The toxic benthic dinoflagellates of the genus Ostreopsis in temperate areas: a review

The genus Ostreopsis includes species largely distributed from tropical to temperate marine areas worldwide. Among the nine species of the genus, O. siamensis, O. mascarenensis, O. lenticularis and O. cf. ovata can produce toxins of the palytoxin group. In the last decade Ostreopsis cf. ovata and O. cf. siamensis originated intense blooms in all the rocky Mediterranean Sea coastal areas, typically during summer-late summer. The correct identification of Ostreopsis species in field samples is often problematic as Ostreopsis species are morphologically plastic and hardly discriminable under light microscopy and, therefore, molecular analyses are required. Ostreopsis blooms are often associated with noxious effects on health of both humans and benthic marine organisms mainly carried by aerosol and direct contact with seawater. Environmental factors have been shown to affect toxin content of Ostreopsis which generally produces more toxins per cell when growing under suboptimal conditions. O. cf. ovata is able to produce both temporary and resting cysts. In particular, the resting cysts are able to germinate in laboratory conditions for as long as 5 months after their formation at 25°C, but not at 21°C; the presence of a temperature threshold affecting cyst germination in the laboratory suggests that temperature represents a key factor for Ostreopsis cf. ovata bloom onset in natural environments as well. Several studies conducted to assess the role of abiotic factors (mainly hydrodynamics, water temperature and nutrients) on the bloom dynamics, revealed that the synergic effects of hydrodynamics, temperature and N:P ratios would lead the Ostreopsis blooms in temperate areas. Ostreopsis abundances showed a significant decrease with depth, likely related to light availability, although there are conflicting data about the relationship between light intensity and Ostreopsis growth in experimental conditions. The relationship between Ostreopsis blooms and salinity is not completely clear, complicated by the influence of high nutrient levels often associated to low salinity waters. Finally, Ostreopsis colonize a variety of substrata, although living substrata seems to allow lower concentration of epibionts than any other substrate, probably due to the production of some allelopathic compounds.</p

New Approach Using the Real-Time PCR Method for Estimation of the Toxic Marine Dinoflagellate Ostreopsis cf. ovata in Marine Environment

Background: We describe the development and validation of a new quantitative real time PCR (qrt-PCR) method for the enumeration of the toxic benthic dinoflagellate Ostreopsis cf. ovata in marine environment. The benthic Ostreopsis sp. has a world-wide distribution and is associated during high biomass proliferation with the production of potent palytoxin-like compounds affecting human health and environment. Species-specific identification, which is relevant for the complex of different toxins production, by traditional methods of microscopy is difficult due to the high morphological variability, and thus different morphotypes can be easily misinterpreted. Methodology/Findings: The method is based on the SYBR I Green real-time PCR technology and combines the use of a plasmid standard curve with a ‘‘gold standard’’ created with pooled crude extracts from environmental samples collected during a bloom event of Ostreopsis cf. ovata in the Mediterranean Sea. Based on their similar PCR efficiencies (95% and 98%, respectively), the exact rDNA copy number per cell was obtained in cultured and environmental samples. Cell lysates were used as the templates to obtain total recovery of DNA. The analytical sensitivity of the PCR was set at two rDNA copy number and 8.061024 cell per reaction for plasmid and gold standards, respectively; the sensitivity of the assay was of cells g21 fw or 121 in macrophyte and seawater samples, respectively. The reproducibility was determined on the total linear quantification range of both curves confirming the accuracy of the technical set-up in the complete ranges of quantification over time. Conclusions/Significance: We developed a qrt-PCR assay specific, robust and high sample throughput for the absolute quantification of the toxic dinoflagellate Ostreopsis cf. ovata in the environmental samples. This molecular approach may be considered alternative to traditional microscopy and applied for the monitoring of benthic toxic microalgal species in the marine ecosystems

Notulae to the Italian flora of algae, bryophytes, fungi and lichens: 2

In this contribution, new data concerning red algae, lichens and bryophytes of the Italian flora are presented. It includes new records and confirmations for the algal genus Grateloupia, the bryophyte genus Didymodon, and the lichen genera Buellia, Cladonia, Letharia, Pertusaria, and Pyrenula

Marine phycotoxin levels in shellfish-14 years of data gathered along the Italian coast

Along the Italian coasts, toxins of algal origin in wild and cultivated shellfish have been reported since the 1970s. In this study, we used data gathered by the Veterinary Public Health Institutes (IZS) and the Italian Environmental Health Protection Agencies (ARPA) from 2006 to 2019 to investigate toxicity events along the Italian coasts and relate them to the distribution of potentially toxic species. Among the detected toxins (OA and analogs, YTXs, PTXs, STXs, DAs, AZAs), OA and YTX were those most frequently reported. Levels exceeding regulatory limits in the case of OA (≤2,448 μg equivalent kg-1) were associated with high abundances of Dinophysis spp., and in the case of YTXs (≤22 mg equivalent kg-1) with blooms of Gonyaulax spinifera, Lingulodinium polyedra, and Protoceratium reticulatum. Seasonal blooms of Pseudo-nitzschia spp. occur all along the Italian coast, but DA has only occasionally been detected in shellfish at concentrations always below the regulatory limit (≤18 mg kg-1). Alexandrium spp. were recorded in several areas, although STXs (≤13,782 μg equivalent kg-1) rarely and only in few sites exceeded the regulatory limit in shellfish. Azadinium spp. have been sporadically recorded, and AZAs have been sometimes detected but always in low concentrations (≤7 μg equivalent kg-1). Among the emerging toxins, PLTX-like toxins (≤971 μg kg-1 OVTX-a) have often been detected mainly in wild mussels and sea urchins from rocky shores due to the presence of Ostreopsis cf. ovata. Overall, Italian coastal waters harbour a high number of potentially toxic species, with a few HAB hotspots mainly related to DSP toxins. Nevertheless, rare cases of intoxications have occurred so far, reflecting the whole Mediterranean Sea conditions

Notulae to the Italian flora of algae, bryophytes, fungi and lichens: 7

In this contribution, new data concerning algae, bryophytes, fungi, and lichens of the Italian flora are presented. It includes new records and confirmations for the algae genus Chara, the bryophyte genera Cephalozia, Conardia, Conocephalum, Didymodon, Sphagnum, Tetraplodon, and Tortula, the fungal genera Endophyllum, Gymnosporangium, Microbotryum, Phragmidium, and Pluteus, and the lichen genera Candelariella, Cladonia, Flavoplaca, Lichenothelia, Peltigera, Placolecis, Rinodina, Scytinium, and Solenopsora

Notulae to the Italian flora of algae, bryophytes, fungi and lichens: 14

In this contribution, new data concerning bryophytes, fungi and lichens of the Italian flora are presented. It includes new records and confirmations for the algal genus Chara, for the bryophyte genera Bryum, Grimmia, Cephaloziella, Hypnum, Nogopterium, Physcomitrium, Polytrichastrum, Rhynchostegiella, Saelania, and Schistostega, the fungal genera Cortinarius, Lentinellus, Omphalina, and Xerophorus, and the lichen genera Acarospora, Agonimia, Candelariella, Cladonia, Graphis, Gyalolechia, Hypogymnia, Lichinella, Megalaria, Nephroma, Ochrolechia, Opegrapha, Peltigera, Placidium, Ramalina, Rhizoplaca, Ropalospora, Strangospora, Toniniopsis, Usnea, and Zahlbrucknerell

The toxic benthic dinoflagellates of the genus Ostreopsis in temperate areas: a review

The genus Ostreopsis includes species largely distributed from tropical to temperate marine areas worldwide. Among the nine species of the genus, O. siamensis, O. mascarenensis, O. lenticularis and O. cf. ovata can produce toxins of the palytoxin group. In the last decade Ostreopsis cf. ovata and O. cf. siamensis originated intense blooms in all the rocky Mediterranean Sea coastal areas, typically during summer-late summer. The correct identification of Ostreopsis species in field samples is often problematic as Ostreopsis species are morphologically plastic and hardly discriminable under light microscopy and, therefore, molecular analyses are required. Ostreopsis blooms are often associated with noxious effects on health of both humans and benthic marine organisms mainly carried by aerosol and direct contact with seawater. Environmental factors have been shown to affect toxin content of Ostreopsis which generally produces more toxins per cell when growing under suboptimal conditions. O. cf. ovata is able to produce both temporary and resting cysts. In particular, the resting cysts are able to germinate in laboratory conditions for as long as 5 months after their formation at 25°C, but not at 21°C; the presence of a temperature threshold affecting cyst germination in the laboratory suggests that temperature represents a key factor for Ostreopsis cf. ovata bloom onset in natural environments as well. Several studies conducted to assess the role of abiotic factors (mainly hydrodynamics, water temperature and nutrients) on the bloom dynamics, revealed that the synergic effects of hydrodynamics, temperature and N:P ratios would lead the Ostreopsis blooms in temperate areas. Ostreopsis abundances showed a significant decrease with depth, likely related to light availability, although there are conflicting data about the relationship between light intensity and Ostreopsis growth in experimental conditions. The relationship between Ostreopsis blooms and salinity is not completely clear, complicated by the influence of high nutrient levels often associated to low salinity waters. Finally, Ostreopsis colonize a variety of substrata, although living substrata seems to allow lower concentration of epibionts than any other substrate, probably due to the production of some allelopathic compounds.</p

Ecology of &lt;I&gt;Ostreopsis&lt;/I&gt; cf. &lt;I&gt;ovata&lt;/I&gt; blooms in the northwestern Adriatic Sea

The ecology of Ostreopsis cf. ovata blooms was investigated to evaluate the role of environmental factors (temperature, hydrodynamism, nutrient concentrations, depth and substratum) on the bloom dynamics. This paper reports the present knowledge on O. cf. ovata blooms along the Conero Riviera (NW Adriatic Sea), on the basis of samplings carried out from 2006 to 2010. The annual maximum of benthic cell abundance was always observed in late-summer, reaching the order of magnitude of 106 cells g-1 fw (corresponding to 107 cells g-1 dw and 104 cells cm-2) on macrophyte samples. Comparing the mean abundances settled on seaweeds with those growing on hard substrata, significantly higher abundances were observed on the latter. Hydrodynamism plays a major role in Ostreopsis blooms, as significantly higher abundances were observed in sheltered sites compared with exposed ones. The abundances of O. cf. ovata showed a marked decrease with depth. Temperature and nutrients do not seem to play an important effect on the O. cf. ovata blooms. High levels of ovatoxins were recorded in natural samples; episodes of death of both benthic invertebrates (limpets, sea urchins and mussels) and macroalgae were commonly observed during O. cf. ovata blooms.</p