In a suburban creek steps from busy roads, biologists sent a mild, electrical current into the water and waited to see what surfaced.<\/p>\n
The stunned fish they scooped up included spiky mottled sculpins, blacknose dace with striking red racing stripes and chunky creek chub \u2014 residents of the largely hidden freshwater world in and around Ontario's towns and cities.\u00a0<\/p>\n
Scientists are using techniques such as electrofishing and environmental DNA sampling to uncover that biodiversity. They are finding far more species than traditional methods have detected, even as many are disappearing or being replaced by invasive species.<\/p>\n
Scientists say protecting creatures from dace and mayfly nymphs to mussels starts with knowing what is there.<\/p>\n
But identifying and measuring freshwater life is challenging.<\/p>\n
A recent study published by University of Guelph biologist Mehrdad Hajibabaei and his team searched for environmental DNA (eDNA) in water from 18 Ontario rivers.\u00a0<\/p>\n
Organisms shed DNA through skin, scales and feces. Using those traces, researchers identified hundreds of aquatic invertebrates that had not been found through traditional methods.\u00a0<\/p>\n
Only 22 species identified through traditional methods were not detected by the DNA survey. Many species were found at just one site, showing how much river life can be missed.<\/p>\n
Last year, CBC News accompanied a team using another technique \u2014 electrofishing \u2014 to count fish in Tannery Creek in Aurora, Ont., near busy streets and subdivisions.\u00a0<\/p>\n
Wearing hip waders, gloves and battery-powered backpacks, Ontario Streams staff dipped pole-mounted rings into the creek, delivering mild electrical shocks that briefly stunned nearby fish. They netted, counted and measured the fish before returning them to the water.<\/p>\n
Kat Lucas, then the group's outreach co-ordinator and spokesperson, said passersby often ask what crews are doing when they see them electrofishing in urban parks around Toronto.<\/p>\n
"They'll be surprised to hear that there are fishes that live in these rivers right through our big cities," said Lucas, who is now an outreach specialist with Credit Valley Conservation.<\/p>\n
Urban creeks are even home to critically endangered species such as redside dace and an Ontario population of Atlantic salmon that went locally extinct a century ago and is now being reintroduced.<\/p>\n
Scientists who compiled data from freshwater surveys around the world reported last year that one-quarter of freshwater animals on Earth are threatened with extinction.\u00a0<\/p>\n
Although half the world's population lives within three kilometres of freshwater, the researchers noted that "declines are continuing, generally out of sight and out of mind."\u00a0<\/p>\n