An Historical Comparison of Finfish Abundance and Community Composition in Chesapeake Bay Seagrass Beds

Worldwide declines in seagrass coverage have generated significant concern for nearshore fishes, as these habitats afford foraging and refuge opportunities for many species during their critical early life history stages. In Chesapeake Bay, eutrophication and other anthropogenic stressors have been cited as causes of an overall decline in the predominant seagrass species (Zostera marina) over the past several decades. The repercussions of this habitat loss for seagrass-associated fish species is largely unknown. Fish abundances in seagrass beds from a trawl survey conducted in the late 1970s were compared to abundances measured in 2009-2011 as part of an ongoing project, using similar methods. Species occurrences were similar between both time periods, with high interannual variability in both abundance and timing of the young-of-the-year recruits. The sciaenids Bairdiella chrysoura and Leiostomus xanthurus were numerically most abundant in both surveys. Since Bay water temperatures have increased over the past few decades (likely due to climate change), it has been hypothesized that southerly species, those more associated with subtropical waters, may currently exhibit increased presence and abundances in shallow water habitats in Chesapeake Bay relative to the 1970s; however, this was not observed and it may be that relatively cold winter temperatures are preventing the establishment of these species in this temperate/subtropical boundary. As eelgrass populations continue to decline in the Bay, species showing affinity for eelgrass habitats are likely to be adversely affected.