Beach crustaceans going locally extinct

Caitlin Coomber

Two species of small, sand-dwelling crustaceans – key prey for shorebirds – are disappearing from beach ecosystems in southern California, according to a new study, funded in part by California Sea Grant.

“These beach invertebrates have gone locally extinct at about 60 percent of the beach sites where they were reported a century ago,” said UC Santa Barbara beach ecologist Jenifer Dugan, a co-author on the paper, which draws on historical and modern field data to reconstruct trends in the animals’ abundances since 1905 at sites from Santa Barbara to San Diego.

The places that still have high numbers of the crustaceans are usually un-groomed and un-armored beaches that are often also backed by bluffs, the scientists reported. These beaches tend to be more “remote” and may have limited vehicle access. Some examples include Blacks Beach in San Diego, Crystal Cove in Orange County and Dume Cove in Malibu. The crustaceans’ populations on the Channel Islands also appear to be relatively healthy, the scientists said.

“The major point is not necessarily that the invertebrates are themselves vanishing, but that they are indicators of bigger changes to the beach ecosystem, which have not been documented before,” said David Hubbard, the paper’s lead author, who is also a marine researcher with UC Santa Barbara.

The small burrowing isopods – which people rarely see because they are nocturnal and hide in their holes by day – are the proverbial canary, at the beach. “What we are seeing is the vulnerability of the entire upper-intertidal beach zone to coastal urbanization,” Hubbard said. It’s a high impact zone. It’s where beaches are groomed, armored and amended with imported sand. It’s where winter sand berms are built.

“Wetlands and rocky intertidal habitats are recognized as threatened ecosystems in California,” he said. “This study shows that the upper intertidal beach ecosystem in Southern California is also imperiled and, in my opinion, in need of more protection and restoration.”

“Climate change and sea level rise will exert further pressures on upper beach zones and biota in southern California and globally,” the scientists wrote in their abstract. “In the absence of rapid implementation of effective conservation strategies, our results suggest many upper intertidal invertebrate species are at risk.”

Dugan and colleagues have been surveying beaches in southern California as part of a larger study investigating long-term changes in sandy beach ecosystems in California. She currently has two ongoing projects with California Sea Grant and the Ocean Protection Council summarized below:

Sandy Beach Ecosystems: Baseline Characterization and Evaluation of Monitoring Metrics for Marine Protected Areas (MPAs) along the South Coast

R/MPA-24 Sep. 2011–Jun. 2014
Jenifer Dugan, UCSB, 805.893.2675,
Henry Page, UCSB, 805.893.2675,
Karina Nielsen, Sonoma State University, 707.664.2962,
Julie Bursek, NOAA/CINMS, 805.382.6141,

This project will produce a comprehensive baseline of the biodiversity of sandy beach ecosystems along the South Coast. Metrics for this include kelp-wrack coverage and composition; abundances and species diversities of marine birds, pinnipeds and macroinvertebrates, and population abundances, biomasses and sizes of target species, including sand crabs, Pismo clams, talitrid amphipods and wrack-associated invertebrates, which preliminary investigations show may be rare or absent on groomed beaches. Human activities at the beach are also being documented, and scientists are partnering with citizen-science nonprofits to develop and test protocols for training volunteers in the collection of long-term beach monitoring information. In addition to the survey work, researchers will be studying the ecological importance of beaches to other coastal and nearshore ecosystems.

Baseline Monitoring of Ecosystem and Socioeconomic Indicators for MPAs along the North Central Coast—Sandy Beaches and Adjacent Surf Zones

R/MPA-14 Mar. 2010–Dec. 2013
Karina Nielsen, Sonoma State University, 707.664.2962,
Steven G. Morgan, BML, 707.875.1920,
Jenifer E. Dugan, UCSB, 805.893.2675,

This project is establishing a benchmark of sandy-beach ecology along the North Central Coast around the time that the new MPAs went into effect through surveys of sand crabs, shorebirds, human activities, wrack and wrack-associated macro-invertebrates at five sites within the new MPAs, five reference sites and seven “extra” beaches also outside of the MPAs. The macro-invertebrate monitoring includes diversity surveys of sand-associated macro-invertebrates eaten by shorebirds and surf-zone fishes. Researchers have collaborated with student citizen-scientists and NOAA National Marine Sanctuaries staff from the LiMPETS program to refine a regional sand crab monitoring program to continue beyond the life of this project and have developed citizen-science protocols for monitoring surf-zone fishes through a volunteer angler program. This year investigators will analyze survey data, with the full MPA baseline monitoring program team, to develop “a synthetic understanding of the baseline status of marine ecosystems inside and outside of MPAs in the North-Central Coast region.”

Written by Christina S. Johnson