MARINE BIOTOXINS SCREENING IN MOST CONSUMED BIVALVES FROM MAPUTO BAY, IN MOZAMBICAN COAST

L. J. B. Banze¹, I. Tamele², V. L. Dias³

¹Eduardo Mondlane University, Escola Superior de Ciências Marinhas e Costeiras, Mozambique, Quelimane, luisajaquelinabanze@gmail.com

² Eduardo Mondlane University, Departamento de Química, Mozambique, Maputo, isitamele@gmail.com

³Eduardo Mondlane University, Departamento de Ciências Biológicas, Mozambique, Maputo, valeraceae@gmail.com

Contextualization: Mozambique, although rare, recent cases of human illness linked to bivalve consumption have been reported, particularly in areas with informal collection and insufficient monitoring by Fisheries Authorities. On Inhaca Island, allergic reactions and diarrhea have been linked to consuming bivalves, especially from Mwapheswane and Xihlolovondwene. Objective: To assess the presence of biotoxins in the most consumed bivalves molluscs on Inhaca Island, Maputo Bay. Metodology: Sampling was conducted over four months (May, June, August, and November) in 2024, at four sites: two natural environments (Mwapheswane and Xihlolovondzwene), where oysters, cockles, and mussels were collected, and two aquaculture farms (Farol and Ponta Torres), where mussels were collected.  Samples were analyzed using Liquid Chromatography-Mass Spectrometry/Mass Spectrometry, and associated microalgae were identified via microscopy.  Preliminary Results: Four toxins were detected: Portimine A, and Pinnatoxins E, F, and G. Portimine A and Pinnatoxin F were present at low concentrations. Pinnatoxins E and G were more widespread, particularly in oysters and cockles from natural environments, with toxin levels peaking during the cooler months. In cockles, Pinnatoxin G consistently exceeded 2.0 µg/kg, while in mussels it reached up to 6.0 µg/kg. Aquaculture mussels also contained both toxins, with concentrations exceeding 8.0 µg/kg only in August. Many dinoflagellates, including Vulcanodinium rugosum, Gimnodinium catenatum, as well as diatoms, including Pseudo-nitzschia ssp, Asterionella formosa, are among the primary species of microalgae that have been identified. Conclusion: The Pinnatoxin E and G were found in all samples, but only occasionally exceeded 6.0 µg/kg. Toxin-producing microalgae, such as Vulcanodinium rugosum, were observed, but further studies are needed to validate these findings at the sampling sites. It is also recommended to catalogue marine microalgae in Mozambique, as current studies have focused primarily on inland waters.

Key-words: Inhaca Island, Molluscs, Pinnatoxin, Toxins