Are mesophotic seamounts reservoirs for potentially toxic dinoflagellates associated with Ciguatera poisoning? A case study from the SW Indian ocean (expédition La Pérouse, 2019) Fig. 1. Location map of La Pérouse seamount off La Réunion. In the western Indian Ocean, a Ciguatera Fish Poisoning (CFP) hotspot is located in the coastal waters of the Mascarene Islands (Mauritius, Rodrigues, Réunion) and the offshore fishing banks of the Mauritius-Seychelles ridge, seamounts near Réunion and Mauritius (Fig. 1). The size of the La Pérouse seamount, 160 km northwest of Réunion Island on the oceanic floor, is comparable to that of Mont Blanc in the Alps. La Pérouse is one of the rare shallow (-60m) seamounts located in the region. The plateau comprises mainly fossil limestone plaques covered with macrophytes, sponges, corals (few), and sand and rubble zones (see back page photo). In 2005, an expedition organized by ARVAM at La Pérouse seamount (also known by local fishermen as 90 miles bank) collected carnivorous fish containing I-CTXs for analysis, as well as samples of sediment and macroalgae which subsequently facilitated the identification of Gambierdiscus spp in the area. During October-November 2019, a diving and scientific expedition (La Pérouse 2019) was organized to generate a first description of the habitats and associated fauna and flora on the seamount based on a High Quality (HQ) photographic inventory. Although few samples for geological and biological analyses were taken, the focus on HARMFUL ALGAE NEWS NO. 64 / 2020 macroalgal biodiversity and sediments meant it was possible to isolate the microalgae assemblage from these samples. A preliminary inventory from these samples collected at depths between -60 & -120m, revealed the presence of the main genera observed in typical CFP habitats: Gambierdiscus, Prorocentrum, Coolia but also athecate taxa such as Amphidinium and gymnodinoid dinoflagellates (Fig. 2), and thecate taxa such as Cabra, Sinophysis, Bysmatrum and scrippsielloids. Interestingly, among potentially toxic taxa, Gambierdiscus spp were clearly predominant in the samples (approx. 95% of isolated cells) while Ostreopsis spp and Fukuyoa spp were very rare. In order to give a precise identification and better evaluation of the diversity, preserved cells from approx. 35-40 morphotaxa have been isolated individually in order to allow SEM observations and molecular sequencing of LSU rDNA from single-cells in the coming months. This study will provide a significant contribution for better knowledge of habitat preferences and vertical distribution of CFP sources. While CFP is traditionally associated with coral reefs near the ocean surface where sunlight conditions are optimal for growth and toxin production, in this case only a low concentration of light penetrates to the depths encountered at La Pérouse seamount, considered in the mesophotic zone. Only blue light reaches the benthic community here and literature about the influence of these conditions on toxin production by primary progenitors involved in seafood poisonings is scarce. This study will also inform results of source & sink mechanisms that allow harmful species to spread at regional scales from these seamounts to coastal ecosystems. Acknowledgements To Sophie Durville and Thierry Mulochau for their enthusiasm and to Laurent Ballesta, Florian Holon and Thibault Rauby for diving deep and bringing samples to the surface. Authors Jean-Pascal Quod, Arvam-Pareto, Technopole de la Réunion, 97438 Réunion (France). Nicolas Chomérat & Gwenael Bilien, Ifremer, LER BO, Station de Biologie Marine, Place de la Croix, F-29900 Concarneau (France) Patrick Durville, SAS Galaxea, Saline les Bains, 97434 Réunion (France) Email corresponding author: jpascal.quod@arvam.com Fig. 2. Benthic dinoflagellates from La Pérouse seamount. (A) Gambierdiscus sp. (B) Amphidinium sp. (C) Prorocentrum sp. (D) Prorocentrum sp. (E) Coolia sp. Scale bars, 10 μm. 13 Harmful Algae News An IOC Newsletter on Toxic Algae and Algal Blooms No. 64 - June 2020 www.ioc-unesco.org/hab The IOC Taxonomic Reference List of Harmful Microalgae The creation of the IOC Taxonomic Reference List of Harmful Microalgae was first discussed 23 years ago at the Fourth Session of the ever the information presented in publications is not always easy to interpret. Toxic blooms often contain several species and studies on individual species are therefore required to determine the species responsible for the toxin production. In addition, species are sometimes difficult to identify considered this to be identical to the previously described P. mexicanum [9]. This statement makes little sense, and Loeblich et al in fact do not mention P. mexicanum in their article. Faust [8] illustrated material which resembled P. rhathymum using the radical arrangement of some of the trichocys Massive salmon mortalities during a Chrysochromulina leadbeateri bloom in Northern Norway From mid May to mid June 2019, fish farmers along the coast of Nordland and Troms, northern Norway, experienced sudden mortalities of caged salmon [1] (Fig. 1). These mortalities were assumed to be due to a blo Fish kill in numbers [2] 13 000 ton fish 7.5 mill salmon 80 mill EUR 14 companies Fig. 2. Map of Norway showing the area where the Chrysochromulina leadbeateri bloom occurred causing massive fish kills in May-June 2019 References 1. Fiskeridirektoratet 2019. https:// www.fiskeridir.no/Akvakult Mass mortality of marine invertebrates associated with the presence of yessotoxins in northern Chile Fig. 1. Map of the study area showing A) Chilean coast; B) Pabellón de Pica, Tarapacá Region C) Bahía Inglesa, Atacama Region; D) Puerto Aldea, Coquimbo Region During the austral summer of 2019, ma research is needed to determine the mechanism of action and the toxin effects on tissues and cells of the main affected species. Finally, there is a need to establish an educational plan to protect the public and avoid the consumption and commercialization of potentially toxic marine invertebrates. First Report of Heterocapsa minima (Dinophyceae) from Aotearoa/ New Zealand Small planktonic armoured dinoflagellates within the genus Heterocapsa are currently represented by 20 species with some having a world-wide distribution [1-2]. Blooms of some Heterocapsa species have been associated with fi Fig. 2. Maximum likelihood (ML) molecular phylogenetic tree of Heterocapsa minima and H. steinii strains isolated from coastal areas of New Zealand based on the LSU rDNA D1/ D2 sequences (20 sequences, 700 positions). The alignment site corresponded to the 69768 bp site of a sequence from H. steinii Yellow-green tides could become a recurrent event along the Ligurian coast (Italy) Fig. 1. A) Sestri Levante and Baia del Silenzio bay, characterized by shallow water and mixed rocky-sandy seabed containing the macrophyte, Posidonia oceanica (dark grey) and carpet-like matte (light grey) habitat. B First report of a high biomass bloom of Peridinium quadridentatum (F. Stein) Gert Hansen from the tropical Cochin estuary SW coast of India Fig. 1. Map showing the area of P. quadridentatum bloom in Cochin estuary, southwest coast of India Peridinium quadridentatum (F. Stein) Gert Hansen is a cos Table 1. Physico-chemical parameters of P. quadridentatum bloom area in Cochin Estuary Parameters Water Temperature (oC) Salinity (psu) Dissolved Oxygen (ml L-1) Nitrate (μmol L-1) Silicate (μmol L-1) Phosphate (μmol L-1) Chlorophyll a (mg m-3) 28 20 2.01 10.6 23.3 1.3 27.5 higher turbidity, lowe Are mesophotic seamounts reservoirs for potentially toxic dinoflagellates associated with Ciguatera poisoning? A case study from the SW Indian ocean (expédition La Pérouse, 2019) Fig. 1. Location map of La Pérouse seamount off La Réunion. In the western Indian Ocean, a Ciguatera Fish Poisoning (CF Using Machine Learning to Observe Abundance Patterns of the Dino flagellate Noctiluca scintillans in the Western English Channel Noctiluca scintillans is a Harmful Algal Bloom (HAB) species with a wide geographic distribution. It frequently blooms and causes negative impacts on marine ecosystems [1] References 1. Sarma VVSS et al 2019. Mar Pollut Bull 138: 428-436 2. Faust MA & RA Gulledge 2002. Contributions for the US National Herbarium 42: 1-144 3. Graham MD et al 2018. Limnol Oceanogr-Meth 16: 669-679 Author Christian Bamber, The Marine Biological Association, Citadel Hill, Plymouth PL1 2PB International validation and recognition of method for paralytic shellfish toxins in bivalve molluscs Food safety scientists from Cefas (UK) and Cawthron Institute (New Zealand) have led an international study over the past four years to gain international recognition for a new method to quantify pa Aotearoa/New Zealands nationally significant Cawthron Institute Culture Collection of Microalgae (CICCM) The CICCM is critical to international research projects and the 500 isolates of microalgae and cyanobacteria in the collection have been sourced from oceans, lakes and rivers in New Zealand, the The 11th EASTHAB Symposium and 4th Philippine HAB Conference The 11th EASTHAB Symposium and 4th Philippine HAB Conference were held back-to-back from December 11 13, 2019 at the Microtel Hotel, Puerto Princesa, Palawan, the Philippines. The theme was Advances in Harmful Algal Bloom Research, Monito Fig. 1. Participants in the 11th EASTHAB Symposium/4th Philippine HAB Conference Fig. 2. Department of Science and Technology secretary Fortunato dela Peña with the keynote, plenary speakers and local organizing committee leads. Left to right: Dr. Ichiro Imai, representative of the Vice Mayor of Pu The ICES-IOC Working Group on Harmful Algal Bloom Dynamics 2020 Meeting The International Council for the Exploration of the Sea (ICES) and the Intergovernmental Oceanographic Commission of UNESCO (IOC) have collaborated closely for 26 years, stimulating research on HAB population dynamics and monit Fig. 2. Shared day between ICES-IOC WGHABD, ICES-IOC WGBOSV and ICES WGITMO ences using molecular methods as well as results from studies in Arctic areas. These studies presented data on HAB and invasive non-native species present in Arctic waters. A USA study focused on the distribution, community Typical benthic habitat with macroalgae and limestone rubble observed at ~ 60m depth on La Pérouse seamount, Indian Ocean (Photo courtesy of L. Ballesta). Eds-in-chief Beatriz Reguera, IEO, Vigo, Spain Eilen Bresnan, Marine Scotland, UK Regional Editors Caribbean: Ernesto Mancera jemancerap@unal.e