Sulphur Springs: Chemical Barriers to Fish Movement
barriers, restoration, dissolved oxygen, survey, upstream, fish passage, fish movement, habitat
Several cold water sulphur springs flow into tributaries of the Welland River on the Niagara Peninsula. Sulphur spring water temperature is approximately 9 ºC throughout the year and it contains little or no dissolved oxygen. The water contains high levels of dissolved hydrogen sulphide (> 11 ppm) and it is lethal to fish. Since 2004 we have conducted a series of experiments designed to illustrate the biological ramifications of the sulphur springs on fish and other organisms. At the Buckhorn Creek sulphur spring, there is a "dead zone" with very little dissolved oxygen, high conductivity >3500 ìS/cm, and redox potentials < -200 eV, that extends over 500 m downstream from the spring outlet. In an electro-fishing survey conducted in 2006, fish were present upstream and downstream from the "dead zone", suggesting that fish passage may be possible during periods of elevated discharge; however, during low flow situations, this spring would be a barrier to fish movement and it reduces the amount of available aquatic habitat in Buckhorn Creek. The Buckhorn Creek spring supports a diverse assemblage of chemotrophic algae and bacteria that may be regionally unique, ecologically significant and worth preserving.The spring also contributes to base-flow in the creek during the summer months.