Climate and catchment influence the postglacial succession of three lakes in south‐central Baffin Island (Nunavut), Canada

ABSTRACT Understanding postglacial ontogeny in Arctic lakes helps contextualize modern‐day climatic change. We used sediment cores to characterize ecological succession in three south‐central Baffin Island lakes from deglaciation (c. 7–8k cal a BP) to present. Trends in diatom (Bacillariophyceae) and chironomid (Diptera: Chironomidae) assemblages were compared between two small lakes (depth ≤ 12 m, area ≤ 0.04 km 2 ) and the north‐western lagoonal system of Nettilling Lake, the largest freshwater lake in the Canadian Arctic Archipelago (sampling depth = 3 m, total area = 5543 km 2 ). Ecological trajectories differed between the small lakes despite morphological similarities. The northern, lower elevation, small lake showed expected acidification and oligotrophication, while the southern, higher elevation lake experienced hydrologic disturbance likely associated with permafrost degradation. The Nettilling Lake core did not show clear ontogenetic processes, but the high sedimentation rate from approx 6.7 to 5.9k cal a BP (likely from glacial melt) obscured in‐depth analysis of subsequent changes. While the composition of chironomid assemblages varied between lakes, all three lakes showed a minor shift from Tanytarsini to Orthocladiinae taxa over their development, which could reflect ontogenetic changes to resource availability. The different trajectory experienced by each study lake highlights the relevance of catchment properties in structuring lake development.