Originally Posted by
DaleW
Did I not read some place that the "experts" where having second thoughts about all the bad things they said about felts(?)
Max Bothwell, a research scientist for Environment Canada, who wrote an influential article that linked angler's felt soled boots to dydimo spread has now reversed himself and said that anglers are not responsible.
Here is his original article, On the Boots of Fishermen:
http://www.env.gov.bc.ca/wat/wq/stud...ymo-blooms.pdf
He now believes that dydimo has been in North American waters and that it is a change in water chemistry, specifically lower phosphorus levels that has caused dydimo blooms.
Read the article in the current issue of American Angler, July-August, 2013, pp 8-9.
"'I no longer believe the problem is North American streams is the result of it (dydimo) being moved around.' ?. Scientists are now convinced that dydimo lives in many streams, but blooms only when the water has far less than the normal amount of phosphorus?? The most damaging dydimo episode in the US seems to have been on Rapid Creek in South Dakota, where a six-mile bloom dramatically impacted a blue ribbon brown trout fishery. In 2007 and 2008, Bothwell and other scientists added phosphorus to sections of Rapid Creek. Sure enough, the dydimo mats shrank"
He published his findings in Freshwater Biology (2012) 57, 641?653 in an article titled:
Didymosphenia geminata growth rates and bloom formation in relation to ambient dissolved phosphorus concentration
"The blooms were present only in rivers where average dissolved P was very low. Didymo in higher nutrient waters had higher cell division rates, shorter stalks, and did not form blooms.
.... the blooms are caused by low nutrients in the overlying water, which promotes excessive stalk production. Subsequent surveys, experiments and observations in New Zealand have all been consistent with low nutrients (specifically low P) driving the blooms."
http://sciblogs.co.nz/waiology/2012/12/19/what-causes-didymo-blooms-rock-snot-in-nz-rivers/
I think this recent discovery makes more sense than the old theory that all of a sudden dydimo sprang due to anglers boots when anglers have been using these same rivers for over a century with no dydimo blooms.
What is causing the dydimo blooms, I surmise, is the current trend of reducing phosphorus in detergents and lawn fertilizer. So as we get rid of phosphorus to prevent algae blooms we get dydimo blooms.
Ever wonder why NZ has such a problem with dydimo? They have lots of crystal clear streams and rivers with low phosphorus because there is little run off from agriculture and lawns.
Basic epidemiology 101 states that we cannot stop the spread of what has already spread. How we then prevent disease is to make the target population less receptive to the disease. We allow the addition of some phosphorus into fertilizers in the river drainage of these dydimo affected rivers.
Regards,
Silver
"Discovery consists of seeing what everybody has seen and thinking what nobody has thought"..........Szent-Gyorgy