Under higher pressure, though, below 100 meters, the vesicle ruptures and the organism dies. In the past, normal mixing annually rotated these phytoplankton (a larger category of micro-organisms that includes cyanobacteria) below 100 meters, killing them off. Now, they're not always mixed below their survival threshold.
As Posch put it: "Lake surface warming creates a fertilizing effect." The results do not bode well, neither for Lake Zurich nor for many other lakes around the world.
Lake Garda in the southern Alps, part of a chain of deepwater lakes in northern Italy, also has a thriving population of P. rubescens. Nico Salmaso, a researcher at the Limnology and Fresh Water Ecology research group at Fondazione Edmund Mach, an agrarian institution, has studied this lake for many years. He says P. rubescens constitutes 85 percent of the cyanobacterial biomass found in the lake.
The health of Lake Garda and its neighbors in Italy's northern Lake District, including lakes Como, Orta and Maggiore, is the foundation of the area's economy.
"Lake Garda alone brings in over 25 million tourists a year," Salmaso said. And then there is the much larger Lake Como, which also has a seasonal cyanobacterial bloom. Its presence, and the presence of other phytoplankton, makes lake water appear muddy and unappealing.
"All of these lakes were once oligotrophic," Salmaso said, meaning low nutrient concentrations, little plant growth, not supporting life. "The only way to control the cyanobacteria is by controlling the external nutrient load."
A successful remediation effort at Lake Maggiore has restored that lake to near-oligotrophic status. With the help of a huge inflow of money from the European and Italian governments, residents and visitors hope to see the same in Lake Garda.
A toxic legacy
P. rubescens and its close cousins in the algae and phytoplankton world, including several other kinds of cyanobacteria, threaten people in ways that are far more serious than soupy-appearing waters.
"Cyanobacteria produce hepatotoxins as well as neurotoxins," Salmaso said. "There is huge concern at the European level in different [subalpine] lake typologies. In Europe, animals are already dying in certain badly affected lakes. A little cyanotoxin can go a long way, and you don't want that."
Cyanobacteria are also now suspected to be at the root of major neurological diseases, long thought to be caused by inherited genetic mutation.
In a landmark scientific paper, researcher Paul Cox and his colleagues, now at the Institute for EthnoMedicine in Jackson, Wyo., found that cyanobacteria produce a neurotoxic amino acid known as BMAA. It has been found in the brains of patients with amyotrophic lateral sclerosis (ALS), Alzheimer's disease and Parkinson's disease. Epidemiologically speaking, this correlation is hardly far-fetched.
In areas surrounding Lake Mascoma in New Hampshire, researchers mapping new ALS cases found the prevalence of the disease to be 10 to 25 times the normal rate among patients who lived in areas with known cyanobacterial blooms. In southern France, where a substantial cluster of ALS cases has occurred, researchers found high BMAA levels in oysters, a favorite local delicacy, which concentrate the toxin.
Although scientists shy away from ascribing direct causality between particular micro-organisms and a specific cluster of disease outbreaks, it is clear to many observers that climate change is making the world a friendlier place to some organisms that can cause harm. The evidence for a causal effect between cyanobacteria and the incidence of ALS, Parkinson's disease and Alzheimer's disease is slowly but surely mounting.
Reprinted from Climatewire with permission from Environment & Energy Publishing, LLC. www.eenews.net, 202-628-6500
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5 Comments
Add Comment"Harmful" is not a scientific term. It has no science valw and degreades this from science to popularism. Science is not about what is good or bad for humans in a particular situation. It is about description of 'what is'.
Reply | Report Abuse | Link to thisI sometimes wonder if any of the so-called 'journalists at SA ever took even a science 101 course. Hint: the properties of matter and energy sand all they develop into are not dependent on a God-created man.
Scientificaly an algae bloom is no more
'good or bad' than a carbom atom is 'good or bad'.
@Sciencefirstandforemost, what gives you the right to tell sciam what they are allowed to publish? There is nothing in sciam's charter that says everything they publish must be pure science. They are entitled to publish opinion pieces, blogs, and commentaries as mush as they like. No one is obligated to restrict their speech to your agenda. Get over yourself.
Reply | Report Abuse | Link to this@Sciencefirstandforemost: What on earth are you talking about? Of course harmful is not a scientific term, and no one would use it to describe the actual observations of an experiment nor a theoretical model. However, even hard science journal articles will use the word harmful in an introduction to put the findings in context and demonstrate why they are relevant to people. As in "our new polymer formation method uses few harmful solvents". It's not populism, it's not even opinion in this case. Blooms of toxic cyanobacterium are HARMFUL to humans who might use the water, and HARMFUL to the existing fauna. Whether long term these blooms lead to a more robust ecosystem (like frequent small forest fires, rather than suppressing them all and building up fuel and eventually a devastating fire) is hard to say, but short term? Harmful.
Reply | Report Abuse | Link to thisYou seem to think of science as a pure undertaking, but the reality is science is expensive and needs funding from people besides the scientists. While the data collected should be objective, the reason for gathering it to begin with needs to be communicated, and that doesn't happen without some relevance to people. Even the most basic science experiments are still done in the hope that even if there isn't a use for the result now, there is a chance at some point it will be.
Scientific American attempts to relate complex scientific findings in a more accessible format for non-specialists. If all they presented were dry lists of experimantal findings, I doubt many people would buy the magazine, and then there would be almost no publications between academic journals and inflammatory newspaper articles. Which do you prefer?
Well, they are a Science magazine. That said, I think this particular article is well written and informative, and mostly sticks to the science. I find the possible links to diseases extremely interesting and hope to see more research into that aspect.
Reply | Report Abuse | Link to thisI quit buying SA many years back, mainly because of the 'opinion pages' disguised as research, but articles such as this (and a few others recently) give me hope.
I know what you're getting at, but, "Harmful" Algal Blooms (HABs) is a commonly used term in scientific literature.
Reply | Report Abuse | Link to thisCase in point:
"Harmful (toxic, food web altering, hypoxia generating) cyanobacterial algal blooms (CyanoHABs) are
proliferating world-wide due to anthropogenic nutrient enrichment, and they represent a serious threat to
the use and sustainability of our freshwater resources."
Paerl, W.H., Hall, N.S. & Calandrino, E.S. 2011. Controlling harmful cyanobacterial blooms in a world experiencing anthropogenic and climatic-induced change. Science of the Total Environment. 409, 1739-1745.
So I guess they did their research after all!