Miss Danielle Bartz1,4, Dr. Alyssa Budd2, Dr. Timothy Grabowski3,4
1University Of Hawai'i at Manoa, Honolulu, USA, 2Commonwealth Scientific and Industrial Research Organisation, Perth, Australia, 3U.S. Geological Survey, Hilo, USA, 4Hawai'i Cooperative Fishery Research Unit, Hilo, USA
Biography:
Dani is currently a PhD candidate at the University of Hawaii at Manoa and a member of the Hawaii Cooperative Fishery Research Unit in Hilo, Hawaii. Originally from South Florida, she has been a lifelong ocean lover, and is an avid fisher, diver, and all-around water woman. Her current research on shark nursery habitats has landed her at the nexus of fisheries science, diverse knowledge systems, genomics and tech development.
Abstract:
Nearshore estuaries are frequently used as nursery habitats by coastal-pelagic sharks. While estuaries are subject to high levels of anthropogenic alteration, the response of shark populations to these changes is poorly understood due to a lack of monitoring. However, monitoring sharks can be challenging due to their relatively low population densities, movement patterns, and the feasibility of expensive tagging studies that may still provide very limited data. The objectives of this study were to reconstruct historical abundance patterns of juvenile sharks in Hilo Bay, Hawai’i through local ecological knowledge (LEK), while simultaneously working to identify a current ecological baseline for the two species most commonly observed within the LEK by using a species-specific environmental DNA (eDNA) approach. Local knowledge-holders consistently noted a decline in the occurrence of juvenile Scalloped Hammerhead (Manō Kihikihi; Sphyrna lewini) in recent decades, coinciding with increasing encounters with Blacktip Sharks (Manō Pa'ele; Carcharhinus limbatus). We attempt to elucidate which sharks are currently using Hilo Bay as nursery habitat by testing seawater samples for the DNA excreted by each species. Our novel eDNA study design resulted after more than a year of pilot sampling at 30 coastal embayments throughout the state, which identified the need to implement various site-specific optimizations, and ultimately lead to the development of an unprecedented filtration technology enabling the most efficient sampling of Hilo Bay given its unique characteristics. Using eDNA to monitor biodiversity trends in coastal waters can provide baseline information, monitor risks, and minimize the need for more invasive methodologies.