Biogeochemistry of Lakes in the Mackenzie Delta

Regions: Inuvialuit Settlement Region, Gwich'in Settlement Area

Tags: physical sciences, water quality, hydrology, carbon dioxide, carbon, methane, nutrient levels

Principal Investigator: Lesack, Lance (23)
Licence Number: 15846
Organization: Department of Geography, Simon Fraser University
Licenced Year(s): 2017 2016 2015 2014 2010 2009 2007 2006 2005 2004 2003 2002 2001 2000 1999 1998 1997 1996 1995 1994 1993
Issued: Mar 15, 2016
Project Team: Mitchell Bergstresser (MSc student, SFU), Kimberly Geeves (BSc student, SFU), Lance Lesack (Principal Investigator, SFU)

Objective(s): To improve the understanding of microbial carbon-processing in Mackenzie Delta lakes and how it is affected by the changing water levels; and, to decipher the impact of water level changes on the ability of the Mackenzie Delta to affect riverine nutrient flow to the ocean.

Project Description: The objectives of this research are to: 1) Improve our understanding of microbial carbon-processing in Mackenzie Delta lakes and how it is affected by the changing water levels/ and 2) Decipher the impact of water level changes on the ability of the Mackenzie Delta to affect riverine nutrient flow to the ocean.


Specific activities for the coming field season include the following:

This work will help resolve what drives microbial communities in Mackenzie Delta lakes to release the carbon in these waters to the atmosphere or to convert the carbon to a form consumed by fish and other organisms. Field work over the 5 years will be based on four areas within the delta, plus delta channels by the water gauging stations of Water Survey Canada, where the research team have worked extensively in the past.

Objective (a): Assess open-water abundances of methane-producing and methane-consuming bacteria among Delta lakes. This will be done by tracking bacterial community compositions within the water columns and sediments in the study lake network throughout the ice-free period. All fieldwork will be based from the Aurora Research Institute in Inuvik. Detailed weakly analyses of bacterial community compositions related to methane during open-water (from June through August) will be compared in 2 thermokarst lakes versus 2 macrophyte-rich lakes versus 2 high flood-frequency lakes within Delta Lakes. These lakes will be accessed from Inuvik by boat. To interpret the bacteria compositions, lake-water samples will also be collected for measurements of dissolved gases, dissolved organic-carbon content, and underwater light transparency.

To understand how results from the above lakes fits within the greater delta, samples of methane-related bacteria and lake-water also need to be collected in a larger set of lakes at 3 differing times from just after ice-out (early June) until late summer (latter August) conditions. Based on past experience, these samples can be collected from the helicopter floats and the flying can be completed in one day.

Objective (b): Assess abundances and distribution of methane-producing bacteria prior to winter ice-out among delta lakes. During spring, the research team will focus field efforts on identifying (for the first time in any Arctic delta lakes) the specific compositions of the bacterial communities that create the high build-up of under-ice methane and the degree to which this happens among delta lakes. This will be done by measuring the end-of-winter bacterial community compositions within the unfrozen water columns and sediments in the study network of 40 lakes within Delta Lakes Area prior to ice out. To interpret the bacteria compositions, lake-water samples will also be collected for measurements of dissolved gases, dissolved organic-carbon content, and sediment samples for organic-carbon content will also be collected. This requires landing on the lakes and augering through the ice for sample collection. Based on past experience with ice augering, this work can be done in a relatively short period by accessing these lakes by helicopter during early to mid-May.

The research team will publish the results of the work in top-ranked scholarly journals that are subscribed to by the library at the Aurora Research Institute. To make results more accessible to communities in the NWT, the Principal Investigator has created and maintains websites on the long-term Mackenzie Delta research (http://www.sfu.ca/limnology) and the past International Polar Year research (IPY-SCARF) (http://www.sfu.ca/ipy). This promotes this research and highlights student opportunities for training in Arctic-based research. The research team have given interviews via newspaper (Globe and Mail, Associated Press, Vancouver Sun, Edmonton Journal, News/North), radio (CBC North, Ends of the Earth), TV (CBC Northbeat), and Web-video (Rosenberg International Forum on Water Management in the Mackenzie River Basin). The research team are also happy to give a presentation or meet with anyone that might be interested in hearing about the work.

The fieldwork for this study will be conducted from May 1, 2016 to August 28, 2016.