Tuesday, June 5, 2007 - 11:00 AM
144

Spatial perspectives on the population and habitat ecology of benthic stream fishes

James H. Roberts, Fisheries and Wildlife Sciences, Virginia Tech, Blacksburg, VA 24061

Most stream fishes require diverse habitats to complete their life-cycles.  The spatial distribution of these habitats can affect how much an individual fish must move, the spatial extent of fish populations, and the likelihood of demographic and genetic exchange with other populations.  Many benthic fishes exhibit ecological traits (i.e., small body size, poor swimming ability, intolerance of silt, and a complex breeding biology) that create unique habitat needs, comprising a framework within which spatial patterns of habitat use and population structure might be predicted.  First, I will ask how benthic traits affect habitat needs during key parts of the life-cycle: spawning, rearing, feeding, and escaping disturbance.  Then, I will discuss the distribution of these habitats within streams and generate predictions about patterns of movement and population structure for benthic fishes.  Finally, I will use my previous and ongoing studies of darters to test these predictions.  For many benthic fishes, I predict that needed habitats should be accessible via localized movements within one channel-unit or reach, and that population structure should develop over these small scales.  However, my studies indicate that although individual darter movements are somewhat restricted by local habitat configurations, darter populations may extend over many stream kilometers.