Detection of a novel ecotype of Pfiesteria piscicida (Dinophyceae) in an Antarctic saline lake by real-time PCR

The heterotrophic dinoXagellate PWesteria piscicida was detected in Ace Lake in the Vestfold Hills, eastern Antarctica by using real-time PCR based on 18S rDNA sequences. Antarctic water samples collected in 2004 were tested by species-speciWc real-time PCR assays for the identiWcation of P. piscicida and P. shumwayae. Positive results were shown with P. piscicida-speciWc real-time PCR, and PCR products were examined by sequence analysis for conWrmation. A phylogenetic tree made from partial 18S rDNA sequences showed that the Antarctic clone clustered with P. piscicida. This result suggests that P. piscicida is present in the extreme conditions of an Antarctic saline lake which has not contained Wsh for thousands of years

Potential invasion of microorganisms and pathogens via 'interior hull fouling': Biofilms inside ballast water tanks

Surfaces submerged in an aquatic milieu are covered to some degree with biofilms - organic matrices that can contain bacteria, microalgae, and protozoans, sometimes including disease-causing forms. One unquantified risk of aquatic biological invasions is the potential for biofilms within ships' ballast water tanks to harbor pathogens, and, in turn, seed other waters. To begin to evaluate this vector, we collected biofilm samples from tanks' surfaces and deployed controlled-surface sampling units within tanks. We then measured a variety of microbial metrics within the biofilms to test the hypotheses that pathogens are present in biofilms and that biofilms have higher microbial densities compared to ballast water. Field experiments and sampling of coastwise and oceangoing ships arriving at ports in Chesapeake Bay and the North American Great Lakes showed the presence of abundant microorganisms, including pathogens, in biofilms. These results suggest that ballast-tank biofilms represent an additional risk of microbial invasion, provided they release cells into the water or they are sloughed off during normal ballasting operations. © Springer 2005