Investigating Trophic Exposure to Marine Microplastics and Plasticizers in a Sentinel Species and the Implications for Seafood Safety

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Project Summary/Abstract This proposed study will expose undergraduate students to hands-on, rigorous research that explores the intersections of oceans, wildlife, and human health. Specifically, students will participate in research to understand the risk of exposure to microplastics and plasticizers (i.e., phthalates) from contaminated seafood. For decades, bottlenose dolphins (Tursiops truncatus) have been used as sentinels of marine pollution risks for coastal communities that rely on seafood. Due to the recent detection of prevalent phthalate exposure in coastal bottlenose dolphins, a sentinel-species approach will be used to address three specific aims: 1) assess the potential for trophic exposure to microplastics; 2) determine if phthalate exposure is an indicator of microplastic exposure; and 3) evaluate spatiotemporal differences in phthalate exposure. This undergraduate research experience will provide an opportunity for students to engage in innovative studies of a federally-protected species, participate in ecotoxicological analyses in state-of-the-art laboratories, develop marketable statistical skills, and enhance their scientific communication through contributions to publications and presentations. Students will also be exposed to a broad range of biomedical fields as they will work closely with scientists with expertise in epidemiology, biostatistics, biology and conservation, ecotoxicology, and environmental health. The oceans contain trillions of plastic particles, mostly microplastics (i.e., particles < 5 mm diameter; approximately 93% of particles), which have been detected in organisms at all levels of the marine food web. These discoveries suggest that seafood safety is being threatened and public health compromised, as microplastic ingestion can lead to gastrointestinal inflammation, altered metabolism, and oxidative stress. Plastics can also leach endocrine-disrupting phthalates, which are associated with infertility, abnormal reproductive organ development, increased breast cancer risk, and poor pregnancy outcomes. The long-term goal of this study is to examine if microplastic-contaminated seafood could be an additional source of human exposure to harmful xenobiotics, and if this exposure varies spatiotemporally. Study aims will be addressed via serial cross-sectional sampling of free-ranging dolphins and their preferred prey in Sarasota Bay, FL. For Aim 1, microplastics will be characterized in dolphin gastric and fecal samples, as well as fish muscle and gastrointestinal tissues. Similarities in particle size, type, and polymer composition will suggest trophic exposure. For Aim 2, phthalate metabolites will be quantified in dolphin urine and fish metabolic tissues to examine correlations with ingested microplastics quantities from Aim 1. For Aim 3, urinary phthalate metabolite concentrations will be compared between two distinct dolphin populations (Sarasota Bay, FL; Barataria Bay, LA) and across time (2010-2024) to understand spatiotemporal differences in exposure risk. Findings from this study will help to evaluate the potential of contaminated seafood as an additional source of microplastic and phthalate exposure for humans, as well as inform intervention and risk communication needs regarding seafood safety.