Abstract

Nearshore fisheries are highly vulnerable to the impacts of climate change and other stressors, such as conversion to urban land cover and overfishing, due to the direct pressure placed on coastal aquatic systems. Studies have demonstrated that coastal fish species distributions have altered in response to warming water temperatures associated with climate change, along with other traditional water quality parameters. Few studies, however, have evaluated these variables in conjunction with the impacts of additional forms of habitat change and degradation, such as conversion to urban land cover. A long-term gillnet survey has been conducted along the coastline of Alabama for 20 years, providing an opportunity for this kind of analysis on an appropriate timescale. Preliminary results indicate an increase in two upper-trophic level estuarine predators: juvenile bull sharks (Carcharhinus lecuas) and gafftopsail catfish (Bagre marinus). Boosted regression trees were used to identify and quantify the impacts of water temperature, depth, salinity, dissolved oxygen, riverine discharge, Chl-a, and percent urban cover change on these changing abundances. Additional analyses will also assess changing trends in model variables over time and identify locations of significant relative abundance (i.e. hot spots) for the species along the coast. These results may demonstrate the impacts of changing environmental conditions on the abundance and distribution of two upper-level estuarine predators, providing insight into what may be early-stage indications of a coastal aquatic community response to climate change and habitat degradation.

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