Publication Abstract

Diel dynamics of young fishes and zooplankton in a lentic side-channel of the River Danube over a 24-hour cycle in late summer

Diel dynamics of young fishes and zooplankton in a lentic side-channel of the River Danube

By G.H. Copp, M. Vranovský, J. Cerný & V. Kovác

The diel dynamics of fish and zooplankton in European rivers have received relatively little study but are important to our understanding of aquatic ecosystem function. To complement daytime investigations to monitor 0+ fish populations in floodplain ecosystems of the River Danube (Slovakia), we carried out a preliminary study of patterns in fish density, fish dispersion and planktonic invertebrate densities in mesohabitats (mid-channel, banks) of a lentic side channel of over a 24-h period in August 1996. We compared our results with the only available data (the postgraduate dissertation of Tobias Schröder) for a floodplain side-channel of similar dimensions (River Rhine, Germany). Little diel pattern was apparent in fish density, except a decrease in relative density of bleak Alburnus alburnus at night that corroborated the general decrease in numbers and activity observed by Schröder. However, the size of bleak increased at night, which suggests increased catchability. Fish and zooplankton densities were negatively correlated, with diel patterns in Crustacea in mid-channel and along one (steep) bank. Although limited to one 24-h cycle, our results appear similar to those from floodplain ecosystems of similar river setting (large river) and differ from those observed in smaller European water courses.

Reference:

G.H. Copp, M. Vranovský, J. Cerný & V. Kovác (2005) Diel dynamics of young fishes and zooplankton in a lentic side-channel of the River Danube. Biologia Bratislava, 60(2): 179-188

G.H. Copp*, M. Vranovsky, J. Cerny and V. Kovác

Biológia Bratilsava, 60(2): 179-188