Stream meiobenthos and flow velocity - do mossy and mineral substrata differ?

摘要

The unidirectional water flow in lotic environments has an important structuring impact on benthic communities, including meiobenthos. We used flow velocity because it was the most simple describable hydraulic factor; however, flow velocity is just one of many characteristics that describe stream hydraulics and affect stream biota (STATZNER et al. 1988). Several authors demonstrated substantial reductions of flow velocities within macrophyte stands (e.g. GREGG & ROSE 1982), yet these reduced velocities are comparable with those measured in the surface layer of gravel or rock bedsediments (GREGG & ROSE 1982, ANGRADI & HOOD 1998). The primary objective of our study was to determine relationships of moss-and surrounding mineral substrata-dwelling meiobenthos with local flow velocity in two low-order streams (the Bystrice River, Czech Republic; the Oberer Seebach, Austria). Meiobenthos dwelling in clumps of Fontinalis antipyretica, which had been used as a model species of a stream bryophyte, were expected to be affected more intensively by flow velocity compared to the surrounding mineral substrata. Differences in meiobenthic distribution between riffle and pool areas, as stream habitats with distinct flow regimes, were assessed as well.