Warmer waters can affect the development of plankton and kelp, foods at the bottom of the chain, said Elizabeth Argyle, director of education at the Living Coast Discovery Center in Chula Vista, California.
"We’re starting to witness fish species found near coastal waters migrating offshore in search of plankton," she said. "That affects sea lions, predators, trying to chase those fish going further offshore to hunt."
She added that seaborne diseases spread more rapidly and afflict ocean wildlife more commonly in warming waters.
Heal the Bay coastal marine scientist Mary Luna said via email that scientists will likely see major changes in sea life if the warming trend continues.
"Off the coast of California it is believed that sustained warmer water temperatures will result in shifts, expansions or reductions in the range of commercially important species or the species that depend on them," she said.
"A few years ago we saw hammerhead sharks all the way up to Malibu, which is not a normal occurrence."
Halibut could be displaced. "Juvenile and adult California halibut may have different diets, and therefore different stages of their life cycle may be affected by warmer waters off of our coast," she said.
Apryl Boyle, an associate director at environmental nonprofit Heal the Bay, agreed, saying the warm ocean creates sea life departures and incursions not normally seen off the coast.
"We see species off of the California coast travel farther north than they normally do to follow their food," she said via email. "A few years ago we saw hammerhead sharks all the way up to Malibu, which is not a normal occurrence. In addition, we saw sea snakes along the Southern California coast, which again is not their normal distribution."
Luna said that sustained sea surface temperatures can also boost rising sea levels, especially when warm oceans fuel winter storms that flood populated beach communities. "During those events coastal communities increasingly see ocean water encroaching into sidewalks and property, places that ocean water and waves historically did not reach," she said.
The last four Southern California summers have seen unusually high sea surface temperatures, said Daniel Rudnick, professor of climate, atmospheric science and physical oceanography at the Scripps Institution of Oceanography, which recorded the all-time high reading off La Jolla.
The warmth has been measured along the entire Southern California Bight and then some — from Baja California to Point Conception, observers say.
"Back in 2014, early on, the water started warming," Rudnick said. "We called it a marine heat wave. The press it called 'the blob.' That warmed up the water for a year. The following year we got one of the biggest El Niños of the past few decades, and that warmed up the water even more. Then there was a La Niña — a cooler-than-normal phase — but the water never really got back to the normal."