Diversity of calanoid copepods in the North Atlantic and adjacent seas: species associations and biogeography

Abstract

Present-day patterns in pelagic biodiversity are the result of the interaction of many fac- tors acting at different scales. Developing an understanding of the processes that regulate the diver- sity of oceanic ecosystems is thus challenging. In this study, diversity of calanoid copepods was decomposed into species associations by means of the recent 'indicator value method' and multivari- ate analyses. For the first time, at an oceanic basin scale and with a spatial resolution approaching the mesoscale, species associations of calanoid copepods have been identified. Nine species associations were determined and have enabled us, (1) to improve the ecological partitioning of this region, and (2) to identify the main factors that regulate pelagic biodiversity in this area. It is shown that temper- ature, hydrodynamics, stratification and seasonal variability of the environment are likely to be the main factors contributing to the ecological regulation of diversity of calanoid copepods. The similar geographical pattern evident between currents/water masses and the species associations suggest that the species groups may be used as an environmental indicator to evaluate long-term changes in the marine environment related to climate change and other increasing human-induced influences.