engleski

Macrophytic vegetation in the oligotrophic Mediterranean Lake Vrana (Island of Cres, Northern Adriatic) – New insight after 50 years

Lake Vrana is a natural oligotrophic lake situated on the island of Cres (northeastern Adriatic Sea). Its macrophytic flora and vegetation were studied in 2010, nearly 50 years after the first comprehensive research on it. Vegetation of vascular plants, including belts of helophytes and submersed vegetation, dominates in the shallowest water. Charophytic vegetation starts to develop at the depth of approximately 8 m and is present in three clear zones dominated by Chara aculeolata, Ch. virgata and Nitella opaca, reaching a final depth of 30 m. The lake and its vegetation belong to habitat type 3140 (hard oligo-mesotrophic waters with benthic vegetation of Chara species), protected by the Habitat Directive. Due to the presence of several charophyte species endangered in the Balkans and Europe, the lake is an important site for the conservation of charophytes at the national and European levels. Great changes in the water regime over the last decades due to increase of water temperature and overexploitation of the lake’s water are exerting a strong negative effect on this protected special reserve. A future comprehensive monitoring program, including climatological observation and surveillance of introduced alien fish populations, should focus on determining the cause of the observed retreat of vegetation in the lake.

charophytes ; macrophytes ; helophytes ; karst lake ; stratification ; Croatia

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