Mr Nicolas Restrepo1, Shawn Gerrity3, Spencer Virgin3, Shane Orchard3, Mads Thomsen3, François Thoral2,3, Jackson Treece1, Sara Ferreira1, David Schiel3, Christopher Battershill2, Neil Gemmell1
1University of Otago, Dunedin, New Zealand, 2University of Waikato, Tauranga, New Zealand, 3University of Canterbury, Christchurch, New Zealand, 4University of Plymouth, Plymouth, England
Biography:
I am a PhD student in the Department of Anatomy at the University of Otago, New Zealand, where my research focuses on using environmental DNA (eDNA) to investigate the effects of land-based stressors on biodiversity and ecosystem function in temperate kelp forests and rocky shore ecosystems. My research interests include marine ecology, conservation genetics, biodiversity monitoring, and the application of genomic technologies to support marine conservation and management.
Abstract:
Land-based human activities are increasing sediment input to coastal catchments, compounding the effects of warming on intertidal ecosystems, yet the consequences for biodiversity at fine spatial scales remain poorly resolved. This study uses environmental DNA (eDNA) metabarcoding to examine how intertidal metazoan community composition, including taonga (culturally significant) species, varies with temperature and land-derived sedimentation across five sites selected for their sediment catchment characteristics in the north-eastern Bay of Plenty, New Zealand. At each site, water samples were collected in triplicate from high, mid, and low intertidal zones using both passive and active (1-litre syringe) filtration, during two sampling events (December 2025 and July 2026), with a third planned. Samples are being processed using two metabarcoding markers: 16S ribosomal RNA (16S rRNA), targeting fish, and cytochrome c oxidase subunit I (COI), targeting broader metazoan diversity. Site-level temperature loggers and sedimentation measurements, linked to in-land land-use activity, are paired with concurrent visual biodiversity surveys to validate eDNA detections and account for imperfect detection in downstream analyses. Community composition will be related to environmental variables using multivariate and model-based approaches, including generalized linear latent variable models and site occupancy detection models. This integrated approach will provide a spatially explicit assessment of how catchment-derived sedimentation and thermal stress structure intertidal biodiversity, with particular relevance to taonga species, offering a robust framework to support coastal management and sediment catchment monitoring in the region.