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Four Very Important Vernal Pool Species Vernal pools in Maine are defined by the presence of one or more of four indicator species. These animals depend upon vernal pool habitat for successful reproduction. The indicator species are spotted and blue-spotted salamanders, wood frogs, and fairy shrimp. Because vernal pools are typically isolated and variable habitats the animals that inhabit them have developed specialized survival strategies to cope with the temperature changes, oxygen stresses, and drought accompanying the seasonal appearance and disappearance of water. Larval amphibians must race against time. Three to five months is needed to complete the amphibian life cycle, from egg laying to metamorphosis. The time between hatch and metamorphosis, however, can be highly variable. Salamanders are able to metamorphose more quickly and at a smaller size when a pool threatens to dry prematurely. Some invertebrates inhabiting the pools, such as fairy shrimp, may complete their life cycle in less than a month. In general, fairy shrimp can be seen swimming in pools that may still be partially frozen, then the wood frogs arrive, followed by blue-spotted salamanders, with spotted salamanders coming to the breeding sites last. In some years, all the species will appear together. To see photos and descriptions of the four primary species, click the links below. |
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