engleski

Relationship between nematode community and biomass and composition of periphyton developing on artificial substrates in floodplain lake

Periphyton colonisation on artificial substrate (microscopic glass slides) was investigated from July to November 2007, in Lake Sakadaš (Danube River floodplain Kopački rit, Croatia). Two different stations (S1 and S2) were chosen due to different post – flood conditions. The aim of the study was to follow temporal changes of nematode community composition and trophic structure in relation to periphyton biomass and bacterial abundance. In bryozoan – dominated periphyton (Plumatella emarginata Allman, 1844) nematodes were represented by 86% and 87% of total associated invertebrate fauna at S1 and S2 respectively. Total nematode abundance (5640 individuals at S1 and 9920 individuals at S2) correlated significantly with CFU Copiotrophs and CFU Oligotrophs abundance at S1 (r = 0.963, 0.998, P = 0.05) and with organic and inorganic content of periphyton at S2 (r = 0.891, 0.899, P = 0.05). Nematode trophic groups (epistrate feeders, chewers, detritus feeders and suction feeders) were equally developed at both stations except detritus feeders whose species richness and abundance were significantly higher at the S1. Epistrate feeders were the most abundant trophic group in nematode assemblages at both stations with Chromadorina bioculata being the dominant species. Change in dominance of epistrate feeders by chewers (Brevitobrilus stefanskii) and suction feeders (Crocodorylaimus sp.) coincided with the occurrence of flood pulse. Effect of flood pulse on nematode community structure was probably indirect, alterating concentration of dissolved oxygen which chromadorids are sensitive to. The structure of nematode community developed through time differs between investigated stations indicating high sensitivity to bacterial abundance, periphyton biomass and P. emarginata mats which made the habitat more diverse and patchy.

periphyton; community dynamics; nematode functional structure; Lake Sakadaš; Danube River floodplain

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