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

Prioritising people in nursing care.

There has been in recent years concern that care in the NHS has not been sufficiently 'patient centred', or responsive to the needs of the patient on a case basis. It has been felt in care that it as been the patient who has had to adapt to the regime of care, rather than the other way around. Putting patients at the centre of care means being responsive to their needs and supporting them through the process of health care delivery.  Patients should not become identikit sausages in a production line. The nurses body, the Nursing and Midwifery Council has responded to this challenge with a revised code of practice reflection get changes in health and social care since the previous code was published in 2008. The Code describes the professional standards of practice and behaviour for nurses and midwives. Four themes describe what nurses and midwives are expected to do: prioritise people practise effectively preserve safety, and promote professionalism and trust. The

Half measures on heat pumps

Through the "Heat and Buildings Strategy", the UK government has set out its plan to incentivise people to install low-carbon heating systems in what it calls a simple, fair, and cheap way as they come to replace their old boilers over the coming decade.  New grants of £5,000 will be available from April next year to encourage homeowners to install more efficient, low carbon heating systems – like heat pumps that do not emit carbon when used – through a new £450 million 3-year Boiler Upgrade Scheme. However, it has been widely criticised as inadequate and a strategy without a strategy.  Essentially, it will benefit those who can afford more readily to replace their boiler.   Undoubtedly, the grants will be welcome to those who plan to replace their boilers in the next three years, and it might encourage others to do so, but for too many households, it leaves them between a rock and a hard place.  There are no plans to phase out gas boilers in existing homes.  Yet, that is wha

No real commitment on climate

Actions, they say, speak louder than words.  So, when we look at the UK government's actions, we can only conclude they don't mean what they say about the environment and climate change.  Despite their claims to be leading the charge on reducing emissions, the UK government is still looking to approve new oil fields.  The Prime Minister, Boris Johnson,  has announced his support for developing the Cambo oil field and 16 other climate-destroying oil projects. Cambo is an oil field in the North Sea, west of Shetland. A company called Siccar Point has applied for a permit to drill at least 170 million barrels of oil there. If it's allowed to go ahead, it will result in the emissions equivalent of 18 coal plants running for a year.  What? Yes, 18 coal plants a year!  Today, as I write, Greenpeace is demonstrating in Downing Street against this project.  I suppose it will get the usual government dismissal and complaints about inconveniencing others.  Well, we know it won't