NWT RESEARCH DATABASE

Regions: Sahtu Settlement Area

Tags: water quality, environmental monitoring, climate change, wildfire, aquatic invertebrates, permafrost thaw

Objective(s): To understand existing and potential impacts of climate change and resource development in the Sahtú region.

Project Description: The overall objective is to understand existing and potential impacts of climate change and resource development in the Sahtú region on four key aspects: 1) the landscape, 2) vegetation, 3) water resources, and 4) aquatic ecosystems. Specifically, the research team seek to understand: a) terrain instability due to permafrost thaw, especially around communities and culturally-important areas; b) vegetation changes due to warming and wildfires, especially in important wildlife habitat areas; c) Groundwater and surface water changes (both quantity and quality) in response to climate warming and development; and, d) aquatic invertebrate responses to these landscape changes. The research team will compile and analyze existing datasets on ground conditions within the Sahtú. Using remotely sensed imagery from 2016 the team will aim to identify all permafrost thaw features within 100km of Sahtú communities. These compiled datasets on ground conditions within these zones of interest will then be used to understand the relationship between surface landscape change and subsurface conditions. This will allow the team to generate a fine-scale permafrost thaw risk map that will identify areas of low, medium, and high risk of permafrost thaw. Field work will then be conducted to validate these maps. In areas where the maps predict low, moderate, and severe risk of thermokarst, the team will quantify: 1) surface topography, surface water ponding, and active layer thickness using high resolution GPS surveying and end of season probing; 2) forest stand density and age as well as total vegetation composition and biomass; and 3) soil bulk density, ground ice content, pH and organic matter concentrations to 3 meters depth using permafrost coring. These variables will give information on environmental conditions that will be used to predict permafrost stability (for example, high active layer thickness is indicative of advanced thawing). The research team will determine trends in ground vegetation recovery and forest succession with time since fire. This data will be used to predict future habitat conditions under regimes of changing wildfire patterns and increased permafrost thaw across the region. Fire history maps (1960-2017) and land cover classifications will be used to identify a range of sites that represent different successional patterns with time since fire. Initially the research team will sample young (2014), medium (1970s) and old (no fire history) sites. At each site two 30m transect will be established. Species composition and abundance in each site will be determined using quadrat sampling at regular intervals along the transect. Organic layer depth and other soil properties will be measured by digging soil pits to the mineral soil layer and measuring distance from mineral layer to top of the organic layer at 5-m intervals along the vegetation transect. Soils cores 0.3m in length will be collected in six locations and returned to the laboratory for soil bulk density analysis. Lichen will be collected to support prediction of lichen biomass accumulation. The second transect will be used for the measurement of forest composition and structure. Sampling of several streams, lakes, and springs will occur. At these sites the research team will install several (0.5-2m long, approx. 5 cm diameter) small monitoring piezometers (short-screened wells) in the streambed, banks and at a range of distances from the water bodies to measure water pressures at different depths. This allows the team to understand the rate and direction of groundwater flow. Sensors placed in piezometers will continuously record groundwater temperature and pressure, minimizing the amount of data collection by hand. Seepage meters, which consist of the bottom closed section of a pail or drum with a small collection bag attached, will be placed upside down into the stream or lake bed. Groundwater that is moving upwards and into the lake or stream can be captured and sampled. These methods also allow for sampling of water for chemical analysis, therefore samples of surface water and groundwater will be taken. Knowing what chemical constituents are in the water allows the team to understand where the water came from (snow, rain or groundwater) and potentially whether groundwater is coming from soil above the permafrost or in rock below the permafrost. Water samples may be extracted from seepage meters, piezometers or directly from the waterbody, but may also be collected by probes driven into the ground temporarily or by diffusion samplers. These diffusion samplers are left for several days and can be picked up and sampled. A metal rod will also be used to measure the depth to the top of permafrost in sampling areas. Piezometers and seepage meters may be left for the duration of the summer field campaign (approx. 2 weeks) or removed before winter freeze up. The research team will collect benthic invertebrates and zooplankton from small waterbodies in the Sahtú Region in sampling the sites. The team aim to sample 50 small lakes and ponds in the region that have experienced different levels and types of disturbance. Benthic invertebrates will be sampled from the nearshore using a standard protocol that involves using a 500µm mesh D-net to collect organisms over a 3m2 area on each lake. When possible, an inflatable boat will be taken out onto the waterbody and a grab sampler (Ponar grab) will be used to collect a small sample of sediment from the lake bottom. Zooplankton will be collected using an 80µm mesh zooplankton net. The net will be towed vertically through the water at the deepest point of the lake. Physical/chemical data from each waterbody will also be collected. The team will use a chartplotter to develop a map of the lake bottom, and water quality parameters such as pH, conductivity, turbidity, chlorophyll-a, and dissolved oxygen will be measured. When time allows, the team will deploy a minnow trap for four hours to determine if fish are present in the waterbodies. Any fish captured will be released alive after inspection of the trap. A 1-liter water sample will be collected from each lake to be processed in the laboratory for additional water quality measurements. The research project was developed in collaboration with local community members during site visits and community workshops. The goals and objectives outlined here are a result of community-identified needs and concerns. The research team will continue this process throughout the research program to ensure that our goals and objectives remain in line with those of the communities in which we will work. The team will also host community meetings, open house events to discuss the research informally, on-the-land events with youth and elders, and involvement of community members in the research. Reports and plain language materials detailing the progress and findings will be provided to interested parties. Researchers on the project are active in the Ne K’? Dene Ts'i?li? Forum, which provides a regular opportunity for research updates to community members, government, and other scientists. Researchers on the project will meet annually with representatives from the Sahtú Renewable Resources Board, ideally through the annual meeting of the Ne K’? Dene Ts'i?li? Forum and the Norman Wells and Tulit’a Renewable Resources Council to discuss research findings. The fieldwork for this study will be conducted from July 1, 2019 to October 31, 2019.