Cyanopeptides occurrence and diversity in a Brazilian tropical reservoir: Exploring relationships with water quality.

Microcystins (MCs) are a class of toxic secondary metabolites produced by some cyanobacteria strains that endanger aquatic and terrestrial organisms in various freshwater systems. Although patterns in MC occurrence are being recognized, divergences in the global data still hamper our ability to predict the toxicity of cyanobacterial blooms. This study aimed (i) to determine the dynamics of MCs and other cyanopeptides in a tropical reservoir, (ii) to investigate the correlation between peptides and potential cyanotoxin producers (iii) identifying the possible abiotic factors that influence the peptides. We analyzed, monthly, eight MC variants (MC-RR, -LA, -LF, -LR, -LW, -YR, [D-Asp3]-RR and [D-Asp3]-LR) and other peptides in 47 water samples collected monthly, all season long, from two sampling sites in a tropical eutrophic freshwater reservoir, in southeastern Brazil. The cyanopeptides were assessed by liquid chromatography-tandem mass spectrometry (LC-MS/MS). The biomass of potential cyanobacterial producers and water quality variables were measured. MCs were detected in both sampling sites year-round; the total MC concentration varied from 0.21 to 4.04 µg L-1, and three MC variants were identified and quantified (MC-RR, [D-Asp3]-RR, -LR). Additionally, we identified 28 compounds belonging to three other cyanopeptide classes: aeruginosin, microginin, and cyanopeptolin. As potential MC producers, Microcystis spp. and Dolichospermum circinalis were dominant during the study, representing up to 75% of the total phytoplankton. Correlational and redundancy analysis suggested positive effects of dissolved oxygen, nitrate, and total phosphorus on MC and microginins concentration, while water temperature appeared to favor aeruginosins. A comparison between our results and historical data showed a reduction in total phosphorus and cyanobacteria, suggesting increased water quality in the reservoir. However, the current MC concentrations indicate a rise in cyanobacterial toxicity over the last eight years. Moreover, our study underscores the pressing need to explore cyanopeptides other than MCs in tropical aquatic systems.

Detection of harmful algal blooms from satellite-based inherent optical properties of the ocean in Paracas Bay - Peru.

Harmful algal bloom (HAB) events in front of Pisco River, inside Paracas Bay and Lagunillas inlet on the southern coast of Peru was identified from a satellite index (IOPifa) generated with daily high-resolution satellite data of phytoplankton absorption (aphy,GIOP) and non-algal detrital material plus CDOM (adCDOM,GIOP) from the Generalized Inherent Optical Properties (GIOP) model of Modis-Aqua, Viirs-Snpp and Viirs-Jpss1 satellites were used. Phytoplankton density field data sampling from HAB's monitoring programs of IMARPE of 2018 and 2019 were used to validate and identify the extent and spatio-temporal variability of these events. The satellite index (IOPifa) identified for Modis-Aqua 9 active HABs, 8 events in final conditions and 6 events that do not represent HAB conditions, while for Viirs-Snpp found 14 active HABs, 7 events in decaying bloom conditions and 13 events that do not represent HABs; and for Viirs-Jpss1 the index identified 7 active events, 14 in final bloom conditions and 6 that do not represent HABs conditions. The one-factor anova model was applied (p-value = 0.32 > 0.05), indicating that there is no evidence of a difference in the population means of the indices for each sensor. Subsequently, the pairwise multiple comparisons analysis with a 95 % confidence level of Tukey's test confirmed that there are no significant differences in the satellite index value, the differences could be associated with the spectral characteristics of the cell density of the species community and the oceanographic and environmental conditions. The spatial overlap between the in situ harmful algal blooms areas and the calculated satellite index, shows the capacity of the IOP satellite data for the HABs detection. However, it was also evidenced that some HAB events with high phytoplankton cell density had low IOPifa values, while other events with lower cell density were easily identified by the satellite index. This would indicate the ability of the ocean inherent optical properties to differentiate the phytoplankton types that cause algal blooms.

Gambierdiscus species diversity and community structure in St. Thomas, USVI and the Florida Keys, USA.

Ciguatera Poisoning (CP) is a widespread and complex poisoning syndrome caused by the consumption of fish or invertebrates contaminated with a suite of potent neurotoxins collectively known as ciguatoxins (CTXs), which are produced by certain benthic dinoflagellates species in the genera Gambierdiscus and Fukuyoa. Due to the complex nature of this HAB problem, along with a poor understanding of toxin production and entry in the coral reef food web, the development of monitoring, management, and forecasting approaches for CP has lagged behind those available for other HAB syndromes. Over the past two decades, renewed research on the taxonomy, physiology, and toxicology of CP-causing dinoflagellates has advanced our understanding of the species diversity that exists within these genera, including identification of highly toxic species (so called "superbugs") that likely contribute disproportionately to ciguatoxins entering coral reef food webs. The recent development of approaches for molecular analysis of field samples now provide the means to investigate in situ community composition, enabling characterization of spatio-temporal species dynamics, linkages between toxic species abundance and toxin flux, and the risk of ciguatoxin prevalence in fish. In this study we used species-specific fluorescent in situ hybridization (FISH) probes to investigate Gambierdiscus species composition and dynamics in St. Thomas (USVI) and the Florida Keys (USA) over multiple years (2018-2020). Within each location, samples were collected seasonally from several sites comprising varying depths, habitats, and algal substrates to characterize community structure over small spatial scales and across different host macrophytes. This approach enabled the quantitative determination of communities over spatiotemporal gradients, as well as the selective enumeration of species known to exhibit high toxicity, such as Gambierdiscus silvae. The investigation found differing community structure between St. Thomas and Florida Keys sites, driven in part by differences in the distribution of toxin-producing species G. silvae and G. belizeanus, which were present throughout sampling sites in St. Thomas but scarce or absent in the Florida Keys. This finding is significant given the high toxicity of G. silvae, and may help explain differences in fish toxicity and CP incidence between St. Thomas and Florida. Intrasite comparisons along a depth gradient found higher concentrations of Gambierdiscus spp. at deeper locations. Among the macrophytes sampled, Dictyota may be a likely vector for toxin transfer based on their widespread distribution, apparent colonization by G. silvae, and palatability to at least some herbivore grazers. Given its ubiquity throughout both study regions and sites, this taxa may also serve as a refuge, accumulating high concentrations of Gambierdiscus and other benthic dinoflagellates, which in turn can serve as source populations for highly palatable and ephemeral habitats nearby, such as turf algae. These studies further demonstrate the successful application of FISH probes in examining biogeographic structuring of Gambierdiscus communities, targeting individual toxin-producing species, and characterizing species-level dynamics that are needed to describe and model ecological drivers of species abundance and toxicity.

Diversity and toxicity of the planktonic diatom genus Pseudo-nitzschia from coastal and offshore waters of the Southeast Pacific, including Pseudo-nitzschia dampieri sp. nov.

To expand knowledge of Pseudo-nitzschia species in the Southeast Pacific, we isolated specimens from coastal waters of central Chile (36°S-30°S), the Gulf of Corcovado, and the oceanic Robinson Crusoe Island (700 km offshore) and grew them into monoclonal strains. A total of 123 Pseudo-nitzschia strains were identified to 11 species based on sequencing of the ITS region of the nuclear rDNA and on ultrastructural and morphometric analyses of the frustule in selected representatives of each clade: P. australis, P. bucculenta, P. cf. chiniana, P. cf. decipiens, P. fraudulenta, P. hasleana, P. multistriata, P. plurisecta, P. cf. sabit, the new species P. dampieri sp. nov., and one undescribed species. Partial 18S and 28S rDNA sequences, including the hypervariable V4 and D1-D3 regions used for barcoding, were gathered from representative strains of each species to facilitate future metabarcoding studies. Results showed different levels of genetic, and at times ultrastructural, diversity among the above-mentioned entities, suggesting morphological variants (P. bucculenta), rapidly radiating complexes with ill-defined species boundaries (P. cf. decipiens and P. cf. sabit), and the presence of new species (P. dampieri sp. nov., Pseudo-nitzschia sp. 1, and probably P. cf. chiniana). Domoic acid (DA) was detected in 18 out of 82 strains tested, including those of P. australis, P. plurisecta, and P. multistriata. Toxicity varied among species mostly corresponding to expectations from previous reports, with the prominent exception of P. fraudulenta; DA was not detected in any of its 10 strains tested. In conclusion, a high diversity of Pseudo-nitzschia exists in Chilean waters, particularly offshore.

Monitoring bacterial composition and assemblage in the Gulf of Corcovado, southern Chile: Bacteria associated with harmful algae.

Harmful Algal Blooms (HABs) have caused damage to the marine environment in Isla San Pedro in the Gulf of Corcovado, Chile. While rising water temperature and artificial eutrophication are the most discussed topics as a cause, marine bacteria is a recent attractive parameter as an algal bloom driver. This study monitored algal and bacterial compositions in the water of Isla San Pedro for one year using microscopy and 16S rRNA metabarcoding analysis, along with physicochemical parameters. The collected data were analyzed with various statistical tools to understand how the particle-associated bacteria (PA) and the free-living (FL) bacteria were possibly involved in algal blooms. Both FL and PA fractions maintained a stable bacterial composition: the FL fraction was dominated by Proteobacteria (α-Proteobacteria and γ-Proteobacteria), and Cyanobacteria dominated the PA fraction. The two fractions contained equivalent bacterial taxonomic richness (c.a. 8,000 Operational Taxonomic Units) and shared more than 50% of OTU; however, roughly 20% was exclusive to each fraction. The four most abundant algal genera in the Isla San Pedro water were Thalassiosira, Skeletonema, Chaetoceros, and Pseudo-nitzchia. Statistical analysis identified that the bacterial species Polycyclovorans algicola was correlated with Pseudo-nitzschia spp., and our monitoring data recorded a sudden increase of particle-associated Polycyclovorans algicola shortly after the increase of Pseudo-nitzschia, suggesting that P. algicola may have regression effect on Pseudo-nitzschia spp. The study also investigated the physicochemical parameter effect on algal-bacterial interactions. Oxygen concentration and chlorophyll-a showed a strong correlation with both FL and PA bacteria despite their assemblage differences, suggesting that the two groups had different mechanisms for interacting with algal species.

A New Bioassay for the Detection of Paralytic and Amnesic Biotoxins Based on Motor Behavior Impairments of Zebrafish Larvae.

The global concern about the increase of harmful algal bloom events and the possible impacts on food safety and aquatic ecosystems presents the necessity for the development of more accessible techniques for biotoxin detection for screening purposes. Considering the numerous advantages that zebrafish present as a biological model and particularly as a toxicants sentinel, we designed a sensitive and accessible test to determine the activity of paralytic and amnesic biotoxins using zebrafish larvae immersion. The ZebraBioTox bioassay is based on the automated recording of larval locomotor activity using an IR microbeam locomotion detector, and manual assessment of four complementary responses under a simple stereoscope: survival, periocular edema, body balance, and touch response. This 24 h acute static bioassay was set up in 96-well microplates using 5 dpf zebrafish larvae. For paralytic toxins, a significant decrease in locomotor activity and touch response of the larvae was detected, allowing a detection threshold of 0.1-0.2 µg/mL STXeq. In the case of the amnesic toxin the effect was reversed, detecting hyperactivity with a detection threshold of 10 µg/mL domoic acid. We propose that this assay might be used as a complementary tool for environmental safety monitoring.

Sublethal effect of the toxic dinoflagellate Karlodinium veneficum on early life stages of zebrafish (Danio rerio).

Dinoflagellates of the genus Karlodinium are ichthyotoxic species that produce toxins including karlotoxins and karmitoxins. Karlotoxins show hemolytic and cytotoxic activities and have been associated with fish mortality. This study evaluated the effect of toxins released into the environment of Karlodinium veneficum strain K10 (Ebro Delta, NW Mediterranean) on the early stages of Danio rerio (zebrafish). Extracts of the supernatant of K10 contained the mono-sulfated KmTx-10, KmTx-11, KmTx-12, KmTx-13, and a di-sulfated form of KmTx-10. Total egg mortality was observed for karlotoxin concentration higher than 2.69 µg L-1. For 1.35 µg L-1, 87% of development anomalies were evidenced (all concentrations were expressed as KmTx-2 equivalent). Larvae of 8 days postfertilization exposed to 1.35 µg L-1 presented epithelial damage with 80% of cells in the early apoptotic stage. Our results indicate that supernatants with low concentration of KmTxs produce both lethal and sublethal effects in early fish stages. Moreover, apoptosis was induced at concentrations as low as 0.01 µg L-1. This is of great relevance since detrimental long-term effects due to exposure to low concentrations of these substances could affect wild and cultured fish.

Ocorrência de florações de cianobactérias e consequências para a saúde pública no Nordeste do Brasil / Ocurrence of cyanobacterial bloom and consequences for public health in Northeastern Brazil / Ocurrencia de las floraciones de cianobacterias y consecuencias para la salud pública en el Nordeste de Brasil

As florações são resultado de interações entre fatores físicos, químicos e biológicos, sendo caracterizadas pelo crescimento massivo de microrganismos. As proliferações de cianobactérias indicam a deterioração na qualidade da água e podem ser consideradas problemas de saúde pública, devido à capacidade de produção e liberação de toxinas pelas cianobactérias nos ambientes aquáticos, especialmente nos reservatórios de abastecimento. Assim, este trabalho teve como objetivo verificar, a partir de uma revisão de literatura, a ocorrência de florações de cianobactérias e cianotoxinas e os efeitos especialmente para saúde pública. A metodologia utilizada foi revisão narrativa de trabalhos selecionados seguindo os critérios de inclusão. Foi verificada a ocorrência de 74 espécies de cianobactérias, sendo Microcystis aeruginosa e Raphidiopsis raciborskii as predominantes. Espécies potencialmente tóxicas foram encontradas em todas as florações relatadas nos trabalhos realizados na região Nordeste. As florações de cianobactérias ocorreram principalmente em reservatórios da região Nordeste, juntamente com cianotoxinas (microcistinas, cilindrospermopiscina e saxitoxina). Têm sido frequentes florações com cianotoxinas em sistemas aquáticos, ocasionando alterações no ambiente aquático. Essas modificações alcançam diversos níveis tróficos e podem alcançar o homem, sendo problema de saúde pública.

The blooms are the result of interactions between physical, chemical, and biological factors, and are characterized by the explosive growth of microorganisms. The proliferations of cyanobacteria indicate deterioration in quality and can be considered public health problems due to the ability of cyanobacteria to produce and release toxins in aquatic environments, especially in supply reservoirs. Thus, this study aimed to review the literature to verify the occurrence of cyanobacteria and cyanotoxin blooms and the effects especially for public health. The methodology used was narrative review of selected papers according to the inclusion criteria. The occurrence of 74 cyanobacteria species was verified, with Microcystis aeruginosa and Raphidiopsis raciborskii being the predominant ones. Potentially toxic species were found in all blooms studies carried out in the Northeast region. Cyanobacterial blooms were found mainly in reservoirs in the Northeast region, along with cyanotoxins (microcystins, cylindrospermopsin, and saxitoxin). Blooms with cyanotoxins have been frequent in aquatic systems, causing changes in the aquatic environment. These changes reach several trophic levels, and can reach man, being a public health problem.

Las floraciones son el resultado de interacciones entre factores físicos, químicos y biológicos, caracterizadas por el crecimiento explosivo de microorganismos. La proliferación de cianobacterias indica un deterioro de la calidad y puede considerarse un problema de salud pública debido a la capacidad de las cianobacterias de producir y liberar toxinas en ambientes acuáticos, especialmente en los embalses de abastecimiento. Así, este estudio tenía como objetivo revisar la literatura para verificar la ocurrencia de floraciones de cianobacterias y cianotoxina, así como sus efectos especialmente en la salud pública. La metodología utilizada fue la revisión narrativa de los documentos seleccionados de acuerdo con los criterios de inclusión. Se verificó la aparición de 74 especies de cianobacterias, de las cuales Microcystis aeruginosa y Raphidiopsis raciborskii fueron las más predominantes. Se encontraron especies potencialmente tóxicas en todos los estudios de floración realizados en los estados de la región Nordeste de Brasil. Las floraciones de cianobacterias se encontraron principalmente en embalses en la región Nordeste, junto con cianotoxinas (microcistinas, cilindrospermopsinas y saxitoxinas). Ha habido frecuentes floraciones con cianotoxinas en los sistemas acuáticos, causando cambios en el medio acuático. Estos cambios alcanzan varios niveles tróficos y pueden llegar al hombre, siendo un problema de salud pública.

Floración algal nociva del dinoflagelado Blixaea quinquecornis en el Perú / Harmful algal bloom of dinoflagellate Blixaea quinquecornis in Peru

Resumen En el presente trabajo, se registra por primera vez floraciones algales nocivas del dinoflagelado Blixaea quinquecornis (Abé) Gottschling, 2017 para aguas costeras del mar peruano. La determinación taxonómica de esta especie se realizó mediante microscopia de luz, electrónica de barrido y contraste interferencial diferencial (DIC). La fórmula tecal encontrada fue: pp, 3', 2a, 7'',5c, 5"' y 2''' 4s. Blixaea quinquecornis fue registrada en las bahías Sechura, Miraflores y Paracas entre el 2014 y 2017, usualmente con altas densidades de 3.2 x105 cel.L-1 (Miraflores) y 2.11x105 cel.L-1 (Paracas) en verano y 4.11 x104 (Paracas) en otoño 2016. Blixaea quinquecornis estuvo alternando con floraciones algales del dinoflagelado atecado Akashiwo sanguinea. El florecimiento de B. quinquecornis se observó con TSM entre 18.5 a 26.6 °C, salinidades entre 34.70 y 35.32 ups, pH entre 7.32 y 8.82 y oxígeno disuelto entre 3.8 y 12.5 mL/L. En Bahía Miraflores, la floración de B. quinquecornis fue asociado positivamente con el incremento de la TSM, salinidad y negativamente con la concentración de nitratos, mientras que las floraciones algales de A. sanguinea se correlacionó positivamente con la concentración de fosfatos y oxígeno disuelto. El registro de la floración de B. quinquecornis en las bahías de Miraflores y Paracas, coincidió con eventos de inusual calentamiento del mar asociado con el evento cálido El Niño 2015-2016.

Abstract In the present work, harmful algal blooms of the dinoflagellate Blixaea quinquecornis (Abé) Gottschling, 2017 are recorded for the first time for coastal waters of the Peruvian sea. The taxonomic determination of this species was done with light microscopy, Scanning Electron Microscopy (SEM), and Differential Interference Contrast (DIC) microscopy. The thecal formula is: pp, 3', 2a, 7'', 5c, 5"' and 2''' 4s. Blixaea quinquecornis was recorded in Sechura, Miraflores and Paracas bays between 2014 - 2016, mainly with algal blooms of 3.2 x105 cel.L-1 (Miraflores) and 2.11x105 cel.L-1 (Paracas) and 4.11 x104 cel.L-1 (Paracas) in autumn of 2016. Blixaea quinquecornis was found alternating with algal bloom produced by the athecate dinoflagellate Akashiwo sanguinea. The physicochemical variables associated with the bloom of B. quinquecornis were SST (18.5 to 26.6° C), salinities (34.7 to 35.325), pH (7.32 to 12.5), and dissolved oxygen (3.8 to 12.5 mL/L). The bloom of B. quinquecornis in Miraflores Bay was positively associated with the increase in SST, salinity and negatively with the concentration of nitrates, whereas the algal blooms of A. sanguinea were positively correlated with the concentration of phosphates and oxygen. The record of the bloom of B. quinquecornis in the 3 bays coincided with unusual sea warming event associated with the El Niño phenomenon 2015-2016.

The effect of iron on Chilean Alexandrium catenella growth and paralytic shellfish toxin production as related to algal blooms.

The dinoflagellate Alexandrium catenella is a well-known paralytic shellfish toxin producer that forms harmful algal blooms (HABs) worldwide. Blooms of this species have repeatedly brought severe ecological and economic impacts to Chile, especially in the southern region, where the shellfish and salmon industries are world-famous. The mechanisms of such HABs have been intensively studied but are still unclear. Nutrient overloading is one of the often-discussed drivers for HABs. The present study used the A. catenella strain isolated from southern Chile to investigate how iron conditions could affect their growth and toxin production as related to HAB. Our results showed that an optimum concentration of iron was pivotal for proper A. catenella growth. Thus, while excess iron exerted a toxic effect, low iron media led to iron insufficiency and growth inhibition. In addition, the study shows that the degree of paralytic shellfish toxin production by A. catenella varied depending on the iron concentration in the culture media. The A. catenella strain from southern Chile produced GTX1-4 exclusively in the fmol cell-1 scale. Based on these findings, we suggest that including iron and paralytic shellfish toxin measurements in the fields can improve the current HAB monitoring and contribute to an understanding of A. catenella bloom dynamics in Chile.

Asynchrony of Gambierdiscus spp. Abundance and Toxicity in the U.S. Virgin Islands: Implications for Monitoring and Management of Ciguatera.

Ciguatera poisoning (CP) poses a significant threat to ecosystem services and fishery resources in coastal communities. The CP-causative ciguatoxins (CTXs) are produced by benthic dinoflagellates including Gambierdiscus and Fukuyoa spp., and enter reef food webs via grazing on macroalgal substrates. In this study, we report on a 3-year monthly time series in St. Thomas, US Virgin Islands where Gambierdiscus spp. abundance and Caribbean-CTX toxicity in benthic samples were compared to key environmental factors, including temperature, salinity, nutrients, benthic cover, and physical data. We found that peak Gambierdiscus abundance occurred in summer while CTX-specific toxicity peaked in cooler months (February-May) when the mean water temperatures were approximately 26-28 °C. These trends were most evident at deeper offshore sites where macroalgal cover was highest year-round. Other environmental parameters were not correlated with the CTX variability observed over time. The asynchrony between Gambierdiscus spp. abundance and toxicity reflects potential differences in toxin cell quotas among Gambierdiscus species with concomitant variability in their abundances throughout the year. These results have significant implications for monitoring and management of benthic harmful algal blooms and highlights potential seasonal and highly-localized pulses in reef toxin loads that may be transferred to higher trophic levels.

Suitcase Lab: new, portable, and deployable equipment for rapid detection of specific harmful algae in Chilean coastal waters.

Phytoplankton blooms, including harmful algal blooms (HABs), have serious impacts on ecosystems, public health, and productivity activities. Rapid detection and monitoring of marine microalgae are important in predicting and managing HABs. We developed a toolkit, the Suitcase Lab, to detect harmful algae species in the field. We demonstrated the Suitcase Lab's capabilities for sampling, filtration, DNA extraction, and loop-mediated isothermal amplification (LAMP) detection in cultured Alexandrium catenella cells as well as Chilean coastal waters from four sites: Repollal, Isla García, Puerto Montt, and Metri. A LAMP assay using the Suitcase Lab in the field confirmed microscopic observations of A. catenella in samples from Repollal and Isla García. The Suitcase Lab allowed the rapid detection of A. catenella, within 2 h from the time of sampling, even at a single cell per milliliter concentrations, demonstrating its usefulness for quick and qualitative on-site diagnosis of target toxic algae species. This method is applicable not only to detecting harmful algae but also to other field studies that seek a rapid molecular diagnostic test.

Summer bloom of Vulcanodinium rugosum in Cienfuegos Bay (Cuba) associated to dermatitis in swimmers.

The marine dinoflagellate Vulcanodinium rugosum produces powerful paralyzing and cytotoxic compounds named pinnatoxins (PnTX) and portimines. Even though, no related human intoxication episodes following direct exposure in seawater or the ingestion of contaminated seafood have been documented so far. This study aimed at investigating a dinoflagellate bloom linked to acute dermatitis cases in two recreational beaches in Cienfuegos Bay, Cuba. We used epidemiological and clinical data from 60 dermatitis cases consisting of individuals in close contact with the bloom. Seawater physical-chemical properties were described, and the microorganism causing the bloom was identified by means of light and scanning electron microscopy. Morphological identification was confirmed genetically by sequencing the internal transcribed spacers ITS1 and ITS2, and the 5.8S rDNA region. Toxic compounds were identified from a bloom extract using liquid chromatography (LC) coupled to high-resolution mass spectrometry (HRMS), and their concentrations were estimated based on low-resolution tandem mass spectrometry (LC-MS/MS). Sixty people who had prolonged contact with the dinoflagellate bloom suffered acute dermal irritation. Most patients (79.2%) were children and had to be treated with antibiotics; some required >5-day hospitalization. Combined morphological and genetic characters indicated V. rugosum as the causative agent of the bloom. rDNA sequences of the V. rugosum genotype found in the bloom aligned with others from Asia, including material found in the ballast tank of a ship in Florida. The predominant toxins in the bloom were portimine, PnTX-F and PnTX-E, similar to strains originating from the Pacific Ocean. This bloom was associated with unusual weather conditions such as frequent and prolonged droughts. Our findings indicate a close link between the V. rugosum bloom and a dermatitis outbreak among swimmers in Cienfuegos Bay. Phylogenetic evidence suggests a recent introduction of V. rugosum from the Pacific Ocean into Caribbean waters, possibly via ballast water.

Copepod Prey Selection and Grazing Efficiency Mediated by Chemical and Morphological Defensive Traits of Cyanobacteria.

Phytoplankton anti-grazer traits control zooplankton grazing and are associated with harmful blooms. Yet, how morphological versus chemical phytoplankton defenses regulate zooplankton grazing is poorly understood. We compared zooplankton grazing and prey selection by contrasting morphological (filament length: short vs. long) and chemical (saxitoxin: STX- vs. STX+) traits of a bloom-forming cyanobacterium (Raphidiopsis) offered at different concentrations in mixed diets with an edible phytoplankton to a copepod grazer. The copepod selectively grazed on the edible prey (avoidance of cyanobacteria) even when the cyanobacterium was dominant. Avoidance of the cyanobacterium was weakest for the "short STX-" filaments and strongest for the other three strains. Hence, filament size had an effect on cyanobacterial avoidance only in the STX- treatments, while toxin production significantly increased cyanobacterial avoidance regardless of filament size. Moreover, cyanobacterial dominance reduced grazing on the edible prey by almost 50%. Results emphasize that the dominance of filamentous cyanobacteria such as Raphidiopsis can interfere with copepod grazing in a trait specific manner. For cyanobacteria, toxin production may be more effective than filament size as an anti-grazer defense against selectively grazing zooplankton such as copepods. Our results highlight how multiple phytoplankton defensive traits interact to regulate the producer-consumer link in plankton ecosystems.

Guanitoxin, re-naming a cyanobacterial organophosphate toxin.

Anatoxin-a(S) is the most potent natural neurotoxin produced by fresh water cyanobacteria. It is also the least understood and monitored. Although this potent cholinesterase inhibitor was first reported in the 1970s and connected with animal poisonings, the lack of chemical standards and identified biosynthetic genes together with limited diagnostics and acute reactivity of this naturally-occurring organophosphate have limited our understanding of its environmental breadth and human health implications. Anatoxin-a(S) irreversibly inhibits acetylcholinesterase much like other organophosphate agents like paraoxon. It is however often confused with the similarly named anatoxin-a that has a completely different chemical structure, mechanism of action, and biosynthesis. Herein we propose renaming of anatoxin-a(S) to clarify its distinct structure and mechanism and to draw renewed attention to this potent natural poison. We propose the new name guanitoxin (GNT) to emphasize its distinctive guanidino organophosphate chemical structure.

Ostreopsis cf. ovata Bloom in Currais, Brazil: Phylogeny, Toxin Profile and Contamination of Mussels and Marine Plastic Litter.

Ostreopsis cf. ovata is a toxic marine benthic dinoflagellate responsible for harmful blooms affecting ecosystem and human health, mostly in the Mediterranean Sea. In this study we report the occurrence of a summer O. cf. ovata bloom in Currais, a coastal archipelago located on the subtropical Brazilian coast (~25° S). This bloom was very similar to Mediterranean episodes in many aspects: (a) field-sampled and cultivated O. cf. ovata cells aligned phylogenetically (ITS and LSU regions) along with Mediterranean strains; (b) the bloom occurred at increasing temperature and irradiance, and decreasing wind speed; (c) cell densities reached up to 8.0 × 104 cell cm-2 on fiberglass screen and 5.6 × 105 cell g-1 fresh weight on seaweeds; (d) and toxin profiles were composed mostly of ovatoxin-a (58%) and ovatoxin-b (32%), up to 35.5 pg PLTX-eq. cell-1 in total. Mussels were contaminated during the bloom with unsafe toxin levels (up to 131 µg PLTX-eq. kg-1). Ostreopsis cells attached to different plastic litter, indicating an alternate route for toxin transfer to marine fauna via ingestion of biofilm-coated plastic debris.

Diel Variations in Cell Abundance and Trophic Transfer of Diarrheic Toxins during a Massive Dinophysis Bloom in Southern Brazil.

Dinophysis spp. are a major source of diarrheic toxins to marine food webs, especially during blooms. This study documented the occurrence, in late May 2016, of a massive toxic bloom of the Dinophysis acuminata complex along the southern coast of Brazil, associated with an episode of marked salinity stratification. The study tracked the daily vertical distribution of Dinophysis spp. cells and their ciliate prey, Mesodinium cf. rubrum, and quantified the amount of lipophilic toxins present in seston and accumulated by various marine organisms in the food web. The abundance of the D. acuminata complex reached 43 × 104 cells·L−1 at 1.0 m depth at the peak of the bloom. Maximum cell densities of cryptophyceans and M. cf. rubrum (>500 × 104 and 18 × 104 cell·L−1, respectively) were recorded on the first day of sampling, one week before the peak in abundance of the D. acuminata complex. The diarrheic toxin okadaic acid (OA) was the only toxin detected during the bloom, attaining unprecedented, high concentrations of up to 829 µg·L−1 in seston, and 143 ± 93 pg·cell−1 in individually picked cells of the D. acuminata complex. Suspension-feeders such as the mussel, Perna perna, and barnacle, Megabalanus tintinnabulum, accumulated maximum OA levels (up to 578.4 and 21.9 µg total OA·Kg−1, respectively) during early bloom stages, whereas predators and detritivores such as Caprellidae amphipods (154.6 µg·Kg−1), Stramonita haemastoma gastropods (111.6 µg·Kg−1), Pilumnus spinosissimus crabs (33.4 µg·Kg−1) and a commercially important species of shrimp, Xiphopenaeus kroyeri (7.2 µg·Kg−1), only incorporated OA from mid- to late bloom stages. Conjugated forms of OA were dominant (>70%) in most organisms, except in blenny fish, Hypleurochilus fissicornis, and polychaetes, Pseudonereis palpata (up to 59.3 and 164.6 µg total OA·Kg−1, respectively), which contained mostly free-OA throughout the bloom. Although algal toxins are only regulated in bivalves during toxic blooms in most countries, including Brazil, this study indicates that human seafood consumers might be exposed to moderate toxin levels from a variety of other vectors during intense toxic outbreaks.

Next Generation Sequencing and mass spectrometry reveal high taxonomic diversity and complex phytoplankton-phycotoxins patterns in Southeastern Pacific fjords.

In fjord systems, Harmful Algal Blooms (HABs) not only constitute a serious problem when affecting the wildlife and ecosystems, but also human health and economic activities related to the marine environment. This is mostly due to a broad spectrum of toxic compounds produced by several members of the phytoplankton. Nevertheless, a deep coverage of the taxonomic diversity and composition of phytoplankton species and phycotoxin profiles in HAB prone areas are still lacking and little is known about the relationship between these fundamental elements for fjord ecosystems. In this study, a detailed molecular and microscopic characterization of plankton communities was performed, together with an analysis of the occurrence and spatial patterns of lipophilic toxins in a HAB prone area, located in the Southeastern Pacific fjord region. Microscopy and molecular analyses based on the 18S rRNA gene fragment indicated high diversity and taxonomic homogeneity among stations. Four toxigenic genera were identified: Pseudo-nitzschia, Dinophysis, Prorocentrum, and Alexandrium. In agreement with the detected species, liquid chromatography coupled with mass spectrometry revealed the presence of domoic acid (DA), pectenotoxin-2 (PTX-2), dinophysistoxin-2 (DTX-2), and 13-desmethyl spirolide C (SPX-1). Furthermore, a patchy distribution among DA in different net haul size fractions was found. Our results displayed a complex phytoplankton-phycotoxin pattern and for the first time contribute to the characterization of high-resolution phytoplankton community composition and phycotoxin distribution in fjords of the Southeastern Pacific region.

Florecimientos algales nocivos producidos por Pyrodinium bahamense en Oaxaca, México (2009-2010) / Harmful algal blooms produced by Pyrodinium bahamense in Oaxaca, Mexico (2009-2010)

Objetivo. Monitorear el dinoflagelado Pyrodinium bahamense y sus toxinas en ostión de roca Striostrea prismatica en Santiago Astata y en Puerto Escondido, Oaxaca, de septiembre de 2009 a junio de 2010. Material y métodos. Se analizó mensualmente la abundancia de Pyrodinium bahamense mediante el método de Sedgewick-Rafter y la concentración de toxinas paralizantes y perfil tóxico en tejido blando del molusco en muestras compuestas de cada zona por el método de cromatografía líquida de alta resolución. Resultados. Se encontró alta abundancia de Pyrodinium bahamense en Santiago Astata en diciembre, febrero, abril y junio, y en Puerto Escondido en abril y junio. Los niveles de toxinas paralizantes fueron superiores al límite permisible para consumo humano en Santiago Astata en noviembre, diciembre, enero, febrero y junio; en la zona de Puerto Escondido, en diciembre y junio. Conclusiones. Estos niveles de toxinas representaron riesgo para la salud pública en la zona de estudio.

Objective. Pyrodinium bahamense monitoring in water and their toxins in rock oyster Striostrea prismatica in Santiago Astata and Puerto Escondido Oaxaca was performed from September 2009 to July 2010. Materials and methods. Pyrodinium bahamense abundance in water, and concentration and toxic profile of paralytic shellfish toxins were analyzed monthly in soft tissue of mollusk in composite samples in high performance liquid chromatography. Results. High abundance of Pyrodinium bahamense was found in Santiago Astata on December, February, April and June; and in Puerto Escondido on April and June. The concentrations of the paralyzing toxin that exceeded the regulatory limit for human consumption of mollusks (800 µg STX eq. kg-1) were presented in Santiago Astata on November, December, January, February and June; and in Puerto Escondido on December and June. Conclusions. For several months there was risk to public health due to the presence of paralytic shellfish toxins above the regulatory limit in oysters from the study area.

Cutaneous protothecosis - case report / Prototecose cutanea - relato de caso

Cutaneous protothecosis is a rare infection caused by achlorophyllic algae of the genus Prototheca. The lesions usually occur on exposed areas, related with trauma, in immunocompromised patients. The most common clinical presentation is a vesicobullous and ulcerative lesion with pustules and scabs, simulating bacterial, fungal or herpetic infections or eczema. The diagnosis is determined by agent identification through histopathology, culture and the carbohydrates assimilation test. The finding of morula-like spherules is characteristic of Prototheca sp. Its rarity and non-specific clinical aspect may difficult the disease diagnosis. We report a case of a diabetic patient, in chronic use of systemic corticosteroids, that developed a skin lesion after trauma to the right leg.

A prototecose cutânea é uma infecção rara causada por algas aclorofílicas do gênero Prototheca. Geralmente as lesões ocorrem em áreas expostas, relacionadas à trauma, em indivíduos imunocomprometidos. A apresentação clínica mais comum é uma lesão vesico-bolhosa e ulcerativa com pústulas e crostas, simulando piodermites, infecções fúngicas, infecções herpéticas ou eczemas. O diagnóstico é realizado pela identificação do agente através do exame histopatológico, da cultura e do teste de assimilação dos carboidratos. O achado de esférulas com aspecto de mórula são características da Prototheca sp. A raridade da doença e o aspecto clínico inespecífico dificultam o diagnóstico da doença. Relatamos um caso em paciente diabética, em uso crônico de corticoide sistêmico, que desenvolveu lesão cutânea após trauma na perna direita.