Latitudinal gradient of copepod functional diversity in the South Atlantic Ocean

Abstract

There is a growing consensus for assessing the multifaceted marine biodiversity by analyzing morphological taxonomy and biological traits to link the biodiversity and ecosystem functioning relationships (BEF) to environmental variability. We applied taxonomic and functional diversity indices to relate copepod biodiversity with ecosystem functioning along different biogeographic zones from the Southwestern Atlantic to the Southern Ocean. To assess the link between functional traits and environmental gradients, we clustered 94 species into functional groups based on the combination of five functional traits. Taxonomic and functional diversity showed a linear decreasing trend along the latitudinal gradient. Species richness peaked at the subtropical latitude (∼30°S), while the functional richness was similar from the tropical up to the temperate region (∼45°S), which hosted on average 70% of the total pool of species, and dropped to only 16% in polar waters. We found that small- and medium-bodied broadcasting, large cruising carnivorous and detritivorous copepods contributed mostly to the larger functional space in tropical and subtropical zones. In turn, dominant copepod species with contrasting traits enhanced the functional divergence and decreased functional evenness poleward. Our results indicate that distinct copepod functional groups with specific environmental preferences are influenced by ecological mechanisms that promote functional richness through complementary resource use and niche partitioning. These findings highlight the relationship between species diversity and ecosystem functioning, which might contribute to ecosystem stability and resilience along environmental gradients.