Description: Two oceanographic surveys for toxigenic phytoplankton in the South and North Atlantic Ocean, including the adjacent Irminger Sea and the Arctic coasts of Greenland and Iceland, were conducted for analysis of putative toxic microalgal species and their respective toxins. During both expeditions, plankton was sampled by phytoplankton net (20 μm mesh) vertical hauls with subsequent size-fractionation, and by filtration of Niskin bottle water samples from discrete depths. In addition, sediment samples at selected stations were taken for identification and analysis of organic-walled dinoflagellate cysts (dinocysts). Among the toxins detected in both areas were domoic acid (DA), pectenotoxins (PTXs), yessotoxin (YTX), and paralytic shellfish toxins (PSTs). In addition, in the northern hemisphere, dinophysistoxins (DTXs) and spirolides were present, but these toxins were not found in Argentinean waters. In the sediments of San Jorge Gulf of Argentina, cysts of the dinoflagellate species Alexandrium tamarense and Protoceratium reticulatum were found, and their respective toxins (PSTs and YTX) were associated with the planktonic samples from the same stations.

Description: Two oceanographic surveys for toxigenic phytoplankton in the South and North Atlantic Ocean, including the adjacent Irminger Sea and the Arctic coasts of Greenland and Iceland, were conducted for analysis of putative toxic microalgal species and their respective toxins. During both expeditions, plankton was sampled by phytoplankton net (20 μm mesh) vertical hauls with subsequent size-fractionation, and by filtration of Niskin bottle water samples from discrete depths. In addition, sediment samples at selected stations were taken for identification and analysis of organic-walled dinoflagellate cysts (dinocysts). Among the toxins detected in both areas were domoic acid (DA), pectenotoxins (PTXs), yessotoxin (YTX), and paralytic shellfish toxins (PSTs). In addition, in the northern hemisphere, dinophysistoxins (DTXs) and spirolides were present, but these toxins were not found in Argentinean waters. In the sediments of San Jorge Gulf of Argentina, cysts of the dinoflagellate species Alexandrium tamarense and Protoceratium reticulatum were found, and their respective toxins (PSTs and YTX) were associated with the planktonic samples from the same stations.

Description: Naturally occurring neurotoxins belonging to two structurally distinct groups of guanidinium alkaloids known collectively as saxitoxins (STXs) and tetrodotoxins (TTXs) share a high affinity and ion flux blockage capacity for voltage-gated sodium ion channels (NaV). Both toxin groups are produced by marine microorganisms and widely distributed among vector species in the oceans, but are also found in terrestrial species. The STXs are often referred to as paralytic shellfish toxins (PSTs) based on their accumulation in shellfish and the symptoms in humans after consumption of toxic seafood. Biosynthesis of STXs is confirmed in four genera of marine dinoflagellates and among about a dozen species of primarily freshwater and brackish water strains of filamentous cyanobacteria. The origin of the STX biosynthetic genes in dinoflagellates remains controversial and may represent multiple horizontal gene transfer (HGT) events from progenitor bacteria and/or cyanobacteria. The recent identification of the biosynthetic genes for STX analogs in both cyanobacteria and dinoflagellates has yielded insights into mechanisms of toxin heterogeneity among species and the evolutionary origins of the respective elements of the toxin gene cluster. The biogenic origins of TTXs and tetrodotoxicity remain even more enigmatic. The TTXs occur primarily in marine pufferfish species, and hence tetrodotoxicity is frequently described as pufferfish poisoning (PFP) after the toxin syndrome in human consumers of such toxic fish. In marine environments, TTXs also appear in invertebrate species, particularly of benthic feeders on suspended particulates and carnivorous vector species. Symbiotic colonizing bacteria or free-living bacteria sequestered via feeding from the water column or sediments are most often invoked as proximal sources of TTXs in marine macrofauna, but endogenous biosynthesis independent of bacteria cannot be excluded. The TTX biosynthetic pathway has not been completely elucidated, and the biosynthetic genes are unknown.

Description: Harmful algal blooms (HABs) have significant impacts on food safety and security through contamination or mass mortalities of aquatic organisms. Indeed, if not properly controlled, aquatic products contaminated with HAB biotoxins are responsible for potentially deadly foodborne diseases and when rapidly growing, HAB consequences include reduced dissolved oxygen in the ocean, dead zones, and mass mortalities of aquatic organisms. Improving HAB forecasting is an opportunity to develop early warning systems for HAB events such as food contamination, mass mortalities, or foodborne diseases. Surveillance systems have been developed to monitor HABs in many countries; however, the lead-time or the type of data (i.e. identification at the Species-level, determination of toxicity) may not be sufficient to take effective action for food safety management measures or other reasons, such as transfer of aquaculture products to other areas. Having early warning systems could help mitigate the impact of HABs and reduce the occurrence of HAB events. In this regard, FAO took the lead in the development of a Joint FAO-IOC-IAEA Technical Guidance for the Implementation of Early Warning Systems for HABs. The document will guide competent authorities and relevant institutions involved in consumer protection or environmental monitoring to implement early warning systems for HABs present in their areas (marine and brackish waters), specifically for those affecting food safety or food security (benthic HABs, fish-killing HABs, pelagic toxic HABs, and cyanobacteria HABs).