Physical and chemical characteristics of lakes across heterogeneous landscapes in arctic and subarctic Alaska

Abstract

Lakes are an important component of high‐latitude regions, providing habitat for fish and wildlife and playing a critical role in biogeochemical and global carbon cycles. High‐latitude lakes are sensitive to climate change, in part due to their development within permafrost soils. Considerable heterogeneity exists across arctic and subarctic landscapes, yet little is known about how this landscape variability influences chemical and physical attributes of lakes. We investigated the physical and chemical limnology of 617 lakes in Alaska's boreal forest and boreal‐arctic transition zone. We categorized lakes into 10 basin types based on parent material, topography, genesis, and permafrost characteristics. Physical parameters varied across lake basin types, with the deepest lakes occurring in ice‐poor glacial deposits and ice‐rich terrain, while the shallowest lakes were observed in floodplain deposits and coastal lowlands. Dissolved inorganic nitrogen (N) and phosphorous (P) concentrations were generally low across all landscapes, whereas total N and P were highest in lakes underlain by ice‐rich Pleistocene loess. Total N and P concentrations were significantly correlated with chlorophyll a, indicating a possible colimitation of primary productivity in these systems. Base cation concentrations helped elucidate lake basin hydrology and the relative influence of shallow versus deep groundwater inputs to surface water. Using these results, we developed a simple conceptual model for each lake and landscape type based on differences in physical and chemical parameters. Overall, we expect that the vulnerability of lake ecosystems to climate change will vary across lake basin types and will be mediated by spatial patterns in permafrost characteristics and subsurface hydrology.

Landsat-Based Trend Analysis of Lake Dynamics across Northern Permafrost Regions

“…The AKS site contains a large variety of landscape types with river valleys and deltas, alluvial plains, coastal lowlands, and gently rolling uplands [63]. Some regions feature ice-rich permafrost with a high abundance of thermokarst lakes and basins, while other areas are permafrost-free [64].…”

Ice roads through lake-rich Arctic watersheds: Integrating climate uncertainty and freshwater habitat responses into adaptive management

“…The abundance and composition of plankton communities in Arctic lakes integrate much information about how the system supports higher trophic levels and responds to physical habitat changes. Although Arctic freshwater ecosystems are often considered oligotrophic (low productivity), shallow depths and terrestrial subsidies from dynamically eroding shorelines associated with thermokarst lakes can produce a wide range of variation in nutrient status and productivity (Kokelj, Zajdlik, and Thompson 2009;Larsen et al 2017). However, seasonal and multiyear analyses of zooplankton data show that biomass and community composition strongly relate to lake connectivity, suggesting top-down control of foodweb dynamics (Beaver et al in review).…”

Groundwater hydrogeochemistry in permafrost regions

“…Larsen et al investigated lake hydrology in Alaska and estimated groundwater input based on major cation concentrations. They found that groundwater has a more significant contribution to lake water balances in discontinuous permafrost areas where there are good connections between surface water and groundwater.…”

“…Cations from mineral weathering (Ca 2+ , Mg 2+ and Na + ), for example, have been widely used to identify the contributions of deeper groundwater to stream flow whereas DOC and potassium concentrations in surface waters are mostly associated with shallow groundwater flow in near-surface organic soils. 9,26,27,36 Larsen et al 61 investigated lake hydrology in Alaska and estimated groundwater input based on major cation concentrations. They found that groundwater has a more significant contribution to lake water balances in discontinuous permafrost areas where there are good connections between surface water and groundwater.…”