The anti-quorum sensing activities towards the bacterium Pseudomonas aeruginosa PA01 (pyocyanin production, biofilm formation and twitching and flagella motility) of two crude extracts (methanol and acetone) of the freshwater sponge Ochridaspongia rotunda (Arndt, 1937) were evaluated in vitro for the first time. Both extracts demonstrated P. aeruginosa pyocyanin inhibitory activity, reducing its production for 49.90% and 42.44%, respectively. In addition, they both showed higher anti-biofilm activity (48.29% and 53.99%, respectively) than ampicillin (30.84%). Finally, O. rotunda extracts effectively reduced twitching and flagella motility of P. aeruginosa. Taken all together, these results suggest that endemic sponge species from the oldest lake in Europe may offer novel bioactive natural products with promising medicinal potential towards P. aeruginosa infections.

This study examined the relationship between the sagittal otolith morphometric variables (length, height and weight) and body growth of the European eel. Eels that were studied ranged in total length from 11.2 to 79.5 cm. The relationships between the sagittal otolith variables and fish somatic growth were described with a non-linear function. The resulting coefficients of determination \((r^2)\) ranged from 0.782 to 0.914. The variable most strongly related to fish size was found to be the sagittal otolith length (OL) with 91.4 % of the variability. The results of this study provide the first comprehensive data regarding the relationship between the sagittal otolith morphometric variables with the body length of Anguilla anguilla.

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Lake Prespa, Lake Ohrid and Lake Skadar are the biggest lakes in the Balkan Peninsula. By reason of continuous existence and relatively stable ecological conditions millions years those lakes have a unique collection of flora and fauna. In this paper is presented biodiversity of macrophyte vegetation from Lake Prespa, Lake Ohrid and Lake Skadar. In those three lakes macrophyte vegetation is distributed in zones (belts). The biodiversity of macrophytes is different in those lakes and it is in direct dependence of different altitudes, lakes surfaces and lakes depths.