Dysbiosis In Epizootic Shell Disease Of The American Lobster (Homarus Americanus)

Epizootic shell disease (ESD) in the American lobster ( Homarus americanus) is continuing to affect the southern New England lobster population, and the etiology of the disease has not been well defined. We hypothesized that a dysbiotic shift in the shell microbial biofilm played a key part in the etiology of the disease. We analyzed the community structure of the surface microflora of apparently healthy and diseased lobsters using multitag pyrosequencing to correlate the abundance of key taxa within the lesions. Discriminant analysis (DA) was used to identify taxa in the microbial community that were associated with diseased and healthy states. Among the 170 bacterial taxa that were identified, 58 were helpful in determining the diseased and healthy states. The remaining 112 were not significantly different between the 2 states. The genus Aquimarina was present in high abundance in both healthy and diseased lobsters, but had a significantly higher abundance on animals in the diseased state. However, DA demonstrated that this genus does not strongly discriminate between the diseased and healthy state. Phylogenetic analysis indicated that there was significant strain diversity of this genus in all the samples analyzed. Our results indicate that the lesions seen in ESD may be viewed as being correlated with a polymicrobial component rather than being caused by a discrete pathogen

On the occurrence of three non-native cichlid species including the first record of a feral population of Pelmatolapia (Tilapia) mariae (Boulenger, 1899) in Europe

Thermally influenced freshwater systems provide suitable conditions for non-native species of tropical and subtropical origin to survive and form proliferating populations beyond their native ranges. In Germany, non-native convict cichlids (Amatitlania nigrofasciata) and tilapia (Oreochromis sp.) have established populations in the Gillbach, a small stream that receives warm water discharge from a local power plant. Here, we report on the discovery of spotted tilapia (Pelmatolapia mariae) in the Gillbach, the first record of a reproducing population of this species in Europe. It has been hypothesized that Oreochromis sp. in the Gillbach are descendants of aquaculture escapees and our mtDNA analysis found both O. mossambicus and O. niloticus maternal lineages, which are commonly used for hybrids in aquaculture. Convict cichlids and spotted tilapia were most probably introduced into the Gillbach by aquarium hobbyists. Despite their high invasiveness worldwide, we argue that all three cichlid species are unlikely to spread and persist permanently beyond the thermally influenced range of the Gillbach river system. However, convict cichlids from the Gillbach are known to host both native and non-native fish parasites and thus, non-native cichlids may constitute threats to the native fish fauna. We therefore strongly recommend continuous monitoring of the Gillbach and similar systems