Fitoplancton del Golfo de Cariaco, estado Sucre, Venezuela

Phytoplankton was sampled monthly during the lune 1995-May 1996 period, at 16 stations 01' the castern Gulf ol' Cariaco. This arca reccives different wastes. Only chlorophyll and diatoms, dinoflagellates, and total density 01' phytoplankton varied by depth. Only salinity and oxygen showcd horizontal spatial differcl1tiation. Phytoplunkton maxima in November- December, were related with low nitrogenous nutrients and tcmperature, high phosphate, chlorophyl1, and dissolved oxygen. The June-October pelÍod was characterized by high temperature, low oxygen, nutrient conccntrations and phytoplankton abundancc. Overall, phytoplankton aOllndanccswerc low. Diatoms dominated during the sampling period, but microt1agellates and dinot1agel1ates liió occasionally. Phytoplankton density was positively cOlTelated with phosphate and ncgatively wilh nitrogen. In spile 01' the high nlllrient suppJy, phytoplankton growth was limited by a redllced ligh! penetratiol1 relaled to concentrations 01' suspended paIticles

Fitoplancton del Golfo de Cariaco, estado Sucre, Venezuela

Phytoplankton was sampled monthly during the lune 1995-May 1996 period, at 16 stations 01' the castern Gulf ol' Cariaco. This arca reccives different wastes. Only chlorophyll and diatoms, dinoflagellates, and total density 01' phytoplankton varied by depth. Only salinity and oxygen showcd horizontal spatial differcl1tiation. Phytoplunkton maxima in November- December, were related with low nitrogenous nutrients and tcmperature, high phosphate, chlorophyl1, and dissolved oxygen. The June-October pelÍod was characterized by high temperature, low oxygen, nutrient conccntrations and phytoplankton abundancc. Overall, phytoplankton aOllndanccswerc low. Diatoms dominated during the sampling period, but microt1agellates and dinot1agel1ates liió occasionally. Phytoplankton density was positively cOlTelated with phosphate and ncgatively wilh nitrogen. In spile 01' the high nlllrient suppJy, phytoplankton growth was limited by a redllced ligh! penetratiol1 relaled to concentrations 01' suspended paIticles

NOTA TÉCNICA - Determination of saxitoxin and its derivatives in mollusk bivalves: Evaluation and optimization of the high performance liquid chromatographic use with fluorescence detection and prior oxidation (Determinación de saxitoxina y sus derivados en moluscos bivalvos: Evaluación y optimización del uso de cromatografía líquida de alta resolución con previa oxidación)

Saxitoxin and its derivatives are potent neurotoxins associated with paralytic shellfish poisoning (PSP) in humans which are primarily produced by dinoflagellates. To evaluate and optimize the use of high performance liquid chromatography (HPLC) with previous oxidation in order to determine saxitoxin and its derivatives, samples of the green mussel (Perna viridis   ) and oysters (Crassostrea   sp) were collected at six locations in Venezuela and at four in Trinidad, the latter along the west coast line, in June 2000. The samples were extracted using the AOAC bioassay mouse procedure. Each extract was oxidized using periodic acid and the oxidation product was injected to the chromatographic column. The method used to HPLC in this work was a modification of Lawrence et al. (1996). The separation of important pairs of toxins (STX/NEO, GTX1,4/GTX2,3) were achieved, but the resolution and height of the peaks of oxidation products of these toxins varied depending on column efficiencies. Some samples had presence of PSP below permissible levels, which was confirmed by using bioassay mouse method. The results showed that the reaction precolumn method gives prompt information about profile of the toxins, which is independent of matrix of receptor organism, and it is a simple method for monitoring PSP in shellfish in the Caribbean

Paralytic Shellfish Poisoning (PSP) in Margarita Island, Venezuela

A severe outbreak of Paralytic Shellfish Poisoning (PSP) occurred in Manzanillo and Guayacán, northwestern coast of Margarita Island, Venezuela, between August and October 1991. A bloom of dinoflagellates including Prorocentrum gracile, Gymnodinium catenatum and Alexandrium tamarense seemed to be responsible for this outbreak. Levels of PSP toxins in mussels (Perna perna) exceeded the international safety limit of saxitoxin, 80 µg STX/100 g meat. PSP toxin values varied between 2 548 and 115 µg STX/100 g meat in Manzanillo, and between 1 422 and 86 µg STX/100 g meat in Guayacán. At both locations, the highest levels were detected in August, when 24 patients exhibited typical symptoms of PSP toxicity after consuming cooked mussels (16 required hospitalization). A high pressure liquid chromatographic (HPLC) procedure was recently used on the 1991 samples. The major toxin detected in samples of both locations was decarbamoyl saxitoxin (dcSTX), but low concentrations of saxitoxin were also found in Manzanillo samples. Gonyautoxins GTX1, GTX2 and GTX3 were detected only at Guayacán, while in both locations, decarbamoylgonyatouxin (dcGTX2,3) toxins were detected. These findings represent the first time that causative toxins of PSP in Venezuela have been chemically identified, and confirm the presence of dcSTX and dcGTX in mussels from the Caribbean Sea. The presence of dcSTX and dcGTX in shellfish is indicative that Gymnodinium catenatum was a causative organism for outbreak of PSP<br>Un severo brote de intoxicación paralizante por moluscos (PSP en inglés) ocurrió en Manzanillo y Guayacán en la costa noroeste de la Isla de Margarita, Venezuela entre agosto y octubre de 1991. Una proliferación de Prorocentrum gracile, Gymnodinium catenatum y Alexandrium tamarense causó el brote. Los niveles de PSP en mejillón (Perna perna) superaron los niveles máximos permisibles de saxitoxina, 80 µg STX/100g carne. Los niveles de toxinas variaron entre 2 548 y 115 µg STX/100 g carne en Manzanillo y entre 1 422 y 86 µg STX/100g carne en Guayacán. En ambas localidades, los máximos niveles se detectaron en agosto, cuando 24 personas presentaron síntomas típicos de PSP después de consumir mejillones cocidos (16 fueron hospitalizados). Se aplicó recientemente cromatografía líquida de alta presión (HPLC) a muestras del año 1991 y la toxina más detectada fue decarbamoyl saxitoxina (dcSTX), pero también se encontró saxitoxinas en muestras de Manzanillo. Las gonyautoxinas GTX1, GTX2 y GTX3 solo se encontraron en Guayacán; en ambas localidades se detectó decarbamoylgonyatouxin (dcGTX2,3). Estos hallazgos representan la primera vez que las toxinas causantes de un brote de PSP en Venezuela han sido químicamente identificadas, confirmando la presencia de dcSTX y dcGTX en mejillones del mar Caribe. La presencia de dcSTX y dcGTX en moluscos, indica que G. catenatum fue el organismo responsable de la intoxicació

Fitoplancton del Golfo de Cariaco, estado Sucre, Venezuela

Phytoplankton was sampled monthly during the lune 1995-May 1996 period, at 16 stations 01' the castern Gulf ol' Cariaco. This arca reccives different wastes. Only chlorophyll and diatoms, dinoflagellates, and total density 01' phytoplankton varied by depth. Only salinity and oxygen showcd horizontal spatial differcl1tiation. Phytoplunkton maxima in November- December, were related with low nitrogenous nutrients and tcmperature, high phosphate, chlorophyl1, and dissolved oxygen. The June-October pelÍod was characterized by high temperature, low oxygen, nutrient conccntrations and phytoplankton abundancc. Overall, phytoplankton aOllndanccswerc low. Diatoms dominated during the sampling period, but microt1agellates and dinot1agel1ates liió occasionally. Phytoplankton density was positively cOlTelated with phosphate and ncgatively wilh nitrogen. In spile 01' the high nlllrient suppJy, phytoplankton growth was limited by a redllced ligh! penetratiol1 relaled to concentrations 01' suspended paIticles

Paralytic shellfish poisoning toxins in green mussels (Perna viridis) from the Gulf of Paria, Trinidad

Paralytic shellfish poisoning (PSP) toxins were determined in green mussels (Perna viridis) collected from one collection site in the Gulf of Paria in Trinidad in 1999 and 2000. Aqueous extracts of PSP were purified by passage through C-18 SPE cartridges, oxidized with peroxide and periodate, respectively, then analyzed by HPLC with fluorescence detection. This procedure provided rapid and highly sensitive screening of samples for PSP toxins. Further purification of PSP-containing extracts using COOH SPE cartridges resulted in the separation and identification of individual PSP toxins. The method of analysis was validated by spike and recovery experiments, with 85–103% recoveries of mixed toxins. PSP toxins determined in our samples in both years were GTX2,3, dcGTX2,3, STX, and dcSTX, while GTX1,4 and NeoSTX were only identified in 1999 and 2000, respectively. In 1999, GTX1,4, GTX2,3 and dcGTX2,3 predominated, as compared to NeoSTX, GTX2,3 and dcGTX2,3 in 2000. However, mussel samples in 2000 contained higher total concentrations of detected PSP toxins than those of 1999. These results represent the first identification of specific PSP toxins in local shellfish and provide a basis for effective monitoring and control of these toxins in Trinidad.Versión del editor2,924

Paralytic shellfish poisoning toxin profiles in green mussels from Trinidad and Venezuela

Paralytic shellfish poisoning (PSP) toxins were determined in green mussels (Perna viridis) from the Gulf of Paria between Trinidad and Venezuela, as well as from the northern coast of Venezuela. Aqueous extracts of samples were purified by passage through SPE C-18 and carboxylic columns, and oxidized by periodate and peroxide reagents, before analysis by LC with fluorescence detection. Spike and recovery of mixed toxins from uncontaminated mussel tissues, with % recoveries from 83 to 103, validated the method of analysis. Saxitoxin (STX), gonyautoxins (GTX), their analogs, and C toxins were identified in mussels from both countries. In the Gulf of Paria, PSP toxin profiles in mussels from the north were similar to each other, as were those from the south. However, the toxin profiles and concentrations varied widely among geographic areas, with GTX analogs and C1,2 toxins predominating. The highest total PSP concentrations (468 μg/100 g), as well as the largest number of individual toxins identified (7 of 8), were found at Playa Patilla on the northern coast of Venezuela, followed by Chaguaramas (244 μg/100 g; 6 of 8) and Güiria (154 μg/100 g; 5 of 8) in the northern Gulf of Paria in Trinidad. While the calculated STX equivalents in each sample were below the maximum permissible level (80 μg/100 g) permitted by Venezuela and other countries, its very detection prohibits their consumption in Trinidad under existing legislation.Versión del edito