Theory on didymo problem

afishinado

afishinado

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Very interesting theory on the spread of didymo:

VIU PROFESSOR UNCOVERS THE MYSTERY OF ROCK SNOT

By Dane Gibson

After spending almost 40 years as a research scientist at Environment Canada, Dr. Max Bothwell is finally hanging up his hip waders. But not before he helped solved a seemingly unsolvable mystery that stumped scientists from around the world – including Bothwell himself – and had him slogging through algae-clogged rivers in countries all over the globe.

Dr. Bothwell is a Vancouver Island University (VIU) adjunct professor and world-renowned expert in algae and algae growth in rivers. Hired by Environment Canada as a research scientist in 1979, over the next decade he published many scientific papers on the topic. It wasn't until 1993 that he came face-to-face with the mystery that would define his professional life. Seemingly out of nowhere mucus-like, thick gelatinous mats of yellowish -brown algae were found clinging to rocks on the river bottoms of some of Vancouver Island's most pristine rivers. Sometimes stretching for kilometers, it wasn't long before the algae known as Didymo, short for Didymosphenia geminata, got the moniker it would be more commonly identified by - "rock snot."

"I was working in Saskatchewan in 1993 when a friend of mine called from Nanaimo and told me huge algae blooms were happening in some very remote rivers on Vancouver Island. He asked if I could come out to take a look because they had never seen anything like it," said Bothwell.

The first recorded bloom occurred in the Heber River near the Vancouver Island community of Gold River. With the support of Environment Canada and the BC Government's Ministry of Environment, Bothwell arrived and found himself conducting extensive field/laboratory testing in several Vancouver Island rivers as well as exploring historical data records to try and figure out what was causing the phenomenon.

"I studied it for a couple of years and realized I couldn't figure it out. Here I was a world authority on river algal blooms and my final report basically concluded something is happening and I don't know what it is," said Bothwell. "I left the field of periphyton ecology and many years passed without rock snot crossing my mind. It was a problem I couldn't solve so I had to forget about it."

Bothwell says the algae blooms are a concern to governments because the blooms have an impact on the environment including river habitats, water flows and fish spawning grounds. The blooms are also despised by anglers who spend a lot of money to fish unspoiled, remote river systems. In 2004 Bothwell received a call from a colleague in New Zealand. They were dealing with an infestation of Didymo and needed help.

"My friend from New Zealand is on the phone saying, 'Rock snot is taking over several rivers on the South Island of New Zealand, it's a disaster - you have to help us!'" said Bothwell. "As he's talking I'm thinking to myself, 'Oh boy, here we go again.'"

Bothwell spent two years working with a team of biologists in New Zealand to develop a strategy for the New Zealand government to deal with Didymo. Their report concluded, among other things, that Didymo, previously unknown in New Zealand, was likely introduced to the country on felt-soled waders used by anglers who came from all over the world to fish. Because of their work the New Zealand government banned the use of felt-soled waders in the country.
But even after finishing his work in New Zealand, reports of rock snot blooms taking over rivers around the world continued to increase. Bothwell spoke about the issue in places as diverse as Chile and New Hampshire, yet he knew ground zero was Vancouver Island and it got him thinking that something other than movement by fishermen had to be happening.

"I started questioning if introduction by anglers could be causing all of this and decided it couldn't be. I began thinking of the Heber River as the smoking gun," said Bothwell. "Blooms were occurring all over the world now, but why did this start happening on Vancouver Island over 10 years previously? What was so special about this place?"
He refocused his attention and with the help of VIU Department of Chemistry student researchers, they began looking for anything unusual that might have affected the Heber around the time of the first recorded blooms. They combed through fishing license data and historical records, but it was reports from the BC Ministry of Forests that eventually led to solving the mystery.

Donovan Lynch is currently the Science Operations Manager for the Pacific Biological Station in Nanaimo but 15 years ago, the VIU chemistry graduate started work with Bothwell on a number of projects, including rock snot. Bothwell offered him a job when he was still a VIU student and it led to him working at Environment Canada for eight years.

"I was keenly interested in the rock snot story because I was an avid fly fisher and did a lot of hiking into remote places. During that time we were finding rock snot in areas you just wouldn't expect," said Lynch. "We had sent out papers saying it appeared to be transferred by hip waders and yet we kept seeing it in rivers that weren't being fished. A lot of the work we did back then led Max onto a different path."

The forestry reports they uncovered showed that in the 1980s the BC government started one of the largest forest fertilization programs in the world. They used helicopters to drop more than 1 million kilograms of urea fertilizer on forests to increase tree production. The data showed some of the first drops occurred in the Heber River watershed.

Bothwell now had a solid event he could focus on. After running experiments and looking at water quality data from that time Bothwell focused in on phosphorus levels in the Heber and was shocked by what he found. Instead of phosphorus levels rising in the rivers due to the fertilizer drops, it actually dropped to next to nothing.

"When they started fertilizing the forests it stimulated not just tree growth but all soil microbial activity. The forest floor is a huge network of microorganisms and it was taking up the phosphorus that would usually run into the river," said Bothwell. "We could finally show that the aggressive growth of rock snot is caused by ultra-low phosphorus conditions, something that was very hard to accept. We all knew that adding more nutrients, especially phosphorus, to a river system always equals more algae and here I came face-to-face with the exact opposite of that. It was unbelievable."

Bothwell's discovery brought a new understanding of how and why rock snot behaves the way it does. It's now suspected that the microscopic algae naturally resides in all rivers and climate change-associated environmental changes trigger the exponential growth that causes the blooms.

Bothwell's hypothesis is that climatic warming of landscapes increases the level of biological activity on land and decreases the amount of phosphorus entering rivers, causing conditions similar to the effect of adding urea fertilizer. Add to that increasing levels of nitrogen from fossil fuel use and you get the perfect conditions for the blooms to occur.

Dr. Bothwell is retiring this year having rewritten the scientific understanding of the causes of Didymo blooms, but he won't be settling in to a life of leisure. He will maintain an office at VIU's Fisheries and Aquaculture Department to support research projects, conduct lectures and provide assistance to VIU's International Centre for Sturgeon Studies.

"To me, it feels like I solved my professional life's greatest mystery. Discovering the connection between low phosphorus and rock snot was an amazing 'aha' moment," said Bothwell. "Now I look forward to working with VIU students who will be going off to find their own great mysteries to solve."


Link to source: https://www.viu.ca/news/viu-professor-uncovers-mystery-rock-snot
 
Somebody please show this to Maryland DNR so that they know for sure their felt sole ban is a scam. Great article afish, thank you for posting.
 
I read the article and wanted to see more evidence that the low Phosphorus was the cause. It would seem that adding phosphorus to the streams should get rid of the rock snot? No record of this being tried,from what I read. GG
 
I think it is safe to say that trout biologists all over are well aware of this, even in MD. I do not see it likely that they would walk back the felt ban for a variety of reasons--social, legal and biological.
 
Interesting, thanks for the link.

The conclusion - that there is an inverse relationship between phosophorus and snot blooms - seems counterintuitve at first. Yet, we anglers have known for a long time that these blooms are prevalent in tailwaters rather than limestone or meadow streams. Streams that have didymo present but no blooms tend to be "richer" and this may play a natural role in suppressing the blooms(?).

Very interesting indeed. I agree, it may be premature to expect felt sole bans to be dropped, but this has been the trend and research such as this will likely continue to press against felt bans.
 
not counter intuitive to me. Many single celled organisms undergo a transformation towards "dormancy" during nutrient limitations. Didymo can be actively replicating (dividing) when nutrients are rich and then go to a protective/survival mode (stalk or mat formation) when starved. Mat formation appears to be an adaptation to obtain phosphorous (although they may do so for the nutrients too, I'm not sure). The low phosphorous is likely sensed due to the inability of cells to make building blocks to replicate their genome (DNA) and undergo cell division.

This behavior is most similar to how a type of bacteria switch between swarmer and stalk cells (for the geeks, see: https://microbewiki.kenyon.edu/index.php/Caulobacter)

It is also similar to biofilm formation- but not as close to the other example (also for the geeks: https://en.wikipedia.org/wiki/Biofilm)

As for the idea of treating streams with phosphorus: bad idea. high phosphorous levels degrades water quality. Among other things it promotes algae growth. This is good for some caddis, but bad for intolerant bugs like may flies and stone flies. Most waste water treatment plants are reducing P levels.

The installation of P reducing measures at the Altoona wastewater treatment plant greatly reduced P levels downstream. This is correlating with (direct cause unclear) the appearance of pollution intolerant may flies and stone flies in the upper little J. The improvement in water quality may actually hurt the grannom and other caddis hatches. This is being monitored.

 
Good info nymph. So what kind of condition change could cause the blooms on the gunpowder to be non existent for years and then all the sudden have heavy blooms every year?
 
IDK. Phosphorous appears to be a trigger, but it in itself likely can't make a stream prone to didymo
 
It just seems strange, it was like a light switch.
 
Really interesting read!!! Ryan can probably attest to this, but I've have always been intrigued with the dydimo behavior in the Savage vs. the North Branch. Anyone who fishes them know that both are tailwaters in close proximity, with similar gradient and hatches... The Savage is much more fertile with bug life density, stream vegetation and scuds. The Savage can have thick didymo depending on high water/ flush events or lack there of... The North Branch displays little to no dydimo blooms to my recollection. The only difference is the limestone doses that the North Branch receives to combat the old acid mine issues and balance the PH. Any scientists/ awesome geeks that can explain this??? As Dave alluded too earlier, I cannot think of too many if any limestone influenced streams that suffer from the dydimo problem. Please prove me wrong if I'm mistaken on this, but I think we are on to something. And if it gets me back into felt sole boots, my knees and ankles would be so grateful.
 
Limestone enhances Phosphate and Nitrate uptake efficiency by plants.
 
The pH levels determines the amount of free versus that sequestered in insoluble complexes. Calcium carbonate should reduce soluble phosphate (calcium phosphate is very insoluble and reduced free usable phosphate). If pH is the difference, it may affect the balance between organic and inorganic phosphate.
This is opposite of your theory. I seem to recall low pH reduced didymo mats (low pH should = more free phosphate). I suspect pH is not the only difference between those streams (I had never visited them and know nothing about them). I would look for something different between those streams.
 
I appreciate the answer that goes far beyond my scientific knowledge base... I don't know specifics, but reason would tell me that the PH levels are similar between the two rivers. The difference being that the Savage has a self balanced PH sustainable for trout, and the N Branch requires man made limestone dosers to combat acidic levels from the old mines around Barnum and Little Georges creek. For some reason the dydimo heavily effects the naturally regulated stream with regards to PH(Savage), and is pretty much non-existent in the North Branch.

The negative side effect of the dosers is that the limestone coated bottom of the North Branch is like ice covered bowling balls to walk on.
 
The savage has always had a ton of native algae, decades before the didymo blooms. The north branch never had any algae, at all. Like 3weight my scientific knowledge on algae isn't good but I think there might be something to what you said about the round rocks. The top pool just below the no trespassing sign was covered in the stuff six months ago, nowhere else though. Last time I was there it was gone, I guess the high flows ripped it out of there.
 
AMD waters could have higher metal contents, sulphates. Ryan has a key piece of information- one stream supports algae growth, the other does not. This might mean the stream is not conducive to supporting enough of a biomass of didymo to form mats
 
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