Ecological Status of the Botic Stream - Effect of Longitudinal Connectivity Disturbance by a Reservoir on Benthic Community Structure

HR: 11:15h
AN: NB42E-04 [Abstracts]
TI: Ecological Status of the Botic Stream - Effect of Longitudinal Connectivity Disturbance by a Reservoir on Benthic Community Structure
AU: * Stastna, G
EM: stastnag@lermo.cz
AF: Czech Technical University in Prague Faculty of Civil Engineering K144, Thakurova 7, Prague, 166 29 Czech Republic
AU: Kabelkova, I
EM: kabelkova@lermo.cz
AF: Czech Technical University in Prague Faculty of Civil Engineering K144, Thakurova 7, Prague, 166 29 Czech Republic
AU: Stransky, D
EM: stranskyd@lermo.cz
AF: Czech Technical University in Prague Faculty of Civil Engineering K144, Thakurova 7, Prague, 166 29 Czech Republic
AB: Reservoirs impose a lentic habitat within a lotic system and thus disrupt stream longitudinal connectivity. We studied a small urban stream affected by a large reservoir (1.310 million m³) in order to determine changes in benthic community structure (BCS) and in the drift and distances upon which they manifest themselves. Benthic invertebrate were collected by Surber sampler at one site above the reservoir and three sites below it (200, 500 and 1000 m). At the same sites drift was measured by drift nets at dawn. Immediately below the reservoir the BCS changed significantly (similarity index 52%). No cased Trichoptera, Gastropoda or Coleoptera were found, whereas lentic species (Daphnidae, Cyclopidae, Hydrida or Ostracoda) appeared. 1000 m downstream the BCS similarity increased to 58%. Benthic Index of Biotic Integrity deteriorated from fair conditions above the reservoir to poor conditions below it. 1000 m downstream it improved to fair conditions again. Drift density dropped from 400 individuals per 100 m³ filtered water above the reservoir to 189 individuals per 100 m³. Further downstream it gradually increased to 789 individuals per 100 m³. Discussion on the uncertainty of the drift measurement due to the quantification of the discharge through the drift net is included.
DE: 9810 New fields (not classifiable under other headings)
SC: North American Benthological Society [NB]
MN: 2005 Joint Assembly