How do algal blooms kill finfish and how can we mitigate their impacts? Algal blooms, water discolorations and their association with fish kills have been recorded since historic times, such as the description in the Bible (1000 years BC) all the waters that were in the river were turned to blood. And the fish that was in the river died; and the river stank, and the Egyptians could not drink of the water of the river (Exodus 7: 20-21). In this case, a non-toxic bloomforming alga became so densely concentrated that it generated anoxic conditions resulting in indiscriminate kills of both fish and invertebrates. Similarly, water discolorations and massive fish kills in Florida coastal waters have been reported by Spanish explorers since the 15th century (now known to be caused by the dinoflagellate Karenia brevis). Finfish held captive in intensive aquaculture systems are extremely sensitive to HABs, and the impact of fish-killing algal blooms on human society thus has been exacerbated by the increase of finfish aquaculture. Shilo 1967 [1] first investigated problems for the Israel Tilapia pond aquaculture industry caused by the haptophyte Prymnesium parvum, but research efforts to understand fish killing mechanisms intensified in 1973 when Chattonella marina raphidophyte blooms (Fig. 1) devastated yellowtail aquaculture in the Seto Inland Sea [2] and in the 1980s when the dinoflagellate Karenia mikimotoi started to impact on the fledgling salmon farming industry in Norway [3]. Fish-killing algal species are responsible for much greater economic impacts (summarized in Table 1) than HAB events leading to seafood biotoxin contamination. The 2016 fish kills in Chile by Pseudochattonella and Alexandrium catenella which led to losses of US$800M triggered social unrest. It is therefore surprising that progress in our understanding of how HABs kill fish has been so slow. Financial support for and research interest in HABs by the fish farm industry has often been shortlived, and ranked lower than investments in fish husbandry, nutrition, and disease control. With the exception of Karenia brevis, so-called fish-killing toxins or ichthyotoxins are not known to have human health impacts and thereHARMFUL ALGAE NEWS NO. 59 / 2018 fore also have not been a priority for seafood regulators. Scientific progress has been hindered by the use of widely different bioassay systems and lack of chemical analytical methods to quantify and characterize ichthyotoxins from seawater medium. Assay systems have included Artemia or Daphnia assays, the use of fish or mammalian erythrocytes, and a wide range of juvenile or adult fish (damselfish, sheepshead minnow, mountain minnow, zebrafish, salmon, sea bass) tested under different exposure regimes. The novel application of a standardised and highly sensitive and reproducible rainbow trout RTgill-W1 cell line assay in Australian, Chilean, Danish, Mexican and US laboratories has allowed significant progress to be made in the past 10 years [4,5]. This assay has been automated in a plate reader measuring cell viability dyes, and been successfully applied also to screen freshly collected natural seawater samples from fishkill events in Australian and Korean waters. cause cells to exude ichthyotoxins and/ or cause cell lysis are critical, and ichthyoxicity by these genera tends to be more variable. The first point of attack by all above algal groups are the fish gills (Fig. 2), resulting a generalized necrotizing degeneration of the epithelium of the secondary lamellae with associated sloughing, often accompanied by swelling of the primary lamellar epithelium and congestion of branchial vessels [3]. Fish gills tend to respond in a singular way and gill pathology is remarkably similar for different ichthyotoxic algae and in different fish species [3, 6-9]. Once the fish gills are compromised, algal neurotoxins if present can penetrate the blood stream, cause fish behavioural changes, and loss of the blood haemoglobins oxygen binding affinity [2]. Several competing theories have been proposed as to the precise mecha- What is the precise mechanism causing fish gill damage? While all high biomass algal blooms (>100 x 103 cells L-1) can cause mechanical stress to the sensitive gill tissues of fish and trigger excess mucus production, of much greater concern for the aquaculture industry are the highly potent, taxonomically unrelated flagellate groups Cochlodinium, Karenia, Chattonella, Pseudochattonella, Heterosigma and Prymnesium. One feature that these algal groups have in common is that they are all fragile cells, which can lyse even upon impact on the gills of fish, especially during the end of blooms, or conditions of osmotic stress or during upwelling. For less fragile fish-killing algae such as Karlodinium or the armoured Alexandrium the conditions that Fig. 1. Mass mortality of (above) yellowtail fish in the Seto Inland Sea in Japan (photo courtesy Prof T.Okaichi) and (below) blue-fin tuna in South Australia (photo courtesy Barry Munday), both caused by Chattonella marina blooms. Higher potency of Australian blooms (kills occurred at 66,000 cells/L) compared to Japan (500,000/L) is attributed to higher sensitivities of tuna but also higher ichthyotoxicity by Australian high-light adapted algal strains [5]. 9 Harmful Algae News An IOC Newsletter on Toxic Algae and Algal Blooms No. 59 - February 2018 www.ioc-unesco.org/hab Content 25 years of HAN and IPHAB...... 1 25 YEARS Harmful Algae News was first published in early 1992 in response to requests from the participants at a number of IOC meetings and pacted by harmful algal events. Since Harmful Algae News turned 20 years old in 2012, it has been a web based e-newsletter which meant longer issues were possible and back issues easily accessible. We are currently working on a searchable index for all Harmful Algae News issues. The start of Harmful Intergovernmental Panel on Harmful Algal Blooms also turned 25! During 1992, the same Year as the IOC published the first issue of Harmful Algal News, it also established an Intergovernmental Panel on Harmful Algal Blooms (IPHAB) which has met every second year since it was formed. The Panel is com A retrospective look at the early days of HAB cyst research, and a look to the future On this occasion of the 25th anniversary of the publication of Harmful Algae News, several of us were asked to look backwards in time to some of the earlier days of HAB science. One area of study that has been a ma dormant stages and that these stages might be associated with certain bottom sediments. This then brings up the question, if benthic resting stages of certain dinoflagellates actually seed coastal red tides, are there localized areas of accumulation, or what we could call seedbeds?..........The poss day, we still do not know if there are other factors at work perhaps a density-dependent or quorum-sensing type of response, or even a response to the presence of grazers or parasites. Exploration of this response has long been limited by the constraints associated with laboratory cultures, but now approach did not stand up to data at my study locations. I raise this issue in this narrative because I want to correct what I feel are unjustified recommendations that may prevent those working on cysts from obtaining the type of biological data that can advance our understanding of certain types o number of cysts in subsurface layers unable to germinate or emerge, presumably due to lack of oxygen or to the tortuous pathway posed by sediment grains and detritus. Many might think that major storms and waves can erode significant layers of sediment and transport cysts long distances, but here ag How do algal blooms kill finfish and how can we mitigate their impacts? Algal blooms, water discolorations and their association with fish kills have been recorded since historic times, such as the description in the Bible (1000 years BC) all the waters that were in the river were turned to blood. A Table. 1. Economic losses from algal blooms for finfish aquaculture in different parts of the world HAB species Chattonella Heterosigma Cochlodinium polykrikoides Heterosigma Chaetoceros Heterosigma Karenia digitata Karenia mikimotoi Country Financial Losses Japan Korea, China Canada British Col emergency harvest operations. To prevent the buildup of histamines, fish should be kept alive as long as possible during harvesting. This can be achieved by diluting algal concentrations via airlift upwelling, or by targeted in-pen emergency application of clays [23] that mop up ichthyotoxins at cla As part of the 25th anniversary issue of Harmful Algal News I am providing an overview of the IOC-UNESCO Taxonomic Reference List of Harmful Algae (www. marinespecies.org/hab/) and will highlight some of the problems which have faced or are facing the Intergovernmental Panel on Harmful Algal Blooms Dinophyceae the authors intended the new genus to be described according to the botanical nomenclature. The lack of a Latin diagnosis therefore made it invalid. The confusion has actually still not been resolved, and the problem needs to be discussed and decided upon by the International Nomenclatur geographically widespread species being able to form fertile offspring, while other populations of the same species are not. Molecular techniques have contributed very significantly to solving many taxonomic problems, but they have not resulted in the emergence of a finite species concept. We have t Algal toxin discovery, management and regulation over the last 25 years Algal toxins in the dark ages (pre-1992) From a historic perspective, knowledge about algal toxins can be divided into truly prehistoric occurrences such as known from paleontological studies [1-2] and more recent historic recor lar rapid increase in known analogues has been observed for the azaspiracid (AZA) group, with the first analogue described in 1998 [64] and a review in 2014 reporting 30 analogues [65]. Only three years later, over 50 analogues are known for this group, including novel phosphate derivatives [66-71]. Butterflies in Brazil Abstracts are not always reliable guides to authors intentions. They are not expected to reveal a great deal about the evidence to be deployed in support of the science, evidence that may not even exist before deadlines for writing abstracts! Nevertheless, as examples of a mino on a decadal time scale, and identified palaeoclimatic oscillations are not necessarily a useful guide to its interpretation. An obvious obstacle to detecting climate signals in HAB data is posed by anthropogenic eutrophication. Another obstacle is the fact that phytoplankton respond directly to the trends, Karenia brevis might appear more often in the South Atlantic Bight of the US and Gymnodinium catenatum bloom more often in northwestern Iberian waters. There was also a warning by Barrie Dale germane to such speculations, that large scale climate models cannot predict local changes. Little m Red tides in Kamchatka coastal waters (Bering Sea, Russia) are a barrier for the salmon fishery and Pacific salmon Fig. 1. Map of Olyutorskiy Bay (Kamchatka, Bering Sea) where a red tide, reported by fishermen, occurred in July 2017. The stars denote fishery sites: red, affected by the bloom; green Fig. 2. Red tide in Olyutorskiy Bay on 15th July 2017 grounds of the Olyutorskiy Bay river basin performed during the second half of August showed an atypical distribution in the rivers. Maximal escapes were recorded in river basins located in the western and eastern parts of the Olyutorskiy Bay ar First report of Gambierdiscus in the Western Mediterranean Sea (Balearic Islands) Gambierdiscus (Dinophyceae) species are benthic dinoflagellates living in marine littoral zones of circumtropical areas and have recently been described in temperate waters [1]. Some species are producers of potent neu the SEASENSING (BIO2014-56024C2-2-R) project and the CERCA Programme/Generalitat de Catalunya. A. Tudó and A. Toldrà acknowledge IRTAURV-Banco Santander for their respective PhD grants (2016 PMF-PIPF-74 and 2015PMF-PIPF-67). The authors are grateful to Vanessa Castan and José Luis Costa for sampling Comparison by light microscopy and qPCR of potentially ichthyotoxic microalgae in Danish on-shore lagoons producing European flounder (Platichthys flesus): Pros and cons of microscopical and molecular methods Fig. 1. Lagoon used for production of European flounder at Fishlab, Denmark. Evaluation o Fig. 2. Comparison of phytoplankton species identification and cell densities (cells L-1) by qPCR (A and C) and light microscopy (target species and groups which potentially could comprise ichthyotoxic organisms) (B and D) in lagoon 1 (A and B) and lagoon 6 (C and D), respectively. The right Y-axis present in a sample then qPCR would miss those probably due to lack of a developed assay. However, LM does require high levels of taxonomic skills and the precision in identification is only as accurate as the taxonomist allows. Different taxonomists trained in different ways using different identif As qPCR measures genetic material rather than viable cells an over estimation of cell numbers can occur due to the inclusion of dead or dying cells. Problems may also occur when targeting multiple copy genes where the organism carries different numbers of the target depending on nutritional status, The Cawthron Institute Culture Collection of Micro-algae (CICCM) The CICCM is designated as a nationally significant database by the New Zealand government and so receives partial funding for its continued existence. Isolates from 13 classes of micro-algae are maintained either as live cultures or c The XVIII International Conference on Harmful Algae is approaching! It is time for nominations for achievement awards (Yasumoto Life Time and Patrick Gentien Young Scientist), registration to the conference as a student if you wish to participate in the Maureen Keller Award competition and fundraisi Forthcoming Events First announcement of the 11th International Conference on Toxic Cyanobacteria (ICTC) We are pleased to disseminate the first announcement of the 11th International Conference on Toxic Cyanobacteria (ICTC) that will be held in Krakow, Poland from May 5 10, 2019. The ICTC is a per International Coordination of Research on Harmful Algal Blooms From GEOHAB to GlobalHAB International cooperation is fundamental to advance understanding of HAB dynamics and to improve our ability to predict them. Fostering this international cooperation was the mission of GEOHAB (Global Ecology and 18th International Conference on Harmful Algae www.icha2018.com IMPORTANT DEADLINES Abstract submission deadline: 15 April 2018 Early bird registration: 15 July 2018 Get the 17 ICHA Proceedings at www.issha.org Eds-in-chief Beatriz Reguera, IEO, Vigo, Spain Eilen Bresnan, MARLAB, Scotland, UK Regi