Mesmerising film shows thousands of red crabs swarming off the coast of Panama. The same dead or dying crabs are now littering California beaches. IBTimes UK

In what could be the latest sign of the turmoil of ocean ecology, yet another wave of thousands of dead or dying red crabs have washed ashore on the beaches of southern California. The tiny pelagic 'red' - or tuna - crabs (Pleuroncodes planipes) are littering stretches of the Orange County coastline, stretching from Huntington Beach south all the way to Laguna Beach.

"It is quite the invasion. It's just one of those phenomena that happens," said Newport Beach Lifeguard Captain Gary Conwell. "Some areas have up to 3 inches (7.6cm) piled up at the high tide line. There are piles of them everywhere all over the beach."

"I was shocked," one beach resident told the Los Angeles Times. "I had no idea that this kind of thing happened. It's so sad."

The beaches remain open as officials continued to reassure the public that the crabs represented no danger.

The slew of crabs on the beaches occur from time to time, but the phenomenon appears to be happening more frequently. Some scientists believe this is because of the increasing ocean temperatures accompanying global warming.

It's the second year in a row the crabs have turned the white-sand beaches into what one local news outlet called an "all-you-can-eat banquet," for scavenging seagulls.

Local maintenance crews will wait to see how many of the crabs the birds clean up or if they're washed out to sea eventually. If they don't clear away quickly, city workers and trucks will cart them away. But, some of the beaches are part of protected marine sanctuaries, and the crabs cannot be touched.

"We are in a marine protected area. There is nothing much we can do," Laguna Beach Lifeguard Lieutenant Kai Bond told the local Newport Beach Patch. "It's up to mother nature to move them around, and it's up to mother nature to take its course."

The crabs are one of many changes ocuring along the coastline. Record numbers of sea lions have been left stranded along the Pacific in the last three years as their fish vanish. The ocean's acid level has also increased significantly due to increased levels of carbon dioxide, making the water acidic enough to begin to dissolve the shells of crustaceans, with oxygen levels also plummeting, increasing the amount of toxic algae in the water.