|
Tadpole Shrimp cont. margins. This is the time period when vernal pools are at their showy best,with a striking profusion of yellow, white, and purple blooms often totally carpeting the pool bottoms and pool margins. At this time, mobile animals begin to disperse from the vernal pools and the vernal pool plants start to produce seeds. As the pools continue to dry, plants turn brown, and the soil dries and may crack. Very few perennial plants have adapted to the vernal pool environment, since California rainfall patterns can include extended drought-like conditions. Annual wetland plants are the most common plants in typical vernal pool communities. Vernal pools are a unique type of habitat, since they are freshwater aquatic ecosystems that are typically dry 7-8 months out of the year. Vernal pool tadpole shrimp (like the related "fairy shrimp" species) only live in ephemeral freshwater habitats, an environment with very few aquatic predators, especially fish. These shrimp are unknown from any marine, estuarine, or riverine system. Vernal pool tadpole shrimp and fairy shrimp serve as food for a variety of vertebrate and invertebrate animals in vernal pools. Both tadpole shrimp and fairy shrimp are readily consumed if there is a temporary connection of vernal pools to more permanent water bodies containing fish. If the connection becomes permanent, these vernal pool crustaceans will eventually disappear, since they have no defenses against direct predation by fish.
A key adaptation of the vernal pool tadpole shrimp to this alternately wet and dry vernal pool environment is the numerous drought-resistant cysts (eggs) |
Last updated:
May 27, 2008
|