Vernal pools are seasonally flooded depressions found on ancient soils with an impermeable layer such as a hardpan, claypan, or volcanic basalt. The impermeable layer allows the pools to retain water much longer then the surrounding uplands; nonetheless, the pools are shallow enough to dry up each season. Vernal pools often fill and empty several times during the rainy season. Only plants and animals that are adapted to this cycle of wetting and drying can survive in vernal pools over time.
These specialized plants and animals are what make vernal pools unique. As winter rains fill the pools, freshwater invertebrates, crustaceans, and amphibians emerge. Vernal pool plants sprout underwater, some using special floating leaves and air-filled stems to stay afloat. Some of these plants even flower underwater! Birds arrive to feed on the vernal pool plants and animals.
In spring, flowering plants produce the brightly-colored concentric rings of flowers that vernal pools are famous for. Native bees nest in vernal pools and pollinate pool flowers. Insects and crustaceans produce cysts and eggs, and plants produce seeds that are buried in the muddy pool bottom. The mud protects cysts, eggs, and seeds from the hot, dry Central Valley summer. By late summer, amphibians have dug deep into the soils and gone dormant, awaiting the next rainy season. Vernal pools have completely dried out and most of the plant and animal species have either disappeared into the soils or set seed and died. In this phase, vernal pools are really “banks” full of resting seeds, cysts, and eggs that can survive through summer, and even extended droughts, until the onset of the rains begin the life cycle anew.
Taken from: http://ceres.ca.gov/wetlands/whats_new/vernal_sjq.html [ceres.ca.gov]
Fiesta Island is a large area of land centrally located in Mission Bay. There is a 5 MPH zone on the east side of the island that is popular for recreational water sports. Permits for this location are usually for Over the Line tournament, walks/runs, bicycle races/time trials and other special events. The Fiesta Island Youth Camp and the Aquatic Center are on the island. There are bonfire rings around the shore of the island and dogs are allowed off leash. There is a a permitted water ski area in Hidden Cove and permits for water skiing only are available from the Lifeguards at their headquarters, 2581 Quivera Court.
Taken from: http://www.sandiego.gov/park-and-recreation/parks/missionbay/fiestaisland.shtml [sandiego.gov]
Vern Pools and Fiesta Island