Environmental Education Week:
It is EE Week! Check out http://www.eeweek.org/ for loads of resources for teachers, like lesson plans and guides, as well as a Nature Center locator and other cool things! EE Week is the week before Earth Day and seeks to instill in environmental ethics in kids from kindergarten to 12th grade.
In honor of EE Week, and because we are covering new [to me] programs this week, I thought I’d write a little about a ubiquitous but overlooked habitat–the pond! Take note though, I am by no means a pond expert and I am also working with kids, so I have no need to go into great detail, nor can I!
Take Pride in Ponds!
A pond is a small freshwater body often housing many an invertebrate and a handful of vertebrates–most noted are the amphibians. Every pond has its own characteristics, like depth, clarity, turbidity, etc. that can vary greatly, offering a unique habitat and a watery stage upon which lifecycles and food chains play. If you’ve ever peeked at all the little creatures running around on the bottom of the pond or in the water, you’ll most likely have spotted creatures in the larval stage of their lives–things like mosquito. dragonfly, caddisfly, and damselfly larvae–all creatures that have to spend a part of their lives in water in another form other than the one they will become when adults. But these larvae, and the mature creatures they aspire to become, are a solid foundation for foodwebs, feeding everything from birds to amphibians to other invertebrates. So to conclude that the habitat prefered by creatures that feed almost everything is an important habitat is a sound thought, eh?
Water Quality through New Eyes
Did you know that whirligig beetles have four eyes? Well, four eyes in the same sense that a person with glasses has four eyes. The beetle’s eyes are separated into two sections, one for looking down into the water and the other for looking above while the beetle swirls around on the surface. In a sense, it’s like having eyes in the back of your head!
Good vision is important, but more important it seems is how one sees the world, in what way one uses their eyes. You can look at pond water with 20/20 vision and still not see what is really going on in all the murk and sludge.
When you think of clean water, what do you think of? A bottle of drinking water…or a pond writhing with micro- and macroorganisms?
I suppose the answer would be both! We humans in industrialized nations pride our sterile drinking water, clean, free of any debris, and a taste that has a slight mineral tinge to it. But Nature’s clean water is in a sense the opposite, because there are things living and dying in it, using it to grow up in, breed in, and of course, go to the bathroom in!
So how do you tell Nature’s clean water from Nature’s dirty water when there are creatures soiling it?!
Someone aptly coined the term -indicator species- to denote any creature that -indicates- the level of disturbance or the relative health of an ecosystem, in our case, anyway. There are other uses for the term, but we’re trying not to get confused here, eh? In aquatic ecology, the amount of disturbance is correlated as the level of stress a species can take and once they’ve passed that level, they will become scarce in that environment. Stress tolerance can be affected by human activities like pollution or increases in sediment.
If You Can’t Take the Heat…
Then what? How does a little ‘bug’s’ stress-level indicate anything about the health of pond water? If one can identify which invertebrates can’t deal well with human-caused stress, ie their stress tolerance is low, then one can identify which ponds have been least affected by pollution or whatnot. Say one finds a certain species of Clubtail Dragonfly larvae in a pond. The presence of that little guy will most likely indicate the water quality is good and the neighbor’s cattle waste isn’t seeping into the pond. But say you suspect that the neighbor’s cattle get in the pond and there is an over-accumulation of organic matter [can be a bad thing!] and you find no clubtails but you do find a plethora of Spreadwing Damselfly larva. Those fellows can deal with high amounts of disturbance, like the neighbor’s cattle, and indicate that the pond is disturbed.
Of course one would prefer a clean pond–a healthy aquatic ecosystem, so the best invertebrates to have in the pond wouldn’t be just one or a few species, but a diverse group with sensitive and very tolerant species mingling happily while supporting the food chain.
Thanks for stopping by!