July 27, 2006
7/28 - Beautiful Evolution, Destructive Humans: The shifted baseline of Susquehanna River mussels
One of the most amaaaaaaazing essays I ever read from Stephen Jay Gould (hero of my documentary feature, "Flock of Dodos") was about the freshwater clams who have a microscopic larval stage. Given the one way flow of a river, why don't the clams end up slowly migrating one way, downstream, since their larvae are too weak to swim against the current? The answer is the ingenious mechanism they've evolved in which their fleshy mantle tissue looks like a fish and serves as a lure to draw in real fish, onto which they squirt their larvae which attach and then hitch a free ride upstream until they finally fall off.
Great story, but now appearing to be a tale from the past in the Susquehanna River according to this article. Dams constructed on the river almost 100 years ago destroyed the eel populations. Eels were probably the major carrier. There are still some clams left around, but as the article says, when you talk to the old timers, its NOTHING like it used to be. Same old story -- everyone has shifted their baselines, having no recollection of the massive beds of mussels that once existed.
Dude, check out my mussels
Posted by Randy Olson at July 27, 2006 09:12 AM