Biodiversity of macrobenthic nematodes in the intertidal and shallow subtidal zones in the Eastern Canadian Arctic

Free-living marine nematodes play a fundamental role in nutrient cycling and food web dynamics, serving as bioindicators of ecosystem health. Despite their ecological importance, nematode biodiversity remains largely unexplored in Arctic coastal waters. This study surveyed macrobenthic nematodes (> 500 mu m) in the high and low intertidal, and shallow (< 10 m) and deep subtidal (10-20 m) coastal zones in four Canadian Arctic ports: Churchill, Deception Bay, Iqaluit, and Steensby Inlet. A total of 57 genera, representing 30 families were identified. Thoracostomopsidae, Oncholaimidae, Xyalidae, and Axonolaimidae were the most dominant families. Assemblages had low similarity in composition (<= 12%) and exhibited varying trophic structures among ports. Churchill and Iqaluit were dominated by deposit feeders, whereas Deception Bay and Steensby Inlet showed high proportions of predators. Overall, lower diversity was observed in intertidal (38 genera) relative to subtidal (54 genera) zones. At each port, abundance, genus richness, and Shannon-Wiener's diversity index showed great variability among coastal zones and sampling sites. Several genera occurred in both intertidal and subtidal zones and assemblages could not be associated with a specific zone. At a broad scale, abundance in subtidal zones was negatively correlated with the duration of sea ice, although evidence of latitudinal patterns in assemblage composition was lacking. Given the rapid changes in Arctic ecosystems due to global warming and anthropogenic activities, this study provides baseline information on macrobenthic nematodes in the Eastern Canadian Arctic and is valuable to develop monitoring programs and taxonomic inventories in high latitude coastal areas.

Automated summary

Free-living marine nematodes in Arctic coastal waters were surveyed, revealing low diversity and varying composition among different ports and zones. The study also found a negative correlation between nematode abundance and sea ice duration in subtidal zones. This research provides baseline information for monitoring and taxonomic inventories in high latitude coastal areas.