Stream diatom assemblages in an Arctic catchment: diversity and relationship to ecosystem-scale primary production

Abstract

We quantified benthic diatom diversity in streams in the Miellajokka catchment, about 200 km north of the Arctic circle in Sweden. Beta diversity among sites was related to local-scale environmental heterogeneity (occurring on the order of 1 km or less), and its magnitude was equal (Sørensen Index = 0.62) to levels previously reported for rivers on regional environmental gradients across 100’s of kilometers of Arctic Fennoscandia. Species turnover was the dominant (77%) component of beta diversity in the Miellajokka catchment. Small, stress-tolerant taxa dominated the assemblages, and there were no clear patterns of functional class among sites. Site ordinates from non-metric dimensional scaling were most strongly correlated with flood frequency (r = 0.83) and water temperature (r = 0.89), which was higher in harsh tundra sites than below treeline. Additionally, site ordinates were correlated (r = 0.83) with ecosystem-scale gross primary production – indicative of a link between diatom diversity and ecosystem function. Our results advance understanding of patterns diatom diversity in Arctic streams by quantifying local-scale variation that is understudied in this region, and by identifying the consequences of this local-scale diversity for an ecosystem-scale process.

The Scaling Relationship for the Length of Tributaries to Lakes

“…deterministic calculations. We expected high junction angles (i.e., close to 90°) based on maps, satellite imagery, and our field experience in the study region (e.g., Klaus et al, 2021;Norman et al, 2022;Riley & Seekell, 2021;Seekell, Cael, Norman, et al, 2021). This is not a trivial expectation because qualitative evidence indicates that there is a substantial range of junction angles, including very low junction angles in some regions (Supporting Information S1).…”