Copepoda and caddisflies in Coldfall
Not a cloud in the sky and up and about early, I decided to visit my local chunk of ancient woodland - Coldfall wood, near Muswell hill.
This is a dog walker’s paradise, for sure. A nice long loop around and an adjoining playing field for that extra bit of running around like the seemingly possessed creatures that they are (the dogs, not the walkers).
I actually came here to walk myself rather than a dog, and am fortunate enough that there are few around at this time; it has rather turned into more of a "watch" than a “walk”. It’s really quite amazing what you see if you wait a little and just observe.
I often hear woodpeckers in here, but have only caught a glimpse on a few occasions. This morning, a “flock” (do they have a more interesting collective noun? Maybe a “Knock” or a “Ruckus”?) of them- beautiful red flashes making lazy upturned arches as they flit between trees and land, attaching themselves vertically completely effortlessly - hopping around a branch - and away. A nuthatch peep-peep-peeps for all its tiny lungs are worth in the distance.
Anyway, birds are great but they’re kinda showy and obvious. At the field end of the wood is an oft-flooded marshy wetland. Yesterday, the water was over the boardwalk but, blessed as we were with a break in the cloud, today it has receded just enough to hover under the planks. I tripod-hoisted myself over the flooded ramp with a conveniently placed branch, and pottered over to the handrail, facing the sun.
On first look, at 6ft up, one would be forgiven for thinking that this water, being collected from London road runoff as well as springs and streams, is pretty lifeless. A green-brown silty turbidity, speckled on top with bits of last year’s seed fall and bark and the odd scrap of water mint, somehow uprooted and seeking a hold on life. A moorhen poot-poots over the flattened, leafless bushes; half submerged.
I’m not one to stay at my natural height near a body of water, for very long. A lazy lean over the rail. Movement here and there; the breeze carries the debris this way and that. Just under the surface, the odd fleck of something travels in an altogether different direction. Is it life, or just the peculiar currents of quickly thermally-stratifying water? I dip my finger, discover debris, and marvel at the mysterious physics of H₂O. One day I’ll understand, perhaps!
So onto the knees. The Corvids around me assume I’m now either a madman or dinner, I suspect. Whatever. At this height above the now conveniently pontoon-topped surface (about a foot) one starts to notice small erratic blips of movement in changing directions. Shaped a little like torpedoes - panniered, when carrying their egg-sacs (if you can imagine such a thing) - these little guys are the Copepods, who seem to be almost ever-present in any slightly temperate splash.
They go about their daily lives flitting around munching algae, and being munched on by larger invertebrates, fish, birds, and - in the ocean - even some whales! Look closely and you are sure to see these tiny crustaceans pretty much everywhere you care to look.
Watch a little longer, and you may notice some debris stray from its wind-blown vector and wriggle itself about. I (somewhat selfishly) plucked the star of this video from where she was wrestling a piece of bark - hoping she’d crawl from the board and back into her home medium. But too clever for me, she simply sat in her camouflaged case waiting for all signs of danger to pass. Perhaps a caddisfly (Trichoptera)?
*Pops her back in* - shortly, a quick show - grappling a stick and moving to hide under the board.
Just in time too, here comes a canine with an ambition to swim the Channel.