Grantee Research Project Results
The Importance of Habitat Patch Context to Stream Fishes
EPA Grant Number: F5E11219Title: The Importance of Habitat Patch Context to Stream Fishes
Investigators: Gillette, David P. , Bell, Geoffrey W. , Lunde, Kevin B.
Institution: University of Oklahoma
EPA Project Officer: Packard, Benjamin H
Project Period: August 5, 2005 through May 7, 2005
Project Amount: $106,548
RFA: STAR Graduate Fellowships (2005) RFA Text | Recipients Lists
Research Category: Academic Fellowships
Objective:
Describing habitats as collections of patches allows incorporation of spatiotemporal heterogeneity and scale into an understanding of species/habitat relationships. By combining the patch concept with ideal habitat selection theory, ecologists can ask whether or not distributions of organisms among habitat patches match that of patch quality (the survival and reproductive potential associated with a patch). Recent investigators have emphasized the role of factors other than within-patch quality, such as patch context, in determining patch use by organisms; patch context is the landscape within which a patch is embedded. Because of the high degree of connectivity among habitat patches in rivers and streams, the context of a habitat patch can be an important determinant of patch quality in these ecosystems. If patches vary in the level of food resources they export downstream, it would be advantageous for organisms relying on drifting food to occupy patches downstream from such “high export” patches. Thus, differences in feeding could lead to differences in the importance of patch context to stream fishes; those that rely on drifting invertebrates for food (“drift-feeders”) are more likely to depend on input from adjacent patches than fishes feeding on the standing crop of invertebrates (“benthic-pickers”).
The objective of this research is to determine the importance of habitat patch context to stream fishes. With this research theory from the field of landscape ecology will be applied in an aquatic setting. The importance of patch context should vary with the trophic functional group of the species in question. The prediction is that the importance of both the riparian zone and upstream habitat patches will be greater for species relying on invertebrate input from outside their occupied patch, than for species feeding on the within-patch standing crop of invertebrates.
Approach:
Multiple approaches to examine the effects of patch context on stream fishes will include; a field survey in a midwestern (USA) stream (currently underway), an experimental field manipulation, and experiments using artificial streams. The field survey provides seasonal “snapshot” views of the relationships between patch characteristics, invertebrate input levels and fish abundance. The experimental field manipulation will utilize a paired design to test for effects of invertebrate input from upstream and riparian patches on growth and condition of fishes. Finally, using sets of artificial streams arranged in a series of riffle-pool sets, manipulation of characteristics of the upstream riffle will be carried out to test for effects on riffle invertebrate community abundance, downstream transport, and growth and fecundity of drift feeding minnows.
Expected Results:
Data from this research will help determine the importance of patch context to stream fishes, as well as determining the attributes of adjoining patches that are important. These questions are much better understood for terrestrial organisms in patchy environments than for aquatic taxa in similar systems, and this research will help determine the appropriate application of landscape ecology theory to aquatic systems, providing insights relevant to the understanding and effective management of these tightly-connected ecosystems.