Effects of climate change on Arctic communities

Coastal ecosystems are more vulnerable to human activities that cause environmental changes, at both local and global scales, than the open ocean. This is particularly true in the Arctic, where fast and dramatic environmental changes such as warming, reduced ice cover, permafrost thawing, increased freshwater discharge, decreased light availability on the seafloor, and poleward migration of temperate species will all have potential consequences on the benthic communities. Here, we will present results gathered by the Sorbonne University team during the H2020 FACE-IT project, which focused on biological- and ecosystem-level shifts occurring in Arctic fjords. Our activities spanned from the identification and compilation of in situ collected data relevant to the anthropogenic forcing of change  on Arctic ecosystems, to experimental work on Arctic kelp communities. It was found that there are 14 key drivers of change, for which data exist, that are broadly divided into five categories. The past, present, and future patterns of change for these drivers were measured/projected, and their systematic interactions with each other were mapped.We will also present results from laboratory experiments carried out in summer and winter on kelp communities in an Arctic fjord. We assessed the response of kelps to warming, freshening, irradiance reduction, and marine heatwaves. We found that individual Arctic kelps  and communities are generally tolerant to the tested environmental changes. However, their productivity decreased during long marine heatwaves and when exposed to reduced irradiance. Furthermore, a potential higher sensitivity to warming in winter was found. Together, our results confirm that the future of Arctic kelp communities themselves appears positive, but their role in future Arctic fjord ecosystems is  uncertain as most other Arctic biota will be more heavily affected.