engleski

Preliminary research of Chironomidae larvae and trophic relations in a Danube floodplain

Floodplains are extremely complex and diverse ecosystems connecting terrestrial and aquatic habitats ; with very complex interactions and trophic relationships between different groups of organisms. Chironomids are considered to be important part of every freshwater ecosystem due to their role in connecting higher and lower trophic levels, feeding on algae, detritus or smaller invertebrates and protozoans, whilst being food for predatory amphibian larvae or fish. Preliminary research of the role of chironomids in fish diet has been conducted in the Kopački Rit Nature Park (Croatia), a large flooding area of the Danube, during autumn and winter period of 2013. We wanted to determine the proportion and, hence the importance, of chironomids in the fish diet by examining their stomach contents. Due to the low water level and low temperatures, large fish were scarce in the catch. A total of 8 fish species were sampled aged from 0+ to 3+, most abundant being Blicca bjoerkna L. 1758 of age 0+. We determined three main food chategories in the diet of the sampled fish, but chironomids were not the main food source. Probable reasons are low abundance of larvae in the sediment (and lack of periphyton and macrophyte), size and age of the sampled fish and low temperatures which cause cessation of feeding. Sediment samples were also taken at the research sites. Benthic fauna comprised of nematodes, oligochaets, copepods, chironomid larvae and few specimens of Ceratopogonidae and Chaboridae larvae. Chiromidae community was mostly represented by Tanytarsini and Chironominii larvae, what is consistent with qualitative composition in diet samples. High temporal variability in chironomid community requires all seasons to be included in fish diet analysis.

chironomids ; fish ; food web ; benthos

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