Skip to main content

Clear blue lakes turning murky in USA

New research reveals that many lakes in the continental United States are becoming murkier, with potentially negative consequences for water quality and aquatic life. These are the findings of a study published in Limnology and Oceanography.

From blue, clear lakes to greenish brown

In the 5 years between 2007 and 2012, the dominant lake type in the United States shifted from clear, blue lakes to greenish-brown, murky lakes. Blue lakes declined by 18% while murky lakes increased by 12%. 





Overall, “blue” lakes decreased by ~ 18% (46% of lakes in 2007 to 28% in 2012) while “murky” lakes increased by almost 12% (24% of lakes in 2007 to 35.4% in 2012).  So, the majority of lakes are now murky.

Regionally, murky lakes significantly increased in the Northern Appalachian, Southern Plains, and Xeric ecoregions.

In the Northern Appalachians, blue lakes decreased by 41.4%, brown lakes increased by 17.8%, and murky lakes increased by 26.8%. In the Northern Plains, green lakes significantly increased by 18.9% and in the Southern Plains, blue lakes significantly decreased by 25.6% and murky lakes increased by 29.8%. in the Upper Midwest, blue lakes significantly decreased by 25%, and in the Xeric region, green lakes significantly decreased by 30% while murky lakes increased by 34.2%
 

So, what is making clear blue lakes murky?

The investigators cannot definitively say what is causing this shift, but they suspect that land cover and land use patterns within a watershed, as well as changes in climate, may be important factors.

Lead author Dina Leech, of Longwood University in FarmVille, Virginia, tells us
Blue lakes typically are those that do not show evidence of nutrient pollution or elevated organic matter while murky lakes have high levels of both. 

Does it matter?

The answer to that question is a resounding yes.  It is indicative of profound changes occurring in the ecosystem and the complex network of life that sustains it.  A shift toward murkiness is a management concern because murky lakes tend to have more algae, including potentially harmful cyanobacteria. And with poor food quality at the base of the food web, over time murky lakes may not be able to support a healthy fishery.  The highest recorded concentrations of the toxin microcystin occurred in murky lakes.

Once lakes become murky it is difficult for them to reverse the process.


Subscribe to The Thin End

Comments

Popular posts from this blog

Ian Duncan-Smith says he wants to make those on benefits 'better people'!

By any account, the government's austerity strategy is utilitarian. It justifies its approach by the presumed potential ends. It's objective is to cut the deficit, but it has also adopted another objective which is specifically targeted. It seeks to drive people off benefits and 'back to work'.  The two together are toxic to the poorest in society. Those least able to cope are the most affected by the cuts in benefits and the loss of services. It is the coupling of these two strategic aims that make their policies ethically questionable. For, by combining the two, slashing the value of benefits to make budget savings while also changing the benefits system, the highest burden falls on a specific group, those dependent on benefits. For the greater good of the majority, a minority group, those on benefits, are being sacrificed; sacrificed on the altar of austerity. And they are being sacrificed in part so that others may be spared. Utilitarian ethics considers the ba

Mr Duncan-Smith offers a disingenuous and divisive comparison

Some time ago, actually it was a long time ago when I was in my early teens, someone close to me bought a table. It was an early flat pack variety. It came with a top and four legs. He followed the instructions to the letter screwing the legs into the top. But when he had completed it the table wobbled. One leg he explained was shorter than the other three; so he sawed a bit from each of the other legs. The table wobbled. One leg, he explained, was longer than the other three. So, he sawed a bit off. The table wobbled. He went on cutting the legs, but the table continued to wobble. Cut, cut, cut! By this time he had convinced himself there was no alternative to it.  He ended up with a very low table indeed, supported by four very stumpy legs and a bit of cardboard placed under one of them to stop it wobbling on the uneven floor.  Mr Duncan-Smith argues that we need a 1% cap on benefits to be 'fair to average earners'. Average  earners have seen their incomes rise by less tha

His way or none? Why I can't vote for Jeremy

There is an assumption that all would be well with the Labour Party if people hadn't expressed their genuine concern with what they consider the inadequacies of Jeremy Corbyn's leadership. If only, it is said, the Parliamentary Labour Party and his Shadow Cabinet had supported him, instead of undermining him, all would have been fine. If they had been quiet and towed the line, then the party would not have been in the mess it is in. So, should they have stayed silent, or speak of their concerns? There comes a point when the cost of staying silent outweighs the cost of speaking out. This is a judgment. Many call it a coup by the PLP. They paint a picture of a right-wing PLP out of touch with the membership.  This is the narrative of the Corbyn camp. But Jeremy Corbyn, over the decades he has been in politics, showed the way.  It was Jeremy Corbyn who opposed almost all Labour leaders and rarely held back from speaking out, or voting time and again against the party line. As