Shellfish farming contamination by marine biotoxins: New insights into the ecological toxic dinoflagellate Dinophysis dynamics and DSP (diarrhetic shellfish poisoning) events for safe production management of marine aquaculture.

Mussel farming is a vital economic activity for several coastal regions, where the presence of the toxic dinoflagellate Dinophysis and associated toxins are regularly monitored in seawater and mussels. A recent study analyzed the ecological dynamics of Dinophysis species assemblages in relation to toxicity events recorded in mussel farms and environmental variables over a period of 25 years (1998-2023) along the Emilia-Romagna and Marche coasts in the northwestern Adriatic Sea. The study found that diarrhetic shellfish poisoning (DSP) toxicity events were primarily recorded in autumn and winter, and were associated with the abundance of specific Dinophysis species, including D. caudata, D. fortii, and D. tripos. These species showed a strong correlation with DSP toxicity events, with correlation coefficients of 0.84, 0.83, and 0.66, respectively. The study also revealed a clear seasonality in the succession of Dinophysis species, with D. acuminata and D. sacculus dominating in spring and summer, followed by D. caudata, and finally D. fortii and D. tripos in autumn. Each Dinophysis species was found to have its own optimum temperature for maximum growth, highlighting the importance of environmental conditions in shaping the dynamics of these species. The long-term observations also showed interannual trends, including an increase in the absence of Dinophysis species and a decrease in toxicity in bivalve mussels, accompanied by declining trends in nutrients such as DIN, phosphate, and total phosphorus, as well as chlorophyll a. Notably, prolonged toxicity events occurred in 2015 and 2022, when surface waters were colder and slightly saltier than the long-term average. The study highlights the importance of long-term observations in understanding the variability of DSP events and Dinophysis dynamics, and the need to consider environmental conditions in the management of aquaculture activities. By analyzing these dynamics, the study aims to improve the management of mussel farming and reduce the risks associated with DSP toxicity events. Link: https://pubmed.ncbi.nlm.nih.gov/40318261/