In vitro experiments were performed with Gymnodinium catenatum Graham strains isolated from three locations in the Gulf of California to determine the variability in toxicity and toxin profiles. Strains were cultivated in GSe at 201 C AE 11 C, 150 lmol photons . m À 2 . s À 1 (12:12 light:dark cycle), and harvested during different growth phases. Growth rates were higher than in previous studies, varying between 0.70 and 0.82 day À 1 . The highest cell yields were reached at 16 and 19 days, with maximum densities between 1090 and 3393 cells . mL À 1 . Bahía de La Paz (BAPAZ) and Bahía de Mazatlán (BAMAZ) were the most toxic (101 pg STXeq . cell À 1 ), whereas strains from Bahía Concepción (BACO) were the least toxic (13 pg STXeq . cell À 1 ). A strain isolated from cyst germination was one of the least toxic strains. No significant changes in toxin content with culture age were observed (0.2 and 0.6 pmol paralytic shellfish poisoning . cell À 1 ). All strains contained neosaxitoxin (NEOSTX), decarbamoyl-saxitoxin (dcSTX), decarbamoyl-gonyautoxin-2,-3, (dcGTX2-3), N-sulfocarbamoylsaxitoxin (B1), N-sulfo-carbamoylneosaxitoxin (B2), and N-sulfo-carbamoylgonyautoxin-2,-3 (C1-2). Bahía Concepción strains had the highest content of C1; BAPAZ and BAMAZ strains had a higher percentage of NEOSTX. Differences in toxin composition with culture age were observed only in BAMAZ and BAPAZ strains. Cultures with a higher percentage of long chains had more NEOSTX, while those with a higher proportion of short chains had a lower content of NE-OSTX. Gulf of California strains are characterized by a high proportion of NEOSTX, and seem to have evolved particular physiological responses to their environment that are reflected in the toxin profile, suggesting different populations.

No abstract

No abstract

No abstract

No abstract

Abstract:We examined the environmental and biological factors related to blooms of the toxic dinoflagellate Pyrodinium bahamense in three shallow, restricted subtropical lagoons in the Gulf of California during the rainy summer. In the San Jos é , Yavaros, and El Colorado lagoons, the vegetative stage peaked at 63, 108, and 151 ( × 10 3 cells l -1), respectively. At San Jos é , production of cysts peaked at 9.7 × 10 3 g -1 of dry sediment mass as the bloom declined. Large diatoms predominated, with P. bahamense the most common dinoflagellate during the blooms. Abundance of P . bahamense at San Jos é was positively correlated with salinity (r = 0.50, p = 0.0003), seawater temperature (r = 0.44, p = 0.005), silicates (r = 0.45, p = 0.003), and ammonium (r = 0.32, p = 0.005), and negatively correlated with dissolved oxygen (r = -0.34, p < 0.0001). No such correlations were found at El Colorado and Yavaros. The environmental window that favors development of blooms is restricted to the summer and is influenced by seawater temperature, salinity, and relative concentrations of ammonium and phosphates that, in turn, depend on rainfall and runoff, which is greater on the eastern side of the Gulf where seawater quality is degraded.

No abstract

The dinoflagellate Cochlodinium polykrikoides isolated from Bahía de La Paz, Gulf of California, showed an important short-term toxic effect on the spotted rose snapper Lutjanus guttatus. This microalga was able to decrease fish liver catalase activity and lipid peroxidation. Fish exposed to live dinoflagellates developed an abnormal mucus secretion on the gills that was directly related to algal cell concentration. Hepatic catalase inhibition and an increase in mucus secretion on the gills occurred when fish were exposed to 2 x 10(6) cells L(-1) of C. polykrikoides. Lipid peroxidation was significantly different at 4 x 10(6) cells L(-1) and the hepatosomatic index decreased at 3 x 10(6) cells L(-1). Our results suggest that oxidative stress contributes, at least in part, to the ichthyotoxic effect of C. polykrikoides from the Gulf of California.