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SIMULATING FISH ASSEMBLAGE DYNAMICS IN RIVER NETWORKS
Citation:
WHITE, D. SIMULATING FISH ASSEMBLAGE DYNAMICS IN RIVER NETWORKS. Presented at University of Oregon Department of Geography seminar, Eugene, OR, May 04, 2006.
Impact/Purpose:
Presentation
Description:
My recently retired colleague, Joan Baker, and I have developed a prototype computer simulation model for studying the effects of human and non-human alterations of habitats and species availability on fish assemblage populations. The fish assemblage model, written in R, is a spatially-explicit, age-structured population model, simulating one or many interacting fish species over multiple years. Time steps are seasons, initially with two seasons per year but potentially with up to six. The smallest spatial unit is a stream segment, typically 100s of meters long and equivalent to a stream reach. Each segment has one or more habitat attributes. Mature fish can move among segments in the stream network to find suitable areas for spawning. Fish of all ages can move among segments to disperse or find areas with better habitat. Fish survival is affected by habitat conditions, competition among species, and predator-prey interactions. Model output is numbers of fish by species and age class, in each segment of the stream network, at each time step. Because of uncertainties in projected fish numbers, the raw output should be interpreted as relative density (e.g., rare to abundant) for general use. Results can also be expressed as species richness and as a fish index of biotic integrity (IBI). Possible uses of this model include exploring effects of introduced species, of barrier introductions or removals, of habitat changes from restoration, and of stream temperature changes responding to synoptic climate change.