Tiny cells with a big impact: An unexpected bloom in the mid-Atlantic Fig. 1. a) Bongo nets fouled with the brown mucilaginous plankton. b) Dark and gelatinous content of the plankton nets scraped into a sample tray. Since 1992, the US NOAA Ecosystem Monitoring (EcoMon) cruises survey the Northeast U.S. Continental Shelf between 36 N and 41 N three to four times a year. Plankton and larval fish are sampled along with physical and chemical oceanographic parameters. During November 2018, the cruise encountered an unusual massive bloom of mucilaginous plankton that completely clogged 165-μm and 335-μm zooplankton nets with a puzzling dark brown slimy substance (Fig. 1). The plankton nets were extensively fouled at 16 of the 60 stations, predominantly north of 40 N (Fig. 2). The fouled double-oblique Bongo plankton tows ranged in depth from the surface to ~ 5 m from the bottom, i.e. between 26 and 57 m, depending on the station (CTD depths). With no microscope on board to observe fresh material, some of the brown slime was scraped from the nets into 95% ethanol, which changed it to a dark green color. Upon return to onshore laboratories, identification of the material by light microscopy remained somewhat elusive, although the super abundant ~7.5-μm cells hinted at the presence of either a diatom or the prymnesiophyte Phaeocystis. Aliquots of the preserved material from station 60 were digested in H2O2 and prepared for scanning electron microscopy (SEM). We identified the tiny cells enmeshed in chitan threads as Thalassiosira mala [1]: a single strutted process (fultoportula) offset from the center of the valve; a ring of marginal strutted processes 1 to 1.5 μm apart from each other; a single labiate process (rimoportula) located within the ring of HARMFUL ALGAE NEWS NO. 67 / 2021 marginal strutted processes; and 25 to 30 areolae in 10 μm (Fig. 3). Copious chitan threads emanate from the ring of marginal strutted processes and are responsible for creating the mucilaginous consistency of the colonies; the threads were markedly obvious on micrographs (Fig. 4). Additional morphological features of this taxon have been previously described [2-3]. Subsequent review of data at 3 m from the Imaging FlowCytobot (IFCB) onboard the EcoMon vessel indeed revealed the presence of numerous colonies as well as single cells of what we can now identify as T. mala (Fig. 5) [4] Because of its small size, this diatom is often misidentified or goes unnoticed by light microscopy; it is however easily detected when intense blooms form massive gelatinous colonies, such as during the widespread event of the EcoMon 2018 cruise. The species is considered cosmopolitan within temperate and tropical waters [3,5] its presence in the mid-Atlantic region is not unusual [5]. It is observed in waters closer to the coast, such as in Narragansett Bay (41 34 N, 71 23 W), so far at non-bloom densities [6] (Figure 6). Given that the EcoMon crew did not visually notice any discoloration of the surface water at the time, one can surmise either that a bloom occurred at depth or that the colonies were abundant and somewhat dispersed through the water column. Vertical profiles of temperatures and salinities indicated generally well-mixed water columns, thus may suggest colony dispersal at most stations rather than thin layers of concentrated materials at depths. For example, at station 56, chlorophyll concentrations were nearly constant at 2.4, 2.4 and 2.1 μg L-1 at 2, 20 and 30 m, respectively (in situ fluorometry) over a very slight sigma-t difference of 0.001 unit. However, at station 60 where the heaviest fouling occurred, the chlorophyll concentrations were Fig 2. Composite maps of chlorophyll a concentration over a range of 0.03 to 30 μg L-1 from the MODIS-Aqua, Suomi-NPP-VIIRS and NOAA20-VIIRS satellite sensors: Nov 3-5 (left panel) and Nov 10-12 (right panel) 2018 during the time of the EcoMon cruise. Sampling on the R/V Sharp took place November 2-12, 2018. Dots on top of the cruise track indicate sampling stations; red dots specify stations with extensive fouling of the nets. The cruise ended at station 60. The thin topographic grey line represents the 100-m depth contour. 7 Harmful Algae News An IOC Newsletter on Toxic Algae and Algal Blooms No. 67 - April 2021 www.ioc-unesco.org/hab SHIOHIGARI and PSP toxins in Japan: Initiatives to save traditional recreatio nal clam picking Shiohigari has been enjoyed by people in Japan for centuries, as depicted in the Japanese a Fig. 2 Clamming parks in Osaka Prefecture (Modified from a digital map of The Geospatial Information Authority of Japan) ingly, they had developed the exchange system to secure viability of their operations before 2002 when PST exceeding the regulatory limit were first detected in clams from seas a Fig. 4 System of exchanging clams which secure food safety at Tannowa clamming park (Modified from [3} of visitors to clamming parks has now recovered. This is a success story of how to mitigate socio-economic impact on recreational clamming in Osaka prefecture due to PST. Thanks to the initiatives HABs and the Mixoplankton Paradigm Mixotrophs are defined as organisms that are able to use photo-autotrophy and phagotrophy or osmotrophy to obtain organic nutrients [1]. It is notable that all phototrophic protists are potentially mixotrophic if only through expression of osmotrophy enabled by the Fig. 2. Indication of proportion of IOC-UNESCO HAB species [6] assigned to each of the HAB plankton functional groups according to key in Fig.1 compiled by cross-reference to a database on mixoplankton species. CM, constitutive mixoplankton; pSNCM, plastidic specialist non-constitutive mixoplankton; Fig. 3. Schematics and model simulation outputs run under the traditional paradigm (left) versus the mixoplankton paradigm (right). See text for explanation. B bacteria; Phyto phytoplankton (non-phagotrophic phototroph); μZ protozooplankton; CM constitutive mixoplankton (photophago-trophic); DIM Tiny cells with a big impact: An unexpected bloom in the mid-Atlantic Fig. 1. a) Bongo nets fouled with the brown mucilaginous plankton. b) Dark and gelatinous content of the plankton nets scraped into a sample tray. Since 1992, the US NOAA Ecosystem Monitoring (EcoMon) cruises survey the Northeas Fig. 3. Scanning electron micrographs of frustules in valve view of Thalassiosira mala. Note the single eccentric strutted process (black arrow), the ring of marginal strutted processes (arrowheads) and the single labiate process (white arrow) located within the ring of marginal strutted processes s Acknowledgements We are grateful to Kyle Turner for helpful discussions regarding the fall 2018 EcoMon cruise and to Dr. Irene Andreu for SEM assistance. Dr. Paul E. Hargraves provided some insights on diatom taxonomy. We acknowledge the dedication of the crew of the R/V Sharp during a particularly First report of an Ansanella granifera bloom in Cuban waters, Caribbean region Fig. 1. Map of the study area showing the location where the dinoflagellate bloom o ccurred in southeastern Cuba. Harmful Algal Blooms (HABs) have been associated with fish and shellfish kills, ecosystem damage, human Fig. 3. Light microscopy images of fixed cells of Ansanella granifera. 4). Ansanella granifera is a dinoflagellate belonging to the family Suessiaceae (order Suessiales) that was recently described from Korea [5]. To our knowledge, the occurrence in waters from southeastern Cuba represents the firs Dolichospermum spiroides blooms in a man-made lake in Sarawak, Borneo pond in Serian, Sarawak, and co-existed with a Microcystis bloom. However, the species and cell density for both genera were not recorded [3]. This is the first documented report of D. spiroides in Sarawak waters. The occurrence An online platform (GEE App) for Trophic State Index monitoring of inland waters in Latin America Fig. 1. a) The dark gray region shows the Paraná River Basin in Brazil; b) Water masses within Paraná River Basin palette according to the Chl-a concentration average for 2020. The red rectangle indica Remote sensing of recurrent cyano HABs in Patos Lagoon, Brazil Fig. 1. Map of Patos Lagoon (southernmost part of Brazil) taken from [7]. Black circles indicate the four sites chosen forNDCI values retrieval [4]. Every austral summer, dense surface growth and accumulations of cyanobacteria threaten ation promoting the prevalence and duration of cyanoHABs. More detailed information will be published soon adding modeling tools to locate dominant cyanoHAB accumulation sites within the PL, and their potential exportation to the ocean. Future studies are needed to discriminate between local effects Blooms of Akashiwo sanguinea (Dinophyceae) in a tropical estuary in northeastern Brazil We report an inter-annual bloom of the unarmored dinoflagellate Akashiwo sanguinea in a pristine estuary (Figure 1F) in Brazil. The estuarine section of the Serinhaém River, Camamu Bay is a species-rich ecosystem can affect the entire structure of a community due to changes in composition due to outcomes of biotic interactions with one species being benefited while another one is harmed. The spatial location of SE10 within an area of potential disturbance driven by urban tributaries alters ecological stoichi Can artisan fishermen help to prevent HABs intoxication? A science communi cation project in Rio de Janeiro, Brazil Fig. 1. Geographic distribution of the main harmful microalgae genera in Brazilian coastal waters. These genera may induce different poisoning syndromes: amnesic shellfish poisoning ( Authors Raquel AF Neves, Júlia Torres, Nathália Rodrigues & Clarissa Naveira, Graduate Program in Neotropical Biodiversity (PPGBIO), Research Group in Experimental and Applied Aquatic Ecology, Federal University of the State of Rio de Janeiro (UNIRIO), Avenida Pasteur 458-307 Rio de Janeiro- RJ, CEP The VIII Workshop the Group HarmAlfonso Vidal (Colombia). Their of dediconsider it urgent to finalize The VIIIofWorkshop of the Group Harmful Algal Blooms the Caribbean (ANCA) of a regional ful AlgalIOCARIBE Blooms of (Intergovernmental the Caribbean catedOceanographic work contributedCommission sig Aotearoa/New Zealand Japan collaboration strengthened through HAB research at Cawthron Institute the 16th Young Researchers Award from the Japanese Society of Phycology for his research on harmful algae in Japan. Acknowledgements The collaboration between New Zealand and Japan has been continued ANNOUNCEMENT: The International Phytoplankton Intercalibration The International Phytoplankton Intercalibration (IPI) Proficiency Testing scheme in abundance and composition of marine microalgae programme 2021 is now open for registration for 2021 through www.iphyi.org. The schedule for 2021 and all The 19th International Conference on Harmful Algae 2021 (ICHA2021) is going virtual! We appreciate the responses that many of you provided in the recent survey which indicated that 85% of respondents will participate in a virtual meeting. The abstract submission deadline is 9 April 2021. Details on In memoriam Maria Esther Angélica Meave del Castillo (1960-2020) María Esther Meave (who also received the nickname Teté or Tey by many of her friends) was born in Mexico city, Mexico (September 5th, 1960) and passed away on December 6th, 2020, after contracting COVID-19. She earned her Master and Leif Bolding, graphic designer and webmaster at the Department of Biology, University of Copenhagen, Denmark, has been an unsung hero of Harmful Algae News. Working behind the scenes since 2000 as responsible for the layout of each issue. Leif retires at the end of April 2021. He will have plenty of