranean ponds with dominance of high abndance of small-sized detritivorous rotifer specimens. In shallow waterbodies of both climates submerged macrophytes enhanced diversity and water quality, while fish mainly showed negative impact. Conclusively, results of studied ecosystems suggested importance of rotifers in their interactions with other zooplankters, aquatic organisms and environmental conditions as significant factor in the assessment of ecosystem functioning, as well as in the lake restoration.

Rotifera, Cladocera, Copepoda/ karst lakes/ permanent and temporary ponds/size and feeding groups

Department of Zooplankton, Hydrobiological Institute, Ohrid, North Macedonia ; Agricultural University of Tirana, Tirana, Albania