A citizen quest to find sea stars along the San Diego coast can help scientists better understand biodiversity

SAN DIEGO — The final week of the year will bring low tides to San Diego’s coastline, giving tide poolers one more chance this month to participate in a statewide quest to find sea stars — otherwise known as starfish.

The Solstice Sea Star Search along the California coast is an initiative from the California Academy of Sciences to track sea star populations, which were widely decimated about a decade ago due to an infection with possible links to climate change.

The project runs twice a year in the months of June and December, around the summer and winter solstices, when tides are typically at their lowest. From Christmas Day through Dec. 30, various tides along the San Diego coast are under one foot.

To participate in the search, locals can look for sea stars and log their finds on the iNaturalist app — community science that helps researchers monitor the populations and the animals’ overall health.

“When you’re mobilizing so many people — not just gatekeeping research and science to institutions — you’re spreading out that responsibility and those efforts to the broader community,” said Olivia Poulos, the community engagement manager for the San Diego Museum of Natural History, which is helping get the word out about the sea star search.

So far, more than 1,600 sea star observations have been logged this month along the coast, including over 60 in San Diego County.

Here’s what else you need to know about the search and how to get involved.

Why do sea stars matter?

Sea stars are often called a “keystone species.” As predators in the intertidal food chain, they help keep the entire ecosystem balanced by eating other organisms like sea urchins, which in turn eat algae, such as seaweed and kelp.

Without sea stars, urchins will eat too much algae, which can destroy kelp forests and overhaul the ecosystem. Urchin barrens — areas devoid of kelp and dominated by sea urchins — have become a more frequent sight on the West Coast with the loss of sea stars.

“The kelp forest is a beautiful, amazing ecosystem with massive kelp that serves as a safeguard for animals,” said Olivia VanDamme, community science coordinator at the California Academy of Sciences.

Around 2013, sea star populations from Mexico to Alaska began to plummet due to sea star wasting syndrome, a disease that causes sea stars to develop symptoms such as skin lesions and lose their arms before eventually killing them. Research has suggested rising ocean temperatures may have played a role, with warmer water making the stars more susceptible to disease.

Some species have begun to recover, but others such as the sunflower sea star — which is proposed for being listed as threatened under the Endangered Species Act — have seen less of a positive recovery and may be considered locally extinct in some areas.

In 2023, scientists as the Birch Aquarium successfully spawned three sunflower sea stars in an effort to bring back the population.

How can I participate? And how is the data used?

To get involved in the Solstice Sea Star Search, download the iNaturalist app on your phone and create an account. You can join the California Academy of Sciences’ Winter Solstice Sea Star Search project on the app, but it’s not required. Once you start logging the sea stars you find, they will automatically be routed to the project.

Searching for sea stars is a fun experience in itself — but your discoveries will also actually help scientists better understand California’s biodiversity.

The California Academy of Sciences is working with the California Ocean Protection Council and California Department of Fish and Wildlife to create an Early Warning and Forecasting System to monitor biodiversity change on the West Coast, using crowdsourced data from tide poolers and outdoor enthusiasts up and down the state.

“There’s no way my team could get enough scientists out into the field on these low-tide days … everywhere in California to see what’s going on,” VanDamme said. “The story with the sea stars is a success story for the field of community science.”

When is the best time to go tide pooling?

From Christmas Day through Dec. 30, the tide will be a foot and under at several spots along the San Diego County coast. There will be a new moon on Dec. 30, a lunar event that often coincides with low tides.

For more information about the specific time of day to go, check out the California Academy of Sciences’ Tides Finder, which shows low tides around the state, including at nine San Diego locations from Imperial Beach to La Jolla. The low tides at those locations this week are spaced out between noon and 4 p.m. each day — perfect for a leisurely lunchtime adventure with family.

Cabrillo National Monument also keeps a log of the tides on the Point Loma peninsula, and there are several websites that track high and low tides in other parts of the county, too.

Where should I go in San Diego?

Cabrillo National Monument, Tourmaline Surfing Park, Torrey Pines and Cardiff state beaches and tide pools in Carlsbad, near Shore Drive and Carlsbad Boulevard, are all good spots for tide pooling.

There are also a few places to go in La Jolla, including pools off Coast Boulevard, south of Cuvier Park, and at La Jolla Shores near the Scripps Pier.

And while the goal this month is to find sea stars, keep your eyes peeled for other critters living at the coast, including anemones, sea snails, octopus and sea slugs like the Spanish shawl.

Be sure to exercise respect for the wildlife and refrain from picking up animals and plants or removing them from their habitat. Walk slowly and cautiously, too, so you don’t accidentally step on one.