In partnership with the Scripps Institution of Oceanography at UC San Diego, the city of San Diego will spend $3.6 million in a five-year study of the region’s kelp forests to determine their overall health and future outlook with global warming.

Thus far, it’s going well, said SIO researcher Ed Parnell.

“It’s basically a continuation of the work we’ve been doing over the years by different agencies,” he said of the new study. “It’s to determine the status of the kelp forest in North County, La Jolla and Point Loma, along with a census of the different animal and plant species that share the ecosystem from the water bottom to the surface, measuring current oxygen and nutrient levels.”

Kelp is a simple, nonflowering, and typically aquatic plant of a large group of marine algae (Laminariales) that includes seaweeds. Algae contain chlorophyll for photosynthesis (using sunlight to create plant foods from carbon dioxide and water) but lacks true stems, roots, leaves and vascular tissue. 

A wide range of sea life uses kelp forests for protection or food, including fish. Kelp forests occur worldwide throughout temperate and polar coastal oceans covering about 25% of the world’s coastlines.

Parnell said early indications are San Diego’s kelp beds are making a comeback from past decimation from El Nino weather patterns. Such events are characterized by the appearance of unusually warm, nutrient-poor water off northern Peru and Ecuador, typically in late December, which impact San Diego.

Where the ocean ecosystem is concerned, cooler is better, said Parnell.

“Cooler water is more nutritious,” he said. “Warmer water is less nutritious, and stresses plant and animal species making them more prone to disease.”

Parnell said long-term studies of San Diego’s kelp forests over the years show a cyclical process of kelp “die-offs and comebacks.”

“With the El Nino of 1977, there was a big change in terms of a larger, more regional and warmer weather pattern,” he said. “Since then, the water’s been warmer and the kelp has been more frequently disturbed.”

Last August, the highest water temperature ever measured in more than 100 years, 78.6 degrees, was recorded in San Diego at Scripps Pier. 

“Last summer, we had Hawaii temperatures here up near the surface,” noted Parnell. But recently, the San Diego kelp has been rebounding along with the return of cooler water temperatures.

“It’s coming back, but it’s not coming back everywhere where it was before,” said Parnell adding, “we have a very shallow thermocline [temperature change in water depth] and very cold water below, so the kelp is doing better this year.”

Parnell characterized varying water temperatures year to year as a “sawtooth” pattern. “We see trends, cycles, in longer frequencies,” he said. “Right now, what we’re seeing is a trend of the California current getting warmer. But now that we’ve returned to colder [water] conditions this year, the kelp is doing better.”

But if ocean water temperatures climb again, the kelp will again becoming increasingly stressed. 

“If we get conditions again like the late ’70s, the kelp may have a harder time making it back, and it could go the way of becoming a relic in some areas,” said Parnell.

A total of 450 dives per year will be conducted at 21 areas in kelp forests along the San Diego coast in the five-year study. The project is funded by the city’s 280,000 sewer customers whose utility bills include a calculation for the kelp project.