Bacteriophage in polar inland waters

Bacteriophages are found wherever microbial life is present and play a significant role in aquatic ecosystems. They mediate microbial abundance, production, respiration, diversity, genetic transfer, nutrient cycling and particle size distribution. Most studies of bacteriophage ecology have been undertaken at temperate latitudes. Data on bacteriophages in polar inland waters are scant but the indications are that they play an active and dynamic role in these microbially dominated polar ecosystems. This review summarises what is presently known about polar inland bacteriophages, ranging from subglacial Antarctic lakes to glacial ecosystems in the Arctic. The review examines interactions between bacteriophages and their hosts and the abiotic and biotic variables that influence these interactions in polar inland waters. In addition, we consider the proportion of the bacteria in Arctic and Antarctic lake and glacial waters that are lysogenic and visibly infected with viruses. We assess the relevance of bacteriophages in the microbial loop in the extreme environments of Antarctic and Arctic inland waters with an emphasis on carbon cycling.

The biological oceanography of Western Rock Lobster larvae

We examine in detail, for the first time, the biological oceanographic mechanisms affecting nutrition, growth and survival of larvae of the Western Rock Lobster while they undergo their planktonic phyllosoma phase in the Eastern Indian Ocean. The Western Rock Lobster is the most valuable single-species fishery in Australia, representing about 20% of the total value of Australia’s fisheries. Variability in settlement of puerulus stage and catch of adults has been shown to be highly correlated with the strength of the Leeuwin Current (in turn impacted by El Nino events) and westerly wind conditions. The below-average puerulus settlement for five years, including the two lowest on record, triggered a profound re-examination of mechanisms driving year class strength of larval settlement, since such fluctuations can pose a serious risk to a sustainable rock lobster industry. Here we present outcomes from the first research voyage (July 2010) of a 3-year study of the biological oceanography of the Western Rock Lobster larvae. We present a new understanding of the feeding of late-stage phyllosoma in the wild, and describe its oceanographic context. We show evidence that the phyllosoma have a preference for key prey with specific nutritional attributes, and suggest that this is directly related to the need to accumulate substantial nutritional reserves before they can metamorphose into the puerulus stage, cross the continental shelf, and settle to form the next generation of fishable adult lobsters. We propose that the autumn phytoplankton bloom within the Leeuwin Current, as identified by satellite ocean colour, is a key food resource driving production of healthy phyllosoma, and thus a strong year class. We speculate that the “Abrolhos Front” is a seasonally important feature supporting shoreward fluxes of phyllosoma. Our study directly addresses the hypothesis that productivity of the oceanic planktonic ecosystem offshore is a critical variable driving phyllosoma health and therefore recruitment success. These water masses have been shown directly to impact the ecological function of Ningaloo Reef and other iconic coastal habitats downstream. In particular, we investigate the alignment of dissolved oxygen and nitrate profiles with ocean carbonate chemistry in three dimensions on and off the continental shelf. We speculate on the origins and impacts of these signatures including the implications for ocean acidification. These are the first measurements of their kind in this region

Characterization of culturable Paenibacillus spp. from the snow surface on the high Antarctic Plateau (DOME C) and their dissemination in the Concordia research station.

Culturable psychrotolerant bacteria were isolated from the top snow on the high Antarctic Plateau surrounding the research station Concordia. A total of 80 isolates were recovered, by enrichment cultures, from two different isolation sites (a distant pristine site [75° S 123° E] and a site near the secondary runway of Concordia). All isolates were classified to the genus Paenibacillus by 16S rRNA gene phylogenetic analysis and belonged to two different species (based on threshold of 97 % similarity in 16S rRNA gene sequence). ERIC-PCR fingerprinting indicated that the isolates from the two different sites were not all clonal. All isolates grew well from 4 to 37 °C and were resistant to ampicillin and streptomycin. In addition, the isolates from the secondary runway were resistant to chromate and sensitive to chloramphenicol, contrary to those from the pristine site. The isolates were compared to 29 Paenibacillus isolates, which were previously recovered from inside the Concordia research station. One of these inside isolates showed ERIC- and REP-PCR fingerprinting profiles identical to those of the runway isolates and was the only inside isolate that was resistant to chromate and sensitive to chloramphenicol. The latter suggested that dissemination of culturable Paenibacillus strains between the harsh Antarctic environment and the inside of the Concordia research station occurred. In addition, inducible prophages, which are potentially involved in horizontal dissemination of genes, were detected in Paenibacillus isolates recovered from outside and inside the station. The highest lysogeny was observed in strains harvested from the hostile environment outside the station.Journal ArticleResearch Support, Non-U.S. Gov'tSCOPUS: ar.jinfo:eu-repo/semantics/publishe