engleski

Food and feeding behaviour of Leuciscus svallize

The results from the natural feeding of Leuciscus svallize (Heckel et Kner 1858) from the Adriatic river system are presented. Nutrition of L. svallize consists of the representatives from the macrobentic groups of organisms: Turbellaria, Trematoda, Cestoda, Nematoda, Gastropoda, Bivalvia, Oligochaeta, Crustacea and Insecta. Along with the Pisces class, the nutrition composition also includes three microphytobentic systematic groups: Cyanophyceae, Bacillariophyceae and Chlorophyceae. The qualitative and quantitative analysis of food consumed showed that the L. svallize has relatively wide nutrition range and that the basic components of food are animal components along with plant components. The relative importance of different components of the diet was assessed using the percentage frequency of occurrence (%F), percentage number (%N), Shorigin index (K) and feeding selectivity (Sel). Seasonal quantitative and qualitative dietary changes were recorded. In the spring Insecta were preferable food, and Crustacea were secondary food. In the summer Insecta were again preferable food, and Pisces was secondary food. In the autumn there were no preferable food, but four different food components can be expressed as the secondary food: Trematoda, Nematoda, Insecta and Pisces. In the winter period Insecta were preferable food and Crustacea were secondary food. The food changes were also recorded with fish length.

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