NWT RESEARCH DATABASE

Regions: Inuvialuit Settlement Region, Gwich'in Settlement Area

Tags: permafrost, remote sensing, biogeochemistry, coastal environment, freshwater biodiversity, environmental DNA

Objective(s): To determine the impact of changing land-ocean matter fluxes and coastal subsea permafrost on nearshore ecosystems and biodiversity in the Beaufort Sea.

Project Description: This licence has been issued for the scientific research application No. 5841. The overall objective of this project is to determine the impact of changing land-ocean matter fluxes and coastal subsea permafrost on nearshore ecosystems and biodiversity in the Beaufort Sea. To reveal the trajectory of coastal habitats, it is critical to (1) determine how fluvial and coastal fluxes from the land to the ocean are changing in seasonality, magnitude and composition, (2) assess the fate of this material in the shallow coastal zone, and how this is impacted by climate change, and (3) elucidate the role of recently submerged permafrost in sediment-water gas exchange. All these factors make the Mackenzie River and coastal Beaufort Sea a model system for studying the interactions between changing climate and biodiversity in the coastal Arctic. This project will build on recent terrestrial and marine field work and close an important gap in the shallow water zone (0-20 m) in Kugmallit Bay and Mackenzie/Shallow Bay near the main outflow channels of the Mackenzie River. All planned sampling locations are based on most crucial scientific needs and can be adjusted to community suggestions or potential restrictions in or near the MPA’s. Three periods for field work are envisioned in this project with different focus objectives. Following, we describe details for each planned field period. (1) December 01, 2023 to December 25, 2024: Methods: During this field work period, we plan to deploy 2 current profiler (https://www.teledynemarine.com/brands/rdi/sentinel-v-adcp) equipped with a conductivity, temperature, depth-meter (CTD SBE 37-SMP https://epic.awi.de/id/eprint/39358/1/SBE-37-SMP-ODO.pdf) to deeper locations (> 7m) on the seafloor in Kugmallit Bay (See pink circles on map December 2023). The moorings will be a 40cm high platform sitting on the seafloor without buoyed ropes or instruments within the water column. The moored profiler + CTD will be recovered in August 2024. We will deploy the instruments from the young sea ice in December or January when the ice is thick enough to travel on it. In addition to mooring deployment, we plan to conduct sediment temperature surveys using a temperature lance (pole with thermometer on the end https://epic.awi.de/id/eprint/56505/1/Miesner_etal_MOSES_TemperatureLance.pdf), as well as CTD profiles (SonTek CastAway CTD: https://www.ysi.com/castaway-ctd) through the water column and take surface sediment cores (Uwitech Gravity Corer: https://www.uwitec.at/en/products/corer-60-usc-06000-2/) to access the characteristics and properties of the sediment. Motivation: The current profiler and the CTD profiles will provide valuable information about the water column characteristics and the variability of particle/sediment load and its transport in the water column close to the mouth of the Mackenzie River. Data from the moored CTD on the seafloor will help us to understand the bottom water temperatures and its salinity throughout the winter and summer seasons. The temperature lance data together with the surface sediment cores will provide crucial information about the impact of warming coastal waters on subsea permafrost and consequently the stability of seafloor sediment and its thermal state. This is important to evaluate the potential release of greenhouse gases as well to access potential sediment redistribution of sediments affecting the local bathymetry and marine navigation in the shallow bay. Logistics: The team for field work during this period will be consisting of 1-3 persons (1. Paul Overduin, 2. Julia Boike, 3. nn). The team will be based in Tuktoyaktuk for most of the period. To access the locations on the Kugmallit coastal sea ice, snowmobiles will be used hired from locals in Tuktuyaktuk (e.g. via Erwin Elias, James Keevik). In addition to field work, we will use our presence in the ISR to continue planning and discussing the future field work in spring and summer 2024 together with community and HTCs in Tuktoyaktuk, Inuvik, and Aklavik. It will also give us the chance to organize logistics for those campaigns (wildlife monitors, snowmobile rental, boat charter, …) (2) April 01, 2024 to April 30, 2024: Methods: During this field work period, we plan on working from the ice in Kugmallit Bay. To work through the ice, we will drill ice holes using an electrical ice auger. The main goal is to retrieve long (1 to 5m) sediment cores (using a UWITEC drilling platform https://nextcloud.awi.de/s/WfGYDnDkGrEAX74) at 4 locations (red triangles on the map April 2024). Across a transect of each of the 4 locations, multiple short surface cores (up to 60cm) should be sampled (green diamonds on map April 2024). At each coring location, the temperature lance will be used to measure the sediment temperature. Additionally, CTD profiles throughout the water column along with water samples (5L) at 3 depths (surface, middle, bottom water) will be taken. The water samples will be taken using a UWITEC water sampler (https://www.uwitec.at/en/products/wasserprobenschoepfer-150-l-usb-50015/) and analyzed after transport in laboratories for a set of biogeochemical parameter (water chemistry, carbon and sediment load, nutrients,…). Motivation: Longer cores (longer than <60cm surface cores) will provide a unique long-term perspective and allow us to define baseline rates of sediment and organic matter flux. Biomarker based reconstructions of environmental and oceanographic conditions will provide an important benchmark to assess how modern climate change has altered land-ocean fluxes and document the impact this has had on ecosystem dynamics. Shorter surface sediment cores will provide insights into the sources of the organic matter that is buried to the sediment, its mineralization or preservation and potential methane production and pathways within the sediment. Additionally, the cores will serve to create baseline biodiversity data from modern environmental DNA and from Middle and Late Holocene sedimentary ancient DNA. With the use of sediments from the past ~300 years, we will track the evolution of bacterial and archaeal communities and phytoplankton blooms in light of increased carbon/nutrient input into the coastal waters near the Mackenzie Delta. Additionally, using the method of environmental DNA, we will be able to determine the arrival time of the salmon population near the Mackenzie Delta and reconstruct Beluga mitochondrial variation to assess whether reduced winter sea ice has increased population connectivity. Data from water samples will provide us a snapshot for the current biogeochemical state of the coastal water, i.e. their carbon and sediment load and CO2 and CH4 concentrations. Furthermore, we will use the water samples to identify the sources of the carbon to access the impact of permafrost thaw and mobilization of carbon to the coastal waters. Logistics: The team for this field work period will be 6-9 researcher, which will be based in Tuktoyaktuk. Together with a hired local wildlife monitors and experienced local snowmobile driver, we plan daily trips to the locations on the coastal landfast ice using snowmobiles and sledges to transport the instrumentation. Three to four snowmobiles, two of which with sledges, will be needed to access the sampling locations. Due to logistical and safety reasons, not all researchers from the team will go out on the ice at the same time. 3 researchers are required to work with the drilling platform and two persons can conduct the transects for surface sediment cores, temperature measurements and water sampling along a transect near the deeper drilling location. At the drilling platform location, we will set up a small tent for shelter and a first processing of the cores. We expect to work 3-4 days at each of the four drill platform locations. Before and after sampling, the team will stay in Inuvik for preparation of gear and freight. (3) August 01, 2024 to August 31, 2024: Methods: Focus of the August field work period is water sampling and optical measurements of the water in Mackenzie/Shallow Bay as well as in Kugmallit Bay. The tentative sampling locations are shown by the blue circles in the map August 2024. We will sample water for a set of biogeochemical parameters (temperature, salinity, pH, dissolved/particulate organic carbon concentration and isotopes, colored dissolved organic matter, biomarker, sediment concentration, methane concentration, optical properties of water constituents). We will collect 10L water in cubitainers from different depth across the water column using a UWITEC water sampler at each location. The water samples will be processed and prepared for transport back on shore. At each water sampling location, we will measure light conditions in and above the water using a set of passive radiometers (https://www.trios.de/en/ramses.html). We will revisit selected locations from the spring field work to collect short surface sediment cores using the UWITEC gravity corer. Sediment sampling will be accompanied by temperature lance measurements. Additionally, we will recover the moorings (shown by purple circles in the map August 2024) that were deployed earlier. Motivation: Investigating the biogeochemistry of the water column in the coastal waters near the Mackenzie outflow will inform us about the transport pathways and potentially the fate of the sediment, carbon, nutrients, and contaminants. By sampling a land to ocean transect we aim to better understand crucial processes such as flocculation and degradation of the organic matter when entering the Arctic Ocean. Furthermore, we try to better quantify the role of the coastal waters as a carbon sink or source and how the impact of the river input. The optical measurements of the water constituents (e.g. absorption and scatter of light by organic matter) as well as the radiometric measurements will help to evaluate and validate remote sensing retrievals of matter (e.g. organic carbon or sediment) concentrations. Remote sensing of Arctic coastal waters is and will be a crucial tool to monitor the rapid changes related to permafrost thaw, sea ice decline and warming waters. Logistics: The field team for this period will consist of 6 to 9 researchers. For the sampling in Mackenzie/Shallow Bay it is envisioned to stay 4-5 nights at a cabin from community members of Aklavik at Shingle Point, which would allow a quick access during good weather and sea conditions to the sampling locations. The team at shingle point will be reduced to 4-5 researcher, while the rest of the team will stay in Aklavik. The sampling locations will be accessed by at least 2 boats hired from Aklavik community members. The boats will be captained by the owner of the boats bringing crucial regional experience to the field team. Processing and first analysis of samples and their preparation for transport will be done after sampling back at Shingle point or in Aklavik. For the sampling in Kugmallit Bay, the team will be based in Tuktoyaktuk. As in Mackenzie Bay, we will use two boats hired from and captained by community members in Tuktoyaktuk. Processing and first analysis of samples and their preparation for transport will be done right after sampling back in Tuktoyaktuk. For safety reasons, sampling from the boats will happen only during suitable weather and sea conditions and both boats will always stay close to each other in case of engine failure. Before and after sampling, the team will stay in Inuvik for preparation of gear and freight. In order to communicate the project and its results, the researchers will stay in contact with the HTC and our local partners, by e.g. sending out informative letters to the HTCs. Communication may range from simple reporting of results to collaborative, reciprocal knowledge-sharing. The researchers have visited the communities (Aklavik, Tuktoyaktuk and Inuvuk in February and July to discuss, prepare and inform about this project (dialogue with communities below) and presented our project at THTC and AHTC and left information material (maps + project flyer). In addition results will be shared when the researchers visit the community again in the year after the field work. Due to the long lasting activities of the Alfred Wegener Institute, we can make sure to report our results even after this particular project ends. It will include: meetings, presentations in the community and schools, written field reports, copies of publications or theses, co-authored publications and interactive multi-media websites. The fieldwork for this study will be conducted from: April 01 - April 30, 2024, August 01 - September 10, 2024