SEARSPORT — What exactly is a vernal pool? The definition of vernal is something that happens in spring and a pool is fairly evident, but the words put together, and it becomes somewhat enchanting, for it means an ephemeral pool or shallow pond that provides a habitat for certain creatures in the spring before it dries out in the summer.
On Wednesday, May 9, nearly a dozen people gathered at Sears Island to check out a vernal pool with Dr. Aram Calhoun, Professor of Wetlands Ecology at UMaine Orono and Dr. Kristine Hoffmann, a herpetologist and blue spotted salamander expert. The free walk and demonstration was hosted by Friends of Sears Island.
At first glance, a shallow pool of water in the woods seems like no big deal — but that’s looking at it with adult eyes. You need to squat down at the edge of the pool like when you were a kid, and really look at what’s in it.
At a vernal pool on Sears Island, Calhoun and Hoffmann started to slosh around in the shallow water to see what they could collect and came back with globs of what looked like clear jelly. These, were in fact, Spotted Salamander egg masses with some of the embryos still growing inside. With a dip net, they also collected tadpoles, explaining that it was already too late in the season to see any wood frog egg masses.
Wood frog egg masses looks like lumpy clear, tapioca and contain 800-1,000 eggs, which develop for roughly 20 days, dependent upon temperature. Tadpoles stay in the water for 80 to 115 days, and then emerge in July and August. By the time the group arrived at this vernal pool, the eggs had already hatched and the tadpoles swimming around were about the size of a baby’s fingernail.
Calhoun and Hoffmann encouraged the group to look under logs and squishy forest leaf litter, and some of the participants came back with their own discoveries: a tiny red-backed salamander and a caddisfly, which predates on the egg masses.
Other tiny creatures that live in vernal pools (that weren’t seen on that walk) include fairy shrimp, (orangeish crustaceans) and pupating mosquitoes, wood frogs, and the rare and elusive blue-spotted salamander. Once the group had the chance to examine the creatures, they were instructed to go put everything back where they found it.
Anyone can go at any time and check out the vernal pools at Sears Island. To get to the spot where Calhoun and Hoffmann took the group, simply take the first left as you walk into the island on the Homestead Trail until you reach a “bridge” on the muddy path of double logs. You’ll start to see a water mass on your right within the reeds and brush. At the very end of those logs, hang a sharp right and walk about 200 feet. Merryspring Nature Center also has a vernal pool which is in an abandoned Rockland-Rockport Lime Company quarry hole. In early spring, you may hear the “quacking” of wood frogs as they make their mating calls and in later spring, wood frog tadpoles and spotted salamander larvae hatch from their eggs.
For more information on Friends of Sears Island’s summer programs visit: friendsofsearsisland.org/
All photos by Kay Stephens
Kay Stephens can be reached at email@example.com