The Mar Menor Oyster Initiative, a strategy to prevent algal blooms in a eutrophic lagoon in Spain Fig. 1. Map of study in Mar Menor, Murcia, SE Spain Marine ecosystems are exposed to a wide range of pressures including water quality degradation, habitat decline, overfishing and climate change, in some instances leading to negative environmental, social and economic consequences. Different approaches can be taken to ameliorate the multiple human stressors altering the oceans, including the restoration of services which have declined through oyster restoration [1]. Oysters provide a variety of ecosystem services and are recognized for their potential to contribute to developing Blue Economies. From water quality improvement to sustainable maintenance of good habitat condition and coastal resilience, oysters can contribute to Nature-Based Solutions to restore impaired aquatic ecosystems [2]. Fossil records provide evidence that these essential services have been developed for millennia but bivalve stocks have decreased worldwide and with their disappearance, coastal ecosystems have also lost their ecologic and economic services [3]. Further declines in water quality and habitat serve as stressors to the bivalves that remain, which may lead to increased disease prevalence or feeding suppression, which can add to the loss of services provided. 6 Typically, coastal lagoons suffer from anthropogenic actions including the massive release of nutrients causing eutrophication (often associated with high biomass harmful algal blooms (HB-HABs). HABs are natural phenomena which may pose risks to human health, environmental sustainability and/or aquatic life due to the production of toxins or the accumulated biomass when increased production is no longer balanced by grazing [4]. In this last case, the high biomass from large algal blooms formed in eutrophic eco- systems may led to a cascade of negative ecological effects including seagrass mortality, fish kills and oxygen depletion [5]. For example, the harmful brown tides caused by the pelagophyte Aureoumbra lagunensis have led to seagrass die off and massive fish kills in Texas and Florida (USA) for their high concentration and persistence but not for the release of toxins [6]. Different ecosystems have suffered the effects of algal blooms, including the Mar Menor, a coastal lagoon suffering from severe eutrophication in Western Spain (Fig. 1). This is one of the largest hypersaline coastal lagoons in Europe with an area of about 135 km2 and an average depth of 3.6 m (maximum 7 m). This lagoon ecosystem is particularly vulnerable to the impacts of human activity because it is a semi-enclosed body of water with a 1-year water residence time. It is particularly affected by the intensive tourism and agricultural development experienced in the area during the last decades, which led to the overlap of several environmental protection measures [7]. Before the anthropogenic influence on the lagoon increased, it was characterized by its oligotrophic and hypersaline waters (70-53 ppt) with the seabed containing sediment with seagrass. After receiving an excess of nutrients during the last three decades, the lagoon suffered from a massive proliferation of plankton in summer 2015, a sign of a eutrophication process that collapsed the entire ecosystem [8] (Fig. 2). Algal blooms recurrently appeared in the following years being Synechococcus sp. the most abundant species in August 2016, November 2017 and January Fig. 2. High biomass microalgal bloom in the north basin of Mar Menor at 6 m depth. Photo P.García/ANSE on October 1st, 2021 HARMFUL ALGAE NEWS NO. 70 / 20221 Harmful Algae News An IOC Newsletter on Toxic Algae and Algal Blooms No. 70 - July 2022 https://hab.ioc-unesco.org/ Mar Menor lagoon: an iconic case of ecosystem collapse Content Featured articles Mar Menor lagoon: an iconic case of ecosystem collapse, Juan M Ruiz, Jaime BernardeauEsteller, M Dolo nodosa present in Mar Menor at least in the last decades. Caulerpa contains high levels of toxigenic secondary metabolites and contributes loads of labile organic matter to the sediments. Decomposition of this organic matter fuels anoxic processes and increased levels of reduced carbon, nitrogen and age basin and is a major source of European winter vegetable production. But the transferred water resources, clearly insufficient to sustain such production, had to be complemented with aquifers that had suffered previous overexploitation and became brackish. These brackish aquifers needed treating Fig. 3. Satellite image (Sentinel 2) after torrential rainfall in September 12th and 13th in the Mar Menor watershed. Tons of terrigenous sediments, carbon, nitrogen and phosphorous are dragged by water runoff from agricultural lands into the Mar Menor lagoon (downloaded from https://www. copernicus provided by President and Staff of the harbours Club Nautico Lo Pagán, Club Náutico La Puntica and Centro de Actividades Náuticas (San Pedro del Pinatar, Murcia, Spain). References 1. Ruiz JM et al 2020. Informe de asesoramiento técnico del IEO, 165pp 2. Belando MB et al 2019. Front. Mar. Sci. Conf The Mar Menor Oyster Initiative, a strategy to prevent algal blooms in a eutrophic lagoon in Spain Fig. 1. Map of study in Mar Menor, Murcia, SE Spain Marine ecosystems are exposed to a wide range of pressures including water quality degradation, habitat decline, overfishing and climate change, in flats, located in the south basin of the lagoon. The rationale of this project is to involve all interested stakeholders for successful large-scale restoration programs, which need public and political support, research, and outreach actions [13]. Acknowledgements Project RemediOS is developed with Multi-specific Harmful Algal Bloom in a Chilean Fjord: A dangerous phytoplankton cocktail Fig. 1. Maps of study area showing: left, NW Patagonian fjords; right, Quitralco Fjord Harmful Algal Blooms (HABs) in Southern Chile (Patagonian fjords) have followed the global trend of increasing reports an Fig. 3. Vertical distribution of A) temperature (blue line), salinity (red line) and chlorophyll a (green line); B) Pseudo-nitzschia spp; C) A. catenella; D) D. acuminata; E) P. reticulatum at a sampling station close to the head of Quitralco Fjord on February 22, 2022 reticulatum (18.3 x 103 cells Red Tide Adaptation and Response Network (REARMAR): bridging local, scientific and policy knowledge for smallscale benthic fisheries in the northern Chilean Patagonia Fig. 1. Expansion of Alexandrium catenella-related PSP outbreaks recorded in the last four decades in Chilean Patagonia. Dashed line l l fishermen leaders and fishery and health authorities were considered inappropriate. Several coordination problems arose when an authorized 6,000 loco landing could not be placed on the market because results of laboratory tests detecting toxins slightly above the regulatory limit (80 ug STX eq An unprecedented harmful algae bloom in the beaches of Rio, Brazil Fig. 1. Images acquired by Sentinel-3s Ocean and Land Colour Instrument OLCI, on A) November 16th, 2021; B) December 5th, 2021. The dark water patch indicates the algal bloom. Source: Priscila Kienteca Lange, UFRJ An extensive and Tetraselmis). We speculate that these calm inlets could have possibly been the source of the massive offshore bloom, but further image and data analysis needs to be conducted. The coast of Rio de Janeiro state is subject to coastal upwelling of the South Atlantic Central Water (SACW water mass) at A High Biomass Bloom of a dinoflagellate (Scrippsiella sp.) in a tropical estuary in northern Bahia State, Northeast Brazil A bloom of Scrippsiella sp. was observed in the Rio Real estuary of Northeast Brazil (Figure 1A; 11o 18 28 S; 37o 16 45 W). According to the KöppenGeiger climate classification [ Limnoraphis robusta bloom in Hanabanilla reservoir, central-southern Cuba Fig. 1. Map showing the areas where the Limnoraphis robusta bloom occurred in Hanabanilla reservoir. Harmful cyanobacterial blooms in freshwater ecosystems can form major water discolorations, threaten ecosystem functioning from Hanabanilla was mainly in early vegetative stage. In contrast, some morphological characters which are indicators of later growth stage such as red-brownish trichomes and hormogonia were present in high abundance in a previous L. robusta bloom from Hanabanilla reservoir [5]. L. robusta occurred MixONET, a new SCOR Working Group # 165 on Mixotrophy in the Ocean Traditional and contemporary methods in Biological Oceanography assume a false plant/animal dichotomy for plankton. This dichotomy has been the bedrock of marine science, operationally separating organisms into phototrophic or phagot Maldonado (Canada), Mengmeng Tong (China), Michaela Larsson (Australia), Patricio Diaz (Chile), Robinson Mugo (Kenya), Tina Šilović (France). The first meeting of the working group was held in silico (February 2022) with the second hybrid meeting scheduled to be held in Baiona (Galicia, Spain) in Ju GlobalHAB/EuroMarine Workshop on Modelling and Prediction of Harmful Algal Blooms The typical harmful algal bloom is a regional- or local-scale phenomenon, a perfect storm of environmental conditions, ocean transport and mixing patterns, and microbial ecology. Because of this complexity, prediction Meeting of the GlobalHAB Scientific Steering Committee, Glasgow, Scotland, May 2022 On May 14th -15th, 2022, the Scientific Steering Committee (SSC) of the IOCSCOR programme, GlobalHAB, celebrated its first hybrid meeting in Glasgow, UK, following virtual meetings throughout the Covid19 pandemic. Th The international community is invited to participate in the GlobalHAB programme, through seeking endorsement of relevant research, monitoring, and modelling activities GlobalHAB APPLICATION FORM FOR ENDORSEMENT OF ACTIVITIES AND PROJECTS To be completed in English and emailed to the Chair of the G Is the activity part of, coordinated with, or af4iliated with, other international/regional programs? Yes: ___ No. ____ If yes, give program title: 8. FUNDING Has funding been obtained? Yes: No: (Prospective) source(s): 9. CONTRIBUTION TO UN DECADE OF OCEAN SCIENCE FOR SUSTAINABLE DEVELOPMENT 203 Microbial life cycles Microbial life cycles in a changing ocean in a changing ocean Contributions that address the following topics are welcome: Contributions that address the following topics are welcome: Diversity of microbial life cycles in different habitats and environments Diversity of micr