NWT RESEARCH DATABASE

Tags: physical sciences, water quality, benthic invertebrates, fish health, water temperature

Objective(s): To determine the range of water temperatures from each of the three cooling systems; to describe fisheries in Jackfish Lake and analyse impacts of the cooling system discharges on the fisheries; and, to record water level data.

Project Description: The main objective of the Jackfish Lake Baseline Environmental Monitoring is to develop and implement a one-year environmental monitoring program to support a 2019 water licence application. Specific objectives are: 1) to determine the range of water temperatures from each of the three cooling systems; 2) to measure annual water temperature regime in Jackfish Lake and analyse any impacts of the cooling system on water temperature; 3) to describe benthic invertebrate and phytoplankton communities in Jackfish Lake and analyse impacts of the cooling system discharges on these communities; 4) to describe fisheries in Jackfish Lake and analyse impacts of the cooling system discharges on the fisheries; and, 5) to record water level data. To record water temperature data, up to 20 HOBO pendant temperature loggers will be installed throughout the lake, in addition up to seven thermistors with a common logger to be installed directly at each intake/discharge structure. One levelogger paired with a barologger will be used to record lake elevation relative to an on-shore geodetic datum. Water quality monitoring in Jackfish Lake will be completed at six stations in Jackfish Lake immediately after ice break-up, as well as one additional program during a period of high temperature. Additional water quality samples may be collected at the intake to the Jackfish facility and in the three discharges from the facility during the spring sampling program. Depth-integrated samples in the euphotic zone will be collected for nutrient analyses to align with the plankton (algal) sampling. Water quality samples will be sent to a qualified lab for analysis of routine parameters, major ions, nutrients, metals, and petroleum hydrocarbons (PHCs). Prior to collecting lake water samples, field profile measurements will be recorded at one-metre depth intervals using a handheld multi-parameter water quality meter to record water temperature, pH, dissolved oxygen, specific conductivity, and total dissolved gases (% saturation). Water depth will also be measured at each lake sampling location. Spot measurements of water temperature, pH, dissolved oxygen, specific conductivity and total dissolved gasses will be collected for the intake and discharge samples. Phytoplankton field work will be conducted throughout the open water period in 2018. Phytoplankton sampling will take place at five locations in Jackfish Lake over five sampling periods. Depth-integrated phytoplankton samples will be collected within the euphotic zone, estimated as two times the Secchi depth. A single phytoplankton sample will be collected at each station, with a duplicate collected every second sampling event, for a total of 28 phytoplankton samples. A single chlorophyll a sample will be collected at each station, filtered in duplicate onto filters in the field and sent to a qualified laboratory for analysis. Benthic invertebrate samples will be collected at five locations within Jackfish Lake. Sampling will be done in September of 2018, which is an optimal time of year to sample due to the relatively large size of invertebrates, largest annual population sizes, and increased stability of the community structure prior to overwintering. Benthic invertebrate community samples will be collected using a standard Ekman grab (15 x 15 x 15 centimetres [cm]) at the designated sampling stations, provided that suitable habitat (soft-bottom substrate) is available. At each station samples will be collected and sieved in the field using a 500-micrometre (µm) mesh sieve bag. Benthic invertebrate community samples will be sent to a qualified taxonomist for taxonomic identification and enumeration. At each of the benthic invertebrate sampling locations, one composite sediment sample will be collected and analyzed (five samples, plus one duplicate sample) to provide supporting information for the benthic invertebrate community analysis. Surficial sediment samples will be collected from the top 10 to 15 cm of sediment using the Ekman grab, and will be submitted for laboratory analysis of particle size, total organic carbon, total metals, and total phosphorus concentrations. In-situ water quality measurements and habitat characteristics will also be recorded at each sampling location to support the benthic invertebrate and phytoplankton community program. Field work will be completed by a three-person crew. Work will be completed using standard fish sampling equipment gear, including a zodiac and gas motor. A combination of fish collection methods will be employed, and may include backpack electrofisher, seine nets, gill nets, minnow traps, and angling. Sampling locations will be documented in the field using a hand-held global positioning system. Visual encounters along the shorelines will also be recorded. Fish collections will be undertaken as per the approved fish permit methods. Supporting environmental information will be recorded for each day of the fish field program. This will include a description of the habitat, weather conditions (i.e., air temperature, wind direction, precipitation type, and percent cloud cover), and in-situ field water quality variables (i.e., water temperature, dissolved oxygen, specific conductivity, and pH). Collected fish will be identified to species, enumerated, measured (total and fork length) to the nearest millimetre (mm); and weighed to the nearest 0.01 gram (g) for small-bodied fish and 1 g for large-bodied fish. An external fish health examination will be conducted. Vouchers will be collected from a subset of fish for identification purposes, where required. Non-lethal ageing structures (scales) will be collected from species captured in sufficient numbers and archived. A total of 10 large-bodied fish of the same species and similar size class will be sacrificed for the collection of muscle samples for tissue chemistry analysis. If incidental mortalities occur then samples will be collected for standard metals and lipids in the tissue. All field work will be completed by trained biologists and engineering who reside in Yellowknife. The study design and final results report will be provided to the Mackenzie Valley Land and Water Board for posting to the public registry. The fieldwork for this study will be conducted from June 4, 2018 to December 31, 2018.