The structural and functional diversity of epiphytic nematodes associated with the submerged macrophyte species, Ceratophyllum demersum, were investigated from July to September 2004 at three stations in the floodplain lake, Lake Sakadas, Croatia. At stations I and II, C. demersum was dominant in the macrophyte patches. At station III, Myriophyllum spicatum was the dominant macrophyte species. When analysis of nematode species composition was done by grouping species with decreasing abundance, a community structure was evident on macrophytes that grew in different parts of the lake. When the abundance of nematodes was taken into account, C. demersum, which grew in different parts of the lake, was not associated with a unique nematode functional structure, and different trophic groups of nematodes were dominant at different stations. Eutobrilus nothus was the dominant nematode species for station I and chewers were the dominant functional group. Eutobrilus nothus, Eumonhystera sp. 1 and Eumonhystera filiformis vulgaris group were abundant nematode species for station II and consequently chewers and detritus feeders dominated at different periods of the investigation. Nematodes from station III were characterised by the highest nematode abundance where Chromadorina bioculata was the dominant species, and epistrate feeders were the dominant functional group. A part of our previously published results was reanalysed in this paper to enable comparison of nematode communities established on C. demersum with those developed on M. spicatum. There was no difference in the nematode functional structure between macrophyte species at the same station when the abundance of dominant species was taken into account, i.e., the same trophic structure was established.
