engleski

Periphytic invertebrate community on artificial substrata in a floodplain lake

Every substrate immersed in the water will be colonized by different organisms within hours. Submerging artificial substrates enables us to monitor this process, determine the colonization and succession patterns, organisms’ intersections and to evaluate the health of the aquatic ecosystem. To determine the community structure and composition of invertebrate fauna in periphyton developed on artificial substrata, plastic frame and glass slides were immersed in a lake from August 2008 to July 2009. The study was carried out in a Danube floodplain area (Lake Sakadaš, Kopački Rit Nature Park, Croatia). On 14 glass slides in total 4804 individuals, belonging to 33 invertebrate taxonomic groups, were found. Three species of Bryozoa (Plumatella fungosa, Plumatella repens and Paludicella articulata), as well as three species of Porifera (Ephydatia fluviatilis, Ephydatia mülleri and Eunapius (Spongilla) fragilis), were the main sessile colonial organisms. The recorded sponge and bryozoan species, except Plumatella repens, were recorded for the first time in this floodplain area. Other dominant taxa were Hydrozoa, Gastropoda, Nematoda, Oligochaeta and Chironomidae larvae. The most abundant Nematoda were Eutobrilus nothus, Neotobrilus sp. and Chromadorina bioculata. Glyptotendipes pallens agg. was the dominant chironomid larvae taxa. On the plastic frame 5385 individuals were recorded and classified into 47 taxonomic groups. High abundance was recorded for oligochaetes (Stylaria lacustris, Nais barbata, Chaetogaster spp., Nais spp., Pristina spp., Specaria sp.) (33% of total), chironomid larvae (19% of total with Glyptotendipes pallens agg., Endochironomus albipennis and Polypedilum sordens as the most abundant) and hydrozoan Hydra sp. (11% of total). Gathering collectors were the most abundant functional feeding group (54% of total), together with predators (16% of total) and filtering collectors (15% of total). Bryozoans and sponges covered the entire frame. An invasive bivalve species, Dreissena polymorpha, was also found on both artificial substrata. A complex three- dimensional periphyton structure and favourable feeding conditions, provided mainly by bryozoans, sponges and bivalves, were important factors for the development of diverse and abundant invertebrate community.

periphyton; glass slides; invertebrate fauna diversity; lentic ecosystem

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