Seaweed gives scientists a history lesson on Monterey Bay

Century-old seaweed is providing brand new insight into the natural history of Monterey Bay. In a new study, researchers tapped into the environmental record contained in seaweed samples that date back more than 140 years.

Located off the coast of central California, Monterey Bay is one of the world’s leading research sites for marine science. The bay has an abundance of nutrients supplied by natural upwelling and supports countless species. 

Despite its significance, however, not much is known about the health and condition of habitats in the bay prior to 1946 – when experts started documenting patterns of natural upwelling.

“This part of California’s Central coast is renowned for the sheer amount of marine life it can sustain. Even through the pressures of the past century, Monterey Bay is still teeming with birds, whales, fishes and seaweeds,” said Monterey Bay Aquarium Chief Scientist Kyle Van Houtan. 

“These plants and animals were around long before scientists, so we thought if we could find historical samples we might learn something by extracting the information stored in their tissues.”

In the Monterey Bay Aquarium’s Ocean Memory Lab, scientists use a variety of chemical analyses to unlock valuable data held in the tissues of various marine life specimens.

“We were able to add nearly seven decades of data, extracted from seaweed samples more than a century old, to better understand historical changes in Monterey Bay,” said study lead author Emily Miller.

“This information offers us a new perspective on one of the features that makes Monterey Bay home to such diversity, its upwelling cycles.” 

“Documenting these patterns helps us to understand shifts in the foundation of the food web, and to make more informed conservation decisions in the future.”

The research team, which included scientists at Stanford University’s Hopkins Marine Station and the University of Hawaii, analyzed pressed seaweed samples from collections dating back to 1878, as well as new specimens. 

The samples came from six species of seaweed, including giant kelp, rockweed, sea lettuce, and grape tongue.

“Izzy Abbott, who was professor of biology at Hopkins, helped to curate and build our collection of algae for over 25 years,” said study co-author Professor Stephen Palumbi. “She and the algae biologists that came before her knew that preserving specimens was vital.” 

“But it took this new approach from Monterey Bay Aquarium to dig into the very atoms of the algae and ask the kelp forest questions about the history of the oceans.”

The analysis produced unprecedented details of the ocean conditions in Monterey Bay during the rise and fall of the sardine fishery in the 1940s and 1950s. The researchers identified poor upwelling conditions in Monterey Bay in the years immediately prior to the crash.

The findings highlight the role of ecosystem changes in the shift from a sardine-dominated system to one that is now anchovy-dominated.

The research may ultimately help to inform ecosystem-based management. According to NOAA, this management approach aims to maintain ecosystems in a healthy and resilient condition so they can continue to provide important ecosystem services.

The study is published in the journal Proceedings of the Royal Society B.

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By Chrissy Sexton, Earth.com Staff Writer