bringing together a wide range of sciences,

including:

Cosmology

Physics

Chemistry

Geology

Meteorology

Biology

&

Ecology

to explain,

amongst other things,

Limnology - "the oceanography of lakes"

But what exactly is meant by "destroy"?  And what kind of "thoughtless intervention" are we talking about?

WT Edmonson sums up the answer in his excellent study - The Uses of Ecology.  "Many large lakes in Europe, North America, and across the world, once valued for their clarity, deep-water fish and aesthetic appeal, have lost all three as a result of the annual development of dense populations of blue-green algae, whose scientific name is cyanobacteria.  Now, blue-greens  individually seen are very handsome: so are dandelions. But whenever either of the these grows in a place where it is not wanted, it makes trouble and people try to remove it and to prevent its continued growth. The results of excessive blue-green growth can be spectacular and cause serious deterioration. (p 57).  And he continues: 

 Here is a statement by Dr Claire Sawyer based on experience with Lake Monona in Wisconsin:  “The most obnoxious conditions produced by algae are those which result from concentration of floating forms under the impetus of a gentle breeze with deposition on the leeward shoreline. Such accumulations, often several inches thick and extending several feet from shore, in the heat of a warm summer sun die, decay, and emit odours that will dampen the spirits of the most ardent recreationist in the area”  [Edmonson p 71-2]

But to be fair to this lake nuisance, cyanobacteria, it should be mentioned that it is one of the oldest surviving life forms on the planet, was single-handedly responsible for creating the oxygen rich atmosphere upon which all terrestrial life depends, donated its magical powers of photosynthesis to plant life enabling vegetation to flourish throughout the world and provide the food without which no animal life would exist, and to this day replenishes that same atmosphere, depleted each day by the respiration of seven billion humans and emissions from their colossal industrial infrastructure with around half its oxygen needs, the other half being provided by the plants upon whom it bestowed its powers of photosynthesis.

So by a grand irony of fate it is the very successfulness of cyanobacteria as a life form - its reproductive prowess over three billion years - which now poses such a great threat to all freshwater resources around the world upon which human communities depend.  Supplied with sufficient human sewage and waste water Cyanobacteria will rapidly multiply and cover the water's surface.   

So this - a picture taken by the shore at Saint-Jorioz, Lake Annecy in 2015...

...could turn into this...

This picture taken on June 4, 2013 shows fishermen working on Chaohu Lake, filled with Cyanobacteria, in Hefei, central China's Anhui province. As temperature rises, Cyanobacteria begins to spread again in Chaohu Lake, worsening the water quality and sending out strong smells, local media reported. CHINA OUT AFP PHOTOSTR/AFP/Getty Images

The disaster, which Dr Servettaz  foresaw awaiting lake Annecy, was eutrophication - and the resulting 'death' of the lake.

Limnologists are dismayed to hear public talk of lakes “dying” from eutrophication because in reality the lake doesn't die. The water remains, and there continues to be life. It's just that there is a significant change in the lake's long-established equilibrium, from a state where the lake is clear and teeming with a variety of life forms to one where there is dominance by one species - cyanobacteria.

Of course to a limnologist the lake is not completely dead – although 95% of the aquatic life that used to be there is, for instance, all the fish are gone. But there continues to be a process of life and death for the cyanobacteria as witnessed by the green slime and sulphurous smell. Probably far fewer birds if there are no fish, and no fishermen or bird spotters of course. And in fact no tourists, because who would want to spend their summer holidays swimming in Lake Stinko.

And if no tourists then around half the economy of Annecy dies, the chambres d’hôte, the hotels, the restaurants, lake trips, sailing schools and waterski instructors. And probably no business is likely to want to relocate to this noisome place. And young people of course will want to escape to pleasanter climes, leaving the old residents, who will in turn slowly die out.

So of the course the limnologists are right - eutrophication doesn’t mean that the lake actually dies.

It just means that the community around it does.

A simple version of the lake Annecy story can be explained with no technical detail, and this has been done in a previous section – Lake Annecy Story. But explaining the problem of eutrophication requires familiarity with a number of basic limnological concepts. Many of these are widely known and well presented in textbooks of biology, ecology, and environmental science, etc, but often they are stated in away that is not easily applicable to the problems discussed here. Therefore, the purpose of this section is to outline a few of the facts that are most relevant to this story, with special reference to lakes and in particular to Lake Annecy.

And the first thing to say is that although eutrophication is often referred to as "pollution",  it has not so much to do with dirt and disease as with nutrition and excessive feeding.  The word itself is derived from the Greek, eutrophia  i.e. 'well+nourish'.   

Eutrophication is a problem of an excess of good things – nutrients. One way of putting it is that eutrophication is to lakes what obesity is to people – a Big Problem and Growing Problem.  It is proof you really can have too much of a Good Thing.  

Or in the more professional words of Dr Edmonson:  "A disturbingly common environmental problem occurs when a lake, formerly in satisfactory condition, begins to produce dense populations of certain kinds of algae. This change is brought about by and increase in the nutrient supply of the lake, known as eutrophication, that is often due to sewage effluent." [Edmondson p 3]

This section outlines the scientific background to this disturbingly common environmental problem, and how this understanding can help people, ordinary citizens, elected representatives and scientists,  to manage the problem and prevent it happening.  As was done at Lake Annecy.

In Autumn 1944 Dr Servettaz set out on a seemingly impossible mission – to persuade his fellow citizens to support the most expensive, most complex and most long-term infrastructural investment in the history of their community, for a reason none of them yet understood. His strategy was simple and resolute. He would persuade people by science. Little by little, with facts, clarity, humour and patience, he would educate everyone he came across to understand lake ecology.

For only when they grasped the “Intimate life of the lake” as he would call it in his account of the story, would they give their support to this vital investment. And so this section is written in the spirit of Dr Servettaz, (although not as detailed as his account and including some more recent knowledge unavailable to him), enough to show the complexity and fragility of the lake’s web of life, and how the thoughtless discharge of human waste into that web of life was threatening to destroy it.

The section begins with some tools or diagrams to which readers may wish to refer, illustrating the physical size of life in the lake, the age of the earth, and various evolutionary trees. There follows a brief history of the young science of limnology leading up to our story of Lake Annecy. Limnology is  generally recognised to have been founded by François-Alphonse Forel (1841–1912) who established the field with his studies of Lake Geneva,  just 80 miles to the north of Lake Annecy.

Another excellent introduction to limnology is Brian Moss' Lakes, Loughs and Lochs.    The remaining chapters in this section draw heavily from his work, not least his excellent concept of thinking of the lake as the setting for a play.  The physical sciences provide the stage, the props and the backdrops to the action.  The actors are the various life forms comprising the biology of the lake.   And when they come together to interact in one ecological system they perform the living drama of lake life.  I follow this structure as I outline the evolutionary origins of lake life. The main section is entitled The intimate life of the lake  following the chapter of the same name in Dr Servettaz's account, which describes the main forms of life currently living in the lake and which were under such threat when Dr Servettaz launched his campaign of education.

Nearly every year since 1966 the physical-chemical-biological condition of Lake Annecy has been studied by the National Institute for Agricultural Research (INRA) - making it one of the longest studied lakes on the planet.  A summary of one of their recent Annual Reports follows, covering with actual, measured data what has been outlined previously in general.  The history of limnology is then brought up to date, and finally there is a brief look at the precarious state of freshwater resources around the world today and the lessons to be learned from the Story of the Safeguarding of Lake Annecy.

Continue Reading    Chapter One