2026/01/14 by Shannon N. Barry, Douglas H. Adams, Matthew J. Ajemian +4 · 1 voice
Environmental Science · #Ichthyology and Marine Biology #Marine animal studies overview #Fish Ecology and Management Studies
paper · doi:10.3354/meps15095
Understanding how marine populations adapt to their environment is important for effective management. Range shifts can decrease genetic diversity, reducing species’ ability to resist extinction. The bull shark Carcharhinus leucas is a large coastal predator that uses shallow water habitats as nurseries, the extent of which defines the adult range. In the northwest Atlantic, the historic northernmost nursery for bull sharks was in the Indian River Lagoon (IRL), Florida (USA). Recently, bull sharks were shown to have founded a new nursery in Pamlico Sound (PS), North Carolina, due to warming water. To describe the evolutionary patterns associated with this change, we investigated genetic connectivity and diversity using 15 microsatellite loci among juvenile bull sharks from both the historic and contemporary IRL, the novel PS nursery, and sites in southern Florida and the Gulf of Mexico. We identified connectivity between the historic IRL and PS populations, indicating an IRL origin for the new nursery. We also found significant structure between the historic and contemporary IRL populations, but not between the contemporary IRL and southern Florida, supporting a population-wide poleward shift. These results show that northwestern Atlantic bull sharks are altering their life history to cope with warming water, and demonstrate for the first time that a large coastal predator is undergoing a genetic response to climate change.