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A strange green organism has spread, clogging up the world's rivers

bbc.com

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Re: A strange green organism has spread, clogging up the world's rivers

#21

Post by freehunter »

hyperbovine wrote: post #19
tokenadult wrote: post #3

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…

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.

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.

Re: A strange green organism has spread, clogging up the world's rivers

#22

Post by freehunter »

privong wrote: post #11
vosper wrote: post #9

"[...] 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 caus…

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.

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.

Re: A strange green organism has spread, clogging up the world's rivers

#23

Post by privong »

freehunter wrote: post #22
privong wrote: post #11

Earlier quoted context omitted.

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.

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.

Here's a review of sorts: http://bioscience.oxfordjournals.org/content/64/6/531.full

And one study: http://www.ias.sdsmt.edu/staff/sundareshwar/Reprints/Sundare...

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.

Re: A strange green organism has spread, clogging up the world's rivers

#25

Post by [deleted] »

freehunter wrote: post #21
hyperbovine wrote: post #19

Earlier quoted context omitted.

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.

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 fa…

[deleted]

Re: A strange green organism has spread, clogging up the world's rivers

#26

Post by hyperbovine »

freehunter wrote: post #21
hyperbovine wrote: post #19

Earlier quoted context omitted.

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.

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 fa…

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.

Re: A strange green organism has spread, clogging up the world's rivers

#27

Post by lvh »

hcarvalhoalves wrote: post #10

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.

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.

Re: A strange green organism has spread, clogging up the world's rivers

#28

Post by hcarvalhoalves »

lvh wrote: post #27
hcarvalhoalves wrote: post #10

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.

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.

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.

Re: A strange green organism has spread, clogging up the world's rivers

#29

Post by freehunter »

privong wrote: post #23
freehunter wrote: post #22

Earlier quoted context omitted.

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.

Here's a review of sorts: http://bioscience.oxfordjournals.org/content/64/6/531.full And one study: http://www.ias.sdsmt.edu/staff/sundareshwar/Reprints/Sundare... 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: th…

Thanks! Exactly what I was looking for.
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