As part of the Elk River Alliance's Community-based Water Monitoring Program, we have been conducting monthly monitoring (April-October) on one site at Alexander Creek. This monthly protocol began in April 2015 and includes a continuous temperature logger, which is left in the water to measure daily minimum and maximum temperatures.
Between April and October, the highest maximum temperature recorded was 13.9C; the lowest minimum temperature recorded was 0.8C; and, the average temperature was 6.7C.
For more information on why water temperature is important for aquatic health, keep reading!
Water temperature is closely correlated with dissolved oxygen saturation, because colder water can hold more dissolved oxygen. (Why?). More dissolved oxygen makes it easier for fish and aquatic invertebrates to breathe. Also, in warmer water organisms have a higher metabolic rate (i.e. they use up more oxygen).
Alexander Creek is home to two types of blue-listed fish species: Westslope Cutthroat trout (Oncorhynchus clarki lewisi) and bull trout (Salvelinus confluentus). Blue-listed species are species of special concern (formerly 'vulnerable') as declared by the Ministry of Environment.
Both the Westslope Cutthroat trout and bull trout are sensitive to temperature and have optimal temperature ranges as well as maximum lethal temperatures which they can survive. Neither fish species can survive temperatures above 20C for an extended period, and temperatures about 18C cause stress in fish. The Ministry of Environment sites a maximum temperature of 15C for aquatic health in streams that host bull trout. Temperature is also important for spawning purposes. In Westslope Cutthroat trout (spring spawners) when mean temperature increases to between 7-10C, Cutthroat trout begin migration to spawning grounds. In bull trout (fall spawners) evidence suggests that spawning is triggered when water temperatures drop below 9C.
For more information on temperature and both species of fish, check out the references below.