Mr Patrick Nichols1, Dr. Alison Sherwood1, Dr. Peter Marko1
1University Of Hawaiʻi at Mānoa, Honolulu, USA
Biography:
Patrick Nichols is a Ph.D. candidate in the School of Life Sciences at the University of Hawaiʻi at Mānoa. His research focuses on marine ecology, specifically the use of environmental DNA (eDNA) for tracking community composition shifts through space and time, as well as for the early detection of invasive species. Nichols has developed innovative techniques for improving the efficiency and sensitivity of eDNA methods for detecting low-abundance species in diverse marine environments. He is passionate about advancing tools for environmental conservation and management of marine ecosystems, making routine eDNA biomonitoring more accessible for managing stakeholders.
Abstract:
Efficient detection and management of non-indigenous species (NIS) are critical for mitigating their ecological impacts. Environmental DNA (eDNA) techniques have revolutionized biomonitoring by enabling sensitive and cost-effective surveys. This study compares the efficacy of passive eDNA samplers (PEDS) to conventional active filtration methods for detecting the cryptogenic macroalga Chondria tumulosa within the Papahānaumokuākea Marine National Monument (PMNM), Hawaiʻi, USA. Site-occupancy models provided a robust framework for evaluating detection probabilities, offering critical insights into the performance and limitations of PEDS for detecting rare taxa. PEDS deployed for a 15 minute passive exposure performed equally to active filtration but exhibited lower qPCR detection rates and higher probabilities of false-positive detections. We also tested two passive membrane types—research-grade mixed cellulose ester filters and low-cost 100% cotton rounds. The more absorbent cotton rounds yielded greater target eDNA concentrations and more reliable detections of C. tumulosa. The overall reduced DNA yields from PEDS underscore the importance of optimizing sampling and processing protocols to balance erroneous detections. Despite these limitations, passive sampling successfully detected C. tumulosa at low abundances (<1%), highlighting its utility for detecting cryptic taxa. PEDS are a cost-effective, versatile, and scalable alternative to active filtration, particularly in remote or resource-limited settings.