Cyclodextrin polymers as passive sampling materials for lipophilic marine toxins in Prorocentrum lima cultures and a Dinophysis sacculus bloom in the NW Mediterranean Sea.

Cyclodextrins, cyclic oligomers that form a conical structure with an internal cavity, are proposed as new and sustainable materials for passive sampling of lipophilic marine toxins. Two applicability scenarios have been tested. First, disks containing ß-cyclodextrin-hexamethylene diisocyanate (ß-CD-HDI) and ß-cyclodextrin-epichlorohydrin (ß-CD-EPI) polymers were immersed in Prorocentrum lima cultures for different days (2, 12 and 40). LC-MS/MS analysis showed capture of free okadaic acid (OA) and dinophysistoxin-1 (DTX1) by cyclodextrins at contents that increased with immersion time. Cyclodextrins resulted more efficient in capturing DTX1 than OA. In a second experiment, disks containing ß-CD-HDI, ß-CD-EPI, γ-CD-HDI and γ-CD-EPI were deployed in harbor waters of El Masnou (NW Mediterranean Sea) during a Dinophysis sacculus bloom in February 2020. Free OA and pectenotoxin-2 (PTX2) were captured by cyclodextrins. Toxin contents were higher at sampling points and sampling weeks with higher D. sacculus cell abundance. In this case, PTX2 capture with cyclodextrins was more efficient than OA capture. Therefore, cyclodextrins have provided information regarding the toxin profile of a P. lima strain and the spatial and temporal dynamics of a D. sacculus bloom, proven efficient as passive sampling materials for environmental monitoring.

Detection of Dinophysis Species and Associated Okadaic Acid in Farmed Shellfish: a Two-year Study from The Western Mediterranean Area.

INTRODUCTION: Diarrhoetic shellfish poisoning (DSP), an alimentary intoxication known to lead to intestinal symptoms, and caused by toxins produced by some dinoflagellates (including several Dinophysis), represents a serious threat to public health. The aim of this paper was to provide information about the occurrence and abundance of potentially toxic harmful algal species causing DSP, and the associated concentration of okadaic acid (OA) toxins. The departing assumption was that in the study area there was an increase in the presence both of Dinophysis species and OA and its derivates that could result in a risk to the health of seafood consumers. MATERIAL AND METHODS: During 2015-2016, water and shellfish samples were collected in the Mediterranean area (Sardinia, Italy). Dinophysis cells were counted according to Utermöhl's method from water samples, while mass spectrometry was used to identify lipophilic toxins in molluscs. RESULTS: A total of 46 non-compliant samples of Mytilus galloprovincialis were observed. Their non-compliance concerned their OA levels above the legal limit. Among toxic dinoflagellates, D. acuminata and D. sacculus were the species found mostly during DSP events. CONCLUSION: No cases of human intoxication have been reported, but continuous surveillance of toxic phytoplankton is necessary to predict and prevent its harmful effects on human health.

Morphometric characterization of Dinophysis acuminata/D. sacculus complex in Guanabara Bay, Brazil / Caracterização morfométrica de dinoflagelados do Complexo Dinophysis acuminata/D. saculus na Baía de Guanabara, Brasil

Abstract: Most studies of Dinophysis acuminata in Brazil are for the southern region, where blooms are recurrent. In 2016, the presence of D. acuminata caused the first-ever production and consumption of species of mollusks commercial embargo from the state of Sao Paulo, Southeast Brazil. Potentially toxic species of Dinophysis have been reported in Guanabara Bay (GB) but only occasionally and in low densities. The present note is the first report of a high-density event (~105 cells L-1) of D. acuminata/D. sacculus complex in GB. D. acuminata/D. sacculus complex species were identified using scanning-electron and inverted-light microscopy. Most of the studied cells possessed a dorsally convex hyposomal plate and had dimensions typical of D. acuminata. However, the observed association with warmer and less saline estuarine waters would indicate that the species could be D. sacculus. Whatever the case, based on the high cell densities observed here, we recommend a continued monitoring for Dinophysis presence in GB.

Resumo: A maioria dos estudos sobre Dinophysis acuminata no Brasil ocorreram na região sul, onde as florações são recorrentes. Em 2016, a presença de D. acuminata causou o primeiro embargo comercial da produção e consumo de espécies de moluscos do estado de São Paulo, sudeste do Brasil. Várias espécies de microalgas potencialmente nocivas foram relatadas na Baía de Guanabara (BG), incluindo espécies tóxicas de Dinophysis, mas estas foram reportadas apenas como ocasionais e em baixas densidades. A presente nota é o primeiro relato de um evento de alta densidade (~ 105 células L-1) do complexo D. acuminata/D. saculus na BG. As espécies foram identificadas através de microscopia eletrônica de varredura e de campo claro. A maioria das células estudadas possuía uma placa hipossômica dorsalmente convexa, e tinha dimensões típicas de D. acuminata. No entanto, a associação observada com águas estuarinas mais quentes e menos salinas indicaria que a espécie seria D. saculus. Qualquer que seja o caso, com base nas altas densidades observadas aqui, recomendamos o monitoramento contínuo da presença de Dinophysis na BG.

First report of the toxin profile of Dinophysis sacculus Stein from LC-MS analysis of laboratory cultures.

Dinophysis sacculus is associated with DSP outbreaks especially in the Mediterranean Sea and is supposed to be mildly toxic based on few toxin results from field samples. First report of LC-MS analysis of D. sacculus cultures from Galicia (NW Spain) showed moderate amounts of OA (7.8 pg cell(-1)) comparable to those found in Dinophysis acuminata from the same region, PTX2 (13.2 pg cell(-1)) and trace amounts of DTX1 (0.8 pg OA equiv. cell(-1)). The contribution of D. sacculus to DSP outbreaks in the Galician Northern Rías should not be underestimated.