Pelagic Sargassum reaching Serranilla Bank, Caribbean Colombia, may pose a risk to baby turtles Fig. 1. Location of Serranilla Bank in the Caribbean Sea (Photo Wikipedia) Floating Sargassum has been known from centuries to occur in the Atlantic Ocean, in a region named the Sargasso Sea. Floating Sargassum mats can form a pelagic ecosystem comprised by two species, S. fluitans and S. natans, which support a high variety of species associated with them [1]. It has been estimated that the Sargasso Sea harbors about 10 million tons of wet biomass [2]. Although deposits of Sargassum occur naturally and regularly on beaches, since 2011 enormous quantities of these seaweeds have been washed ashore in the Caribbean Sea, Gulf of Mexico, and, in 2011, even reached the West coast of Africa [3-5]. Multiple hypotheses have been proposed to explain such events, amongst which stand the excess of nutrient loads, a change in trade currents, and global climate change [6]. To some extent, Sargassum biomass may be beneficial to the environment, because it provides food and shelter to a number of organisms, it may help fight beach erosion and provides nutrients to beach habitats [6]. However, when biomass is very high, it may have negative effects: the accumulation of algae on the sea surface precludes light penetration and affect corals, sea grasses and benthic macroalgae [7]. Drift algae on the beach may become a barrier to nesting turtles and/or to baby turtles finding their way to the ocean [7-9]. Cleaning up the excessive biomass along the beaches may enhance beach erosion [6] and decomposition on the shore may change water chemistry and induce hypoxia, with consequent fish die-off [10]. Serranilla Bank is an ancient atoll in the Caribbean Sea, at 15o 50 N and 79 o 50 W (Fig. 1). It has several small keys emerging from the water to form some permanent islands. These small islands, far from other emerged territories, have been recognized recently as important nesting areas for sea turtles (Barrientos-Muñoz and Ramirez-Gallego, pers. comm.). In September 2017, the Colombian Commission for the Ocean (CCO), with the participation of other Colombian agencies and institutions (Colciencias, Dimar) and the logistic support of the Colombian Navy (Armada de Colombia), organized a scientific expedition to Serranilla Bank. During this expedition, which is the first and largest effort to date to study the biodiversity of this remote area of Colombia, we observed a large amount of floating Sargassum reaching the beaches of Beacon Key, the largest island in Serranilla Bank (Fig. 2). The algae accumulated on the beaches, and formed a thick 40 cm high mat (Fig. 3). On the beach, there were a large number of turtle nests (Barrientos-Muñoz and Ramirez-Gallego, pers. comm.) which, by the time of the Sargassum wave, were ready to disclose and the baby turtles go to sea. Some baby turtles were observed having troubles passing the barrier posed by the Sargassum mat (Fig. 4), and were vulnerable to predation by ghost crabs, rats and other predators. Considering that all the sea turtles species in the Caribbean are at risk of extinction, large amounts of Sargassum in Serranilla Bank may pose an additional threat to the survival of these organisms. Acknowledgements The authors are greatly indebted to the Comision Colombiana del Océano (CCO), to the Armada Nacional de Colombia, to Colciencias, and to Dimar for organizing the Scientific Expedition Seaflower 2017, Serranilla Bank. We thank Karla Georgina Barrientos-Muñoz and Cristian Ramirez-Gallego, from the Fundación Tortugas del Mar, for sharing their knowledge on sea turtles and Santiago Estrada-Robledo, from the Reef Shepherd Scuba diving school, for the aerial photo of Sargassum. The present study was financed by Universidad Nacional de Colombia, sede Caribe. Fig. 2. Aerial photo of drifting Sargassum reaching Beacon Key. (Photo credits: Santiago Estrada-Robledo) 4 HARMFUL ALGAE NEWS NO. 58 / 2017 Harmful Algae News An IOC Newsletter on Toxic Algae and Algal Blooms No. 58 - November 2017 www.ioc-unesco.org/hab Call to Contribute to Global Harmful Algal Bloom Status Reporting From 25 to 28 September 2017 sixteen HAB experts from 13 countries gathered at the headquarters of the IOC IODE (Inte the first of which will be launched in Nantes. Follow the development of the Global HAB Status Report at http://haedat. iode.org/ and see who is involved and how you may engage. Acknowledgements We thank Ward Appeltans and Pieter Provoost at the IOC/IODE Project Office for hospitality and technical PSP# # # # # # DSP# # # # # # AZP# ! ! ! Fig. 4. Maps showing the incidence of PSP, DSP and AZP during the period 2014 to 2016 in the North Atlantic as reported by the ICES-IOC WG HABD. Areas such as Northern Canada and Greenland are not routinely sampled and countries with pink borders have sti Pelagic Sargassum reaching Serranilla Bank, Caribbean Colombia, may pose a risk to baby turtles Fig. 1. Location of Serranilla Bank in the Caribbean Sea (Photo Wikipedia) Floating Sargassum has been known from centuries to occur in the Atlantic Ocean, in a region named the Sargasso Sea. Floating S NEW!! Harmful Algal Blooms (HABs) and Desalination: A Guide to Impacts, Monitoring, and Management Manuals and Guides 78 Harmful Algal Blooms (HABs) and Desalination: A Guide to Impacts, Monitoring, and Management Fig. 3. Sargassum accumulation as a thick mat on the nesting beach Edited by: Dona A red tide event associated with the dinoflagellate Karenia mikimotoi in the Firth of Clyde, Scotland Fig. 1. Maximum abundance of K. mikimotoi by month and year for monitoring sites in Scottish coastal waters. The densest bloom observed exceeded 4 million cells per litre in July 2016. The potenti Fig. 5. Theoretical effect of the K. mikimotoi bloom on background dissolved oxygen concentration (black horizontal dashed line: Firth of Clyde summer averaged SEPA data 2005-2015). Cell density was sufficient to cause hypoxia on 3 occasions at 4.59mg L-1[8] or once at 2mg L-1 (grey dashed lines). A First evidence of high saxitoxin concentration in Crassostrea iridiscens associated with Gymnodinium catenatum blooms at Banderas Bay, Jalisco México Fig. 1. Location of sampling stations in Banderas Bay Jalisco México during Gymnodinium catenatum bloom from March to June of 2017. Banderas Bay has Fig. 2. High saxitoxin concentration in Crassostrea iridiscens associated with Gymnodinium catenatum blooms in Banderas Bay, Jalisco México. Fig. 4. Micrographs of live cells of Gymnodinium catenatum from Banderas Bay at 400x (a) and 200x (b); Seawater discoloration due to a G. catenatum patch duri ICES-IOC Working Group on Harmful Algal Blooms Dynamics The report of the International Council for the Exploration of the Sea (ICES) and Intergovernmental Oceanographic Commission of UNESCO (IOC) Working Group on Harmful Algal Bloom Dy namics (ICES-IOC WGHABD) is now available on the ICES website ( SEAFDEC-MFRD Regional Training Course in Malaysia Harmful algal blooms (HAB) and their socio-economic impacts are recognized internationally due to the negative impacts from HABs on the the coastal ecosystem, safety and security of food and drinking water, and human health hazards. Some incidents an Forthcoming events Workshop on morpho-molecular methods for the study of dinoflagellate cysts ICES-IOC-IMO Working Group on Ballast and Other Ship Vectors 5-7 March 2018 Monday 12th and Tuesday 13th February 2018 Location: Cawthron Institute, 98 Halifax Street East, Nelson 7010, New Zealand Organi the 18th international conference on harmful algae from ecosystems to socio-ecosystems SAVE the date! FATMA GUELLATI/UPMC-UNIV BADJI MOKHTAR Minyvel Environnement/Phenomer Nicolas Chomérat/IFREmer Véronique Séchet/IFREmer Olivier BARBAROUX/IFREmer Stéphane LESBATS/IFREmer Olivier DUG Rex Munday in Memoriam Dr Rex Munday, an internationally renowned toxicologist, sadly passed away on the 20th July this year. His wife Christine, daughter Sarah (Finch) and son John were with him. Rex published with all his family at different times, an example being the paper Munday, Munday and Mun Rex Mundays HAB research highlights Discovery of Tetrodotoxin in grey side-gilled sea slugs: Rex had a sharp wit, best illustrated with an anecdote from 2013. We had collected hundreds of samples to explain why dogs were dying on Auckland beaches and sent twelve to Rex for toxicity screening using l ! Oostende OBIS/HAEDAT training workshop participants. Eds-in-chief Beatriz Reguera, IEO, Vigo, Spain Eilen Bresnan, MARLAB, Scotland, UK Regional Editors Caribbean: Ernesto Mancera jemancerap@unal.edu.co Europe: Philip Hess Philipp.Hess@ifremer.fr India: K.B. Padmakumar kbpadmakumar@gmail.c