The Occurrence of Karenia species in mid-Atlantic coastal waters: Data from the Delmarva Peninsula, USA.

A bloom of Karenia papilionacea that occurred along the Delaware coast in late summer of 2007 was the first Karenia bloom reported on the Delmarva Peninsula (Delaware, Maryland, and Virginia, USA). Limited spatial and temporal monitoring conducted by state agencies and citizen science groups since 2007 have documented that several Karenia species are an annual component of the coastal phytoplankton community along the Delmarva Peninsula, often present at background to low concentrations (100 to 10,000 cells L-1). Blooms of Karenia (> 105 cells L-1) occurred in 2010, 2016, 2018, and 2019 in different areas along the Delmarva Peninsula coast. In late summer and early autumn of 2017, the lower Chesapeake Bay experienced a K. papilionacea bloom, the first recorded in Bay waters. Blooms typically occurred summer into autumn but were not monospecific; rather, they were dominated by either K. mikimotoi or K. papilionacea, with K. selliformis, K. brevis-like cells, and an undescribed Karenia species also present. Cell concentrations during these mid-Atlantic Karenia spp. blooms equalled concentrations reported for other Karenia blooms. However, the negative impacts to environmental and human health often associated with Karenia red tides were not observed. The data compiled here report on the presence of multiple Karenia species in coastal waters of the Delmarva Peninsula detected through routine monitoring and opportunistic sampling conducted between 2007 and 2022, as well as findings from research cruises undertaken in 2018 and 2019. These data should be used as a baseline for future phytoplankton community analyses supporting coastal HAB monitoring programs.

A survey of Dinophysis spp. and their potential to cause diarrhetic shellfish poisoning in coastal waters of the United States.

Multiple species of the genus Dinophysis produce diarrhetic shellfish toxins (okadaic acid and Dinophysis toxins, OA/DTXs analogs) and/or pectenotoxins (PTXs). Only since 2008 have DSP events (illnesses and/or shellfish harvesting closures) become recognized as a threat to human health in the United States. This study characterized 20 strains representing five species of Dinophysis spp. isolated from three US coastal regions that have experienced DSP events: the Northeast/Mid-Atlantic, the Gulf of Mexico, and the Pacific Northwest. Using a combination of morphometric and DNA-based evidence, seven Northeast/Mid-Atlantic isolates and four Pacific Northwest isolates were classified as D. acuminata, a total of four isolates from two coasts were classified as D. norvegica, two isolates from the Pacific Northwest coast were identified as D. fortii, and three isolates from the Gulf of Mexico were identified as D. ovum and D. caudata. Toxin profiles of D. acuminata and D. norvegica varied by their geographical origin within the United States. Cross-regional comparison of toxin profiles was not possible with the other three species; however, within each region, distinct species-conserved profiles for isolates of D. fortii, D. ovum, and D. caudata were observed. Historical and recent data from various State and Tribal monitoring programs were compiled and compared, including maximum recorded cell abundances of Dinophysis spp., maximum concentrations of OA/DTXs recorded in commercial shellfish species, and durations of harvesting closures, to provide perspective regarding potential for DSP impacts to regional public health and shellfish industry.

Interactions of E. coli with algae and aquatic vegetation in natural waters.

Both algae and bacteria are essential inhabitants of surface waters. Their presence is of ecological significance and sometimes of public health concern triggering various control actions. Interactions of microalgae, macroalgae, submerged aquatic vegetation, and bacteria appear to be important phenomena necessitating a deeper understanding by those involved in research and management of microbial water quality. Given the long-standing reliance on Escherichia coli as an indicator of the potential presence of pathogens in natural waters, understanding its biology in aquatic systems is necessary. The major effects of algae and aquatic vegetation on E. coli growth and survival, including changes in the nutrient supply, modification of water properties and constituents, impact on sunlight radiation penetration, survival as related to substrate attachment, algal mediation of secondary habitats, and survival inhibition due to the release of toxic substances and antibiotics, are discussed in this review. An examination of horizontal gene transfer and antibiotic resistance potential, strain-specific interactions, effects on the microbial, microalgae, and grazer community structure, and hydrodynamic controls is given. Outlooks due to existing and expected consequences of climate change and advances in observation technologies via high-resolution satellite imaging, unmanned aerial vehicles (drones), and mathematical modeling are additionally covered. The multiplicity of interactions among bacteria, algae, and aquatic vegetation as well as multifaceted impacts of these interactions, create a wide spectrum of research opportunities and technology developments.

Morphological and phylogenetic data do not support the split of Alexandrium into four genera.

A recently published study analyzed the phylogenetic relationship between the genera Centrodinium and Alexandrium, confirming an earlier publication showing the genus Alexandrium as paraphyletic. This most recent manuscript retained the genus Alexandrium, introduced a new genus Episemicolon, resurrected two genera, Gessnerium and Protogonyaulax, and stated that: "The polyphyly [sic] of Alexandrium is solved with the split into four genera". However, these reintroduced taxa were not based on monophyletic groups. Therefore this work, if accepted, would result in replacing a single paraphyletic taxon with several non-monophyletic ones. The morphological data presented for genus characterization also do not convincingly support taxa delimitations. The combination of weak molecular phylogenetics and the lack of diagnostic traits (i.e., autapomorphies) render the applicability of the concept of limited use. The proposal to split the genus Alexandrium on the basis of our current knowledge is rejected herein. The aim here is not to present an alternative analysis and revision, but to maintain Alexandrium. A better constructed and more phylogenetically accurate revision can and should wait until more complete evidence becomes available and there is a strong reason to revise the genus Alexandrium. The reasons are explained in detail by a review of the available molecular and morphological data for species of the genera Alexandrium and Centrodinium. In addition, cyst morphology and chemotaxonomy are discussed, and the need for integrative taxonomy is highlighted.

Characterization of Dinophysis spp. (Dinophyceae, Dinophysiales) from the mid-Atlantic region of the United States1.

Due to the increasing prevalence of Dinophysis spp. and their toxins on every US coast in recent years, the need to identify and monitor for problematic Dinophysis populations has become apparent. Here, we present morphological analyses, using light and scanning electron microscopy, and rDNA sequence analysis, using a ~2-kb sequence of ribosomal ITS1, 5.8S, ITS2, and LSU DNA, of Dinophysis collected in mid-Atlantic estuarine and coastal waters from Virginia to New Jersey to better characterize local populations. In addition, we analyzed for diarrhetic shellfish poisoning (DSP) toxins in water and shellfish samples collected during blooms using liquid-chromatography tandem mass spectrometry and an in vitro protein phosphatase inhibition assay and compared this data to a toxin profile generated from a mid-Atlantic Dinophysis culture. Three distinct morphospecies were documented in mid-Atlantic surface waters: D. acuminata, D. norvegica, and a "small Dinophysis sp." that was morphologically distinct based on multivariate analysis of morphometric data but was genetically consistent with D. acuminata. While mid-Atlantic D. acuminata could not be distinguished from the other species in the D. acuminata-complex (D. ovum from the Gulf of Mexico and D. sacculus from the western Mediterranean Sea) using the molecular markers chosen, it could be distinguished based on morphometrics. Okadaic acid, dinophysistoxin 1, and pectenotoxin 2 were found in filtered water and shellfish samples during Dinophysis blooms in the mid-Atlantic region, as well as in a locally isolated D. acuminata culture. However, DSP toxins exceeded regulatory guidance concentrations only a few times during the study period and only in noncommercial shellfish samples.

Identification, growth and toxicity assessment of Coolia Meunier (Dinophyceae) from Nova Scotia, Canada.

Benthic dinoflagellates of the toxigenic genus Coolia Meunier (Dinophyceae) are known to have a global distribution in both tropical and temperate waters. The type species, C. monotis, has been reported from the Mediterranean Sea, the NE Atlantic and from Rhode Island, USA in the NW Atlantic, whereas other species in the genus have been reported from tropical locations. Coolia cells were observed in algal drift samples collected at seven sites in Nova Scotia, Canada. Clonal isolates were established from four of these locations and identified with light and scanning electron microscopy, then confirmed with genetic sequencing to be C. monotis. This is the first record of this species in Nova Scotia. The isolates were established and incubated at 18 °C under a 14:10 L:D photoperiod with an approximate photon flux density of 50-60 µmol m-2 s-1. Growth experiments using an isolate from Johnston Harbour (CMJH) were carried out at temperatures ranging from 5 to 30 °C under the same photoperiod with an approximate photon flux density of 45-50 µmol m-2 s-1. Cells tolerated temperatures from 5 to 25 °C with optimum growth and mucilage aggregate production between 15 and 20 °C. Methanol extracts of this isolate examined by Liquid Chromatography-Mass Spectrometry (LC-MS) did not show the presence of the previously reported cooliatoxin. Toxic effects were assayed using two zebrafish bioassays, the Fish Embryo Toxicity (FET) assay and the General Behaviour and Toxicity (GBT) assay. The results of this study demonstrate a lack of toxicity in C. monotis from Nova Scotia, as has been reported for other genetically-confirmed isolates of this species. Conditions in which cell growth that could potentially degrade water quality and provide substrate and dispersal mechanisms for other harmful microorganisms via mucilage production are indicated.

Osmotic stress does not trigger brevetoxin production in the dinoflagellate Karenia brevis.

With the global proliferation of toxic harmful algal bloom species, there is a need to identify the environmental and biological factors that regulate toxin production. One such species, Karenia brevis, forms nearly annual blooms that threaten coastal regions throughout the Gulf of Mexico. This dinoflagellate produces brevetoxins, which are potent neurotoxins that cause neurotoxic shellfish poisoning and respiratory illness in humans, as well as massive fish kills. A recent publication reported that a rapid decrease in salinity increased cellular toxin quotas in K. brevis and hypothesized that brevetoxins serve a role in osmoregulation. This finding implied that salinity shifts could significantly alter the toxic effects of blooms. We repeated the original experiments separately in three different laboratories and found no evidence for increased brevetoxin production in response to low-salinity stress in any of the eight K. brevis strains we tested, including three used in the original study. Thus, we find no support for an osmoregulatory function of brevetoxins. The original publication also stated that there was no known cellular function for brevetoxins. However, there is increasing evidence that brevetoxins promote survival of the dinoflagellates by deterring grazing by zooplankton. Whether they have other as-yet-unidentified cellular functions is currently unknown.

Harmful algal bloom species and phosphate-processing effluent: field and laboratory studies.

In 2002, the Florida Department of Environmental Protection began discharging phosphate-processing effluent into Bishop Harbor, an estuary within Tampa Bay. Because of concerns that the effluent would serve as a nutrient source for blooms of the toxic dinoflagellate Karenia brevis, a field monitoring program was established and laboratory bioassays were conducted. Several harmful algal bloom (HAB) species, including Prorocentrum minimum and Heterosigma akashiwo, were observed in bloom concentrations adjacent to the effluent discharge site. Blooms of diatoms were widespread throughout Bishop Harbor. K. brevis was observed with cell concentrations decreasing with increasing proximity to the effluent discharge site. Bioassays using effluent as a nutrient source for K. brevis resulted in decreased cell yields, increased growth rates, and increased time to log-phase growth. The responses of HAB species within Bishop Harbor and of K. brevis to effluent in bioassays suggested that HAB species differ in their response to phosphate-processing effluent.

Brevetoxins, like ciguatoxins, are potent ichthyotoxic neurotoxins that accumulate in fish.

Brevetoxins and ciguatoxins are closely related potent marine neurotoxins. Although ciguatoxins accumulate in fish to levels that are dangerous for human consumption, live fish have not been considered as potential sources of brevetoxin exposure in humans. Here we show that, analogous to ciguatoxins, brevetoxins can accumulate in live fish by dietary transfer. We experimentally identify two pathways leading to brevetoxin-contaminated omnivorous and planktivorous fish. Fish fed with toxic shellfish and Karenia brevis cultures remained healthy and accumulated high brevetoxin levels in their tissues (up to 2675 ng g(-1) in viscera and 1540 ng g(-1) in muscle). Repeated collections of fish from St. Joseph Bay in the Florida panhandle reveal that accumulation of brevetoxins in healthy fish occurs in the wild. We observed that levels of brevetoxins in the muscle of fish at all trophic levels rise significantly, but not to dangerous levels, during a K. brevis bloom. Concentrations were highest in fish liver and stomach contents, and increased during and immediately following the bloom. The persistence of brevetoxins in the fish food web was followed for 1 year after the K. brevis bloom.

Saxitoxin puffer fish poisoning in the United States, with the first report of Pyrodinium bahamense as the putative toxin source.

BACKGROUND: From January 2002 to May 2004, 28 puffer fish poisoning (PFP) cases in Florida, New Jersey, Virginia, and New York were linked to the Indian River Lagoon (IRL) in Florida. Saxitoxins (STXs) of unknown source were first identified in fillet remnants from a New Jersey PFP case in 2002. METHODS: We used the standard mouse bioassay (MBA), receptor binding assay (RBA), mouse neuroblastoma cytotoxicity assay (MNCA), Ridascreen ELISA, MIST Alert assay, HPLC, and liquid chromatography-mass spectrometry (LC-MS) to determine the presence of STX, decarbamoyl STX (dc-STX), and N-sulfocarbamoyl (B1) toxin in puffer fish tissues, clonal cultures, and natural bloom samples of Pyrodinium bahamense from the IRL. RESULTS: We found STXs in 516 IRL southern (Sphoeroides nephelus), checkered (Sphoeroides testudineus), and bandtail (Sphoeroides spengleri) puffer fish. During 36 months of monitoring, we detected STXs in skin, muscle, and viscera, with concentrations up to 22,104 microg STX equivalents (eq)/100 g tissue (action level, 80 microg STX eq/100 g tissue) in ovaries. Puffer fish tissues, clonal cultures, and natural bloom samples of P. bahamense from the IRL tested toxic in the MBA, RBA, MNCA, Ridascreen ELISA, and MIST Alert assay and positive for STX, dc-STX, and B1 toxin by HPLC and LC-MS. Skin mucus of IRL southern puffer fish captive for 1-year was highly toxic compared to Florida Gulf coast puffer fish. Therefore, we confirm puffer fish to be a hazardous reservoir of STXs in Florida's marine waters and implicate the dinoflagellate P. bahamense as the putative toxin source. CONCLUSIONS: Associated with fatal paralytic shellfish poisoning (PSP) in the Pacific but not known to be toxic in the western Atlantic, P. bahamense is an emerging public health threat. We propose characterizing this food poisoning syndrome as saxitoxin puffer fish poisoning (SPFP) to distinguish it from PFP, which is traditionally associated with tetrodotoxin, and from PSP caused by STXs in shellfish.