engleski

A survey of rotifer studies in karst habitats: A case study deep vs. shallow lakes of Balkan Peninsula

Great share of karst area is situated in the Mediterranean region. Recently, due to high turistic pressure and climate changes freshwater ecosystems, particularly lakes and ponds, undergo drastic, negative environmental changes. Unfortunately, rotifers are still understadied component of those threatened ecosystems, instead they play an important and pivotal role in the the foodwebs of both, deep and shallow waterbodies, and they 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 of euryvalent rotifers (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 ratio indicated notable deterioration particularly in Mediterranean ponds with dominance of high abundance of small-sized detritivorous rotifer specimens. In shallow waterbodies of both climates submerged macrophytes enhanced diversity and water quality, while fish 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.

trophic state ; zooplankton traits ; temperate and Mediterranean climates

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