Persistence and trophic transfer of algal toxins in benthic-pelagic coupled food webs

The Virginia Institute of Marine Science (VIMS) received a $866,588 Cooperative Agreement from the National Oceanic and Atmospheric Administration (NOAA) under the Center for Sponsored Coastal Ocean Research Coastal Ocean Program (CFDA 11.478), effective June 1, 2025 through May 31, 2028. This three-year research initiative focuses on understanding the persistence and trophic transfer of four algal toxins—domoic acid, okadaic acid, microcystins, and azaspiracids—across benthic-pelagic coupled food webs in two estuarine systems: Chesapeake Bay, Virginia and Barataria Bay, Louisiana. The project will deliver critical scientific data and food-web modeling capabilities to support coastal management decisions related to harmful algal bloom impacts on commercially valuable fisheries and public health.

VIMS will conduct quarterly field surveys and laboratory studies to characterize how multiple toxin classes co-accumulate and persist through estuarine food webs, from primary consumers such as oysters to higher trophic level species including bull sharks. The research leverages existing monitoring programs at VIMS and the Louisiana Department of Wildlife and Fisheries to generate actionable toxicokinetic and food-web dynamics information. This work addresses a critical knowledge gap regarding the behavior of freshwater and marine toxins that converge in productive transition zones along the East and Gulf coasts, ultimately supporting evidence-based management of harmful algal bloom impacts in coastal regions.

Introduction to problem: many coastal regions within the US are impacted by an array of algal toxins, with production of multiple toxin classes overlapping in space and time. Freshwater and marine toxins converge, as tributaries carrying upstream harmful algal blooms (HABS) empty into productive transition zones that harbor other toxigenic species associated with higher salinities. These freshwater and marine algal toxins then have the potential to CO-accumulate in primary consumers of ecological and commercial value, e.g., oysters, and higher trophic level species, e.g., the bull shark. The food-web dynamics and toxicokinetics responsible for the accumulation and persistence of toxins, such as domoic acid, okadaic acid, microcystins, and azaspiracids, are largely unknown, especially in benthic-pelagic coupled food webs of estuaries along the east and gulf coasts of the US. Rationale: these four toxin classes will be the focus of the proposed work as they are regional toxins-of-concern that CO-occur, span the freshwater to marine continuum, are associated with amnesic, diarrhetic, hepatotoxic, and azaspiracid shellfish poisoning in humans, respectively, and range in solubility, mode of action, and molecular weight. Objectives and work plan: overall, the four objectives will focus on understanding the persistence and trophic transfer of four toxins in two estuaries: chesapeake BAY, virginia (VA) and barataria BAY, louisiana (LA) systems with CO-occurring freshwater and marine toxins and multiple lucrative fisheries. To ultimately provide critical data for food-web modeling (OBJ. 4), a combination of field and laboratory studies will be utilized. The project will center around quarterly field surveys of the benthic-pelagic coupled food webs of VA and LA, leveraging longstanding programs at vims and louisiana department of wildlife and fisheries (OBJ. 1). Quarterly food web surveys will provide sediments, water, and sufficient biomass from 10 taxa for toxin quantification from each feeding strategy, habitat type, and trophic level across benthic and pelagic food webs. The combination of a controlled laboratory study (OBJ. 2) and an intense, focused field study (OBJ. 3) will assess the persistence of toxins in the sediments, water column, and taxa associated with a range of trophic levels. As part of OBJ. 3, animal exposures will determine accumulation and depuration rates and toxin distribution across tissues, i.e., toxicokinetics, and quantify physiological impacts, i.e., oxidative stress.