A thick biofilm covers everything in the river. It shimmers in breezes of current like wheat in a field. The covering is probably thicker than what should be here since a component of biofilm is algae, fueled by excess nitrogen. Still this thick furry growth is normal this time of year, and it is critically important for nutrient cycling and spiraling in streams. It makes the river furry and so slick that I have a hard time walking. I had to crawl to avoid an uncontrolled descent as I made my way back downstream from a mid falls pool. If I floated, I wouldn’t have been able to control my speed. Not enough friction on the rocks.
This was another fishless trip and while I really miss seeing fish, I enjoyed the alien stream scape caused by the excess biofilm growth. Motion sticks out from the undulating background and I see something I have never witnessed before underwater. A leach stretches out from under a rock into the current. I’m not sure what this invertebrate is doing but it is fascinating. I have seen leaches on rocks picked from the stream, but never one under water, in its element. A friend showed me a picture of a giant Amazon leach last week, a full foot long blood sucker, and I would like to see that in the water too, just like most Amazonian species. My leach stayed attached to the bottom on one end and only stretched a few inches into the current, then retracted.
I have been talking a lot about another blood sucker, sea lamprey, lately. I became fascinated with this fish when we found one during a fifth grade trip last May, and concerned about them while I worked on curriculum for an upcoming Freshwaters Illustrated movie about efforts to protect Pacific lamprey. I have included the lamprey story as part of a presentation I do on our declining migratory fish. Even outdoors lovers, and folks committed to conservation get a twisted look on their faces when I tell them about the importance of protecting lamprey. Granted, they feel like muscular tubes of mucous, and the way they make a living is freakish, unless you are a lamprey.
These organisms might not be the most beautiful or cuddly, but they are all critical parts of the stream system, and their biology is fascinating. The world would be a lesser place if it didn’t have biofilms, leaches and lamprey. It’s all about perspective. Yuck is in the eye of the beholder.