Water Temperature Monitoring
Maine rivers have been greatly impacted by human activity, such as timber harvesting, agriculture, and industry. Physical alterations (channelizing, removal of riparian vegetation, etc.) and obstructions (dams, roads) have significantly changed the thermal regime of river systems throughout the state. Ponding above dams, lack of overstory, decreased access to cold water refugia - all of these examples of human impact have impacted river temperatures, greatly affecting habitat suitability for a wide variety of aquatic organisms.
Many species have known thresholds; above or below certain temperatures may result in decreased growth, metabolism, and reproductive ability. Knowing the thermal regime of rivers influences the ability to manage for various aquatic species, particularly those that are endangered or threatened. Certain fishes, such as Brook Trout and Atlantic Salmon, are highly sensitive to temperature, particularly when temperatures are sustained above a maximum threshold. For example, temperature limits for Atlantic salmon feeding (positive growth) are between 7.0° ±0.3°C and 22.5° ±0.3°C. (Elliot 1991). Brook Trout exhibit a similar temperature tolerance range, where temperatures below 7°C and above 24°C result in little to no growth (Picard 2003).
In 2006, we began monitoring water temperatures within Maine watersheds in order to better understand areas of high and low habitat suitability for target species. To date, we've set out temperature data loggers at 261 sites within the East Machias, Machias and Narraguagus rivers of Downeast Maine. The first stages were based on opportunity: placing the loggers at our aquatic connectivity project sites. In 2011, we began more systematically collecting temperature data in the mainstem and tributaries of high priority rivers, based on their populations of endangered Atlantic Salmon.
With this data, we hope to further prioritize our habitat restoration efforts and increase habitat quality for all aquatic organisms within these systems.
For more information, see the following reports and presentations.
Craig S, Lowery I. Assessing the Efficacy of Fish Presence and Species Composition at GIS-Derived Stream-Road Crossings in Two Low Gradient Headwater Streams in Downeast Maine. US Fish and Wildlife Service, Project SHARE. 27 April 2010.
Picard C, Bozek M, and W. Momot. Effectiveness of Using Summer Thermal Indices to Classify and Protect Brook Trout Streams in Northern Ontario. North American Journal of Fisheries Management 23:206-215. 2003.
Last updated: January 8, 2016