Insight into the latitudinal gradient of biodiversity based on spatial variations in pelagic ciliate communities along the western Arctic Ocean

The latitudinal dynamics of biodiversity has been the focus of global attention. This study is based on the latitude gradient of biodiversity in the spatial changes of pelagic ciliate communities in the western Arctic Ocean. The gradient pattern of pelagic ciliate communities across four latitudes were investigated from the water surface at 22 sampling station in the northern Bering Sea of the western Arctic Ocean and Chukchi Sea from August 5 to August 24, 2016. Based on multivariate analyses, the results showed that (1) the spatial patterns of pelagic ciliates represented a significant latitudinal gradient along the western Arctic Ocean; (2) the species number and abundance of pelagic ciliate communities declined from 64°N to 80°N; (3) variations in the horizontal distribution of ciliates were significantly correlated with changes in physicochemical variables, especially water temperature and Chl a; Thus it is suggested that the expected latitudinal decline of biodiversity was evident along the western Arctic Ocean. [Display omitted] •The community patterns of pelagic ciliates showed a significant latitudinal gradient.•The horizontal variation of the ciliates was significantly correlated with abiotic variables.•Species richness and abundance of the ciliates were significantly related to Chl a.•The pelagic ciliates showed latitudinal decline of biodiversity in Arctic Seas.