Diversity and regional distribution of harmful algal events along the Atlantic margin of Europe.

The IOC-ICES-PICES Harmful Algal Event Database (HAEDAT) was used to describe the diversity and spatiotemporal distribution of harmful algal events along the Atlantic margin of Europe from 1987 - 2018. The majority of events recorded are caused by Diarrhetic Shellfish Toxins (DSTs). These events are recorded annually over a wide geographic area from southern Spain to northern Scotland and Iceland, and are responsible for annual closures of many shellfish harvesting areas. The dominant causative dinoflagellates, members of the morphospecies 'Dinophysis acuminata complex' and D. acuta, are common in the waters of the majority of countries affected. There are regional differences in the causative species associated with PST events; the coasts of Spain and Portugal with the dinoflagellates Alexandrium minutum and Gymnodinium catenatum, north west France/south west England/south Ireland with A. minutum, and Scotland/Faroe Islands/Iceland with A. catenella. This can influence the duration and spatial scale of PST events as well as the toxicity of shellfish. The diatom Pseudo-nitzschia australis is the most widespread Domoic Acid (DA) producer, with records coming from Spain, Portugal, France, Ireland and the UK. Amnesic Shellfish Toxins (ASTs) have caused prolonged closures for the scallop fishing industry due to the slow depuration rate of DA. Amendments to EU shellfish hygiene regulations introduced between 2002 and 2005 facilitated end-product testing and sale of adductor muscle. This reduced the impact of ASTs on the scallop fishing industry and thus the number of recorded HAEDAT events. Azaspiracids (AZAs) are the most recent toxin group responsible for events to be characterised in the ICES area. Events associated with AZAs have a discrete distribution with the majority recorded along the west coast of Ireland. Ciguatera Poisoning (CP) has been an emerging issue in the Canary Islands and Madeira since 2004. The majority of aquaculture and wild fish mortality events are associated with blooms of the dinoflagellate Karenia mikimotoi and raphidophyte Heterosigma akashiwo. Such fish killing events occur infrequently yet can cause significant mortalities. Interannual variability was observed in the annual number of HAEDAT areas with events associated with individual shellfish toxin groups. HABs represent a continued risk for the aquaculture industry along the Atlantic margin of Europe and should be accounted for when considering expansion of the industry or operational shifts to offshore areas.

Current distribution and potential expansion of the harmful benthic dinoflagellate Ostreopsis cf. siamensis towards the warming waters of the Bay of Biscay, North-East Atlantic.

In a future scenario of increasing temperatures in North-Atlantic waters, the risk associated with the expansion of the harmful, benthic dinoflagellate Ostreopsis cf. siamensis has to be evaluated and monitored. Microscopy observations and spatio-temporal surveys of environmental DNA (eDNA) were associated with Lagrangian particle dispersal simulations to: (i) establish the current colonization of the species in the Bay of Biscay, (ii) assess the spatial connectivity among sampling zones that explain this distribution, and (iii) identify the sentinel zones to monitor future expansion. Throughout a sampling campaign carried out in August to September 2018, microscope analysis showed that the species develops in the south-east of the bay where optimal temperatures foster blooms. Quantitative PCR analyses revealed its presence across almost the whole bay to the western English Channel. An eDNA time-series collected on plastic samplers showed that the species occurs in the bay from April to September. Due to the water circulation, colonization of the whole bay from the southern blooming zones is explained by inter-site connectivity. Key areas in the middle of the bay permit continuous dispersal connectivity towards the north. These key areas are proposed as sentinel zones to monitor O. cf. siamensis invasions towards the presumably warming water of the North-East Atlantic.

Spectral Characterization of Eight Marine Phytoplankton Phyla and Assessing a Pigment-Based Taxonomic Discriminant Analysis for the in Situ Classification of Phytoplankton Blooms.

Early stage identification of harmful algal blooms (HABs) has gained significance for marine monitoring systems over the years. Various approaches for in situ classification have been developed. Among them, pigment-based taxonomic classification is one promising technique for in situ characterization of bloom compositions, although it is yet underutilized in marine monitoring programs. To demonstrate the applicability and importance of this powerful approach for monitoring programs, we combined an ultra low-cost and miniaturized multichannel fluorometer with Fisher's linear discriminant analysis (LDA). This enables the real-time characterization of algal blooms at order level based on their spectral properties. The classification capability of the algorithm was examined with a leave-one-out cross validation of 53 different unialgal cultures conducted in terms of standard statistical measures and independent figures of merit. The separation capability of the linear discriminant analysis was further successfully examined in mixed algal suspensions. Besides this, the impact of the growing status on the classification capability was assessed. Further, we provide a comprehensive study of spectral features of eight different phytoplankton phyla including an extensive study of fluorescence excitation spectra and marker pigments analyzed via HPLC. The analyzed phytoplankton species belong to the phyla of Cyanobacteria, Dinophyta (Dinoflagellates), Bacillariophyta (Diatoms), Haptophyta, Chlorophyta, Ochrophyta, Cryptophyta, and Euglenophyta.

Physiological response of Prorocentrum lima (Dinophyceae) to varying light intensities.

The benthic dinoflagellate Prorocentrum lima is among the most common toxic morphospecies with a cosmopolitan distribution. This study explored if strains from different environments and different morphotypes, isolated from three locations in the Atlantic Iberian Peninsula and two from the Mediterranean Sea, showed different responses to varying light regimes, after confirming that all strains belonged to the same ribotype. Growth rates and photosynthetic parameters such as Fo, Fv/Fm, and rETRmax were analysed with a Coulter counter, a water-PAM and a fast repetition rate fluorometer. The photosynthetic properties were investigated in a high light stress experiment using strains acclimated to low light (LL) and high light (HL). The highest growth rate was 0.23 day-1 at 80 and 100 µmol photons m-2 s-1 for strains Dn150EHU and Dn60EHU, originated from different locations. Under control conditions (18°C and 90 µmol photons m-2 s-1), growth rate was on average 0.10 day-1. The HL stress exposure induced photodamage to all strains and the recovery period was not sufficiently long for full recovery of Fv/Fm. However, cells acclimated to HL showed a better recovery than the LL acclimated ones. Furthermore, some assumptions are discussed in relation to strains' original location.

The Genetic Diversity of Mesodinium and Associated Cryptophytes.

Ciliates from the genus Mesodinium are globally distributed in marine and freshwater ecosystems and may possess either heterotrophic or mixotrophic nutritional modes. Members of the Mesodinium major/rubrum species complex photosynthesize by sequestering and maintaining organelles from cryptophyte prey, and under certain conditions form periodic or recurrent blooms (= red tides). Here, we present an analysis of the genetic diversity of Mesodinium and cryptophyte populations from 10 environmental samples (eight globally dispersed habitats including five Mesodinium blooms), using group-specific primers for Mesodinium partial 18S, ITS, and partial 28S rRNA genes as well as cryptophyte large subunit RuBisCO genes (rbcL). In addition, 22 new cryptophyte and four new M. rubrum cultures were used to extract DNA and sequence rbcL and 18S-ITS-28S genes, respectively, in order to provide a stronger phylogenetic context for our environmental sequences. Bloom samples were analyzed from coastal Brazil, Chile, two Northeastern locations in the United States, and the Pribilof Islands within the Bering Sea. Additionally, samples were also analyzed from the Baltic and Barents Seas and coastal California under non-bloom conditions. Most blooms were dominated by a single Mesodinium genotype, with coastal Brazil and Chile blooms composed of M. major and the Eastern USA blooms dominated by M. rubrum variant B. Sequences from all four blooms were dominated by Teleaulax amphioxeia-like cryptophytes. Non-bloom communities revealed more diverse assemblages of Mesodinium spp., including heterotrophic species and the mixotrophic Mesodinium chamaeleon. Similarly, cryptophyte diversity was also higher in non-bloom samples. Our results confirm that Mesodinium blooms may be caused by M. major, as well as multiple variants of M. rubrum, and further implicate T. amphioxeia as the key cryptophyte species linked to these phenomena in temperate and subtropical regions.

Characterization of a Strain of Fukuyoa paulensis (Dinophyceae) from the Western Mediterranean Sea.

A single cell of the dinoflagellate genus Fukuyoa was isolated from the island of Formentera (Balearic Islands, west Mediterranean Sea), cultured, and characterized by morphological and molecular methods and toxin analyses. This is the first report of the Gambierdiscus lineage (genera Fukuyoa and Gambierdiscus) from the western Mediterranean Sea, which is cooler than its eastern basin. Molecular analyses revealed that the Mediterranean strain belongs to F. paulensis and that it bears LSU rDNA sequences identical to New Zealand, Australian, and Brazilian strains. It also shared an identical sequence of the more variable ITS-rDNA with the Brazilian strain. Toxin analyses showed the presence of maitotoxin, 54-deoxyCTX1B, and gambieric acid A. This is the first observation of the two latter compounds in a Fukuyoa strain. Therefore, both Gambierdiscus and Fukuyoa should be considered when as contributing to ciguatera fish poisoning. Different strains of Fukuyoa form a complex of morphologically cryptic lineages where F. paulensis stands as the most distantly related nominal species. The comparison of the ITS2 secondary structures revealed the absence of CBCs among strains. The study of the morphological and molecular traits depicted an unresolved taxonomic scenario impacted by the low strains sampling.

Characterization of Prorocentrum elegans and Prorocentrum levis (Dinophyceae) from the southeastern Bay of Biscay by morphology and molecular phylogeny.

Benthic Prorocentrum species can produce toxins that adversely affect animals and human health. They are known to co-occur with other bloom-forming, potentially toxic, benthic dinoflagellates of the genera Ostreopsis, Coolia, and Gambierdiscus. In this study, we report on the presence of P. elegans M.Faust and P. levis M.A.Faust, Kibler, Vandersea, P.A. Tester & Litaker from the southeastern Bay of Biscay. Sampling was carried out in the Summer-Autumn 2010-2012 along the Atlantic coast of the Iberian Peninsula, but these two species were only found in the northeastern part of the Peninsula. Strains were isolated from macroalgae collected from rocky-shore areas bordering accessible beaches. Morphological traits of isolated strains were analyzed by LM and SEM, whereas molecular analyses were performed using the LSU and internal transcribed spacer (ITS)1-5.8S-ITS2 regions of the rDNA. A bioassay with Artemia fransciscana and liquid chromatography-high-resolution mass spectrometry analyses were used to check the toxicity of the species, whose results were negative. The strains mostly corresponded to their species original morphological characterization, which is supported by the phylogenetic analyses in the case of P. levis, whereas for P. elegans, this is the first known molecular characterization. This is also the second known report of P. elegans.

The genus Pseudo-nitzschia (Bacillariophyceae) in a temperate estuary with description of two new species: Pseudo-nitzschia plurisecta sp. nov. and Pseudo-nitzschia abrensis sp. nov.

The genus Pseudo-nitzschia contains potentially toxic species of problematic taxonomy, making it one of the most intensively studied diatom genera. The study of 35 clonal strains isolated from the Bilbao estuary, an area that experiences recurrent blooms of Pseudo-nitzschia, revealed the presence of two new species, P. abrensis and P. plurisecta, differing from their congeners in both morphology and gene sequence. The morphological features were analyzed by LM and EM, whereas molecular analyses were based on the internal transcribed spacer (ITS) and large subunit (LSU) regions of the rDNA. P. plurisecta appears closely related to P. cuspidata/P. pseudodelicatissima in the phylogenetic tree, whereas P. abrensis forms a moderately supported clade with P. heimii/P. subpacifica and P. caciantha/P. circumpora. Comparison of the secondary structure of ITS2 regions reveals marked differences in the most highly conserved regions among related taxa. Morphologically, the new species differ from their closest congeners in the arrangement of the poroid sectors and the density of valve striae and fibulae. The two species share similar pigment composition, and belong to the group of Pseudo-nitzschia species containing only chlorophyll c2 and c3 .

URGORRI COMPLANATUS GEN. ET SP. NOV. (CRYPTOPHYCEAE), A RED-TIDE-FORMING SPECIES IN BRACKISH WATERS(1).

The morphology, ultrastructure, phylogeny, and ecology of a new red-tide-forming cryptomonad, Urgorri complanatus Laza-Martínez gen. et sp. nov., is described. U. complanatus has been collected in southwestern European estuaries, blooming in the inner reaches of several of them. The estuarine character of the species is also supported by its in vitro salinity preferences, showing a maximum growth rate at 10 psu. U. complanatus is a distinctive species and can be easily distinguished by LM from other known brackish and marine species. Cells are dorsoventrally flattened. The plastid has two anterior lobes. One pyrenoid is located in each of the lobes, and a third one on the posterior part. Thylakoids are arranged in pairs and do not penetrate pyrenoids. The plastid is reddish due to the presence of the phycoerythrin Cr-PE545. An orange discoidal eyespot lies beneath the nucleus, in the posterior ventral face of the plastid. A long furrow runs from the vestibulum, and a gullet is lacking. The periplast is composed of an inner sheet. The nuclear 18S rDNA based molecular analysis reveals U. complanatus is not related to any of the main cryptomonad lineages. Based on ultrastructural and pigment data, the most probable relatives are those merged under the family Geminigeraceae. Its lack of derived characters, together with the presence of characters proposed in previous studies to be primitive, suggests Urgorri could be considered representative of the cryptophycean ancestral character state.

Structural Confirmation of a Unique Carotenoid Lactoside, P457, in Symbiodinium sp. Strain nbrc 104787 Isolated from a Sea Anemone and its Distribution in Dinoflagellates and Various Marine Organisms.

The molecular structure of the carotenoid lactoside P457, (3S,5R,6R,3'S,5'R,6'S)-13'-cis-5,6-epoxy-3',5'-dihydroxy-3-(ß-d-galactosyl-(1→4)-ß-d-glucosyl)oxy-6',7'-didehydro-5,6,7,8,5',6'-hexahydro-ß,ß-caroten-20-al, was confirmed by spectroscopic methods using Symbiodinium sp. strain NBRC 104787 cells isolated from a sea anemone. Among various algae, cyanobacteria, land plants, and marine invertebrates, the distribution of this unique diglycosyl carotenoid was restricted to free-living peridinin-containing dinoflagellates and marine invertebrates that harbor peridinin-containing zooxanthellae. Neoxanthin appeared to be a common precursor for biosynthesis of peridinin and P457, although neoxanthin was not found in peridinin-containing dinoflagellates. Fucoxanthin-containing dinoflagellates did not possess peridinin or P457; green dinoflagellates, which contain chlorophyll a and b, did not contain peridinin, fucoxanthin, or P457; and no unicellular algae containing both peridinin and P457, other than peridinin-containing dinoflagellates, have been observed. Therefore, the biosynthetic pathways for peridinin and P457 may have been coestablished during the evolution of dinoflagellates after the host heterotrophic eukaryotic microorganism formed a symbiotic association with red alga that does not contain peridinin or P457.

NOVEL UNARMORED DINOFLAGELLATES FROM THE TOXIGENIC FAMILY KARENIACEAE (GYMNODINIALES): FIVE NEW SPECIES OF KARLODINIUM AND ONE NEW TAKAYAMA FROM THE AUSTRALIAN SECTOR OF THE SOUTHERN OCEAN(1).

Six new species of unarmored dinoflagellates in the family Kareniaceae were isolated from the Australian sector of the Southern Ocean in March 2006: Takayama tuberculata de Salas sp. nov, Karlodinium antarcticum de Salas sp. nov., Karl. ballantinum de Salas sp. nov., Karl. conicum de Salas sp. nov., Karl. corrugatum de Salas sp. nov., and Karl. decipiens de Salas et Laza-Martínez sp. nov. These new taxa were characterized using light and electron microscopy and sequencing of the LSU rDNA and are well supported based either on their morphology or molecular phylogeny. Takayama tuberculata, isolated just north of the polar front (55°-57° S), is genetically close to T. tasmanica, but smaller, with a significantly reduced number of amphiesmal vesicles. Medium-sized Karl. antarcticum, also isolated from near the polar front, is characterized by its long ovoid cell outline and very long apical groove. The small Karl. ballantinum has a very short apical groove. The large Karl. conicum has a distinct conical epicone and spherical posterior nucleus. The small Karl. corrugatum, from just south of the polar front, has distinctive parallel striations on the epicone surface and a distinctively shaped and placed ventral pore. The large and widespread Karl. decipiens, distributed through Southern Ocean waters from the polar front to Tasmanian coastal waters, and coastal Spain, has a helicoidal chloroplast arrangement and a large central nucleus. This study represents the first description of species in the potentially ichthyotoxic family Kareniaceae recorded from the Southern Ocean.