Examining Linkages among Microcystins, Shellfish Contamination, and Toxin Transfer in Oysters and Blue Crabs across a Coastal North Carolina Sound

ABSTRACT – RESEARCH PROJECT 1 The primary objective of Project 1, as an integral component of the North Carolina Center for Coastal Algae, People, and Environment (NC C-CAPE), will be to address significant public health risks due to the proliferation of harmful algal blooms (HABs) in coastal waters. The transfer of cyanobacterial toxins, specifically microcystins

(MCs), to oysters and blue crabs has been verified at five sites across NC's estuarine habitats, raising concerns about hepatotoxic shellfish poisoning (HSP) from human shellfish consumption. This project aims to advance our understanding of current and future ecosystem and human health risks from HABs by collecting pivotal

information on MC distribution and toxin mixtures, and by determining the scope of seafood contamination to guide stakeholder mitigation efforts, inform risk assessment and prediction, and aid animal and human health studies. Aim 1 is to characterize the environmental conditions that lead to increased MC and

cyanobacterial presence in Pamlico Sound to test the hypothesis that increases are observed in response to site-specific shifts in environmental and hydrological conditions (e.g., salinity, temperature), and will primarily be associated with increased transport from upriver sources following severe weather events. Field sampling will

involve cutting-edge real-time sensing platforms, event-driven sampling, and routine monitoring to determine species composition, toxin concentrations and mixtures within the largest US lagoonal estuary, the Pamlico Albemarle Sound System. Aim 2 is to quantify MC contamination in shellfish to test our hypothesis that MC

transfer to oysters and blue crabs is widespread and linked to downstream transport of cells and toxins. Shellfish from Pamlico Sound will be analyzed for MC body burdens and relationships with cyanobacterial abundance and toxin patterns in the surrounding environments and pertinent physicochemical conditions. Aim 3 is to

characterize the temperature-dependent kinetics of MC transfer and detoxification in oysters and co- occurring predator the blue crab. We will test the hypothesis that MC transfer from lower trophic levels (oysters) to higher trophic levels (blue crabs) represents a balance between bioaccumulation and detoxification

(i.e., dilution) and that climate-induced changes in temperature will affect future risks related to shellfish body burdens and HSP to human health. Project 1 will inform Project 2 with the overall goal of understanding human health risks associated with the exposure to MCs and MC mixtures, provide Project 3 with diverse algal bloom

metrics and environmental covariates for integration and probabilistic modeling to assess and predict the spatial and temporal variability in cyanotoxin levels under current and future climate scenarios, and Project 1 researchers will participate in center-wide initiatives by NC C-CAPE's Community Engagement Core to

translate project findings, to build data sharing practices to connect with community stakeholders, and participate in community science initiatives.