engleski

Vertical distribution of morphological forms of Cylindrospermopsis raciborskii in a floodplain lake

The cyanobacterium Cylindrospermopsis raciborskii (Woloszynska) Seenaya et Subba Raju is a toxic, invasive, originally tropical to subtropical species, which has spread in many freshwater ecosystems of temperate regions. The aim of this study was to determine the vertical distribution and morphological changes of C. raciborskii in summer of 2011 in Lake Sakadaš (Kopački rit Nature Park). Samples were collected at the surface and at every meter depth to the lake bottom. At the beginning of the development (in August), the presence of only one morphological form (primary filament) of C. raciborskii was recorded (1.21 x 106 ind./L). In September, the massive development of this species was found (27.81 x 106 ind./L). Together with the primary filament, there were six other morphological forms of secondary filament. The morphological forms differentiated according to t he size (length and width) of filament as well as akinete size. Trichomes with one heterocyte were the most represented secondary filaments in the whole water column. Their presence was between 59.01% (in the bottom layer) to 84.85% (in the surface layer) of the total number of C. raciborskii individuals. Continuous monitoring of this invasive species will contribute to spread control and promote water protection measures and biodiversity of Kopački Rit floodplain, as well as other freshwater ecosystems of central and southern Europe.

invasive species; primary and secondary filaments; trichomes; akinetes; heterocytes

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