Coastal Environmental Dataset for the Central Kitikmeot - ArcticKelp (2023–2024)

This dataset compiles environmental measurements collected during coastal surveys conducted in the central Kitikmeot Sea (Cambridge Bay, Dease Strait, and Queen Maud Gulf) during the open-water seasons of 2023 and 2024, with the objective of identifying the main environmental drivers influencing kelp forest distribution. Variables measured include depth, temperature, salinity, photosynthetically active radiation, pH, and dissolved oxygen. Site-level environmental conditions were recorded over sampling windows of approximately 10 days in each year. Temperature (°C) and salinity (PSU) profiles were obtained using a CastAway® CTD (96 casts in total), while dissolved oxygen (DO; mg L⁻¹) and pH were measured concurrently at a subset of sites using HOBO® U26-001 (DO) and MX2501 (pH) data loggers (36 deployments in total: 21 in 2023 and 15 in 2024), deployed approximately 1 m above the seafloor. Spatial variation in seawater conditions was characterized using principal component analysis (PCA) of depth-integrated environmental profiles at each site, and differences between kelp and non-kelp sites were assessed using Wilcoxon rank-sum tests on integrated PC1 scores. Results showed that kelp forests were spatially restricted (mean cover 8.6%) and formed dense patches dominated by Saccharina latissima. Kelp occurrence was significantly associated with earlier sea-ice breakup (p = 0.05), with reduced variability and a lower probability of absence at earlier-opening sites. Kelp forests consistently occurred in colder, more saline waters and within a narrower range of environmental conditions than bare sites, and were also associated with slightly higher DO and pH. PCA-based analyses further confirmed significant differences in integrated temperature–salinity profiles between bare and kelp sites (p = 0.04). Overall, kelp forests were associated with more exposed, well-mixed environments, whereas warmer, fresher, and more stable coastal waters were dominated by urchin barrens of Strongylocentrotus droebachiensis. These findings highlight the role of physical forcing and seasonal dynamics in structuring Arctic kelp ecosystems under changing climatic conditions.