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Habitat
These aquatic
creatures have evolved and adapted to a very specific environment. They inhabit
seasonal wetlands known as vernal pools. These pools form in shallow depressions
or terraces, and experience various flooding and drying periods annually. They
are directly associated to areas of the Earth that are classified as having a
Mediterranean climate (Keeley and Zedler, 1998). These pools experience
flooding, or inundation that begins with autumnal rain. The water does
not easily percolate through the ground due to the impervious nature of soil
layers which are directly associated with vernal pools (Holland, 1978). Soils
such as: cemented hardpans, claypans, and beds of ancient volcanic flow are
California vernal pool soil types (Holland, 1978). Vernal pools encounter four
stages in their annual cycle: (I) a wetting phase, (II) an aquatic/ inundation
phase, (III) a saturated-terrestrial phase and (IV) a drought phase (Keeley and
Zedler, 1998, Barry, 1995). The water that collects in vernal pools experiences
daily changes in temperature, ph, and dissolved CO2 and oxygen (Keeley and
Zedler, 1998). Vernal pools range in size from small single pools 2
m square to lakes 356,253 m square and are often interconnected complex pool
systems (Helm, 1998, Keeley and Zedler, 1998, Goettle, 1997). The vernal pool
tadpole shrimp generally occupy pools ranging 2-15 cm in depth and a volume of 23-
9,262573 m3