On the topic of invasive species, here's one about algae spreading worldwide on the soles of hip waders: "Fly Fishers Serving as Transports for Noxious Little Invaders".
“We people are clearly the vector for its spread,” said Jonathan McKnight, a wildlife biologist with the Maryland Department of Natural Resources who is trying to protect streams like the Youghiogheny River from didymo, whirling disease and other aquatic invaders.
“It’s fly fishermen who are doing it,” Mr. McKnight said. “The people who love and appreciate those rivers the most have got to be the ones protecting them.” He said his department planned to ban felt soles this fall.
Not in the story: the British Columbia streams where didymo originated were mostly under glaciers 10,000 years ago. It was a rapid invader in that habitat long before fishermen got involved.