Shellfish Flesh Research Articles

Development of a bioassay employing the desert locust ( Schistocerca gregaria) for the detection of saxitoxin and related compounds in cyanobacteria and shellfish

J. McElhiney, L. A. Lawton, C. Edwards and S. Gallacher. Development of a bioassay employing the desert locust ( Schistocerca gregaria) for the detection of saxitoxin and related compounds in cyanobacteria and shellfish. Toxicon 35, 417–420, 1998.—Monitoring paralytic shellfish toxins (PST) in shellfish and freshwater cyanobacteria is largely dependent on the mouse bioassay. An alternative assay was devised using the desert locust Schistocerca gregaria. The bioassay successfully identified the optimum extraction procedure for PST from cyanobacterial cells and was also suitable for screening acid extracts of shellfish flesh. These results demonstrate the potential of the locust bioassay for the routine screening of PST in a range of sample matrices.

An Assessment of the Impact of Inland Surface Water Input to the Bacteriological Quality of Coastal Waters

ABSTRACTThe introduction of ultraviolet disinfection in Jersey has achieved significant improvements in water quality. However, bathing waters in St Aubin's Bay and shellfish flesh have failed to comply with microbial standards. Streams and seepages from coastal structures were investigated as potential indicator organism sources (total and faecal coliforms, faecal streptococci). Seepages were an unimportant bacterial source as concentrations were low. Geometric mean concentrations in streams were up to four orders of magnitude higher than in final sewage‐treatment works effluent, and concentrations increased significantly at high stream discharge. Rainfall‐induced pulses of poor water quality occurred two to three times per week during the 1993 summer season. Natural discharges from island catchments thus contribute significantly to the bacterial load received at the coast, especially during high flow events. These observations have implications for other UK and European schemes using tertiary disinfection technology to attain water quality targets in coastal waters.

Mussel Drying and Food Storage in the Late Holocene, SW Cape, South Africa

AbstractVery large and homogenous open air shell middens (“megamiddens”) along a stretch of Atlantic coastline in the SW Cape reflect hunter-gatherer subsistence strategies dramatically different from those employed before and after the megamidden phase. Presented here are the results of experiments in the drying and preservation of shellfish flesh as a means of understanding the behavior involved in depositing these middens. Various techniques for drying shellfish were attempted, the results of which were assessed by bacteriological and compositional analyses of the samples. Results indicate that shellfish can be dried effectively for later consumption with relatively little effort and technology. Bulk processing of mussels would appear to be one plausible explanation for the megamidden phenomenon. Dietary implications of this research are briefly considered.

Comparison and Evaluation of Different Microbiological Quality Criteria for Shellfish and Shellfish-Growing Waters

The objective of this study is to compare different microbiological criteria based on the control of shellfish-growing waters and shellfish flesh, to assess the microbiological quality of the shellfish harvested in a marine zone affected by discharges of a moderately polluted river. Two species of shellfish grown in Mediterranean countries, cockles (Cardium edule) and striped venus (Chamelea gallina) were chosen to carry out this study. A total of 55 samples of diellfish and sea water were collected over the four seasons of the year. According to the results obtained, the US, EEC and Spanish criteria, based on the level of faecal coliforms in shellfish flesh, guaranteed appropriately their safety for human consumption, but among the criteria based on the level of Escherichia coli, only the Australian criterion has been shown to be totally safe, this microorganism being the best indicator of the presence of Vibrio parahaemolyticus and Salmonella. For the criteria based on the analysis of indicators in seawater, the indicators which relate to the age of faecal pollution, such as spores of clostridium sulfite reducer and faecal streptococci are the best indexes of the presence of pathogens in shellfish. Furthermore, criteria that establish the percentage of water samples that fulfill the microbiological level specified, or log-normal distributions of indicators such as total coliforms, faecal coliforms and E. coli, are better than mean counts.

Detection of bacteriophage tracers in bivalve molluscan shellfish

Procedures to enumerate commonly used bacteriophage tracers in bivalve molluscan shellfish were evaluated. Bacteriophages specific to Serratia marcescens, Escherichia coli and Enterobacter cloacae can be recovered from shellfish flesh by chloroform treatment of homogenates and subsequent clarification of samples by centrifugation. Bacteriophages were enumerated using a soft agar overlay technique. Hard clams appeared to release toxic compounds during homogenization which dramatically reduced counts of Ent. clocae bacteriophage.