10,000 lakes...in Florida?

There has been debate about the value of secondary forest, and I have read similar debate about the equivalency of restored ecosystems to their natural counterparts. But what about another common semi-natural system, artificial lakes?

My grandmother lives in Florida in a condo development with an artificial lake behind her building. I’ve observed that, in Florida, there are many, many grandmothers who live adjacent to many, many artificial lakes. I’m not sure if the lakes are usually stocked with fish or not, but I’ve seen a good deal of birds around these lakes, such as the pictured group of white ibises, Eudocimus albus, and the cattle egret, Bubulcus ibis, below.

The abundance of waterbirds suggests some ecosystem value from artificial lakes. Some ecologists argue that birds are good indicators of community health (though probably not these birds, which are quite common in disturbed systems).

However, these lakes must be quite eutrophied. They are generally adjacent to well-trimmed lawns and golf courses that I presume are well-fertilized. A close-up photo of the lakewater nearshore shows a thick algal slime in the lake. To sum up: These artificial lakes are probably crappy habitat, but at least there are a lot of them…

lake blue

From maritima

Glacial lakes (fed primarily by glacial meltwater) are often a milky blue-green. These surreal lakes captivated me when I visited Torres del Paine National Park in Chile in October 2008. A park ranger explained to me that the unique color comes from suspended sediment, or "rock flour," reflecting sunlight. When I visited Mendoza, in the foothills of the Argentine Andes, in November, I noticed the same color quality in a lake there (see images of Pehoe Lake in Torres del Paine and the lake in Mendoza above). I think that the blue color in the Mendoza lake is probably also related to suspended sediment - there must be impressive erosion from the Andes each year. The lake was fed by a turbid, muddy, braided river. Water color can be affected by a number of factors, such as algal growth, bottom color, and depth, so I can't be sure, but it seems highly likely that the same process of erosion and sediment suspension caused this lovely scene in dry, sunny Mendoza as in the famously harsh landscape of Torres del Paine.

From maritima