Abstract
Shallow lakes are dominant features in subarctic and Arctic landscapes and are responsive to multiple stressors, which can lead to rapid changes in limnological regimes with consequences for aquatic resources. We address this theme in the coastal tundra region of Wapusk National Park, western Hudson Bay Lowlands (Canada), where climate has warmed during the past century and the Lesser Snow Goose (LSG; Chen caerulescens caerulescens) population has grown rapidly during the past ∽40 years. Integration of limnological and paleolimnological analyses documents profound responses of productivity, nutrient cycling, and aquatic habitat to warming at three ponds (“WAP 12”, “WAP 20”, and “WAP 21″), and to LSG disturbance at the two ponds located in an active nesting area (WAP 20, WAP 21). Based on multiparameter analysis of 210Pb-dated sediment records from all three ponds, a regime shift occurred between 1875 and 1900 CE marked by a transition from low productivity, turbid, and nutrient-poor conditions of the Little Ice Age to conditions of higher productivity, lower nitrogen availability, and the development of benthic biofilm habitat as a result of climate warming. Beginning in the mid-1970s, sediment records from WAP 20 and WAP 21 reveal a second regime shift characterized by accelerated productivity and increased nitrogen availability. Coupled with 3 years of limnological data, results suggest that increased productivity at WAP 20 and WAP 21 led to atmospheric CO2 invasion to meet algal photosynthetic demand. This limnological regime shift is attributed to an increase in the supply of catchment-derived nutrients from the arrival of LSG and their subsequent disturbance to the landscape. Collectively, findings discriminate the consequences of warming and LSG disturbance on tundra ponds from which we identify a suite of sensitive limnological and paleolimnological measures that can be utilized to inform aquatic ecosystem monitoring.
Highlights
Shallow lakes and ponds are abundant in subarctic and Arctic regions and provide important habitat and resources for a variety of wildlife and human populations
Ecology and Evolution published by John Wiley & Sons Ltd
In subarctic and Arctic regions experiencing the dual effects of climate warming and changes in avian populations, few studies have comprehensively examined and discriminated limnological responses to these stressors, yet this knowledge is required to assess the status of aquatic resources and to anticipate how they may evolve in the future
Summary
Shallow lakes and ponds are abundant in subarctic and Arctic regions and provide important habitat and resources for a variety of wildlife and human populations. Due to their small water volumes and high surface area to volume ratios, they are responsive to multiple environmental stressors, which may lead to limnological regime shifts or rapid transition to a new suite of limnological conditions. The influence of avian populations has been identified as a driver of regime shifts in subarctic and Arctic lakes and ponds (e.g., Luoto et al 2014), and they have long been recognized to cause disturbance in other habitats (e.g., terrestrial landscapes, salt marshes; Jefferies et al 2006; Kotanen and Abraham 2013). In subarctic and Arctic regions experiencing the dual effects of climate warming and changes in avian populations, few studies have comprehensively examined and discriminated limnological responses to these stressors, yet this knowledge is required to assess the status of aquatic resources and to anticipate how they may evolve in the future
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