Dance of the mayflies
& mayfly conversation with Lorna Visser and bug expert Daniel Hellyer
An amazing occurrence happened the other day at our Snk'mip marsh nature sanctuary: we experienced an invasion of dancing fairies.
We've been engaged in a multi-year project at this wetland nature sanctuary (located in BC's West Kootenay region at the north end of Slocan Lake). Thus far, we've cleaned up tons of debris and derelict structures, restored the damaged wetland (which had previously been in places mined and in other places infilled), filled in and ecologically restored the area of an unauthorized gravel pit, built dozens of ponds and pools and enhanced marsh habitat overall for rare and threatened species.
This summer, in addition to our previous work restoring the main wetland water body to its full extent, we installed 6 new ponds large and small using amphibian-safe synthetic pond liners (using these liners allows us to create ponds where otherwise the water would simply drain away). Water impoundment is very important for habitat creation for insects, birds, threatened amphibians and reptiles.
In early August we created a large new pond on a flat bench of land that had been created by the previous owner: this area was an ugly zone of mostly knapweed, an area with low ecological value. Our restoration expert Robin Annschild advised us that the best thing to do with this area was to create a beautiful new liner-pond there, and thus work began (the pond-creation process is explained below). We had help from a crew of enthusiastic volunteers for this task.
At left: a pond-liner being installed by enthusiastic volunteers. The edge of the liner is staked down to prevent it from shifting once it is refilled with the dirt/gravel and coarse woody debris that ensure the pond's ecological functioning.
When the pond was complete, we pumped some marsh water into the new pond in order to settle the dirt and material we had placed into it, and to protect the pond liner from the sun and heat. Almost immediately this new pond was swarmed by dragonflies hunting smaller insects. When we sprayed water up into the air, they would swoop and play in the spray.
Then, just days after this pond was created from scratch, the most amazing natural miracle happened: hundreds of insects hovering over the pond, bouncing up and down in almost perfect synchrony, joyfully dancing on the surface of the water. Boing! boing!… they danced up and down about 4 to 5 feet.
We were incredibly fortunate to witness this
invasion of happy fairies dancing on the water of this brand-new wetland pond: clearly a blessing from Mother Earth for our endeavours.
The insects were identified as mayflies by our local bug expert Daniel Hellyer. And Google tells us this: "As dusk approaches, males swarm above the water, flying into the breeze and performing a mating flight or dance. Females join the swarm, rising and falling as the dance continues. The male grabs a passing female with its elongated front legs and the pair mate in flight.” Amazing!
Here follows a short conversation between Valhalla Foundation for Ecology director and Snk'mip project lead Lorna Visser, and local insect expert Daniel Hellyer:
Lorna: These mayflies are clearly an amazing and nuanced creature. Thanks for confirming that what we saw was a massive mayfly dance, what a thrill.
Daniel: An amazing show, indeed. I’ve never witnessed it myself — consider yourself very fortunate.
Lorna: But you’ve seen mayflies before, right?
Daniel: Yes, when (Daniel's partner) Helen and I were on a bicycle tour in Nova Scotia, we stopped by a stream for a rest. When we left, Helen saw a mayfly subimago on her pannier (the subimago emerges from the water and flies off to rest somewhere before a final molt. It is the only insect I know that molts AFTER it has wings.)
This one latched onto Helen’s pannier for 50 kilometres, through the wind and over bumps, until we stopped for the night. I then carefully carried it down to another stream where it could make its final molt and transformation into the imago stage, spend the night, and then begin dancing and mating in the morning light.
Lorna: Sounds like fun! Tell me more about these creatures.
Daniel: After the eggs are laid, all mayflies fall and die. The insect order is called Ephemerata. They’re here for a good time, not a long time. And it’s feast time for trout, swallows, ducks, frogs, and anyone who enjoys a high-protein meal.
Lorna: It’s pretty surprising that they showed up so suddenly at the Snk’mip Marsh Sanctuary, in this brand-new pond, isn’t it?
Daniel: Yes. Mayflies, dragonflies, and other aquatics spend most of their lives under the water in or near the muddy bottom. However I wonder if a pond liner might interfere with the varied and complex activities that doubtlessly occur in a certain depth of sediment?
Lorna: Good question. To address that, regarding the ecological viability of the bottom substrate of the pond-liner ponds we create, let me explain the procedure.
1. First we dig a bowl-shaped depression which has to be level or all the water would run out of the low side... doing this at Snk'mip was quite the engineering challenge given the overall 20 to 25 percent slope of the property. Then we rake out the sharp rocks and smooth the bowl-shape nicely — this is a lot of hard physical work, I can tell you that from personal experience.
2. Over this depression is placed a layer of protective geotextile, then the pond-liner (looks like rubber but it's actually amphibian-safe plastic), and then another layer of geotextile. The geotextile "sandwich" protects the very expensive pond liner from being broken by, for example, a bear's claws or a deer's sharp hooves, should one of those animals walk through the pond.
3. Then we carefully place dirt and gravel into the pond, quite a deep layer of dirt e.g. 6+ inches of material. This is the same material we previously dug out of the pond depression so we're not putting in any dirt that wasn't already there. Then we add a few large rocks and various coarse woody debris items including stumps and dead logs (for shade and shelter below, and as perches for turtles, birds, etc. above). Then we carefully fill the pond so as not to disturb the fines in the dirt/gravel layer.
So I think it's fair to say that the bottom of the completed liner-pond is pretty much identical to what would be there in a natural pond (if the area held water to form a pond).
Daniel: Interesting. See anything else of note?
Lorna: Yes, the liner-ponds we created last year are very well used, to the point that this spring I saw a Western Painted Turtle (a threatened species) in the liner-pond we created in the former gravel pit area. I was stunned, and of course thrilled beyond belief, as we thought turtles were extirpated here. That's a pretty good endorsement of these ponds' ecological validity.
Photos: Mayflies: Daniel Hellyer Pond installation: Lorna Visser
Western Painted Turtle in Snk'mip liner-pond: Debbie Pitaoulis
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