Dihydrodinophysistoxin-1 produced by Dinophysis norvegica in the Gulf of Maine, USA and its accumulation in shellfish

© The Author(s), 2020. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Deeds, J. R., Stutts, W. L., Celiz, M. D., MacLeod, J., Hamilton, A. E., Lewis, B. J., Miller, D. W., Kanwit, K., Smith, J. L., Kulis, D. M., McCarron, P., Rauschenberg, C. D., Burnell, C. A., Archer, S. D., Borchert, J., & Lankford, S. K. Dihydrodinophysistoxin-1 produced by Dinophysis norvegica in the Gulf of Maine, USA and its accumulation in shellfish. Toxins, 12(9), (2020): E533, doi:10.3390/toxins12090533.Dihydrodinophysistoxin-1 (dihydro-DTX1, (M-H)−m/z 819.5), described previously from a marine sponge but never identified as to its biological source or described in shellfish, was detected in multiple species of commercial shellfish collected from the central coast of the Gulf of Maine, USA in 2016 and in 2018 during blooms of the dinoflagellate Dinophysis norvegica. Toxin screening by protein phosphatase inhibition (PPIA) first detected the presence of diarrhetic shellfish poisoning-like bioactivity; however, confirmatory analysis using liquid chromatography-tandem mass spectrometry (LC-MS/MS) failed to detect okadaic acid (OA, (M-H)−m/z 803.5), dinophysistoxin-1 (DTX1, (M-H)−m/z 817.5), or dinophysistoxin-2 (DTX2, (M-H)−m/z 803.5) in samples collected during the bloom. Bioactivity-guided fractionation followed by liquid chromatography-high resolution mass spectrometry (LC-HRMS) tentatively identified dihydro-DTX1 in the PPIA active fraction. LC-MS/MS measurements showed an absence of OA, DTX1, and DTX2, but confirmed the presence of dihydro-DTX1 in shellfish during blooms of D. norvegica in both years, with results correlating well with PPIA testing. Two laboratory cultures of D. norvegica isolated from the 2018 bloom were found to produce dihydro-DTX1 as the sole DSP toxin, confirming the source of this compound in shellfish. Estimated concentrations of dihydro-DTX1 were >0.16 ppm in multiple shellfish species (max. 1.1 ppm) during the blooms in 2016 and 2018. Assuming an equivalent potency and molar response to DTX1, the authority initiated precautionary shellfish harvesting closures in both years. To date, no illnesses have been associated with the presence of dihydro-DTX1 in shellfish in the Gulf of Maine region and studies are underway to determine the potency of this new toxin relative to the currently regulated DSP toxins in order to develop appropriate management guidance.Partial support for this research was received from the National Oceanic and Atmospheric Administration, National Centers for Coastal Ocean Science Competitive Research, Ecology and Oceanography of Harmful Algal Blooms Program under awards NA17NOS4780184 and NA19NOS4780182 to Juliette Smith (VIMS) and Jonathan Deeds (US FDA), and Prevention, Control, and Mitigation of Harmful Algal Blooms program award NA17NOS4780179 to Stephen Archer. This paper is ECOHAB publication number EC0956

The Arctic Summer Cloud-Ocean Study (ASCOS): Overview and experimental design

The climate in the Arctic is changing faster than anywhere else on Earth. Poorly un-derstood feedback processes relating to Arctic clouds and aerosol-cloud interactionscontribute to a poor understanding of the present changes in the Arctic climate system,and also to a large spread in projections of future climate in the Arctic. The problem is exacerbated by the paucity of research-quality observations in the central Arctic. Im-proved formulations in climate models require such observations, which can only comefrom measurements in-situ in this difficult to reach region with logistically demandingenvironmental conditions.The Arctic Summer Cloud-Ocean Study (ASCOS) was the most extensive central Arctic Ocean expedition with an atmospheric focus during the International Polar Year(IPY) 2007–2008. ASCOS focused on the study of the formation and life cycle of low-level Arctic clouds. ASCOS departed from Longyearbyen on Svalbard on 2 August andreturned on 9 September 2008. In transit into and out of the pack ice, four short re-search stations were undertaken in the Fram Strait; two in open water and two in the marginal ice zone. After traversing the pack-ice northward an ice camp was set up on12 August at 87◦21′N 01◦29′W and remained in operation through 1 September, drift-ing with the ice. During this time extensive measurements were taken of atmosphericgas and particle chemistry and physics, mesoscale and boundary-layer meteorology,marine biology and chemistry, and upper ocean physics. ASCOS provides a unique interdisciplinary data set for development and testing ofnew hypotheses on cloud processes, their interactions with the sea ice and ocean andassociated physical, chemical, and biological processes and interactions. For exam-ple, the first ever quantitative observation of bubbles in Arctic leads, combined withthe unique discovery of marine organic material, polymer gels with an origin in the ocean, inside cloud droplets suggest the possibility of primary marine organically de-rived cloud condensation nuclei in Arctic stratocumulus clouds. Direct observations ofsurface fluxes of aerosols could, however, not explain observed variability in aerosol concentrations and the balance between local and remote aerosols sources remainsopen. Lack of CCN was at times a controlling factor in low-level cloud formation, andhence for the impact of clouds on the surface energy budget. ASCOS provided de-tailed measurements of the surface energy balance from late summer melt into theinitial autumn freeze-up, and documented the effects of clouds and storms on the surface energy balance during this transition. In addition to such process-level studies, theunique, independent ASCOS data set can and is being used for validation of satelliteretrievals, operational models, and reanalysis data sets.ISSN:1680-7375ISSN:1680-736