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 in desalination plants which systematically diverted their nitrate rich (up to 600mg L-1) waste into the lagoon. The intensive agriculture activities increased the nutrient load of the aquifers (ca 150 mg nitrate L-1). The fact that after decades of massive inputs of nutrients, these were not reflected in any apparent damage to the lagoon is paradoxical. At least until 2016, relatively clean waters and seabeds dominated by conspicuous communities of benthic macrophytes [15] were observed. In fact, different experimental approaches have provided evidence that before the collapse, macrophyte meadows played a key role in the control of man-driven nutrient inputs in the lagoon [16]. Benthic communities of filter feeder, in particular bivalve molluscs such as the flat oyster (Ostraea edulis) and the giant Mediterranean fun mussel, or Nacra (Pinna nobilis), that reached populations of 135 and 1.4 million individuals respectively [17, 18], may also have contributed to this con- trol although specific studies supporting such hypothesis do not exist. 3. Alternative hypotheses Another possible mechanism to explain the abovementioned paradox is stoichiometric imbalance of the main macronutrients (N, P, Si). For example, phosphorus is not very abundant in groundwaters, and its input to the lagoon mainly takes place by surface runoff through the watershed. Therefore, inputs of different nutrients are uncoupled in time and space. Intensive agriculture is a major cause of soil erosion and N and P transported by runoff have contributed to a sharp rise of nutrients in the lagoon in recent decades. In addition, climate change is expected to contribute to increase the frequency and intensity of extreme climate events. As an example, during the 2019 DANA, about 60 million m3 of water containing between 150 and 190 t of dissolved phosphate entered the lagoon [1] (Fig. 3). Phosphates are immediately taken up by the vegetation and/or deposited in the sediments, and only after resuspension and/or remineralization may become bioavailable again. There are other mechanisms, such as denitrification that may contribute to recycling but unfortunately, knowledge about biogeochemical cycles in the Mar Menor Fig. 2. Before the 2016 event, benthic macrophyte communities with dominance of seagrass Cymo docea nodosa (thin long leaves) and chlorophyte Caulerpa racemosa (wider shorter fronds) occu pied large areas in Mar Menor. The giant fun mussel Pinna nobilis was a typical bivalve species in this ecosystem. Underwater photo taken in summer 2014 at 5 m depth in a site where the seagrass has completely disappeared. Photo: Juan M. Ruiz HARMFUL ALGAE NEWS NO. 70 / 2022 and its associated basin are practically non-existent. These cycles, together with the sources of the elements integrating them, the relative importance of each one and the entry routes and transformation processes are crucial aspects that need to be unveiled before taking measures to reduce the nutrients load and recover the ecosystem. A new alternative state? As a result of the collapse in 2016, a large part of the lagoon resilience mechanisms and its ecosystem services were severely damaged. Eighty-five per cent of the macrophyte meadows extension and 95% of the giant mussel Pinna nobilis [2, 18], both with key roles in the control of nutrients and dissolved organic matter in the water column, were destroyed. The loss of these control mechanisms was clear evidence of the degree of deterioration reached (Fig. 4). Unfortunately, very little information is available about other components of the lagoon ecosystem to give a global evaluation of the disaster. Nevertheless, the reported losses agree with the growing feeling that the lagoon is nowadays a much more unstable system as compared with decades ago, more fluctuating and more vulnerable to environmental changes. In fact, since 2016 there has been a succession of phytoplankton blooms and high turbidity alternating with periods of clear water. But in contrast with the massive bloom of Synechococcus reported in 2016, blooms from recent years were dominated by the diatom genera Nitzschia, Cyclotella, Cylindrotheca and Chaetoceros, with the potential to trigger low oxygen events that threaten marine organisms as was the case during the mass mortalities of fish and other components of the wild fauna and flora in summer 2021. The first mass mortality event occurred in autumn 2019 (Fig. 5), although in that time it was forced by strong and persistent water column stratification after the massive discharge of freshwater into the lagoon (Fig. 3). These extreme events are characteristic of coastal areas in an advanced process of eutrophication. Nevertheless, despite their huge negative socioeconomic impact, little is known about the drivers and mechanisms behind the unreported high biomass HABs before the 2016 event. 3 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