An abundance exchange model of fish assemblage response to changing habitat along embayment–stream gradients of Lake Ontario, New York

A spatially explicit abundance exchange model (AEM) was developed to predict distribution patterns of five fish species in relation to their population characteristics and habitat preferences along two embayment–stream gradients associated with Lake Ontario, New York. The five fish species were yellow perch (Perca flavescens), bluegill (Lepomis macrochirus), logperch (Percina caprodes), bluntnose minnow (Pimephales notatus), and fantail darter (Etheostoma flabellare). Preference indexes of each target fish species for water depth, water temperature, current velocity, cover types (aquatic plants, algae, and woody debris), and bottom substrates (mud, sand, gravel-cobble, and rock-bedrock) were estimated from the field observations, and these were used to compute habitat preference (HP) of the associated fish species. Fish HP was a key variable in the AEM to quantify abundance exchange of an associated fish species among habitats on each study gradient. According to the results, the AEM efficiently determined local distribution ranges of the fish species on one study gradient. Results from the model validation showed that the AEM with its estimated parameters was able to quantify most of the fish species distributions on the second gradient. Overall, the AEM is rigorous for quantifying the distribution patterns of the target species along the changing habitat gradients. With its flexible structure that is applicable for array functions and differential equations from both static and dynamic components, the AEM can be modified to determine patterns of organism distribution in complex systems with different environments and geography.