Žuvų mitybinės nišos Lietuvos ežerų pelagialėje /

• Main Author: Tretjak, Eva
• Other Authors: Kaupinis, Algirdas
• Format: Bachelor Thesis
• Language: Lithuanian; English
• Published: Institutional Repository of Vilnius University 2016
• Subjects: Copepods; Ruff
• Online Access: https://repository.vu.lt/VU:ELABAETD23322273&prefLang=en_US

The aim of this research was to examine the diet of fish that dwell in pelagic. Material for the stomach content analysis was collected during the months of June-September in 2015. Total numbers of 117 fishes (vendace, smelt, ruffe, and perch) were examined. The food objects of vendace diet significantly vary among studied lakes, except in Bosmina and Chaoboridae. It was found out that prey composition in vendace diet significantly differs amongst all of the lakes. Vendace diet was dominated by copepods in lakes Rašia, Luodis and Dusia, while Baluošo and Alaušo vendaces’ consumed mostly cladocerans and Baltųjų Lakajų vendace diet during the months of June and August was dominated by chironomids. Ruff diet in Alaušas and Baltieji Lakajai lakes was based on amphipods. Dusia and Baluošas lakes smelt diet was very different. Smelt diet in lake Dusia consisted mostly of Daphnia sp., while lake Baluošas smelts consumed more mysids. In the lakes of Luodis and Dusia perch diet was predominantly Leptodora. The trophic level of these four fish species was assessed by stomach content analysis. It was found out that the trophic level of vendace in studied lakes is from 1.95 to 3.39 and it significantly differs among them. The trophic level of smelt is from 2.25 to 3.19, perch’s from 1.82 to 3.35 and ruffs’ - from 3.16 to 3.90.