Global Occurrence, Environmental Fate, and Toxicological Effects of Okadaic Acid Group Toxins

Under the impact of global climate change and anthropogenic activities, the distribution of toxigenic microalgae and phycotoxins is expanding rapidly, potentially threatening marine ecosystem health and human health. Okadaic acid group toxins (OAs), a class of lipophilic polyether compounds mainly produced by Dinophysis and Prorocentrum species, are widely distributed globally and affect the growth and development of marine organisms as well as the safety of seafood consumption. Currently, over 60 derivatives of OA have been detected in toxigenic microalgae and shellfish, including various diol esters, sulfated diesters, and 7-O-acyl esters. These toxins are widespread in seawater, suspended particles, sediments, porewater, and sea spray aerosols. In marine environments, natural solar radiation is the predominant factor triggering the degradation of OAs, while temperature influences the stability of dinophysistoxin 1 (DTX1), an analog of OA, to some extent, and the role of microorganisms is relatively minor. Through food chains, OAs can accumulate in organisms at different trophic levels, including shellfish, crabs, fish, and marine mammals, with shellfish being the primary bioaccumulators. Exposure to OAs, whether as dissolved compounds or via ingestion of their producing microalgae, induces diverse toxic effects on marine organisms, including oxidative stress, immune disruption, DNA damage, apoptosis, developmental abnormalities, and behavioral changes in species. This review summarizes the chemical diversity, environmental distribution, fate, bioaccumulation, and toxicological effects of OAs, and highlights the major limitations and future research directions. Future studies should include more derivatives of OAs in environmental and biological investigations, clarify the distribution and behavior of OAs in sea spray aerosols, and evaluate the chronic effects of environmentally relevant concentrations of OAs on marine organisms. The combined toxicity of OAs with emerging pollutants should also be systematically assessed to provide more reliable evidence for risk management in marine ecosystems.