NWT RESEARCH DATABASE

Tags: water quality, permafrost, hydrology, greenhouse gases, aquatic ecology, methane, organic carbon

Objective(s): To examine the effects of permafrost and flooding on the ecological structure and carbon exchange of contrasting lakes in the Mackenzie River Delta.

Project Description: This study will examine the effects of permafrost and flooding on the ecological structure and carbon exchange of contrasting lakes in the Mackenzie River Delta. Permafrost thaw in lake catchments can cause increased transport of organic carbon and dissolved nutrients to lakes with effects on the hydrology and water chemistry of lake environments. Patterned ground marked by ice-wedge polygons is formed by freezing and thawing of the soil, which forms cracks into which ice can spread and cause the soil to uplift. An increase in the prevalence of patterned ground formations in lake catchments could also serve as a conduit for the transport of dissolved organic matter and nutrients to lakes. While this organic carbon may be used as a food source by microorganisms and invertebrates in the water, an issue of concern is that much of it will be released to the atmosphere as methane or other greenhouse gases. Flooding caused by ice jams is also an important factor in many lakes in the Mackenzie Delta, particularly those adjacent to the main channels. Lakes exposed to flooding in the spring receive an influx of nutrients and a period of increased connectivity to other aquatic habitats, and these factors are expected to have an effect on invertebrate composition and productivity. The objective is to understand the importance of these factors on Lake Ecosystem function, and how this understanding can be used to predict and monitor future changes. The research team will use helicopter access to collect water samples (1 Litre) from Mackenzie Delta lakes, and use a boat to collect water samples from lakes in the vicinity of Inuvik. The team will be using a multi-parameter probe (YSI) to measure depth, water temperature, pH, conductivity and dissolved oxygen. Water samples (~2L) will be collected using pre-cleaned plastic bottles, by collecting samples from just below the water surface. Two sediment cores will be extracted from each lake (gravity corer, 8.4 cm diameter), and transported back to the lab for processing. Algae, zooplankton, and benthic invertebrates for food web analysis will be collected. These samples will be brought back to the Aurora Research Institute for preservation and processing. The research team is available to give presentations about the research to interested community organizations. Once the research is complete, the research team will prepare a poster that can be displayed at the Aurora Research Institute that outlines the findings. Copies of any publications that result from this research will be sent to the Aurora Research Institute library. The fieldwork for this study will be conducted from July 15, 2015 to August 25, 2015.