Two tiny crustaceans whose burrows in the sand were once familiar sights to beachgoers are on their way to being extirpated from Southern California, according to a new study.
Scientists at UC Santa Barbara found that two species closely related to the roly poly have vanished from more than 60% of beaches from Point Conception to the U.S.-Mexico border, where they were recorded a century ago.
"We were really surprised at how strong the pattern of loss is," said Jenny Dugan, a biologist at the university's Marine Science Institute. "They're not going to last long in Southern California the way things are going."
The trend is alarming, the researchers said, because the critters are considered indicator species whose steady decline over decades bodes ill for other creatures such as grunions and snowy plovers, which also need wide stretches of undisturbed sand to survive.
The nocturnal crustaceans, known as isopods, spend their daylight hours in burrows several feet below the sand and serve as an important source of food for shorebirds. The critters only emerge from the sand to feed on kelp at night, which helps explain why they are not as well known to Californians as their garden-variety cousin, the roly poly.
The coast-dwelling crustaceans could be wiped out entirely unless more sandy beaches are set aside for conservation, the researchers said. But their fate could already be sealed by climate change.
That's because the undeveloped, ungroomed sandy beaches they still populate are some of the same stretches of coastline at risk from sea level rise. Those natural beaches are often ringed by bluffs, homes or parking lots, leaving them nowhere to go as the sea swells inland.
Scientists discovered the decline using data going back more than a century, including a Smithsonian monograph that documented their presence along Santa Barbara in 1905 and beach surveys conducted in the wake of the 1969 Santa Barbara oil spill.
The findings were published online this week in the journal Estuarine Coastal and Shelf Science.