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 Columbia New Zealand Hong Kong Norway USD500M, 1973 USD135M,1980/90 USD95M, 1995 USD2M, 1999 USD35M, 1980-90 NZD12M USD32M, 1998 USD6M, 1988 Alexandrium catenella Pseudochattonella/ A. catenella Chile USD60M, 2002/ USD800M, Jan-Mar 2016 Chattonella Karenia South Australia Tasmania AUD45M, 1996 AUD3M, 2003 nism of how algae kill fish. These include: free fatty acids (FFA), reactive oxygen species (ROS), and phycotoxins such as brevetoxins, karlotoxins, gymnocins, or varying combinations of all previous compounds. Polyunsaturated fatty acids (PUFA) Shilo working with fish-killing Prymnesium pointed out how lipid micels released by the algae can impact on the fish gill lamellae and interfere with osmoregulation [1]. Okaichi, investigating Chattonella, focused on free fatty acids damaging fish gills [2]. This was pursued by French researchers including Patrick Gentien [10] working with Karenia mikimotoi (as Gyrodinium aureolum), who identified free fatty acids such as OPA (octadecapentaenoic acid) and EPA (eicopentaenoic acid) as having the highest ichthyotoxic potency. Mardones [11] also confirmed the ichthyotoxicity by DHA (docasahexaenoic acid) from Alexandrium catenella. Paradoxically these compounds are well-known to have a beneficial effect for human health, notably heart disease, when consumed in moderation and used to replace saturated fat. These PUFA compounds are prone to oxidative degradation, in which free radicals steal electrons from the lipids in cell membranes, resulting in cell damage. In whole fish experiments it has been convincingly demonstrated that exposure to OPA and EPA did cause fish gill damage at concentrations in seawater of ap10 proximately 3ppm [7,12]. This is short however of what dense algal blooms would generate. Reactive Oxygen Species (ROS). The role of Reactive Oxygen Species in ichthyotoxicity has long been suggested from whole fish experiments with Heterosigma and Cochlodinium, where application of ROS mopping enzymes such as catalase and peroxidase significantly improved fish survival [13, 14]. Japanese researchers led by Oda [15] focused on the fish-killing raphidophyte Chattonella which is a potent producers of ROS notably when algal cells are ruptured. Several other fish-killing algae such as Karenia and Alexandrium catenella are also strong ROS producers, but for Heterosigma, Karlodinium and Prymnesium ROS on its own cannot explain ichthyotoxicity. Using a xanthinexanthine oxidase chemical reaction to generate superoxide at concentrations equivalent to fish-killing Chattonella, Marshall [7] demonstrated that superoxide on its own does not kill fish. Similarly, Trick and co-workers [16] showed that hydrogen peroxide produced by Heterosigma did not explain ichthyotoxicity. ROS also exhibited negligible impact in the RT fish gill assay [5]. Synergism between ROS and free fatty acids Pursuing the role of ichthyotoxicity by EPA, Marshall [7] demonstrated that when damselfish were challenged with EPA in the presence of ROS, this increased the potency of EPA by up to 15 fold (Fig.3). Similarly, DHA in synergism with ROS became 9 times more ichthyotoxic [11]. The precise nature of the lipid peroxidation products generated remains poorly known, and new analytical methods for the detection of such compounds in seawater during fish kills (e.g. using SPATT collectors) are much needed. Role for true phycotoxins? The dinoflagellate Karlodinium is known to produce chemically welldefined linear polyketide karlotoxins, which at ecologically realistic concentrations can account in full for their fishkilling potency [17]. While prymnesins from the haptophyte Prymnesium have attracted considerable interest [18] it remains to be shown whether these compounds can account for their ichthyotoxic potency. Similarly, cytotoxic chemical compounds such as gymnocin from Karenia mikimotoi remain to be shown to play a quantitative role in ichthyotoxicity [19]. Polyether ladder brevetoxins from the Florida Karenia brevis are well known as the cause of Neurotoxic Shellfish Poisoning in humans but purified brevetoxin PbTx2,3 exhibited limited ichthyotoxicity against RTgill cells [5], suggesting that peroxidation pathways may need be invoked in fish kills. The production of brevetoxins by raphidophytes is disputed [20]. Neuroactive compounds (but not brevetoxin) have recently been claimed also for the raphidophyte Heterosigma [21]. Mardones [11] found no evidence for a role of saxitoxins in fish gill damage, which instead could be explained by DHA and ROS synergism. Using the fish-gill ichthyotoxicity assay, karlotoxin and DHA could account for fish kills in their own right, but not EPA, STX, PbTX, OPA nor OTA. Synergisms between DHA x ROS and EPA x ROS were able to explain fish kills, and so could fatty acid aldehydes. Implications for mitigation of fish-kill events Several different strategies are currently practised in the fish farm industry to mitigate the ichthyotoxic effects of HABs. These include: cessation of fish feeding, towing away of cages from affected areas, perimeter skirts to protect against algal surface slicks, aeration or HARMFUL ALGAE NEWS NO. 59 / 2018 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