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Lipophilic toxins were investigated in different benthic compartments of Paranagua Bay, southern Brazil. Relatively low concentrations of okadaic acid (OA) were frequently reported in macrophyte extracts (maximum 0.64 ng g-1), mainly in sheltered estuarine areas, correlated with the cell abundance of toxigenic benthic dinoflagellates, Prorocentrum lima. Non-conjugated OA was also detected in benthic marine animals, mostly during summer-autumn 2016. Higher OA concentrations were found in the viscera of Genidens genidens fish (24.3 ± 3.7 ng g-1) and in soft tissues of Mytella guyanensis bivalves (21.3 ± 2.13 ng g-1), whereas lower levels were less frequently reported in many other benthic feeders, including cephalopods, gastropods, crustaceans and fishes. Although OA concentrations were below the levels associated with acute human intoxication, possible chronic effects to benthic animals and their consumers cannot be disregarded due to the frequent presence of this biotoxin in various fishery resources. Human health risks are substantially enhanced for small-scale fishing communities and other socioeconomically vulnerable populations.

The present study investigated selected benthic dinoflagellates isolated from different regions from the Western Atlantic, with respect to their morphology, growth, toxicity, and toxin production in culture. A total of nine strains of benthic dinoflagellates belonging to three genera were cultivated: Amphidinium massartii, Amphidinium operculatum (2 strains), Coolia malayensis (2 strains), Prorocentrum hoffmannianum (2 strains), and Prorocentrum mexicanum, whose morphological and genetic characterizations matched previous descriptions, and Prorocentrum sp., morphologically related to P. cf. norrissianum. The two strains of C. malayensis from Brazil attained the highest growth rates (0.42–0.47 day−1), but the lowest cell densities (2.2–2.9 × 104 cells mL−1) in culture. The highest cell densities were recorded for A. massartii from Cuba (3.8 × 105 cells mL−1). All species/strains investigated exhibited moderate toxicity to larvae of the brine shrimp Artemia salina; A. massartii being the most toxic species and Prorocentrum sp. the least one. Additionally, extracts of Prorocentrum species (P. hoffmannianum and Prorocentrum sp.) tested positive in mouse bioassays following intraperitoneal injection. Moderate to high concentrations of okadaic acid (OA), but no dinophysistoxins (DTXs), were found in both P. hoffmannianum strains from Cuba; but no diarrheic toxins were detected in either P. mexicanum from Cuba or Prorocentrum sp. from southern Brazil. Finally, five novel amphidinols were detected in cultures of both A. massartii (Cuba) and A. operculatum (Brazil) by LC-MS/MS, with molecular weights of 1440.8 (two isomers), 1360.8, 1287.7, and 984.6. These findings clearly indicate the need to include benthic species among the harmful microalgae surveyed in regional monitoring programs of phytoplankton.

Ciguatera poisoning is caused by the consumption of reef fish or shellfish that have accumulated ciguatoxins, neurotoxins produced by benthic dinoflagellates of the genera Gambierdiscus or Fukuyoa. Although ciguatera constitutes the primary cause of seafood intoxication in Cuba, very little information is available on the occurrence of ciguatoxins in the marine food web and the causative benthic dinoflagellate species. This study conducted on the south-central coast of Cuba reports the occurrence of Gambierdiscus and Fukuyoa genera and the associated benthic genera Ostreopsis and Prorocentrum. Gambierdiscus/Fukuyoa cells were present at low to moderate abundances depending on the site and month of sampling. This genus was notably higher on Dictyotaceae than on other macrophytes. PCR analysis of field-collected samples revealed the presence of six different Gambierdiscus and one Fukuyoa species, including G. caribaeus, G. carolinianus, G. carpenteri, G. belizeanus, F. ruetzleri, G. silvae, and Gambierdiscus sp. ribotype 2. Only Gambierdiscus excentricus was absent from the eight Gambierdiscus/Fukuyoa species known in the wider Caribbean region. Eleven clonal cultures were established and confirmed by PCR and SEM as being either G. carolinianus or G. caribaeus. Toxin production in each isolate was assessed by a radioligand receptor binding assay and found to be below the assay quantification limit. These novel findings augment the knowledge of the ciguatoxin-source dinoflagellates that are present in Cuba, however further studies are needed to better understand the correlation between their abundance, species-specific toxin production in the environment, and the risk for fish contamination, in order to develop better informed ciguatera risk management strategies.

Balliella pseudocorticata (Ceramiaceae, Ceramiales) se registra por primera vez para Cuba. Los especímenes fueron recolectados en el litoral arrecifal oriental de la provincia de Cienfuegos, centro-sur de la isla, y fueron identificados por sus características morfológicas distintivas.

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.

Benthic dinoflagellates belonging to the genus Prorocentrum are known to produce diarrhetic toxins such as okadaic acid (OA) and its analogues, dinophysistoxins (DTXs), as well as prorocentrolides and other unidentified fast-acting toxins. The present study is a comparative analysis focused on the morphology, genetic, growth, toxin production, and toxicity by strains belonging to the Prorocentrum lima species complex, isolated from different regions along the western Atlantic coast. While cell dimensions (38–45 × 24–30 μm) and shape (ovoid) were similar between strains from Cuba and Recife (Northeast Brazil), cells of the strain from the estuarine complex of Paranagua Bay (South Brazil) were shorter (36–41 × 25–28 μm) and oblong to ovate-oblong (elliptical) in shape. This latter strain exhibited similar LSU rDNA and identical ITS1-5.8S rDNA-ITS2 sequences to those of P. cf. lima “morphotype 5,” which is closely related to Prorocentrum caipirignum by LSU, but separated from it by ITS. This southern Brazilian strain attained the highest growth rate (0.34 ± 0.01 div day−1) and cell densities (11.2 × 105 cell mL−1) in batch culture. Intracellular OA concentrations were higher for the other two strains during the late exponential and stationary phase, but similar for all strains (9.50–10.06 pg cell−1) at the early exponential growth phase; consistently lower levels of DTX-1 were produced by two strains, except the one from Recife. Finally, live cells of the strains from Cuba and Recife were more toxic to A. salina metanauplii, whereas the southern Brazilian strain exhibited higher culture medium toxicity. The contrasts in growth and toxicity potential revealed for these morphologically and genetically distinct Prorocentrum strains might be relevant for the local management of diarrhetic poisoning outbreaks in shellfish harvesting and aquaculture sites, including in estuarine areas.

An important consequence of eutrophication is the increased prevalence of harmful algal blooms that affect transitional and coastal waters, and ecosystems in open seas. In this work, data on phytoplankton biomass, presence of harmful/toxic algal blooms and bottom dissolved oxygen were analyzed as indicators of overall eutrophic condition in the Cienfuegos Bay, Cuba. Samples were collected every three months during the year 2009 at fifteen representative stations within the bay. In the dry and early rainy seasons, high chlorophyll a values, harmful/toxic dinoflagellate blooms and fish mortality episodes were encountered within riverine-urban wastewater discharge zones, whilst most part of the bay did not evidence symptoms of eutrophication. During the rainy season, some stations showed biological stress-hypoxia for the bottom water oxygen, and a strong increase in spatial dispersion was observed in the phytoplankton biomass, due to a substantial increment in not toxic diatom abundance, resulting in a moderate level of eutrophic conditions for chlorophyll a in the entire bay. The key factor that supports the seasonal variation in phytoplankton composition and abundance appears to be the water residence time inside the bay. Uma importante consequência da eutrofização é o incremento e persistência das florações algais nocivas que afetam as águas de transição e costeiras, e ecossistemas em mar aberto. Neste trabalho, dados sobre a biomassa do fitoplâncton, presença de florações algais nocivas/tóxicas e oxigénio dissolvido no fundo foram analisados como indicadores da condição eutrófica geral na Baía de Cienfuegos, Cuba. Foram recolhidas amostras a cada três meses durante o ano de 2009 em quinze locais representativas dentro da baía. Nas estações da seca e do começo do período chuvoso, altos valores de clorofila a, florações algais nocivas/tóxicas e episódios de mortandades de peixes foram encontrados dentro de zonas de descargas de rios e de resíduos urbanos, enquanto a maior parte da baía não evidenciou sintomas de eutrofização. Durante o período chuvoso, alguns locais mostraram estresse biológico-hypoxia para o oxigénio dissolvido no fundo e um forte incremento na dispersão espacial foi observado na biomassa do fitoplâncton devido a um incremento substancial na abundancia de diatomáceas não tóxicas, resultando num nível moderado de eutrofização para a clorofila a em toda a baía. O fator chave que suporta a variação sazonal na composição e abundância do fitoplâncton parece ser o tempo de residência da água dentro da baía.

The aim of this study was to carry out a taxonomic survey of red marine benthic algae that occur in the littoral zone of central-southern Cuba. The samplings were performed in the period 2010–2012at 12 stations predominantly in reef environments. A total of 81 taxa were recorded and distributed in 9 orders and 24 families. Ceramiales was the most represented order with 38 taxa, followed by Corallinales with nine taxa. Hypoglossum caloglossoides represents a new record for Cuban benthic marine algae. Forty-nine species of macroalgae are new additions to the flora of reef environments from the central-southern region of Cuba. Sixty species of the region are provided in Figures (2–61). Dichotomaria obtusata was the most common species found. Some species such as Ceramium fujianum, Gloiocladia iyoensis, Griffithsia schousboei var. anastomosans and Dasya ocellata have been found in Cuba only in the central-southern region. Calcified crustose and articulated coralline algae were found to be common in the coral reef locations, while filamentous turfs and fleshy or frondose macroalgae were commonly found in the stations of shallow or intertidal waters. The floristic composition of red marine benthic algae indicates the central-southern coast of Cuban archipelago as a site of elevated species richness and that its coral reef environments are in a status of good health due to prevalence of calcareous coralline macroalgae.