March 26, 2016
Pond life in motion. Video by Kelsey Bailey. When we planned the Nature Gardens, there was never really any doubt that we would include a pond. Water sources are highly attractive to wildlife, so even while the concrete was being scraped off the work site, we began to imagine the creatures that might use ours. We were particularly interested to see what types of microscopic animals might arrive, as when they are properly displayed (and magnified), they present to the public a stunning and unfamiliar fauna. In 2012 the pond was established as an essentially barren pool of rock with a few planters. Over the years the garden team has carefully added additional substrate on the bottom, more planters, and balanced the flow of the pumps and waterfall to make for quiet areas of micro habitats. What has grown is a pond that is rich with possibility for different groups of animals to utilize. The shallow shelf above the waterfall is an ideal place for yellow-rumped warblers to bathe and groom, and the faster moving water under the bridge are potential places for our native chub to hide and spawn. Like most urban habitats, however, the microscopic world of pond life has been little studied.
One chironomid larva eating another. Photo by Kelsey Bailey. Recently, we took a sample of the debris gathered in the base of the plant by the dock, looking for those long imagined microscopic creatures. We found a lively community of strange, active animals that surprised even us with its diversity and beauty. The most easily visible are the snakelike immature stages (larvae) of non-biting midges of the family Chironomidae. Chironomid larvae are common in our pond, where they feed on algae, smaller organisms, or sometimes even each other! They attach their posterior end to a twig or root and wave around, looking for food in a mesmerizing, never-ending dance. Also common in the pond are tiny crustaceans called ostracods, which look like animated seeds that scurry along the bottom, looking for food. Their patterned exterior is clamshell-like, with their many appendages extending between the “shells," propelling them rapidly through the water.
Water mite. Photo by Kelsey Bailey. Unlike the ostracods that zoom around in the samples, the water mites are slow and tanklike in the water. They look like heavy-bodied spiders and they plod through the vegetation
Planarian flatworm. Photo by Kelsey Bailey. Other, lightly less common creatures are the freshwater copepods, that dart through the water in jerky spurts, often carrying a pair of egg sacs behind them. We saw one planarian flatworm (though 2 ½ years ago, another staffer found one and wrote this blog about them), a comical looking animal that appears perpetually cross-eyed, a caddisfly larva with its case, and a few things that defy identification at this time. Besides the photos displayed here, have a look at the accompanying video to get an idea of what this stuff looks like in real time. It’s an easy and fun way to get a look at an alien ecosystem that occurs on our own planet.