Vertical variation of pelagic ciliate communities in the western Arctic Ocean

The vertical distribution and structure of pelagic ciliate communities were investigated at 32 stations (western Arctic Ocean) in a summer sea-ice reduction region from August 1 to September 10, 2012. The distributions of species number, abundance, biomass, dominant species number and abundance, and structural diversity indices showed clear vertical trends associated with vertical changes in the water column. In addition, vertical patterns in community structure accurately reflected those environmental conditions. Multivariate correlation analysis demonstrated that vertical variation in ciliate communities was significantly related to a series of environmental variables. Community structure parameters, especially Shannon diversity (H′) and Margalef richness (D), showed strong relationships with vertical changes in chlorophyll a and might provide better predictors in future studies. Furthermore, heterotrophic and mixotrophic assemblages both demonstrated clear vertical distribution patterns, and microzooplankton have shown significantly relationship with chlorophyll a. These results provide basic data on vertical variation in ciliate communities in the western Arctic Ocean and have considerable potential to understand how pelagic ciliates structured in water column.