In Santa Monica, heatwaves are often synonymous with traffic and tourists, but as scientists begin seeing the real-time effects of climate change along the California coast, periods of abnormally high heat also prove insight into changing ocean dynamics that could become the “new normal” if rising temperature trends continue.
Speaking to the Daily Press on Thursday, Heal the Bay Associate Director of Operations Laura Rink said heatwaves work like a window into what the future could hold for marine species in the Santa Monica area.
“When we have these warming events, and we see the effects of them, it can be a sobering reminder that if the warming effects continue to happen more frequently, or over longer periods, because of climate change, it is really going to drastically affect all the different trophic levels of life and animals within our ocean,” Rink said. “So, it should be a reminder that if humans don’t make changes that it’s just going to continue happening and we can have concerns for both human and animal health.”
Rink, who holds a degree in aquatic biology, has worked in aquariums for about 15 years. Currently, she oversees exhibit operations and care for all the animals at the Heal the Bay Aquarium, a nonprofit science center located beneath the Santa Monica Pier.
Although ocean water temperatures are by and large not as volatile as air temperatures, heatwaves do have a direct effect on the temperature of the sea, especially the water temperature near the surface, where algae lives.
“Heat … affects tiny organisms first,” Rink said, “and then works its way through different trophic levels in our ecosystems.” That means, during times of especially high water temperature, algae is among the first species to react, often creating algal blooms. Although Rink was quick to point out that not all algal blooms are harmful, some release toxins that travel up the food chain and can affect numerous species including humans.
“Algae sits on the surface of the water, so that’s where you get these bigger blooms. You have more sunshine and more heat, so it can replicate faster,” Rink said. “Warming up the upper layers also prevents mixing of the water because it’s colder water that sinks. So, you’re going to have less mixing of the ocean, which then causes, again, more blooms and more issues with potentially harmful toxins in the water.”
Those issues are currently on display farther north along the coast in the Bay Area.
On Thursday afternoon, the California Department of Fish and Wildlife tweeted reports of data from what it called “citizen scientists” reporting about 10,000 yellowfin goby deaths, along with hundreds of striped bass and white sturgeon, due to an algal bloom in the San Francisco Bay — although the department acknowledged it believed current numbers could be an undercount of true mortality.
San Francisco Bay Regional Water Quality Control Board Executive Officer Eileen White told the Associated Press on Wednesday that a triple-digit heat wave forecast for the holiday weekend may help the Bay Area’s die-off grow even more.
In San Francisco’s South Bay, concentrations of chlorophyll — an indicator of algae density —measured on Aug. 10 were the highest observed in more than 40 years, White told the AP.
Blooms are also self-perpetuating, according to data from the Environmental Protection Agency, or EPA: “Algal blooms absorb sunlight, making water even warmer and promoting more blooms.”
Here in Southern California, Rink said algal blooms have sickened sea lions that have been found stranded at increased rates in recent weeks.
“Actually, I just heard about increased strandings and issues with sea lions in Southern California, along the coast,” Rink said. “The algae produces this toxin that is eaten by certain species of fish that then the lions eat, and it is a neurotoxin that affects their brain activity and behaviors and can cause a lot of issues with those specific mammals. Not to mention, it’s not good for humans to consume any of the marine life that takes in this toxin.”
Of particular concern to Rink is local sport fishermen who fish off the Santa Monica Pier and other near-shore fishing spots. Since fish you catch yourself isn’t tested for toxins, it’s important to be especially careful during heatwaves to avoid fishing in water that appears cloudy or might be near a bloom to avoid ingesting toxins in the fish.
Aside from algal blooms, higher water temperatures can damage kelp forests (which Rink called “the rainforests of the ocean”) and cause migration patterns for some species to shift — some heading into the Santa Monica area from the south and others moving up north to beat the heat.
“A couple years ago, we had a big migration of pelagic red crabs that came up the coast,” Rink said. “They are typically a much more southern, Baja California species, and they came all the way up into our waters, which is unusual. The same thing happened for warm water species like seahorses, that come up. So you start seeing these different migrations that we don’t normally see.”
While Rink said she couldn’t speculate whether or not the six-to-eight-foot shark spotted off Manhattan Beach last weekend was there due to the increased water temperatures, she confirmed that sharks are among species that breed in warm water.
“A lot of species breed in warm waters, especially elasmobranchs — sharks and rays,” Rink said. “So, as our waters warm up further along our coasts, we’re going to start seeing breeding grounds move as well, which will populate the species in areas that are normally not in or normally not in as high of numbers. So, it could very much change the dynamics and encounters with species like sharks.”