Carmel Mountain Vernal Pool Hike
By Antonella Zampolli
The abundant January rains set the stage for a spectacular vernal pool visit. The hike was organized by the Friends and led by David Hogan of the Chaparral Lands Conservancy. We visited vernal pools in Carmel Mountain Preserve, where recently the Conservancy and Eagle Scout candidate Dylan Kearse built a viewing deck spanning the width of one vernal pool, allowing visitors to peer over the side directly over the water, and installed new much needed signage.
The Friends provided the funding necessary to buy the building material, and were consequently treated to a special interpretative hike through the preserve and to the new deck. The hike was well attended with about 30 participants who enjoyed the viewing deck, which allowed for excellent observation of the pool, teeming with tadpoles, fairy shrimps and various insects. As you can see in the video below, fairy shrimps were large enough to be captured with a smartphone.
Vernal pools are temporary water ecosystems, found typically on top of mesas in basins where silts, cobbles and sometimes clay form a hardpan that limits percolation, allowing winter rains to form these winter wetlands. Vernal pools were once abundant in San Diego County and other places in California, but due to extensive development on the mesas, it’s estimated that only 3% remain today.
Once water percolates and/or evaporates, vernal pools become hard to spot for the untrained eye, making it even harder to protect them as they often get trampled. But during their wetland stage, and before the summer heat dries them completely, they host a variety of plants and animals, 7 of them recognized endangered species. One endangered species we spotted was the San Diego Fairy Shrimp (Branchinecta sandiegonensis), a small crustacean that swims upside down; its fertilized eggs, called cysts, can survive in the desiccated vernal pool grounds for decades, waiting for the right conditions to emerge and continue the life cycle. We also saw the San Diego Button Celery (Eryngium aristulatum var. parishii), a species present only in vernal pools of San Diego and of the Sant Rosa plateau, just starting to emerge. We also enjoyed following the antics of the many tadpoles swimming and hunting.
On the path to the vernal pools we also found many flowering wart-stemmed ceanothus (Ceanothus verrucosus), lichens, mosses and hematite concretions.
The Friends are planning two more guided hikes to see the endangered vernal pool habitats: we’ll visit del Mar Mesa Preserve February 18th, and will return to Carmel Mountain Preserve on March 19th. Check the Event Calendar on our homepage for details and to learn about other guided hikes offered in the Preserves and nearby Open Spaces.
