Nonadditive and nonstationary properties in the spatial distribution of a large marine fish population
Friday seminar by Lorenzo Ciannelli
Density-independent and density-dependent variables both affect the spatial distributions of species. However, their effects often are separately addressed using different analytical techniques. We apply a spatially-explicit regression framework that incorporates localized, interactive and threshold effects of both density-independent (water temperature) and density-dependent (population abundance) variables, to study the spatial distribution of a well-monitored flatfish population in the eastern Bering Sea. Results indicate that when population size was beyond a threshold a further increase in population abundance promotes habitat expansion in a nonadditive fashion with water temperature. In contrast, during years of low population size, habitat occupancy was only affected positively by water temperature. These results reveal the spatial signature of intraspecific abundance distribution relationships and the nonadditive and nonstationary responses of species spatial dynamics. Furthermore these results underscore the importance of implementing analytical techniques that can simultaneously account for density-dependent and density-independent sources of variability when studying geographic distribution patterns.
College of Oceanic and Atmospheric Sciences, Oregon State University, Corvallis, Oregon 97331, USA