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 uptake of amino acids and sugars, processes that were much studied back in the 1970s and 1980s. Over the last decade, however, there has been an increasing awareness of the importance of the activity of plankton combining phototrophy and phagotrophy [2]. And that includes many HABs, which are not just algae, but also predators. That awareness of the importance of phagotrophy in so-called algae prompted a reclassification of protist plankton functional groups [3] according to their different modes of photo+phago trophic nutrition. The most basic division was between those species with a constitutive (innate) ability to photosynthesise, and the non-constitutive species that acquired phototrophy from their prey. Subsequently, to remove the ambiguity between mixotrophy enabled by {photo + osmo trophy} versus {photo + osmo + phago trophy}, the use of the term mixoplankton was proposed [4] for those capable of phagotrophy. Phytoplankton was then proposed to describe protists capable of phototrophy but not phagotrophy. Planktonic cyanobacteria, including HAB species, would by default also be phytoplankton. The role of mixotrophic plankton in HABs has long been recognised [5]. With the newly proposed mixoplankton term and its allied paradigm [4] that sees the potential for bacteria-mixoplankton and mixoplanktonic predatorprey interactions, the question arises as to how HAB species align with this new take on marine science? In order to identify and hence differentiate between the mixotrophic and mixoplanktonic HABs, we have adapted the new protist functional group classification [3] specifically for Harmful Algal Bloom species (Fig. 1). In Fig. 1 example species names have been obtained from the IOC-UNESCO HABs list [6] and assigned to functional groups according to the mixoplankton database [7]. The primary difference between the HAB functional group classification presented here and the protist functional group classification [3] is the inclusion prokaryotic plankton as there are various known HAB species within this group. As before [3], this HAB functional group classification chart starts with the question of whether the HAB species is capable of carbon fixation. A negative response to this leads us to one end of the spectrum the pure heterotroph describing the traditional protozooplankton (or, microzooplankton) functional group. Within the current IOC-UNESCO HABs list [5] there is one only species, Phalacroma rotundatum which falls within this group. However, if the HAB species has the ability to photosynthesize, the next question is whether the species can also engage in osmo-heterotrophy. A null response results in what would be a purely photo-autotrophic organism; there are no known HAB species which would satisfy this description indeed there is no known microbe that aligns with this state. A yes response gives us a mixotroph capable of photo-autotrophy and osmo-heterotrophy. Once we have a mixotroph, the next criteria to test is whether the mixotroph is also capable of phagotrophy. A negative leads to the traditional phytoplankton which include the HAB species within the Bacillariophyceae (diatom) and cyanobacteria groups. A positive response results Fig. 1. Functional group classification key for Harmful Algal Bloom Species. N, no; Y, yes. Key developed from the protist functional group key [3] with example species from the IOC-UNESCO HABs list [6] aligned to functional groups according to the Mixoplankton Database [7] 4 HARMFUL ALGAE NEWS NO. 67 / 2021 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