Today was the most beautiful day I’ve experienced since my arrival. When Kug does “nice weather” it does it pretty darn smashingly – warm sunshine, light breeze, and the view goes on for miles. (A few less mosquitoes, and it would be perfect!) I spent most of the day mucking about in various ponds, streams, and river outlets sampling for aquatic invertebrates.
For this type of work I don a pair of armpit-high chest waders, arm myself with a d-ring net and stomp around in the water, stirring up substrate, scooping overhanging vegetation, and searching rocks and other debris for critters. I’m mostly interested in finding dragon/damselflies, mayflies, stoneflies and caddisflies (all of which spend their adult lives on land but reside in water during their larval stages), but heck, I’ll pretty much snatch up anything that moves! Once my net has a nice little collection of “brown muck”, it gets dumped in a shallow pan with a bit of water.
At first, all you see in the pan is, well, brown muck. But slowly, as the sediments settle, the vegetation stops swirling, and your eyes find the correct depth of focus…POW! Wiggly things! Swimming things! Creepy-crawly things! The brown muck is suddenly alive! Then begins the painstaking task of tweezing and sucking out all the interesting stuff and transferring it to vials of ethanol.
My first panful of muck revealed a surprise:
Flat fish! (It looks grumpy!)
Ok, ok, so it’s a vertebrate, but…but…OMG! A flatfish! I’ve never seen one in the wild before, and this little guy (about the size of my palm) was just beautiful, albiet in a grumpy-looking sort of way. I also found a number of small sticklebacks and a few other minnow-sized fish I wasn’t familiar with.
Anyways, back to the insects. Right now, most of my stream-muck is overflowing with black fly larvae. I’m actually rather relieved about this, as black flies are high on my List of Important Things to Find while I’m here, and my searches for the first two weeks yielded nothing; this must be the first crop. Black fly larvae require flowing water to survive. They anchor their rears to a substrate (usually submerged vegetation or rocks) using a combo of tiny hooks on the abdomen and silk threads; if they want to move downstream, they drift down while tethered to lines of silk. They extract food from moving water with a filtration system comprised of labral fans on the head. When removed from the water, the larvae curl into a protective “U” shape. Plucking one off its substrate with forceps seems to nearly always result in a frustrating battle with a tangle of silk threads (you THINK you’ve got the darn thing in a vial, so you pull up your forceps, and ooops! It’s now hanging loose somewhere…blarg).
After wrapping up my sampling at the “flat fish creek”, I drove down to a river outlet running west of the Coppermine…it was shallow, warm and wonderfully pebbly, providing an interesting contrast to all the mud and sand I’ve been seeing in other aquatic habitats here.
In small riffles where the water current picked up speed, I could see black fly larvae dotting the smooth, colourful stones inches beneath the water’s surface.
They are quite sparse here; I’ll have to get a photo of them on vegetation in other locations, because the numbers are simply mind-blowing! In some places, every available surface underwater is covered with a black mat of wrigglers!