A multivariate approach to large-scale variation in marine planktonic copepod diversity and its environmental correlates
Résumé
We have investigated the relationships between covariations in environmental variables and variations in distributions of marine copepod diversity over an extensive latitudinal range from 86.5 degrees N to 46.5 degrees S. For this purpose, 7 data sets (representing 13,713 samples) of copepod species composition data and 11 environmental data sets were assembled. Principal components analysis was applied to investigate the relationships among the mean and seasonal variations in environmental descriptors (ocean temperature, chlorophyll a [ Chl a], net primary production, and other physical and chemical properties of the ocean) and their relationships with spatial variations in copepod diversity. High copepod diversity corresponded to a combination of high ocean temperature and salinity and low Chl a and nutrient concentrations (nitrate, silicate, phosphate). To a lesser extent, high-diversity regions were also correlated to low seasonal variability in oxygen, ocean temperature, and mixed-layer depth. Regression on principal components provided a robust prediction of global copepod diversity (R-2 = 0.45, p < 0.001) as our subset of environmental data was representative of the full range of environmental variability that occurs globally.