NWT RESEARCH DATABASE

Regions: North Slave Region

Tags: contaminants, biodiversity, ecology, freshwater ecosystem, evolution, mine-impacted lakes

Objective(s): To determine ecological and evolutionary processes, and interactions between ecology and evolution that are potentially limiting and/or facilitating the biological recovery of mining-impacted lakes around Yellowknife, NWT.

Project Description: This licence has been issued for the scientific research application No.5253. The long-term project objective is to determine ecological and evolutionary processes, and interactions between ecology and evolution (eco-evolutionary interactions), that are potentially limiting and/or facilitating the biological recovery of mining-impacted lakes around Yellowknife, NWT. The objective in the first year of this program are to have an improved understanding of the contemporary ecology of these subarctic lakes, along a disturbance gradient from the historic gold mines in Yellowknife, NWT: To quantify freshwater biodiversity across trophic food web groups, from bacteria to plankton to fish, using cutting-edge approaches in environmental DNA (eDNA) metabarcoding technology (eDNA: eukaryotic: 18S, bacterial: 16S, fish: 12S). This includes sampling 15 remote lakes last sampled ten years ago for water chemistry, with the new addition of these ecological data, within 30 km of Yellowknife, NWT. This sampling will be complimented by traditional sampling for zooplankton and phytoplankton using preserved samples. Collection of water chemistry – surface grab water samples will be collected for the laboratory analyses of dissolved organic carbon, absorbance at 440 nanometer, nutrients (total nitrogen and total phosphorus), pH, conductivity, temperature, pH, and water samples for analyses of oxygen isotopes. Dissolved oxygen, pH, water temperature (oC) and conductivity will be measured using a Professional Plus Model YSI multi-parameter sonde at the deepest point of each lake. Secchi depth (m) will be estimated by lowering a secchi disk on the shaded side of boat. The research team will collect water samples to quantify dissolved organic carbon, total nitrogen, total phosphorous, chlorophyll-a, and oxygen isotopes. Samples will be analyzed at the Université du Québec à Montréal (UQAM) analytical laboratory. The team will use data provided and in collaboration with Aurora College for inference of metal concentrations in lake water. Oxygen isotopes will be analysed at the University of Ottawa. Crustacean zooplankton communities will be collected by whole water column vertical tows with a 35-cm diameter Wisconsin net from 0.5 m off the bottom to the surface in deeper lakes, or gently pumped for a fixed volume using a bilge pump in shallow lakes less than 2 m deep. The zooplankton will be sampled from four sampling stations along an open-water transect across each lake. The crustacean zooplankton will be anaesthetized with bromoseltzer, preserved with 95% ethanol, and then brought back to the laboratory at the UQAM for identification. The four samples will be subsequently pooled to a single sample per lake for identification and enumeration in the laboratory. The crustacean zooplankton will be identified to species level with a high- resolution dissecting microscope and species will be enumerated for the number of individuals per liter. Crustacean zooplankton will be counted using a protocol that targeted mature individuals that could be identified unambiguously to species, as well as to detect rare species. Phytoplankton will be quantified by three different methods: a) total algal biomass by measurement of concentration. One liter of water will be filtered with a 1.2 micrometer GF/C filter in Yellowknife, preserved, and analysed in at the laboratory at UQAM; B) Collection of 1 liter surface sample of water, and preservation of a subsample of 200-ml of water with Lugol’s solution; C) in-situ identification and quantification of the relative abundance of major phytoplankton taxonomic groups by Fluroproble. Eight 1-L surface water samples will be collected eDNA samples will collected from each lake for eDNA sampling: 4 pelagic samples and 4 littoral samples. These water samples will be immediately filtered on the lakeshore on a chlorophyll filtering manifold. One litre of water from each site will be filtered through a 1.2 micrometer glass fibre filter (GF/F) using a vacuum hand pump. As a negative control, 500 mL of distilled water will be filtered prior to filtering lake samples. After filtration, filters will be immediately folded and stored in a sterile 2 mL microcentrifuge tube containing 700 microliter of buffer that will then be labelled and individually sealed in a zippered plastic bag. Samples will be then immediately placed in a cooler bag containing two frozen gel packs. Filters will be transported to Aurora College, where they were stored in a zippered plastic bag in a -20 degree Celsius freezer. Filters will be transported by flight to Montreal while stored on dry ice; upon arrival they were immediately placed in a -80 degree Celsius freezer. During field sampling, all equipment will be sterilized between lakes using 10% bleach. Communications for research planning and collaboration with Aurora College are already in progress, and have been in progress since 2019. First communication for intent of research project to the Yellowknives Dene First Nation will be sent by email. Field sampling and coordination with Aurora College and reporting of preliminary eDNA results to Aurora College and Yellowknives Dene First Nation via in-person meeting. Collaboration with Aurora College for sharing water chemistry and morphometric lake characteristics. The fieldwork for this study will be conducted from June 28, 2022 to July 13, 2022