Stuck on the back window of a car I was traveling behind was a sign, "Say No to Didymo!"
You mean there are people out there who aren't saying No to didymo?
I find it hard to believe that anyone is a great promoter of Didymo, that wondrous sludge that's taking over our New Zealand rivers and causing problems for fish and other creatures living in these waters.
Didymosphenia geminata is also known as rock snot (a far more descriptive and useful name), and is a pervasive river weed that covers rocks, and water plants and river bases with a thick brown slime. Even though it looks like slime, it's actually feels more like cotton wool - cotton wool, that is, that's been used for some rather dubious purposes such as wiping a baby's bottom.
If we want to get scientific, rock snot is an algae which starts off as a cell that's invisible to the naked eye, and spreads whenever it finds a home - which isn't hard for this unpleasant relative of seaweed.
Who would want to say Yes! to didymo? Fishermen abhor it because it tangles up lines, swimmers sometimes get eye irritation from it, people often mistake its trailings for shredded toilet paper and think someone else has been discharging sewerage into the river.
No one yet seems to know why this pernicious algae has received a license to spread so thoroughly, though some scientists consider it might have something to do with climate change, wherein the warmer waters favor this beast. It may be that a particular genetic variety is tougher than other algae.
And unfortunately it's very difficult to deal with. Telling fishermen and swimmers to clean off their boots or feet after using water is of minimal use, since the algae needs a minute amount of assistance to spread.
And before we interfere with it in some chemical fashion we need to be sure that we aren't damaging something else in the process. Perhaps what is needed is some other natural "creature" that enjoys eating brown sludge to come along and start disposing of it. But where is such a creature?
