Tracking biodiversity in changing Arctic waters: insights from eDNA metabarcoding in Svalbard

Monitoring biodiversity patterns and their changes in Arctic coastal ecosystems is critical under ongoing climate change. However, common current approaches require high effort and expertise and this in turn limits the spatial and temporal scale of these monitoring efforts. Here, we investigated both the fish and the marine invertebrate communities across Svalbard using a multi-marker environmental DNA metabarcoding approach. We collected and analysed marine water, sediment and zooplankton filtered from marine water from sites influenced by the warm West Spitsbergen Current and the cold East Spitsbergen Current. Following metabarcoding amplification using mitochondrial COI, 12S, 16S and nuclear 18S markers and high-throughput sequencing, we retrieved an extensive overview of Svalbard marine biodiversity. Water, sediment and especially zooplankton samples collected across Svalbard revealed spatial differences in community composition, with significantly distinct assemblages in the northwest and southeast of Svalbard. We identified potential bioindicator species for use in rapid assessment of impacts of marine temperature increase and confirmed observed patterns of ongoing shifts in community structure as a response to changes in dominant water masses. Overall, our findings show that species composition depending on fine-scale climate variation of Arctic waters can be effectively studied and monitored using environmental DNA. These insights can help us understand current and evolving climate-driven changes.