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Student Vernal Pool Projects

What Is That Oversized Puddle In My Backyard?

A slide program by Laura Viegas
Reading Memorial High School, Reading, MA


This script provides a background into the breeding habits of animal species necessary for a wetland to be considered a vernal pool. It continues with a brief overview of the various organisms living in a New England vernal pool.

View of vernal pool 6. What is an oversized puddle that holds water for two to three months in spring and summer and supports breeding populations of wood frogs, mole salamanders and fairy shrimp, but no fish? Well, if you guessed vernal pools then you are correct. Vernal Pools are found in many areas all over the world where temporary wetlands can be accounted for. Their appearance varies from place to place because of the diverse climate, soils and vegetation.
dry vernal pool 4. In the summer vernal pools have very little water or are totally dry. Therefore, vernal pool species have evolved over time to adjust to this drying and refilling of water. At the same time, populations of fish do not have the requirements to survive.
15. A vernal pool is not a vernal pool if certain animal species are not present. These obligate species either breed or spend their whole lives in the pool. Some of these include Mole salamanders and wood frogs, who only come to a vernal pool during the springtime breeding season. Other obligate species such as fairy shrimp spend their entire lives in the pool. In Massachusetts, obligate species include wood frogs, four types of mole salamanders and fairy shrimp.
Wood frogs laying eggs 16. Wood Frogs mate when the male embraces the female attempting to squeeze her eggs out. In this manner, he may fertilize them. The wood frog's egg masses are about the size of a tennis ball. Their eggs are laid in communal sites amidst the vegetation.
Wood frog tadpoles 19. In mid-April, the wood frog's eggs are ready to hatch. After hatching, the tadpoles will remain attached to the vegetation near the egg masses until they feel comfortable enough to leave. The newly hatched tadpoles are about one-half inch in length. They appear to be masses of dots upon leaves in the pool.
Tadpole with legs 20. By the end of April, they have grown into small, black tadpoles of about one inch in length. These tadpoles feed on leaf litter and vegetation in the vernal pool. In late July, the tadpoles will have grown to their full size, leaving the pool, only to return in a few years for breeding purposes.
Blue-spotted salamander 32. The second group of the three kinds of obligate species are mole salamanders. This group includes four types of salamanders: spotted, marbled, Jefferson and the blue-spotted salamander which is shown here. After the first spring rain, the blue-spotted, spotted, and Jefferson salamanders begin their journey to a nearby vernal pool where they can breed.
Spotted salamander 21. These mole salamanders partake in the breeding extravaganza at a vernal pool yet they do not live there. These animals, including this spotted salamander, spend their lives upland from the pool in the adjacent forest, only to come down during breeding night. They proceed to lay eggs and then return to their upland habitats.
Jefferson salamander 37. The Jefferson salamander also engages in the spring breeding ritual. These salamanders are extremely rare in Massachusetts and hard to catch even during breeding season.
Eggs of spotted and blue-spotted salamanders 34. The males of the mole salamander start a breeding dance that eventually leads to the deposition of spermatophores. These are later picked up by a female in her cloaca, where the eggs are internally fertilized, and eventually laid as egg masses. Like wood frogs, these salamanders attach their eggs to vegetation in the vernal pool.
Marbled salamander 38. Marbled salamanders breed in the opposite season of its fellow mole salamanders. They will travel to the dried-up pool in fall, where she will lay her eggs in anticipation of fall rain that causes the water table to rise and leads to the refilling of the vernal pool. The mother usually stays with her eggs until the pool refills and then goes on her own way. Her eggs will hatch in fall or early spring.
Fairy shrimp 43. Fairy shrimp are small crustaceans that are also obligate species of Vernal Pools. In Massachusetts, there are three different kinds of Fairy shrimp, but it is hard to tell one from another. Fairy shrimp permanently live in vernal pools. They survive as long as the vernal pool contains cool water. They die when it drains. However, their eggs rest upon the dry bottom allowing them to live onward to next season.
Spring peeper 45. There are certain species that might use a vernal pool to breed but can also survive elsewhere. These are the facultative species which include spring peepers and a variety of other organisms. Facultative species may not define a vernal pool, but are still considered very important members of the vernal pool community.
Wood turtle 58. Don't think that facultative species are limited to frogs and other newt-like creatures. Other organisms, such as the box turtles, spotted turtle and this wood turtle, are also facultative. These turtles migrate to and from the pool at various times to feed or breed in or near the pool. Turtles can be found near the vernal pool or in the vegetation as the pool slowly drains.
Water scorpion 69. Other facultative are the many types of predatory insects, like this water scorpion. Camouflaged organisms like these are very hard to find as their stick-like frame blends in well with vernal pool debris.
Fingernail clams and whorled snail 62. Both flat and turret-shaped snails are common facultative species of vernal pools. These snails feed upon the vegetation found in the pool. Fingernail clams are also common in vernal pools. They attach themselves to the bottom of the pool and upon the vegetation. They eat microorganisms and detritus that they filter from the water.
Ribbon snake in moss 59. This ribbon snake and other snake species come to vernal pool shores to feed upon the abundant animal life in and around the pool.
View of vernal pool in late spring 11. So, next spring when you are out sloshing through an oversized puddle, search for some salamander and wood frog eggs or evidence of fairy shrimp. You might be in a vernal pool

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