HR: 11:15h
AN: NB52C-04    [Abstracts]
TI: How to Compare Biomass and Drift of the River Benthos?
AU: * Bogatov, V V
EM: bogatov@ibss.dvo.ru
AF: Institute of Biology and Soil Science, Far Eastern Branch, Russian Academy of Sciences, 159, pr-kt 100 letia Vladivostoka, Vladivostok, 690022 Russian Federation
AB: Drift flux per unit bottom area (D_b) of different river reaches can be expediently estimated as biomass of transported organisms at a particular collection time through the cross sectional area of water flow for width of 1 m and height equals to the depth of river part (H, m) at the time of sampling (D_b, mg/m²/day). In this case, independent of river depth, water velocity and discharge D_b for 24 h will be defined as simple multiplication of two parameters: D_b = L(m) × M_b (mg/m³/day), where L is distance of drift and M_b is daily migratory activity of the aquatic organisms equals biomass of organisms lifted during 24 h from 1 m² of the river bottom into the water column with volume 1 m² × H. This method allows one to calculate specific drift rate (D_cb), which takes into account benthic density on the river bottom and is estimated with units of inverse time, i.e., the fraction of benthic biomass that enters the drift in 24 hours. So D_b = D_b/B, where B is biomass of benthos, mg/1 m² The specific drift rate calculated for various groups of invertebrates surprisingly showed a negative correlation between D_cb and benthic biomass. Thus, our results contradict the generally accepted hypothesis describing drift as competition among aquatic organisms for food and substratum.
DE: 1845 Limnology
SC: North American Benthological Society [NB]
MN: 2005 Joint Assembly