San Diego’s climate crisis: oyster hatchery challenged by warming ocean (text and audio)

Making a living from the ocean in Southern California is never easy, but the planet’s changing climate is creating additional hurdles for a 50-year-old oyster farm.

Climate change is putting extra pressure on industries that rely on the ocean to survive.

It is a lesson Andrew Chang lives every day he comes to work at the Carlsbad Aquafarm in San Diego County.

On a recent day, he was standing on a small floating pier in the Agua Hedionda lagoon. “Okay,” Chang said as he kneeled down and peered into deep box full of tiny oysters. “If you want to take a closer look.”

He dips into the box and pulls up a handful. Most are less than a quarter of an inch long.

Chang is on a Flupsy, a floating system that pulls water and nutrients up through silos full of the fledgling shellfish.

“The term would be seed,” Chang said. “Oyster seed. And they’re anywhere from one to three centimeters. To begin with.”

Farm lives underwater

When these oysters get big enough, they are placed in square plastic trays about the size of a card table. Those trays are stacked ten high, attached to a buoy, and anchored in the lagoon.

Aquafarm Production manager Matt Steinke uses a small boat to tour the “field.”

Pelicans and seagulls perch on the floating balls and barrels and they only move when the boat gets close.

Steinke stopped near a buoy sitting low in the water and he pulled the underwater stack of trays close to the surface.

“Now these stacks of oysters are about 100 to 150 pounds. The top tray is empty, we just put a couple of rocks in the top and it keeps the rack compressed together,” Steinke said.

The oysters live here, filtering water until they are full grown. That takes six months to a year. The shellfish’s last stop before going to market is a few days of rinsing inside purification trays.

This seed, to lagoon, to rinse station, to market cycle was abruptly interrupted in 2007, when a changing climate intervened.

Oyster industry challenged by acidification

The planet’s oceans were absorbing larger amounts of carbon, turning the colder waters of the Pacific Northwest increasingly acidic. Unfortunately for oyster growers, that is where all of their seed stock was grown.

“When ocean acidification hit the Pacific Northwest, they were reporting a 90 to 95 percent failure in their normal production and you ended up with a lot of farmers who had open space to grow things and they are unable to buy seed. And that problem persisted for a few years,” Steinke said.

The industry adapted and here in Carlsbad they grow some of their own seed, but the threat remains.

“It’s possible that in twenty or 15 years we start seeing more failures of the crop. Possible in our waters or in the rest of the industry,” Steinke said.

And the change is already happening. The ocean is warming as it absorbs carbon dioxide.

Those warmer ocean waters are less likely to mix with nutrient-rich water at deeper levels. In essence, the warmer water is choking off the food supply.

And that is not all.

“The warmer the oceans get, the less oxygen it can accommodate. And low oxygen is not good in general for ecosystems,” said Dan Cayan, a climate researcher at the Scripps Institution of Oceanography. He added that the acidity of the ocean has increased by about 30 percent.

Those changes and the resulting impacts happen gradually but it has the owner of the oyster farm already preparing.

Looking toward the future

“The alarm for me is that it’s changing faster than some aspects of nature can keep up. Because nature adapts. And it adapts as it can. But sometimes its going faster than wildlife and marine life can keep up with so spaces where they’re familiar with or adapted to surviving they are no longer available for them,” said Thomas Grimm, Carlsbad Aquafarm CEO.

Grimm is working to keep his business from being overwhelmed by changes in the ocean ecosystem. Part of his solution is under the buoys in the southern tip of the lagoon.

“Those are our research floats,” Grimm said. “There are both ball floats and barrel floats. But underneath them are families of oysters and different configurations. Some are very small groupings and specialized cages from Australia. And they’re used to grow out specially bred oysters from a research project at USC.”

Oysters have survived other ecological upheavals, and Grimm thinks finding and breeding resilient species is an important strategy to deal with the changes.

“So you have to be ahead of what’s going on and have enough resilient stock that is adapted to the changing chemistry as you point out,” Grimm said.

Erik Anderson, kpbs, 17 September 2019. Text and audio.

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