Spatial distribution and short-term changes of benthic macrofauna in Lake Balaton (Hungary)

Spatial and short-term changes in the composition and density of the macrob enthic fauna were studied in Lake Balaton, a large shallow lake in Central Europe (Hungary). Spatial differences were examined along five transects an d short-term changes at two stations of different trophic state. The macrob enthos consisted almost exclusively of Tubificidae and Chironomidae of the species Chironomus gr. plumosus, Procladius choreus, Tanypus punctipennis, Microchironomus tener and Cladotanytarsus sp. The Oligochaeta biomass showe d a significant short-term decrease from 1995 to 1998, and their average bi omass proved to be 0.86 and 0.79 g WFW (wet formalin weight) m(-2) in 1996 and 1997, respectively. Chironomidae showed significant spatial and short-t erm differences following variations in primary production. Higher primary production resulted in higher biomass (up to 153.4 g WFW m(-2) and 9785 ind . m(-2) in 1995) of Chironomus-Procladius community, while lower primary pr oduction resulted in a very low biomass and abundance of the predatory Proc ladius-Tanypus-Microchironomus community (average: 3.16 g WFW m(-2) and 131 1 ind. m(-2) in 1997). As compared to other lakes of similar climatic condi tions, the total production of oligohaetes and chironomids proved to be ver y low in 1996 and 1997 (49.2 and 54.1 KJ m(-2) yr(-1), respectively). The 9 0% of the average chironomid production of Lake Balaton in 1996 and 1997 be longed to Ch. gr. plumosus (5.63 and 5.13 g m(-2) yr(-1)), P. choreus (4.3 and 3.47 g m(-2) yr(-1)) and T. punctipennis (0.27 and 2.21 g m(-2) yr(-1)) .