Dispatches from a Vernal Pool
Vernal pools, like coral reefs, are theatres showcasing life and death struggles between prey and predators.
There are few places I’d rather be in the springtime than standing in the cool water of a vernal pool with wood frogs quacking and leopard frogs grunting. These temporary ponds are wonderful places to get your feet wet. The life they support is astonishing.
An apt comparison would be the exotic life that abounds in and around coral reefs. Life in a vernal pool is generally smaller scale, but it rivals coral reefs in many other ways.
The crazy exuberance of shapes and forms for example, or the diverse methods of feeding, locomotion and reproduction. Vernal pools, like coral reefs, are theatres showcasing life and death struggles between prey and predators. Dragonfly nymphs, salamander larvae and diving beetles are the sharks, the crocodiles, the barracudas.
Their quarry are clouds of crustaceans – daphnia, copepods, fairy shrimp – and innumerable insects, including swarms of mosquito larvae.
Video in this blog shows Jefferson salamander eggs strung like aquatic ornaments along submerged branches in a vernal pool. Most of the egg masses, laid in early April, will soon release their amphibian spawn into the water column.
Jefferson Salamander Eggs
Another video is of fairy shrimp and a few fellow travellers (mosquito larvae and predacious diving beetle larvae) that got caught in my net. I isolated the fairy shrimp in a small aquarium to allow easier filming. Watch closely and you’ll see fairy shrimp mate. Try not to blush!
Mating Fairy Shrimp
In three months or so, vernal pools will be dry. The fate of their multitudes is varied. Many will die, with eggs left as a surety for next year. Some will fly to permanent water. Newly transformed frogs and salamanders will adopt a terrestrial lifestyle and other creatures, like snails, will simply stay put, resting dormant in the detritus until water reanimates them.
Next spring, that new water will reanimate me as well. I’ll return to the vernal pools, wearing chest waders and a smile.