

A strange green organism has spread, clogging up the world's rivers - alonestar
http://www.bbc.com/earth/story/20140922-green-snot-takes-over-worlds-rivers?OCID=fbindia

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tokenadult
This finding reported in the article is interesting: "Related to this
discovery is an extreme irony. Governments and organisations around the world
have, for a very long time, tried to stop algal blooms from strangling rivers
by reducing phosphorous pollution, believing the algal feed off this nutrient
boost. But in doing so, they might have encouraged the green snot that is
Didymo. 'It goes against everything we’ve been thinking for 50 years,' says
Spaulding."

The main takeaway from this interesting article is that we still need to do a
lot more foundational science about microorganisms and their ecological
relationships with various changes in the natural environment.

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hyperbovine
Or more fundamentally: attempts at eco-engineering are destined to fail. This
is the most ironclad reason I can come up with for why conservation is the
only route.

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freehunter
The problem is, things get damaged. Sometimes very severely. It's not possible
to keep everyone from acting irresponsibly, and as humans in a modern society,
we have a lot of impact on nature. All it takes is one ship with a handful of
zebra mussels to infest the entire Great Lakes ecosystem. All it takes is one
person accidentally releasing Asian grass carp for it to infest the entire
country. All it takes is one farmer using a bit too much fertilizer to form
massive algae blooms in a nearby lake.

Conservation is an important preventative step. But that's like telling a
bleeding person that they shouldn't have stepped on that nail. The damage is
done, and the patient needs antibiotics and stitches now. It's important to
prevent damage from being done, but it's just as important to fix it after the
fact.

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hyperbovine
With both Asian carp and zebra mussels, (and lionfish and starlings etc etc
etc) we are essentially powerless to stop their advance. To extend your
metaphor, we literally have nothing in the way of antibiotics and stitches to
salve this wound. We need to be trying orders of magnitude more than we
actually are to prevent such calamities from happening in the first place.
People have this misplaced faith the we as a race can engineer our way of out
any problem, and it's just not true. Ban the nail, I say.

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hcarvalhoalves
Diatoms are primary producers and the fastest growers. If they are thriving
it's a signal the water quality has dropped and they are doing their job,
consuming the excess nutrients, so trying to kill it makes no sense.

While they feed on nitrogen and phosphorus their limiting nutrient is
silicates, so maybe it's tied to siltation (erosion making it's way into water
bodies). I don't see this mentioned on the article.

~~~
lvh
Part of the main thesis of the article is that _unlike_ what we've seen from
diatoms in the past:

\- the growth is not a traditional growth in the reproduction sense; \- the
growth appears to be linked to _low_ phosphorous levels, not high ones.

As a result, I don't think your first comment makes any sense.

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hcarvalhoalves
It's about nutrient imbalance, not simply excess of nutrients across the
board.

You can have, e.g., a high silicates and low phosphorus situation driving this
particular diatom, simply because phosphorus is not the limiter (as I have
already stated is the case for diatoms). If you had a different nutrient
balance, there would be competition with other organisms, so no growth in the
first place.

Whether it's reproductive or vegetative growth is irrelevant, because the
mechanism of competition is the same: it covers surfaces and outcompetes other
colonies.

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vosper
"[...] its biggest impact seems to be aesthetic. 'The main effect of Didymo is
how it changed the appearance of rivers and streams,' she says. 'It's not
toxic. It really doesn't do anything really awful.'

This is true, but it can cause problems for people swimming downstream:
"people swimming in waters downstream from areas containing high
concentrations of Didymo have complained of eye irritations, which may be
caused by the silica of the frustules."

[http://www2.gnb.ca/content/gnb/en/departments/natural_resour...](http://www2.gnb.ca/content/gnb/en/departments/natural_resources/fish/content/Didymo.html)

~~~
privong
Is it true? I have been told (by an ecologist) that it can use up nutrients
and overwhelm a stream, killing a lot of the original inhabitants. Apparently
its "invasive behavior" is an interesting response to a lack of nutrients – it
undergoes explosive growth in an effort to search for nutrients. I can see
where that might be an undesirable run-away process.

~~~
freehunter
I would be interested in knowing more about how it undergoes explosive growth
when its food supply gets low. Sounds like the opposite of most species, and
that's an interesting evolution to take.

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privong
Here's a review of sorts:
[http://bioscience.oxfordjournals.org/content/64/6/531.full](http://bioscience.oxfordjournals.org/content/64/6/531.full)

And one study:
[http://www.ias.sdsmt.edu/staff/sundareshwar/Reprints/Sundare...](http://www.ias.sdsmt.edu/staff/sundareshwar/Reprints/Sundareshwar%20et%20al%202011%20GRL%20with%20Auxiliary%20material.pdf)

Abstract from the second paper:

 _In recent decades, the diatom Didymosphenia geminata has emerged as nuisance
species in river systems around the world. This periphytic alga forms large
“blooms” in temperate streams, presenting a counterintuitive result: the
blooms occur primarily in oligotrophic streams and rivers, where phosphorus
(P) availability typically limits primary production. The goal of this study
is to examine how high algal biomass is formed under low P conditions. We
reveal a biogeochemical process by which D. geminata mats concentrate P from
flowing waters. First, the mucopolysaccaride stalks of D. geminata adsorb both
iron (Fe) and P. Second, enzymatic and bacterial processes interact with Fe to
increase the biological availability of P. We propose that a positive feedback
between total stalk biomass and high growth rate is created, which results in
abundant P for cell division. The affinity of stalks for Fe in association
with iron-phosphorus biogeochemistry suggest a resolution to the paradox of
algal blooms in oliogotrophic streams and rivers._

~~~
freehunter
Thanks! Exactly what I was looking for.

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mcmancini
This crap has been a PITA a for flyfishers for a while. Rock snot is an apt
name for it because it is treacherous when you're wading. Personally, I prefer
felt boots because they have better traction, but they're also an easy vector
for didymo and it's just not responsible to use them anymore since I'm in
multiple rivers. I ended up switching to rubber boots. Not nearly as nice to
walk in, but far less likely to have didymo hitchhiking along when practicing
proper river hygiene.

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nether
Didymo is edible btw, and Rob Rhinehart has talked about future Soylent
ingredients being made by bio-engineered algae.

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ChuckMcM
Where did you see / read that? That suggests an expansion in the turtle
population. I haven't seen anything like that mentioned yet but would love to
find it. I'm still on the lookout for a species that evolves into something
which can only survive in an EPA superfund site so that cleaning up the site
will cause the extinction of the new species. Just thinking about the
Environmental Impact Statements on that possibility makes me chuckle.

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ggchappell
Interesting article, but the images I'm getting are all extremely low quality.
Tried both Chrome & FF.

EDIT: Well, downvotes or not, I'd still like to know what is going on. Here is
a screenshot of part of my browser window while viewing the article.

[https://imgur.com/IcEyM3R](https://imgur.com/IcEyM3R)

I assume others are getting higher quality images (?).

~~~
ars
It was fine for me, although the images were much delayed on loading, so there
is some javascript acting there. Are you using noscript?

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ggchappell
> Are you using noscript?

No. The only thing I explicitly block is flash. (Also, I don't recall having a
problem like this before.)

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ars
What url do you have for the bad images?

A good image url is:
[http://ichef.bbci.co.uk/wwfeatures/1280_720/images/live/p0/2...](http://ichef.bbci.co.uk/wwfeatures/1280_720/images/live/p0/27/l1/p027l1df.jpg)

~~~
ggchappell
I get this:
[https://ichef.bbc.co.uk/wwfeatures/304_171/images/live/p0/27...](https://ichef.bbc.co.uk/wwfeatures/304_171/images/live/p0/27/l1/p027l1df.jpg)

Probably this isn't worth a whole lot of work; I guess it thinks I'm on a
phone (I'm not).

~~~
ars
What's your user agent? Maybe you set it funny and forgot.

[http://www.useragentstring.com/](http://www.useragentstring.com/)

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dildog
The Andromeda Strain

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czahor
And then it will disappear, and the only person who will truly know what
happened will be Fox Mulder.

