Summary:

The aim of this study is the examination of the effect of condition texture, substrate type and stream flows on the colonization of stream invertebrates, resulting in community structure and their abundance within the bar. The researcher carried out in the 8 meter - long section of the Jalowiecki stream, behind the bar after obstacle (Pic. 1). Within the bar 7 measurements points were located: 1A, 1B, 1C, 2A, 2B, 2C and 3. The research section of the stream was divided into tree transects: initial, middle and final. In each transect measurement points were located. In the points mentioned above biological samples were taken and granulometric measurements were done (measurements of water depth, flow rate and stone size). During the research also chemical measures were taken. The macroinvertebrate samples were taken 5 times a year: November 1999, April 2000, June 2000, August 2000 and October 2000. Granulometric measurements were done only once in June 2000. Rivers are dynamic physical, chemical and biological entities. The article describes research on settlement of benthic macroinvertebrates. The community structure of benthos was studied in the bar of the Jałowiecki stream in the Makowski Beskid Mountains.Basing on geomorphologic (granulometric) and hydrologic measurements in research points of the sandbank different habitats types of benthic invertebrate were selected. Type 1 – located on top of (bystrzyki), type 2 – located close to proximal part of the bar, type 3 – located opposite to the bank river to the bars and type – 4 located in the shadow of rocks. Within the, bar the stream flow was from 1.04 m³/s to 0.19 m³/s. Grains were of quite different shape. The shapes were by far most common – 54-57 %. On the second place were ellipsis – 41 % and the balls were last common. It was turned out that point bar has a significant influence on benthos community structure and their abundance. Research results suggest that a thorough understanding of the structure of benthic invertebrates requires knowledge of disturbance history, as well as more readily measured habitat parameters such as shear stress, shear velocity, Froude’s and Reynolds numbers.