Landscape determinants of pelagic and benthic primary production in northern lakes. (15th September 2022)

• Record Type: Journal Article
• Authors: Puts, Isolde Callisto; Ask, Jenny; Siewert, Matthias B.; Sponseller, Ryan A.; Hessen, Dag O.; Bergström, Ann‐Kristin
• Is Part Of: Global change biology. Volume 28:Number 23(2022)
• Page Start: 7063
• Page End: 7077
• Publication Date: 2022-09-15
• Subjects: autotrophic structuring -- carbon fertilization -- climate change -- CO2 -- DOC -- GPP -- hydrology -- land cover; Climatic changes -- Environmental aspects -- Periodicals; Troposphere -- Environmental aspects -- Periodicals; Biodiversity conservation -- Periodicals; Eutrophication -- Periodicals; 551.5
• DOI: 10.1111/gcb.16409
• Languages: English
• ISSNs: 1354-1013

Abstract

Abstract: Global change affects gross primary production (GPP) in benthic and pelagic habitats of northern lakes by influencing catchment characteristics and lake water biogeochemistry. However, how changes in key environmental drivers manifest and impact total (i.e., benthic + pelagic) GPP and the partitioning of total GPP between habitats represented by the benthic share ( autotrophic structuring ) is unclear. Using a dataset from 26 shallow lakes located across Arctic, subarctic, and boreal northern Sweden, we investigate how catchment properties (air temperature, land cover, hydrology) affect lake physico‐chemistry and patterns of total GPP and autotrophic structuring. We find that total GPP was mostly light limited, due to high dissolved organic carbon (DOC) concentrations originating from catchment soils with coniferous vegetation and wetlands, which is further promoted by high catchment runoff. In contrast, autotrophic structuring related mostly to the relative size of the benthic habitat, and was potentially modified by CO2 fertilization in the subarctic, resulting in significantly higher total GPP relative to the other biomes. Across Arctic and subarctic sites, DIC and CO2 were unrelated to DOC, indicating that external inputs of inorganic carbon can influence lake productivity patterns independent of terrestrial DOC supply. By comparison, DOC and CO2 were correlated across boreal lakes, suggesting that DOC mineralization acts as an important CO2 source for these sites. Our results underline that GPP as a resource is regulated by landscape properties, and is sensitive to large‐scale global changes (warming, hydrological intensification, recovery of acidification) that promote changes in catchment characteristics and aquatic physico‐chemistry. Our findings aid in predicting global change impacts on autotrophic structuring, and thus community structure and resource use of aquatic consumers in general. Given the similarities of global changes across the Northern hemisphere, our findings are likely relevant for northern lakes globally. Abstract : Visualization of landscape determinants of pelagic (light green) and benthic (dark green) gross primary production (GPP) along a gradient in colored dissolved organic carbon (DOC; left to right). This DOC gradient is driven by changes in altitude and climate across Arctic (high altitude), subarctic (mid altitude), and boreal (low altitude) regions of northern Sweden. Along this gradient, lakes become browner, more nutrient rich, warmer, and lower in pH (modifying the DIC pool from HCO 3 − to CO2 ), resulting in a shift from systems where GPP is benthic driven to those where it is pelagic driven. These changes also underpin a unimodal relationship between total GPP and DOC across the region.