Large blooms of the dinoflagellate Karenia brevis cause annual harmful algal bloom events, or "red tides" on Florida's Gulf Coast. Each year, the Clinic for the Rehabilitation of Wildlife (CROW) is presented with hundreds of cases of aquatic birds that exhibit neurologic clinical signs due to brevetoxicosis. Double-crested cormorants (Phalacrocorax auratus) are the most common species seen, and typically present with a combination of ataxia, head tremors, knuckling, and/or lagophthalmos. Blood lactate levels are known to increase in mammals for a variety of reasons, including stress, hypoxia, sepsis, and trauma, but there is limited literature on blood lactate values in avian species. The objective of this study was to determine the prognostic value of blood lactate concentration on successful rehabilitation and release of birds presenting with clinical signs consistent with brevetoxicosis. Blood lactate levels were collected on intake, the morning after presentation and initial therapy, and prior to disposition (release or euthanasia) from 194 birds (including 98 cormorants) representing 17 species during the 2020-2021 red tide season. Overall, mean blood lactate at intake, the morning after intake, and predisposition was 2.9, 2.8, and 3.2 mmol/L, respectively, for released birds across all species (2.9, 2.9, and 3.2 mmol/L for released cormorants); 3.4, 3.4, and 6.5 mmol/L for birds that died (4.0, 3.5, and 7.9 mmol/L for cormorants that died); and 3.1, 3.5, and 4.7 mmol/L for birds that were euthanized (3.5, 4.7, and 4.9 mmol/L for cormorants that were euthanized). On average, birds that died or were euthanized had an elevated lactate at all time points as compared to those that were released, but these results were not statistically significant (P = 0.13). These results indicate that blood lactate levels do not appear to be useful as a prognostic indicator for successful release of birds, including double-crested cormorants, affected by brevetoxicosis.

Beginning in April 2002, three species of Florida puffer fish from around the state of Florida, USA were monitored for the presence of saxitoxin (STX). In total, 873 southern (Sphoeroides nephelus), 171 checkered (S. testudineus), and 53 bandtail (S. spengleri) puffer fish were collected between 2002 and 2006 from eight regions: Jacksonville, the Indian River Lagoon, Tequesta, the Florida Keys, Charlotte Harbor, Tampa Bay, Cedar Key, and Apalachicola. Emphasis was placed on collecting specimens from the Indian River Lagoon (IRL), where recreational harvesting of puffer fish led to 28 cases of saxitoxin puffer fish poisoning (SPFP) between January 2002 and May 2004. Southern puffer fish from the northern IRL routinely contained the highest concentrations of STX, with average levels in the skin of 1787μg STXequiv./100g tissue. Elevated concentrations were also found in the muscle (1102μg STXequiv./100g), gut contents (539μg STXequiv./100g), gonads (654μg STXequiv./100g), and liver (214μg STXequiv./100g). Lower, yet significant (above the action limit of 80μg STXequiv./100g tissue), concentrations of STX were also detected in the skin (599μg STXequiv./100g), muscle (233μg STXequiv./100g), gut contents (197μg STXequiv./100g), and gonads (239μg STXequiv./100g) of southern puffer fish from Tequesta in the southern IRL, as well as in the gonads (122μg STXequiv./100g) of Jacksonville southern puffer fish and the skin (265μg STXequiv./100g) of Tampa Bay southern puffer fish. STX concentrations above the action limit were also found in the skin of bandtail puffer fish from the IRL (620μg STXequiv./100g), Tequesta (374μg STXequiv./100g), and the Florida Keys (230μg STXequiv./100g). Checkered puffer fish collected from the IRL, Tequesta, and the Florida Keys on average were nontoxic, containing STX levels below the action limit in all tissues.

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 ngg(-1) in viscera and 1540 ngg(-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 I year after the K brevis bloom. (c) 2007 Published by Elsevier Ltd.

High-performance liquid chromatography (HPLC) with post-column derivatisation and fluorescence detection has been commonly used for analysing paralytic shellfish poisoning (PSP) toxins. However, identifying peaks with confidence requires that steps be taken beyond simple chromatographic runs, owing in part to the abundance of substances in natural samples that have intrinsic fluorescence and may co-elute with toxins. The aim of this study was to assess HPLC toxin detection in samples collected from two puffer fish poisoning (PFP) events. Since 2002, PSP toxins have been detected in southern puffer fish Sphoeroides nephelus from the Titusville region of Florida. Despite a current harvesting ban on southern puffer fish in this area, PFP reports continue. Unconsumed puffer fish from two human poisoning events in 2004 were analysed by HPLC for PSP toxins. Saxitoxin was the dominant congener in unconsumed puffers. Decarbamoyl saxitoxin and B1 were also detected. These toxins were confirmed through a series of HPLC steps and subsequently by other methods. This work serves as an example of procedures necessary for HPLC toxin detection, provides a comparison of HPLC with other detection methods, and demonstrates the continued threat of PSP toxicity associated with puffer fish from the Titusville area of Florida.

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 handrail (Sphoeroides spengleri) puffer fish. During 36 months of monitoring, we detected STXs in skin, muscle, and viscera, with concentrations up to 22,104 jig STX equivalents (eq)/100 g tissue (action level, 80 mu g STX eq/100 g tissue) in ovaries. Puffer fish tissues, clonal cultures, and natural bloom samples of A bahmense 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. bahmense 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.

Unexpected brevetoxin vectors may account for deaths long after or remote from an algal bloom.