Exploring implications of a snook expansion into northern Florida for food webs and minimum flows in coastal springs and rivers

Mike Allen, Professor, School of Forest, Fisheries, & Geomatics Sciences; Director, Nature Coast Biological Station, UF

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Globally, rising temperatures have resulted in numerous examples of poleward shifts in species distribution patterns with accompanying changes in community structure and ecosystem processes. In the Gulf of Mexico, higher mean temperatures and less frequent winter freezes have led to the expansion of tropics-associated marine organisms. We have quantified a substantial northern expansion of the Common Snook Centropomus undecimalis into the Cedar Keys area of Florida, USA (29 deg N). Using data from a long-term monitoring program, we report an exponential increase in catches of snook in the area since 2007, with a fully established and reproducing population by 2018. Snook have high diet overlap with native fish predators, and thus their expansion in this region could have strong food web implications. Further, evidence suggests that Snook are using coastal rivers and springs as thermal refugia during winter, and the degree of refuge habitat could be strongly influenced by freshwater flow rates. Here we present ongoing data collection and highlight collaboration among state and federal agency partners to assess the impact of Snook on coastal systems, including food web impacts and implications for setting minimum flow and level regulations.