I use the word ‘bug’ here, to describe little creatures with … legs. Insects, but more than that. Not everything I call ‘bug’ living underneath the ice are insects, some turn out to be crustaceans.
In the beginning of October, before it started snowing, there was a brief period when the thermometer dropped below zero Celsius long enough so that small lakes and ponds were able to freeze without the ice being mixed or covered with snow. A few days of clear ice!
Now, there is a rule of thumb that ice has to be four inches thick before it should be walked on. The ice was not quite that thick, but the lake I set foot on is only a few feet deep and, from previous winters, I know where the weak spots are.
In the Yukon, overflow is water on ice, often hidden as a wet surprise underneath a layer of snow. When you are lucky, it melts the snow on top and forms dark grey spots on the snow-covered lake -- this shows some of the weak spots on the ice.
To go out onto the ice, there are all sorts of things I take into account, such as, is it thick enough? Is there flowing water underneath the ice? Could there be hollow spaces between ice and water?
And you need to be aware of the surrounding area. For example, walking on swamp grass can be a wet experience on any given day, even when there is a layer of ice over it.
But for that brief period early in October, the ice was clear as glass, and, stepping on it, right away I saw multiple lines drawn on the bottom of the lake in the light coloured mud. Laying down on my belly, and peering down through the ice, I saw that these lines were being drawn by what looked like an inch long stick.
Yes, the sticks were moving. They were caddisflies, moving along the bottom of the lake in their protective casing.
In the guidebook Insects of the Yukon, edited by H.V. Dank, and J.A. Downs, I read that there are 145 species of caddisflies (Trichoptera) in the Yukon. Most of them here on the little lake I was laying on and seem to have similar casings with black and white bands. The caddisfly makes its casing with silk and the material available in the location where they live. Here, on the little lake, that means dark stuff and white mud particles. These casings are works of art.
Suddenly, a big bug skittered away along the bottom of the lake, disappearing into vegetation. It seemed huge, compared to all the other creatures, being at least an inch long.
Emailing with Jennifer Fang, an aquatic biologist in Toronto who has spent time looking at bugs here in the Yukon, I learned that this might have been a Hydrophilidae (scavenger beetle), or a Dytiscidae (diving beetle).
Bonnie Burns, a water specialist in the Yukon, confirmed that diving beetles are fun creatures to watch. Again reading Insects of the Yukon, which says there are 113 different species of diving beetles known in the territory.
Next, I peered into different places on different ponds. In the meantime, on my next visit to that lake, I found that snow had covered the ice, and I found myself bringing my prospector's rock pick to hack a small hole in the ice to look again. That's how I discovered Corixidae, also known as water boatmen, of which there are 12 known species in the Yukon.
True to their name, water boatmen move through the water in rowboat fashion, their legs look like oars. Some are very tiny.
I also discovered crustaceans. Amphipoda is a tiny crustacean known as freshwater shrimp, side swimmers or scuds. As one of the holes I made was slowly freezing over, a scud came up for a look with its black beady eyes. It seemed to realize the ice was reforming and quickly swam back to a warmer place and I think I saw it digging itself into the mud.
The people that are with me, or the ones I talk to later, might not all lay on the ice peering down, but they are enamored with my quest. They mention even smaller creatures living in Yukon lakes: copepods, rotifers and cladocerans. They point out creatures who live on the ice: arachnids, spiders and what could have been a caddisfly come out of its casing for the occasion.
Oh, and then there are snow fleas and what about snow flies, creatures that are basically made out of antifreeze.
It is a big world out there and not all of us sleep through the winter.