The Rocky Intertidal

Explore the Tidepools of Cabrillo National Monument

(Exerpt from the 2010 Fall/Winter Cabrillo Journal)

By Park Ranger Bonnie Phillips

The tidepools at Cabrillo National Monument provide a rare glimpse of the abundant life in our oceans. The Rocky Intertidal is a place where children see their first hermit crabs or sea anemones, and where adults can find solace and escape from their busy lives. Whether you come to see the amazing critters or to enjoy the spectacular seascape views, the tidepools are often where people fall in love with the ocean.

The tidepools are part of a very fragile environment and the National Park Service is entrusted with the mission of making sure they remain “….unimpaired for the enjoyment of this and future generations” as set forth by the NPS Organic Act on August 25,

1916. Providing for recreation and education while not harming the unique coastal habitat creates a difficult and delicate balance. It’s the volunteers, who dedicate their time and passion for education, who help make it all possible.

In 1990, National Park Service researchers Jack Engle and Gary Davis launched a massive project to study the tidepools. Over the course of five years they discovered that seven of 13 key tidepool species were on the decline. In previous decades there just wasn’t as much awareness of how visitors might be impacting the tidepools. It was common for visitors to walk away with shells or living animals as souvenirs. As visitation grew, it became apparent that Cabrillo National Monument’s tidepools were in jeopardy. In 1996 several recommendations were made, including hiring a full-time marine biologist. The Natural Resource Management and Science Division at Cabrillo leads teams of rangers and volunteers who conduct tidepool monitoring twice per year. This scientific data collection helps keep track of the key species and assesses their health. Another recommendation from the Engle-Davis project included the establishment of a closed zone. The southernmost part of the peninsula is closed to the public. It’s a control zone and ensures a section of the tidepool area is free from human impact. Without this closed section, it would be impossible to separate human impact on the tidepools from any other environmental factors. Finally, a recommendation was made to staff the tidepools with a team of volunteer docents to remind visitors of the sensitive ecosystem and to educate people about the wonderful and yet often unfamiliar animals they might find. All of these recommendations make up the ongoing TPERP, or Tidepool Protection, Education and Restoration Program.

Since the TPERP volunteer program began in 1996, several species have made full recoveries. It’s a credit to the individuals who donate their time and share their passion for ocean conservation. Some TPERP volunteers have been with the program since it began 14 years ago.

Despite having 20 years of collected tidepool data, there is still much work to be done and many questions to be answered. Many visitors ask, “Where are the Ochre Sea Stars and why don’t we see any Black Abalones?” While we know some answers and some possibilities, it is up to researchers to solve some of these mysteries. This is one of the reasons the rocky intertidal environment is so important. It is one of the few places where ocean research can be conducted in a natural environment, without actually going out into the open ocean. It also offers a unique gradient. There is a great difference between the animals that can live in the higher splash zone of the tidepools as compared to those animals in the lower intertidal zone that are mostly submerged. Scientists have access to these different species in one small area. However, one obstacle to research is that very little rocky intertidal area actually exists along the California coastline, and what does exist is often not protected to the extent it could be. Since Cabrillo’s tidepools are so well protected, they are often visited by students and researchers from well-known scientific institutions such as Scripps Institution of Oceanography. While the Ochre Sea Star and Black Abalone may be absent from the Cabrillo Tidepools, there are numerous critters that delight visitors during the low tide season. Bat Stars, Knobby Blue Sea Stars, Two-Spotted Octopuses and countless other species make the Cabrillo Tidepools home.

The best viewing is between October and May, with the peak viewing times falling during the winter season. Summer visitors are often disappointed when they can’t find the tidepools. Here at Cabrillo National Monument, there is approximately an eight to ten foot tidal range. At six feet or more, you’ll find the waves crashing against the cliffs and, at a negative two foot low tide, you can walk west about the length of a football field through the exposed tidepools. It’s not until late autumn when those lowest low tides start happening during daytime park hours. It all has to do with the seasons and Earth’s position in relation to the sun and the moon. When the Earth, sun and moon align during the full moon and new moon, we have spring tides. This means the gravitational pull creates a tidal bulge, giving us extremely low and high tides. These tides are very predictable and are indicated on a calendar. If you want to experience low tide at Cabrillo National Monument, it’s recommended you check a tide calendar, or call ahead to the park to find out when the next good viewing opportunity will occur. Many people visit only during the summer months and are surprised during a rare winter visit to find so much intertidal exposure.

So please visit the tidepools during the winter season. Learn about all the amazing creatures, like the Sandcastle Worm, the California Spotted Sea Hare and the Giant Owl Limpet. Catch a glimpse of what lives in our ocean. Just remember to gently touch the animals with one finger. While the shells may be beautiful, keep them in the tidepools, as they support a great amount of microscopic life as well as important algae, a food source for many intertidal animals. Those shells also become the homes for hermit crabs and serve as protection for other organisms. The tidepools can be considered a nursery for many of the ocean animals that spend their young lives here before heading out to sea. You’re invited to explore and enjoy while keeping in mind the great care and respect that goes along with a visit to any nursery. There will undoubtedly be a TPERP volunteer on hand to ensure that you do.

Be careful…. you just might fall in love with the ocean too.

Last revised 05-Aug-14