The limnological response of Arctic deltaic lakes to alterations in flood regime

ABSTRACT

Arctic freshwaters are being rapidly altered by global climate change with consequences to hydrology, biogeochemistry, and ecology, but in many cases the trajectory of these changes is poorly understood. We collected a unique 5-year time series of major ion, nutrient, and trace metal data from lakes in the Mackenzie Delta (NT, Canada) to examine limnological changes during a period of variable flood conditions, including years of recent historic high and low peak river levels. Previous work in the Mackenzie Delta has established that lake water chemistry is strongly related to connection time with the river during the period of spring ice-jam flooding or via channel connections through the growing season. We show that differences in peak spring water levels explain differences in lake chemistry in lakes isolated from the channel during the summer. Isolated, macrophyte-rich lakes in the Mackenzie Delta have been shown to be CO₂ absorbers during summer. We demonstrate a response to alterations in flood regime by variables related to macrophyte productivity in isolated lakes with the greatest connectivity to the river that suggests productivity declines with increasing connection time. The connectivity of low-elevation lakes, which represent a majority of lake number and area in the Mackenzie Delta, has been projected to increase with climate change. Our work suggests that an increase in connection time may decrease the macrophyte productivity of these lakes, with potential consequences to the CO₂ balance of individual lakes and the Mackenzie Delta as a whole.

KEYWORDS:

• Arctic lakes
• carbon balance
• climate change
• hydrological connectivity
• Mackenzie Delta

Acknowledgements

This research was conducted as a part of Scientific Research Licenses 15272, 15403, 15652, 15811, and 16149 from the Aurora Research Institute and supported by an NSERC Discovery and NSERC Discovery Northern Research Supplement grants to RQ and Northern Scientific Training Program support to RWS. We thank the Western Arctic Research Centre, Aurora Research Institute for technical and logistical support, and to Jolie Gareis, William Hurst, and Edwin Amos for their valuable advice and assistance. We are grateful to Suzanne Tank (University of Alberta) for comments on an earlier version of this manuscript. We thank Andrew Medeiros, Christopher Luszczek, Sara Masood, Frankie Talarico, Cait Carew, and Dmitri Perlov from York University for assistance in the field.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by Canadian Network for Research and Innovation in Machining Technology, Natural Sciences and Engineering Research Council of Canada.