But scientists are uncertain how to predict the timing and average duration of flooding of any given pool without consistently monitoring each site.
“The problem is that we have no way of knowing how long a particular pool is flooded just by looking at it,” said Frank Golet, a professor of natural resources science at the University of Rhode Island. “When a pool is without surface water, you might not even recognize it as a pool. And people who want to protect vernal pools from human impacts can’t afford the time to monitor individual pools for months to find out if they are flooded long enough to provide viable breeding habitat for these species.”
So URI graduate student Dennis Skidds of Cumberland and junior Eric Walsh, a resident of Lincoln, spent the summer making regular visits to 65 vernal pools in southern Rhode Island to learn what features of the pools – size, depth, vegetation, geology – can be used to predict when and for how long a given pool will be flooded.
“Hydroperiod – how long ponds are flooded – defines whether a pool is going to be good breeding habitat for certain species like wood frogs, spotted salamanders and marbled salamanders,” said Skidds, 28, a Brown University graduate. “If land managers have a good idea about how to predict whether a particular pool is good habitat, they’ll know better whether the site should be protected. But past studies have had no predictive value as to how long a pool has standing water.”
This study hopes to change that.
Each amphibian species has an optimum period when breeding pools must be flooded. Wood frogs, for instance, need their pools to be flooded from late March through July, just enough time for their eggs to hatch and tadpoles to metamorphose into frogs. Marbled salamanders, on the other hand, lay their eggs in the fall, so they need breeding pools that hold water from November to late July.
The objective of this five-year research project, according to Skidds, is to try to correlate hydroperiod with other environmental factors. Does the presence of a particular plant within the pool, for instance, suggest the pool will remain flooded through the summer? Might the type of soils indicate when the pool dries up?
Walsh, 20, said he and Skidds began last March “collecting edge measurement data at each pool every other week to see where the water level was, and then we did perimeter measurements in May and June. After that we set up transects at each pool for vegetation sampling, identifying all the vegetation along the transect and estimating the vegetation coverage along the line.”
Vegetation data were collected through September, along with tree basal area data, which Walsh described as “the amount of biomass of trees around the pool. It’s a factor that might affect the rate of drying in the pools.”
While the student researchers haven’t begun to draw conclusions following the first year of field work, Skidds said “it’s heartening to see that a good many of the pools we sampled had wood frog populations, because there’s been a concern that their population has been going down.” In addition to wood frogs and spotted salamanders, Skidds and Walsh saw several populations of the less common marbled salamander, as well as many other common creatures typically found in vernal pools, like fairy shrimp, water scorpions and predaceous diving beetles.
“There are lots of beautiful places in Rhode Island that I didn’t know existed,” said Skidds. “Some of the pools we studied are in beautiful settings. It’s nice to know we have places like that left.”
Funding for the project was provided in part by a Wald Science Research Grant from The Nature Conservancy. Walsh also received support from the URI Agricultural Experiment Station through the URI Coastal Fellows Program, a unique program designed to involve undergraduate students in addressing current environmental problems. Now in its sixth year, the Coastal Fellows Program teams students with URI faculty, research staff and graduate students to help undergraduates gain skills that will ensure their future success.
“I learned more this summer than I could ever learn in the classroom,” said Walsh, who hopes to someday become a herpetologist. “It’s been a great experience that I’d definitely recommend to other people if they have a chance.”
Upon graduation, Skidds plans to continue working on habitat conservation, “hopefully for some of the organizations that could use the information we’re collecting in this project, like The Nature Conservancy, Audubon Society, or state wildlife agencies.”
Note to Editors: Several digital images of the students conducting their fieldwork are available for your use. Contact Todd McLeish at 874-7892 or tmcleish@uri.edu.