Dispersal of Organisms in a Patchy Stream Environment under Different Settlement Scenarios

• Published in: The Journal of animal ecology Vol. 69; no. 4; pp. 608 - 619
• Main Authors: Bond, Nick R., George L. W. Perry, Downes, Barbara J.
• Format: Journal Article
• Language: English
• Published: Oxford, UK British Ecological Society 01.07.2000; Blackwell Science Ltd; Blackwell; Blackwell Scientific Publications; Blackwell Publishing Ltd
• Subjects: Animal and plant ecology; Animal ecology; Animal, plant and microbial ecology; Biological and medical sciences; cellular model; dead water zones; drift distances; Ecological modeling; Fresh water ecosystems; Freshwater ecology; Fundamental and applied biological sciences. Psychology; Human ecology; Invertebrates; Landscape ecology; Landscapes; Larvae; Marine ecology; spatial pattern; Streams; Synecology; Freshwater environment; Spatial distribution; Larva; Stagnant water; Environmental factor; Dead zone; Stream; Drift; Invertebrata; Colonization; Dispersion
• ISSN: 0021-8790; 1365-2656
• DOI: 10.1046/j.1365-2656.2000.00420.x

1. Previous work in streams, where many organisms disperse downstream by drifting in the water column, has suggested dispersal distances could be related to the overall proportion of the stream within dead water zones (DWZ), places such as backwaters, pools or behind large obstacles, where the water is out of the main flow and is stored temporarily. However, dispersal distances might also be influenced by the spatial organization of DWZ within a reach; this would require us to distinguish between reaches containing many small DWZ compared with those having a few large ones in order to understand fully differences in dispersal patterns among reaches differing in this regard. 2. We constructed a spatial model of flow in stream reaches, in which we varied the density and size distribution of DWZ distributed through the reach. We defined flow conditions under which stream organisms, modelled as passive particles, would settle or continue to drift downstream. We then examined the horizontal dispersal profiles of such particles through reaches differing in arrays of DWZ. 3. Our results support those of previous studies, but suggest that the spatial arrangement of DWZ may be just as important as the overall proportion of DWZ within a reach. On a more general note, the importance of patch configuration observed in this study reflects the growing view that a thorough understanding of population and ecosystem processes will require the explicit consideration of spatial pattern in the environment.