It was one of the largest, longest and most lethal harmful algae blooms in Southern California’s recorded history, claiming the lives of hundreds of dolphins and sea lions between Baja California and the Central Coast. And now, finally, it’s over.

Levels of toxic algae species in Southern California coastal waters have declined in recent weeks below thresholds that pose a threat to marine wildlife, according to the Southern California Coastal Ocean Observing System, or SCCOOS, which monitors algae blooms.

Although this provides a much-needed respite for marine mammals and the people working to save them from neurotoxin poisoning, scientists warned that the coastal ecosystem isn’t in the clear yet.

Just as January’s firestorms struck well outside Southern California’s typical fire season, this explosion of harmful algae appeared earlier in the year than have previous blooms. Further outbreaks are still possible before the year is up, said Dave Bader, a marine biologist and the chief operations and education officer for the Marine Mammal Care Center in San Pedro.

“It’s definitely over, but we still have the work of rehabilitating the [animals] that we have saved,” Bader said Wednesday. “And we’re not out of the woods with this year at all.”

Bader was among a group of ocean specialists who gathered at the AltaSea complex at the Port of Los Angeles to brief Mayor Karen Bass on the coastal effects of January’s fires.

That disaster didn’t cause the algae blooms. This is the fourth consecutive year such outbreaks have occurred along the Southern California coast, fueled by an upwelling of nutrient-rich waters from the deep ocean.

Yet multiple research teams are currently investigating whether the surge of additional runoff into the sea resulting from the firestorms may have contributed to the recent bloom’s intensity.

No data on the subject are available yet. But given the relationship between nutrients and harmful algae species, Mark Gold of the Natural Resources Defense Council said he would not be surprised if the fires played a role in this year’s severity.

“As a scientist who’s been looking at impacts of pollution on the ocean for my whole career, … one would expect that [fire runoff] is also having impacts on harmful algal blooms, from the standpoint of the intensity of the blooms, the scope, the scale, etc.,” said Gold, the organization’s director of water scarcity solutions. “We’ll find that out when all this analysis and research is completed.”

In terms of animal mortality, this year’s bloom was the worst since 2015-16 outbreak that killed thousands of animals between Alaska and Baja California, said SCCOOS director Clarissa Anderson of UC San Diego’s Scripps Institution of Oceanography.

Four different algae species were present this year. The two most dangerous produce powerful neurotoxins that accumulate in the marine food chain: Alexandrium catenella, which produces saxitoxin, and Pseudo-nitzschia australis, which produces domoic acid.

The toxins accumulate in filter-feeding fish, and then poison larger mammals who gobble up the fish in mass quantities. (This is why the blooms don’t pose the same health risks to humans — very few people eat up to 40 pounds of fish straight from the sea each day.)

Beginning in February, hundreds of dolphins and sea lions started washing up on California beaches, either dead or suffering neurotoxin poisoning symptoms such as aggression, lethargy and seizures. A minke whale in Long Beach Harbor and a gray whale that stranded in Huntington Beach also succumbed to the outbreak. Scientists believe countless more animals died at sea.

The outbreak was more lethal than those in recent years, Bader said, and veterinarians were able to save fewer animals than they have in the past.

Researchers are still grappling with the catastrophe’s full impact on marine mammal species. The outbreak was particularly deadly for breeding females. California sea lions typically give birth in June after an 11-month gestation. At the blooms’ peak, “they were actively feeding for two,” Bader said.

Domoic acid crosses the placenta. None of the pregnant animals the center rescued delivered live babies, he said.

“We don’t really know what the environmental impact, long term, is of [blooms] four years in a row, right during breeding season,” Bader said. “The full impact of this is going to be hard to know, especially at a time when research budgets are being cut.”

As climate change has shifted the timing and intensity of the strong wind events that drive upwellings, “we’re coming into a future where we unfortunately have to expect we’ll see these events with recurring frequency,” Bader told Bass at the roundtable. “The events that drove the fires are the events that drove the upwelling.”

During the breeding season, the center sees a lot of underweight, malnourished elephant seal pups, many of which are still too young to fend for themselves or even swim. Sometimes, they also see elephant seals with parasites or traumatic injuries, such as dog bites or blunt force trauma from boat propellers.

For the last few years, the Marine Mammal Center has been testing any patients with bird-flu-like symptoms, which include respiratory and neurological problems, for the virus.

California lawmakers are taking aim at proposed rules to implement a state law aimed at curbing plastic waste, saying the draft regulations proposed by CalRecycle undermine the letter and intent of the legislation.

In a letter to Gov. Gavin Newsom and two of his top administrators, the lawmakers said CalRecycle exceeded its authority by drafting regulations that don’t abide by the terms set out by the law, Senate Bill 54.

“While we support many changes in the current draft regulations, we have identified several provisions that are inconsistent with the governing statute … and where CalRecycle has exceeded its authority under the law,” the lawmakers wrote in the letter to Newsom, California Environmental Protection agency chief Yana Garcia, and Zoe Heller, director of the state’s Department of Resources Recycling and Recovery, or CalRecycle.

The letter, which was written by Sen. Catherine Blakespear (D-Encinitas) and Sen. Benjamin Allen (D-Santa Monica), was signed by 21 other lawmakers, including Sen. John Laird (D-Santa Cruz) and Assemblymembers Al Muratsuchi (D-Rolling Hills Estates) and Monique Limón (D-Goleta).

CalRecycle submitted informal draft regulations two weeks ago that are designed to implement the law, which was authored by Allen, and signed into law by Newsom in 2022.

The lawmakers’ concerns are directed at the draft regulations’ potential approval of polluting recycling technologies — which the language of the law expressly prohibits — as well as the document’s expansive exemption for products and packaging that fall under the purview of the U.S. Department of Agriculture and the Food and Drug Administration.

The inclusion of such blanket exemptions is “not only contrary to the statute but also risks significantly increasing the program’s costs,” the lawmakers wrote. They said the new regulations allow “producers to unilaterally determine which products are subject to the law, without a requirement or process to back up such a claim.”

Daniel Villaseñor, a spokesman for the governor, said in an email that Newsom “was clear when he asked CalRecycle to restart these regulations that they should work to minimize costs for small businesses and families, and these rules are a step in the right direction …”

At a workshop held at the agency’s headquarters in Sacramento this week, CalRecycle staff responded to similar criticisms, and underscored that these are informal draft regulations, which means they can be changed.

“I know from comments we’ve already been receiving that some of the provisions, as we have written them … don’t quite come across in the way that we intended,” said Karen Kayfetz, chief of CalRecycle’s Product Stewardship branch, adding that she was hopeful “a robust conversation” could help highlight areas where interpretations of the regulations’ language differs from the agency’s intent.

“It was not our intent, of course, to ever go outside of the statute, and so to the extent that it may be interpreted in the language that we’ve provided, that there are provisions that extend beyond … it’s our wish to narrow that back down,” she said.

These new draft regulations are the expedited result of the agency’s attempt to satisfy Newsom’s concerns about the law, which he said could increase costs to California households if not properly implemented.

Newsom rejected the agency’s first attempt at drafting regulations — the result of nearly three years of negotiations by scores of stakeholders, including plastic producers, package developers, agricultural interests, environmental groups, municipalities, recycling companies and waste haulers — and ordered the waste agency to start the process over.

Critics say the new draft regulations cater to industry and could result in even higher costs to both California households, which have seen large increases in their residential waste hauling fees, as well as to the state’s various jurisdictions, which are taxed with cleaning up plastic waste and debris clogging the state’s rivers, highways, beaches and parks.

The law is molded on a series of legislative efforts described as Extended Producer Responsibility laws, which are designed to shift the cost of waste removal and disposal from the state’s jurisdictions and taxpayers to the industries that produce the waste — theoretically incentivizing a circular economy, in which product and packaging producers develop materials that can be reused, recycled or composted.