Sample site coordinates, environmental data, number of copies of target DNA/ul for each sample and limit of detection plot

Human activities in coastal areas are accelerating ecosystem changes at an unprecedented pace, resulting in habitat loss, hydrological modifications, and predatory species declines. Understanding how these changes potentially cascade across marine and freshwater ecosystems requires knowing how mobile euryhaline species link these seemingly-disparate systems. As upper trophic level predators, bull sharks (Carcharhinus leucas) play a crucial role in marine and freshwater ecosystem health. Telemetry studies in Mobile Bay, Alabama suggest that bull sharks extensively use the northern portions of the bay, an estuarine-freshwater interface known as the Mobile-Tensaw Delta. To assess whether bull sharks use freshwater habitats in this region, environmental DNA surveys were conducted during the dry summer and wet winter seasons in 2018. In each season, 5 x 1 L water samples were collected at each of 21 sites: five sites in Mobile Bay, six sites in the Mobile-Tensaw Delta, and ten sites througho...