It's the end of summer; nature's colors are beginning to segue from lush green to the bold electricity of deep chrysanthemum purple, vibrant goldenrod and blazing pumpkin orange. The sunshine is still hot enough to bring out the tank-tops and shorts, but mornings are cool enough to entice me to toss on a sweater. Night air is crisp, tantalizing me with the scent of wood smoke and the soothing chorus of crickets.
This is the time of year when most people's thoughts turn to hearth and home, getting the firewood delivered for the coming winter, canning and preserving the garden's bounty, bustling for back-to-school items. Yet this is the time of year when I get wistful about the Black River. Summer vacationers have gone home, kids are in school, and water levels are usually lower, inviting me to go "creek crawling." It's when I'm up to my knees in the water that I enter the realm of the crawdad (or crayfish or mudbug, depending on where you call home).
Crayfish are one of the most recognizable critters in any river, although small children have occasionally mistaken them for baby lobsters or small crocodiles. Nibblers of old leaves, algae, fish eggs, dead things as well as live, crayfish are one of the many omnivorous janitors of the river. They are in turn a decent meal for raccoons, otter, mink, kingfishers, heron, fish and turtles, not to mention many humans.
In 1911, naturalist Anna Bostford Comstock wrote admiringly of crayfish in her book "Handbook of Nature Study", describing their "graceful lines," "large assortment of executive appendages," and the escaping creature's "spasmodic jerk" of the tail which speedily pulls it from harm's way. I find myself reflecting on the crayfish as a member of the river-bottom community. Here in Vermont, we are used to six species: the Common Crayfish, the Calico, the Spinycheek, Northern Clearwater, Virile and the Rusty. The features that tell them apart range from behavioral to biological, and I'm just barely beginning to learn them.
Some species can travel for some distance over dry land to the next body of water, some o are nocturnal, some are more aggressive than others, some have a higher metabolism than other. Some have "warts" on their claws, some have spots on their shells. Ridges or smooth plates on the forehead, various spiky or pointy bits that are different from other species, details and shades of subtlety that a good crustaceologist would have no trouble with. Not being even a poor crustaceologist, my goal in learning about the differences between crayfish has to do with the recent discovery (by Moira, Crayfish Hunter) of a Rusty crayfish in the Black River.
Rusty is considered in Invasive Species in most biological and ecological circles; he is considered "native" to the Ohio River Basin, just a few hundred miles away. He either travelled to New England as live bait for fishermen or as specimens for biology teachers. To me, Rusty is rather like the Klingon of the crayfish universe. His large size and aggressive behavior go hand in claw with his high metabolism. Rusty has a distinctively ridged forehead, a rusty-red smudge on either side of his carapace, just below the "armpit" of the claw. He tends to not just fend off predators but also seek out new worlds all day by chasing nocturnal crayfish from their rocky homes. Rusty is also a messy eater; it is suggested that he can spread nuisance aquatic weeds by clipping and snipping for his dinner while lots of little plant bits wash downstream to create new beds of weeds.
By the same token, as the Rusty crayfish move into our waterways and hybridize with other species, I find myself asking questions: Will they eat more of the pond weeds and nuisance plants in our rivers and streams, helping keep those densities in check? Will our fish and other predators become accustomed to Rusty behavior, and adapt to eat them? Will Vermonters to host crayfish boils alongside our pancake breakfasts?
I believe that part of living on this planet is learning How Things Work. That's a tall order, learning the ways of the universe while living inside it. It's sort of like living in a house that you're renovating. It can sometimes be difficult to see the bigger picture. If we include ourselves in that picture, though, our perspective may clarify and deepen a bit, like the reflection of a lake once ripples have cleared. Rusty crayfish are likely here to stay; I'll be keeping an eye on them as time goes by, watching to see how the Black River handles their presence and taking my cue from there.