16 research outputs found
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