Climate change and marine diversity in the high latitudes: Holocene insights from the Baffin Bay-Labrador Sea region

Abstract

Anthropogenic climate change has already caused shifts in Arctic species distributions, but regional patterns of diversity change are complex. We examine ecosystem responses during the Holocene, based on micropalaeontological community composition and Shannon diversity index analyses of 11 marine sediment records from West of Greenland, uncovering distinct community-specific responses to climate change. We also explore surface sample species-environment relationships for plankton groups across the region. Recent surface sediment dinoflagellate cyst (dinocyst) diversity peaks with warmer sea-surface temperatures, while diatom diversity shows a complex but weakly positive relationship with sea-ice cover. The diversity of dinocysts in the sediment and relationship with sea-surface temperatures suggest that dinocysts may be more vulnerable to ecological homogenization, although this is tentative as the fossil record is biased towards certain species. We also find that benthic foraminifera exhibit stable diversity over the Holocene despite some community turnover, highlighting community resilience to shifts in meltwater, productivity, and sea-surface temperature. Diatom records have high diversity but exhibit more distinct assemblages, suggesting limited connectivity across this latitudinal gradient. There is an inflection in Holocene diversity trends with diverging patterns seen in the planktic micropalaeontological groups at around 70°N. By integrating diversity metrics across multiple communities, this study reveals complex ecological responses and provides some insight into the resilience of high-latitude assemblages, particularly in response to changes in meltwater influence, productivity and surface conditions.