Watershed and Lake Attributes Dictate Landscape Patterns of Resource Flows in Mountain Lakes. Issue 4 (2nd April 2021)

• Record Type: Journal Article
• Authors: Smits, Adrianne P.; Currinder, Bryan; Framsted, Nicholas; Loken, Luke C.; Lucero, Delores; Neal, Kelly A.; Parisek, Christine A.; Sickman, Jim; Sadro, Steven
• Is Part Of: Water resources research. Volume 57:Issue 4(2021)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2021-04-02
• Subjects: allochthony -- food webs -- lakes -- mountains -- radiocarbon -- resource flows -- stable isotopes; Hydrology -- Periodicals; 333.91
• DOI: 10.1029/2020WR027673
• Languages: English
• ISSNs: 0043-1397

Abstract

Abstract: The extent to which terrestrial organic matter supports aquatic consumers remains uncertain because factors regulating resource flows are poorly understood. We sampled 12 lakes throughout the Sierra Nevada (California, USA) spanning large gradients in elevation and size to evaluate how watershed attributes and lake morphometry influence resource flows to lake carbon pools and zooplankton. We found that the size and composition of carbon pools in lakes were often more strongly determined by watershed or lake features rather than by elevational position. Using three different tracers of resource origin (δ 13 C, Δ 14 C, C:N ratio), we found terrestrial contributions to most lake resource pools (dissolved organic carbon, particulate organic matter (POM), sediments) and pelagic consumers (zooplankton) were more strongly related to local‐scale watershed features such as vegetation cover or watershed area: lake area rather than to elevation. Landscape patterns in multiple tracers indicated consistent contribution of within‐lake C sources to bulk resource pools across elevations (POM, sediments, zooplankton). δ 13 C‐enrichment of lake C pools and overlap with δ 13 C of terrestrial resources can arise due to reduced fractionation of 13 C by phytoplankton under CO2 limitation, therefore we recommend careful consideration of potential environmental drivers when interpreting among‐lake patterns in δ 13 C. Our findings emphasize the importance of local‐scale variation in mediating terrestrial contributions to lake food webs. Key Points: Lake and landscape features are better predictors of the composition of lake resource pools than elevation Allochthony gradients in mountain systems can vary substantially among different lake resource pools Aquatic producers are the dominant contribution to lake carbon pools across a large gradient in landscape vegetation cover