http://digital.csic.es/bitstream/10261/25111/1/10.1.1.112.5446.pdf

Perkinsosis in molluscs: A review

The recurrent detection of parasitic zoospores among aquatic heterotrophic flagellates (HFs) has recently modified our view of how the microbial loop is organized, and called into question the role of eukaryotic parasites in the aquatic trophic food web. The Perkinsozoa group, already known to play a significant role as parasite in marine systems, is of special interest here, since it has recently been detected in several lakes by constructing clone libraries. In marine systems, this group is known to consist solely of intracellular parasites of molluscs or phytoplanktonic species, but their hosts in freshwater environments are still unknown, and little is yet known about their functional importance in planktonic systems. This review summarizes the main information currently available about Perkinsozoa through a description of their phylogenetic position, their life cycles, and regulatory factors, and the consideration of the specificities of their hosts in marine systems, and the few data recently acquired in lakes.

Perkinsozoa, a well-known marine protozoan flagellate parasite group, newly identified in lacustrine systems: a review

Histopathological effects of petroleum hydrocarbons and heavy metals on the American oyster (Crassostrea virginica) from Tabasco, Mexico

The eastern oyster (Crassostrea virginica) is affected by two protozoan parasites, Perkinsus marinus which causes Dermo disease and Haplosporidium nelsoni which causes MSX (Multinucleated Sphere Unknown) disease. Both diseases are largely controlled by water temperature and salinity and thus are potentially sensitive to climate variations resulting from the El Nino-Southern Oscillation (ENSO), which influences climate along the Gulf of Mexico coast, and the North Atlantic Oscillation (NAO), which influences climate along the Atlantic coast of the United States. In this study, a 10-year time series of temperature and salinity and P. marinus infection intensity for a site in Louisiana on the Gulf of Mexico coast and a 52-year time series of air temperature and freshwater inflow and oyster mortality from Delaware Bay on the Atlantic coast of the United States were analyzed to determine patterns in disease and disease-induced mortality in C. virginica populations that resulted from ENSO and NAO climate variations. Wavelet analysis was used to decompose the environmental, disease infection intensity and oyster mortality time series into a time–frequency space to determine the dominant modes of variability and the time variability of the modes. For the Louisiana site, salinity and Dermo disease infection intensity are correlated at a periodicity of 4 years, which corresponds to ENSO. The influence of ENSO on Dermo disease along the Gulf of Mexico is through its effect on salinity, with high salinity, which occurs during the La Nina phase of ENSO at this location, favoring parasite proliferation. For the Delaware Bay site, the primary correlation was between temperature and oyster mortality, with a periodicity of 8 years, which corresponds to the NAO. Warmer temperatures, which occur during the positive phase of the NAO, favor the parasites causing increased oyster mortality. Thus, disease prevalence and intensity in C. virginica populations along the Gulf of Mexico coast is primarily regulated by salinity, whereas temperature regulates the disease process along the United States east coast. These results show that the response of an organism to climate variability in a region is not indicative of the response that will occur over the entire range of a particular species. This has important implications for management of marine resources, especially those that are commercially harvested.

Differential modulation of eastern oyster (Crassostrea virginica) disease parasites by the El-Niño-Southern Oscillation and the North Atlantic Oscillation

Cytotoxic and antibacterial properties of Mytilus galloprovincialis, Ostrea edulis and Crassostrea gigas (bivalve molluscs) hemolymph [hemocyte lysate]

Poorly documented, but apparently sporadic oyster Crassostl-ea v~rginjca mortality in the coastal lagoons Carmen, Machona and Mecoacan at the southern extreme of the Gulf of Mexico inTabasco, Mexico, has been attributed by local oystermen to pollution resulting from oil refinery operations. In September 1992 we sampled oysters in these lagoons to investigate the potential for disease-induced mortality from the oyster pathogen Perkinsus marinus. Prevalence of P marinus was 100% at Lodazal, a high salinity (31 ppt) site in Carmen lagoon and 60% at Rio San Felipe, a low salinity (15 ppt) site. At Los Jimenez. a high salinity (32 ppt) site in Machona lagoon with previous high mortality, prevalence of P marinus was 90% and weighted prevalence, a measure of intensity, was 3.1, a high value associated with heavy infections and mortality. Samples collected at the Buena Vista aquaculture facility in Mecoacan lagoon revealed 60 to 100 % prevalence of P marinus, although most infections were low intensity. P mannusis a potential source of oyster mortality in these coastal lagoons; more intensive sampling is necessary to determine the mortality attributable to P madnus.

/pdf/perkinsus-marinus-apicomplexa-as-a-potential-source-of-4xjmcwpa7w.pdf

RS Alvarez

Papers

Perkinsus-marinus (Apicomplexa) As A Potential Source Of Oyster Crassostrea-virginica Mortality In Coastal Lagoons Of Tabasco, Mexico