RANGE-WIDE DECLINES AND SPATIAL SYNCHRONY IN AMBER DARTER (PERCINA ANTESELLA) POPULATIONS IDENTIFIED WITH MULTIVARIATE ANALYSIS
High spatial synchrony—correlated abundance fluctuations among distinct populations—is associated with increased extinction risk, but is not examined in status assessments mandated by the Endangered Species Act. Alongside traditional viability metrics (i.e., the number of populations, their spatial extent, and the status of each population), consideration of spatial synchrony in these assessments may provide additional insight into extinction risk as well as the relative importance of intrinsic and extrinsic factors on population dynamics. We demonstrate a method for estimating abundance trends in populations of the Endangered Amber Darter (Percina antesella), while simultaneously quantifying spatial synchrony among its two populations in the Conasauga and Etowah rivers in Georgia, U.S.A. Our analysis was performed using multivariate autoregressive state-space (MARSS) models with annual sampling data from 1996-2017. Our results indicate that Amber Darters have declined substantially in both rivers, with greater than 9% annual losses in both the Conasauga and Etowah rivers, suggesting range-wide imperilment. Furthermore, there was little evidence for independent population fluctuations between the rivers, which may compound overall extinction risk. Broadly, this analysis demonstrates the utility of MARSS modeling and considerations of spatial synchrony in vulnerability assessments.
Edward Stowe (Primary Presenter/Author), Odum School of Ecology, University of Georgia, email@example.com;
Seth Wenger (Co-Presenter/Co-Author), University of Georgia, firstname.lastname@example.org;
Bud Freeman (Co-Presenter/Co-Author), University of Georgia, email@example.com;
Mary Freeman (Co-Presenter/Co-Author), US Geological Survey, firstname.lastname@example.org;