Vernal pools hold waters of life

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1 Vernal pools hold waters of life MARCH 16, 2010, 12:02 AM The endangered fairy shrimp swims on its back and feeds by filtering nutrients from the brackish waters. John Gibbins

2 Short-leaved dudleya is among the plant life found at the vernalpools in Rancho Peñasquitos.

3 In Rancho Peñasquitos, small mushrooms grew in a patch of microbial soil for a brief time during San Diego s rainy season.

4 Kearny Mesa is among the places in the county were vernal pool basins are clustered. POOL SPECIES Seven federally protected species live in vernal pools across San Diego County: California Orcutt grass Otay Mesa mint Riverside fairy shrimp San Diego button celery San Diego fairy shrimp San Diego mesa mint Spreading navarretia SOURCE: Chaparral Lands Conservancy At first blush, the shallow ponds that dot the Miramar plateau near state Route 163 seem like mere puddles. One formed when a piece of heavy equipment rolled off a dirt road and created a trough that filled with water during winter storms. But these spots don t dry up a few days after it rains. They can last several weeks, long enough to create habitat for dozens of species including shrimp, frogs, worms, insects and water-loving plants, some of which have nearly disappeared from California. It s just its own little tiny universe, said Katie Davis, a University of San Diego lab technician who studies seasonal

5 wetlands. She s trying to catalog the kinds of crustaceans that inhabit a series of vernal, or spring, pools on Carmel Mountain. It s part of a growing effort to study, restore and safeguard ponds that once covered about 200 square miles of the county. Today, the San Diego City Council is expected to authorize acceptance of a $500,000 federal grant that would help create a new conservation plan for vernal-pool habitat. About 3 percent of historical vernal pools remain in Southern California, typically on mesas that are popular for development projects. The rest have been bulldozed to make way for roads, homes and businesses. Destruction of the ponds has eased in the past decade because landowners risk federal penalties and lawsuits from conservation groups if they harm protected plants and animals living there. In several places across San Diego County, including Montgomery Field and an elementary school site in Otay Mesa, the pools have slowed or halted expansion plans. Researchers and wildlife advocates describe vernal ecosystems as biological gold mines. One of their most important functions is providing protein, in the form of tiny invertebrates, for amphibians and migrating birds. The signature vernal-pool species is arguably the endangered San Diego fairy shrimp, a quarter-inch-long crustacean that swims on its back and feeds by filtering nutrients from the brackish waters. Vernal pools are just seething with almost-microscopic crustaceans and insect life, and many of those have not been described by science, said David Hogan, director of the Chaparral Lands Conservancy in Mount Laguna. It s not a high-profile campaign like saving the California condors or protecting sea otters, but Hogan said appreciation for the ponds is swelling as residents realize their biological significance. I have been amazed at how many people know about vernal pools and are excited to see all of the amazing things that come to life with the rains, he said. The El Niño years are when the vernal pools really pop. Meteorologists have described this winter as one of the strongest El Niño seasons since record-keeping began, and that could produce above-average rainfall. Roughly 2,500 vernal-pool basins were identified in the city of San Diego during an inventory completed in the early 2000s. They re clustered in Del Mar Mesa, Kearny Mesa, Mira Mesa, Otay Mesa and a few other spots. Vernal pools also appear in the Mediterranean climate zone from southern Oregon to northern Baja California. They form in soil depressions where layers of hardpan clay prevent rain from percolating into the ground, said John Howard, landfill operations manager for San Diego. Lands next to Miramar Landfill are dotted with vernal pools including the one formed by the wayward piece of machinery forcing Howard to become an expert in them and prevent their destruction on city-managed property. Think of the topsoil as a sponge, Howard said. When it gets saturated, then pounding occurs. Buried in the ground of vernal basins are countless seeds and cysts that can survive for a decade or more until they re brought to life by standing water. In wet years, the pools will spill over the top and carry seeds to other spots. That mixing of genes helps life-forms continue to evolve, as they have for eons. There are two extreme conditions here that plants and animals have to deal with in order to survive drought and inundation, Howard said.

6 (Species) all have their own unique niche, he added. Some prefer the deeper water. Some prefer medium water. Some prefer shallow water. So when all the water dries up and goes away, vernal pools are known to have a ringing effect of color based on the species of flowers and plants at slightly different elevations. Vernal-pool species go through their life cycles in a matter of weeks, making sure to spread their seeds before they die. One such plant is the San Diego button celery, which shoots spindly branches a few inches out of the glassy pools. It looks like the kind of thing that a fastidious gardener would remove, but don t even think about doing so, Howard said. If you pull this one, it costs you $10,000, he said, referring to the fine for harming this federally protected plant. Historically, vernal pools were largely seen as a nuisance by the public and developers, said Marie Simovich, a biology professor at the University of San Diego and an expert on seasonal wetlands. Her assistant researchers, including Davis, are studying roughly 20 pools at the Carmel Mountain Preserve, where mountain bikers and horse riders routinely splash through them and disrupt their delicate biological balance. Late last month, the team took water samples at the site to create a list of creatures that live there and help ensure that any work at the site is biologically sound. Just restoring a puddle that holds water is not restoring the ecosystem, Simovich said. San Diego city officials are considering various strategies to enhance and protect the pools with support from Hogan s conservancy. His group helped secure money to study the Carmel Mountain pools from the Arizona-based Center for Biological Diversity, which supports endangered species. Hogan also is seeking about $450,000 from the San Diego Association of Governments to restore damaged pools and plant sensitive species at the site, which was slated for housing development in the early 1990s. He and others have helped set aside about 300 acres to protect the pools. I still consider it a miracle that it was largely conserved, Hogan said. This property in particular is like a little Noah s Ark of nature surrounded by a sea of development. Copyright 2018, The San Diego Union-Tribune