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 sulphur compounds. Fig. 1. Maps of macrophytes assemblages in Mar Menor lagoon before and after the 2016 anoxic event. Drastic changes in the distribution of the two dominant macrophyte species, the green alga Caulerpa prolifera and seagrass Cymodocea nodosa, are illustrated thresholds, known in ecological theory as tipping points, had been crossed. Tipping points are levels of pressure beyond which the ecosystem can no longer cope with change, and suddenly shifts from one state to another (ecosystem shift), usually more deteriorated, but equally stable state [5]. How did this iconic ecosystem reach this condition? In the first place, it is necessary to know the environmental framework of Mar Menor, a shallow (maximum depth 7m) hypersaline coastal lagoon with a catchment basin of 1,300 km2 and a water renewal time of about 1 year [6]. According to available information on the semi-arid climate prevalent in the SE Iberian Peninsula, the only freshwater inputs to the Mar Menor are from runoff associated with a few torrential rains which occur every year (250 mm year1), and some more diffusive groundwater inputs. Recently developed models [7] indicate that the current input from runoff is quantitatively more important than that from aquifers. Nevertheless, the little and dispersed data available are not sufficient to provide reliable data for lagoon management. 2 1. Impact of the Estacio channel widening In 1973, widening of the Estacio Channel, one of the five natural connections (golas) between the lagoon and the Mediterranean, was carried out [8]. This public work, now considered a landmark of the anthropogenic transformation of the lagoon, changed the hydrodynamic regimen and led to a decline in salinity, from 50-52.5 in the early 1970s to the current values (42-48) which show an interannual variability determined by the frequency and intensity of the DANAS or gota fría, i.e. intense cold spells bringing heavy rainfall. The increased exchange favoured the entry of some Mediterranean species and the decline of some others, members of the autochthonous fauna and flora. Water exchanges through the Estacio channel are now the main control of the lagoon hydrodynamics. One of the most favoured introduced species was the green macroalga Caulerpa prolifera, a well-known opportunistic macrophyte able to take up nutrients very efficiently and colonize extensive areas rapidly. This species has properties conferring the ability to outcompete native macrophyte assemblages, in particular meadows of the seagrass Cymodocea 2. Introduced macroalgal species and uncontrolled wastewater discharges There is no argument about the increased primary production and deposits of organic matter sedimented in the lagoon during the last 60 years [9], but the negative impact of these changes on the ecosystem may have been overestimated, and conclusions have not been based on scientific evidence. A good example of this criticism concerns the supposed regression of native seagrass meadows, in particular C. nodosa, as a consequence of the expansion of C. prolifera [10]. Recent studies have confirmed that angiosperms did not decline during the decades preceding the collapse. Conversely, these studies provided evidence of the coexistence of the two macrophytes at least during the last forty years before the 2016 event [11] (Fig. 2) indicating a benthic primary production enhancement. Increased primary production supported by high availability of nutrients is an intrinsic feature of eutrophic ecosystems [12]. Therefore, man-made changes induced on the lagoon hydrodynamics were not the only factor that explained the expansion of C. prolifera. Uncontrolled discharges of untreated wastewaters from urban and tourist developments took place years before the channel widening. In the 1990s, the wastewater treatment plan for Mar Menor was completed and wastewaters were no longer flushed into the lagoon (at the expense of being discharged into adjacent Mediterranean waters). Nevertheless, problems related with high nutrient inputs persisted or even increased due to the rapid development of intensive agriculture which started in the 1950s [13]. This kind of agriculture replaced the traditional drylands at the expense of aquifer overexploitation. The new agricultural practices marked another step towards deterioration of the lagoon [14]. Today, the irrigation area occupies 40% of the total drainHARMFUL 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