Base de données de recherche des TNO

Régions: Inuvialuit Settlement Region, Gwich'in Settlement Area, Dehcho Region, North Slave Region, South Slave Region

étiquettes: physical sciences, water quality, sediment quality, monitoring

Objectif(s): To evaluate and compare complex and abundant lake ecosystems by learning: where, by how much and why Canadian lakes have changed during the last centuries.

Description du projet: The objective of this project is to evaluate and compare complex and abundant lake ecosystems. This will be addressed through answering these 4 core questions: 1. Where, by how much and why Canadian lakes have changed during the last centuries? 2. How do taxonomic, molecular and biochemical features of planktonic, benthic and microbial communities change with lake alteration and which ones can most effectively be used as indicators of the health of Canadian lakes? 3. What are the optical, size, shape and watershed properties of Canadian lakes that can be applied to “scale up” assessments of health to groups of lakes using satellite data? 4. How will lake ecosystems and their services respond to different scenarios of environmental change? The sampling team of four will put a boat in the lake and find the deepest spot to perform measurements as well as water collection. A mobile lab is set up, which consists of a 10 feet by 10 feet pop-up tent where the team do filtrations and water processing. Water samples parameters include temperature, dissolved oxygen, acidity, fluorescence. A multisonde (RBR multiparametric sonde) is lowered vertically in the water at a constant speed, from surface to 1 m above the bottom of the lake. To measure transparency a secchi disk is used which is a black and white patterned disk used to measure a lake’s clarity. The team record the depths where the disk disappears when descending and reappears when retrieving. To sample bacteria the team will fill two 250 ml plastic bottles with water from about 0.3 m below the surface. To sample dissolved gases the team fill four 140 ml plastic syringes with subsurface water and shake vigorously to release the dissolved gases and store the gases in small glass vacuumed container. For isotopic composition the team fill three 12 ml glass vacuumed container and one 30 ml plastic bottle with water from about 0.3 m below the surface. To sample zooplankton and phytoplankton the team will lower the zooplankton net 1m above the bottom of the lake (max 25 m) and bring back to the surface at slow and constant speed. Methane in sediments from littoral zone will be sampled through disturbing the bottom of the lake near the shore with a boat oar to release gases. Gases will be collected in a 100 mL plastic syringe using a funnel and transfer it in small glass vacuumed containers. Sampling of sediment (mud) at the bottom of the lake is done through anchoring the boat at the deepest point. The sediment corer is lowered and brought back to the surface to retrieve the sediments. Repeat three times. The mud will be used to compare the current and past state of the lake. A national database will be created for Lake Pulse project, which will include data from this sampling effort. The research team will visit 663 lakes across Canada to measure a wide range of lake health variables to extensively characterize these lakes, and these variables will be included in the database. Since the team will be using satellite data to extrapolate lake health from the lakes sampled to a wide range of Canadian lakes, these variable will also be entered in the database. Furthermore, the team collaborate with partners to integrate their large databases into the National Lake Pulse Database. These partners includes several provincial and federal government agencies. Finally, the data in this database will have a public access. In addition, a web portal will be created. The main goal of this portal will be to provide interpreted results to the public. People will be able to compare their lake of interest with other lakes in their area and across Canada. Information on the watershed of their lake and the land use inside of it will also be available. The team are in the process of identifying and implementing other types of interpreted results based on the needs of lake stewardship groups.