This is it.
The second stop up a watery food chain.
Muck. Grab a handful and watch it squirm. If you're lucky, that is.
This is where the magic happens, the cauldron where algae and plant matter nourishes the gross, wiggly critters that keep this and other waterways alive. Life being what it is, the act of taking these pics invited a hitchhiker on my toe eagerly sucking my blood. A wee little leech gave me a lesson on just where I stand in the food chain. But that's another story for another time.
Right now, of particular interest is this little muck dweller:
The lowly diporeia. He lives in muck, and he was once the backbone of the...the...ya know...backbone doesn't quite fit considering he's not even in the chordate phylum. Let's say he was once a large part of the exoskeleton of the Great Lakes eco-system. And, as you probably guessed, he's in serious trouble. This squirming, rice sized, energy-dense shrimp is on the chopping block.
These fellas used to be THE food of choice for the bigger fish living in the Great Lakes and inland lakes. Just a few years back they numbered 10,000 per cubic meter...and not just in the muck. They'd find their way into the open waters by the billions and fish would feast on their energy rich bodies like they had done for ten thousand years. They used to make up 70% of the biomass of lake bottom.
Now...they're gone from whole regions of the Great Lakes.
Gone.
They eke by in the muck and scientists measure their numbers to determine the health of a body of water. But in the Great Lakes, they're vanishing.
So what do the larger fish eat now?
They eat far less nutritious zebra mussels, and some barely survive on that. Whitefish, smelt, lake perch are showing up emaciated and small, and slimy sculpin and lake trout populations plummeted by 95% since 1988.
The Great Lakes are on the verge of ecological collapse.
So what's causing the diporeia to die off?
For one, invasive zebra and quagga mussels who voraciously filter out the algae eaten by the diporeia.
But it may not be all the invasive species' fault. As it turns out, common pesticides even in trace amounts wipe out diporeia.
In Sepúlveda's study, she and her team contrasted levels of metabolites between a group of control animals and that of an atrazine-exposed population of laboratory-reared Diporeia. They found that animals subjected to atrazine, a commonly used pesticide present in minute levels in Lake Michigan, significantly increased or decreased bodily production of five identifiable chemicals. These included an insect pheromone, a fatty acid, an amino acid and a hydrocarbon, she said.
"We are just beginning to interpret these data, but they give us a better idea of how pollutants affect them," Sepúlveda said. "If nothing else, our results suggest that seemingly insignificant levels of pollution could significantly harm animals like Diporeia."
The project should help address suggestions by some researchers that Diporeia and/or invasive zebra and quagga mussels may be capable of bioaccumulating or affecting levels of pollutants in a way that might intensify their harmful effects, Sepúlveda said.
--article
Runoff from pollutants used on land hits the "muck" particularly hard and arrests the very base of the eco-system. Careless actions such as dumping oil or other chemicals improperly, or even the use of garden variety pesticides and herbicides anywhere near waterways therefore have a magnified impact on the entirety of a system. Be mindful of what's going into the ground.
These tadpoles just appeared in black lake very recently after a loud chorus of spring peepers last week. If you can catch glimpses of the minnows I'll be impressed. Their coloration matches the bottom sand exactly and they're fast.