Effects on the oyster Crassostrea virginica caused by exposure to the toxic diatom Nitzschia pungens f. multiseries


1993 2003 May 31


Roelke DL
Fryxell GA
Cifuentes LA

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Domoic acid (DA) is produced by some diatom species and has become a problem to the shellfish industry. Nitzschia pungens f. multiseries a known DA producer, has been discovered in Galveston Bay, Texas. The region produces a large part of the total national oyster harvest. The threat of contamination or mortality to the oyster fishery due to N. pungens f. multiseries was investigated by performing feeding experiments with Crassostrea virginica using clonal cultures of the diatom. Emphasis was placed on oyster feeding behavior, tissue toxicity, and depuration. C. virginica readily fed on cell concentrations greater than natural blooms. The percentage of cells filtered from the seawater was consistently around 80%. The filtration rate ranged from 0.01 to 2.02 liters/hr. These variables along with oyster openness were not effected by the cell concentration, cell toxicity, or total toxicity of N. pungens f. multiseries. There were no detrimental effects observed to C. virginica. Whole body analyzes showed DA accumulation ranging between 1 and 2 mu g -g. The 'gut' had five times the toxicity of the adductor muscle and the gills/mantle -labial pulps tissue fractions. Approximately 70% of the total DA in the oyster resided in the 'gut.' Oysters showed no correlation between whole body toxicity and whole body weight. Whole body depuration of DA from C. virginica was slow over a 72 hour period (14%). Domoic acid outbreaks may not be confined to the coasts of North America. Two persons in the USA exhibited signs of ASP after eating smoked Korean oysters. Monitoring of several brands of this product was conducted, and domoic acid was not detected




ASW,USA,Texas,Galveston Bay, Behavior, Biological poisons, Contamination, Crassostrea, Crassostrea virginica, domoic acid, feeding behavior, Filtration, Fisheries, Galveston Bay, Monitoring, Mortality, Neurotoxins, Nitzschia pungens multiseries, North America, oyster fisheries, Oysters, pathology, Q1 01221 General, Q1 01261 General, Q1 01483 Species interactions: general, Q1 01627 Food quality and standards, Q5 01524 Public health,medicines,dangerous organisms, Shellfish, Texas, Toxicity, Toxicology, USA