Rock snot's rise stumps scientists
Rock snot has been spotted in parts of British Columbia since at least the late 1980s, but whether the brownish slime has significant impacts on aquatic systems remains unclear, says a federal government scientist.
Rock snot, or Didymo, is a type of algae that lives primarily at the bottom of rivers. Its disgusting nickname comes from its greenish-brown colour, though large masses are often described as looking like toilet paper because they take on a white-ish hue.
Max Bothwell, an Environment Canada research scientist who co-authored a paper on the cause of rock snot blooms in 2014, says he was first exposed to it in the Bulkley River in the mid-1990s. Blooms were found on Vancouver Island in the mid-1980s.
"It seems most research has indicated that the largest, pronounced mats form when phosphorus concentration ... gets very low in rivers," he told Daybreak North.
"This has been an enigma for a long time because traditionally, aquatic biologists associate large amounts or accumulations of algal material in either lakes or rivers … with adding phosphorus or nutrients to rivers."
Bothwell says most studies indicate that rock snot has no major impact on the growth or survival of aquatic species. However, he says research out of Colorado suggests Didymo blooms have resulted in a lower growth rate of brook trout.
Bothwell says "the overall picture is not clear," and more research is needed.
Dartmouth College ecologist Brad Taylor, who co-authored the 2014 study with Bothwell, has said that rock snot blooms can make it harder for salmon and trout to see and forage for food. They can also increase the abundance of a worm that hosts a parasite that causes "whirling disease" in salmon and trout.
The Invasive Species Council of British Columbia also says on its website that massive blooms of rock snot causes "significant negative impact to freshwater fish, plants and invertebrates through habitat and food web alteration."
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