Polar Climate Change as Manifest in Atmospheric Circulation.

PURPOSE OF REVIEW: Dynamic manifestations of climate change, i.e. those related to circulation, are less well understood than are thermodynamic, or temperature-related aspects. However, this knowledge gap is narrowing. We review recent progress in understanding the causes of observed changes in polar tropospheric and stratospheric circulation, and in interpreting climate model projections of their future changes. RECENT FINDINGS: Trends in the annular modes reflect the influences of multiple drivers. In the Northern Hemisphere, there appears to be a "tug-of-war" between the opposing effects of Arctic near-surface warming and tropical upper tropospheric warming, two predominant features of the atmospheric response to increasing greenhouse gases. Future trends in the Southern Hemisphere largely depend on the competing effects of stratospheric ozone recovery and increasing greenhouse gases. SUMMARY: Human influence on the Antarctic circulation is detectable in the strengthening of the stratospheric polar vortex and the poleward shift of the tropospheric westerly winds. Observed Arctic circulation changes cannot be confidently separated from internal atmospheric variability.

Fatal septicemia caused by the zoonotic bacterium Streptococcus iniae during an outbreak in Caribbean reef fish.

An outbreak of Streptococcus iniae occurred in the early months of 2008 among wild reef fish in the waters of the Federation of St Kitts and Nevis, lasting almost 2 months. Moribund and dead fish were collected for gross, histological, bacteriological, and molecular analysis. Necropsy findings included diffuse fibrinous pericarditis, pale friable livers, and serosal petechiation. Cytological and histological analysis revealed granulocytic and granulomatous inflammation with abundant coccoid bacterial organisms forming long chains. Necrosis, inflammation, and vasculitis were most severe in the pericardium, meninges, liver, kidneys, and gills. Bacterial isolates revealed ß-hemolytic, Gram-positive coccoid bacteria identified as S. iniae by amplification and 16S ribosomal RNA gene sequencing. Results from biochemical and antimicrobial susceptibility analysis, together with repetitive element palindromic polymerase chain reaction fingerprinting, suggest that a single strain was responsible for the outbreak. The inciting cause for this S. iniae-associated cluster of mortalities is unknown.