Nearshore Protected Bays as Nursery Grounds: Evaluating Seasonal Variation in Leopard Sharks and California Bat Rays in Pillar Point Harbor Using eDNA
Sam Rico
Department of Biology
Faculty Supervisor: Karen Crow
Elasmobranch habitats are under threat worldwide with most species facing significant conservation challenges due to their slow reproductive rates and declining populations. They are slow to mature and exhibit low fecundity. Despite their importance in maintaining ecosystem diversity and resilience, monitoring populations and evaluating habitat use is challenging because they don’t breathe air at the surface, and are therefore difficult to observe. As such, most survey techniques such as seine nets, scuba, and baited remote underwater video (BRUV) are invasive, labor intensive, biased, and interrupted by weather conditions (Gold et al.,2023). To address these challenges, this research utilizes environmental DNA (eDNA) analysis, a non-invasive and reliable method for studying marine species, because it detects genetic material collected from seawater that originated from mucous, skin cells, or feces. Here, we utilize eDNA to detect seasonal variation in habitat use of the two most abundant nearshore elasmobranchs in California, Triakis semifasciata (leopard shark) and Myliobatis californica (California bat ray). Leopard sharks are known to utilize protected nearshore habitats as nursery grounds, but nothing is known about habitat utilization at Pillar Point Harbor, California. We designed custom assays, that are specific to our focal taxa based on the cytochrome b locus.