engleski

Pondweeds (Potamogeton) in Croatia - recent status and ecology

Monitoring of macrophytes in Croatian rivers and lakes in the period from 2009 to 2016 has resulted in comprehensive data set considering distribution and ecology of water plants. Among them, pondweeds (Potamogeton) are one of most frequent groups in macrophytic vegetation. Up to now, their recent distribution, affiliation to plant communities and ecological conditions of water where they occur, were very scarce or even completely lacking. Thus, a new insight into pondweeds of Croatia has been based on sampling on over 300 localities and on revision of existing data. For the flora of Croatia 20 taxa of Potamogeton are quoted based on existing data and recent studies, including five hybrids. However, some records are very old and uncertain, e.g. for P. alpinus, P. compressus and P. polygonifolius there are only single herbarium records from the mid-19th century. Some species, as P. filiformis are rare with single findings, and other have less than dozen known localities. Based on our field research, only six species have wider distribution (P. nodosus, P. natans, P. pectinatus, P. lucens, P. perfoliatus and P. crispus), enabling more reliable ecological analyses. They showed that e.g. higher abundance of P. pectinatus in streams is correlated with increased levels of nitrites, that occurrence of P. crispus indicates higher levels of nitrates ; while P. perfoliatus and P. lucens are usually present in ecologically stable environment. Furthermore, two hybrid taxa new for the flora of Croatia were recorded – P. × salicifolius (P. lucens × P. perfoliatus) and P. × angustifolius (P. gramineus × P. lucens) – both on localities where parental taxa were present. Thus, to the extent of our knowledge, Croatian flora has rich pondweed flora, but with low number of commonly distributed species and some still doubtful records.

macrophytes ; water quality ; aquatic vegetation

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