Scientists Tackle the Case of the Vanishing Seaweed at Channel Islands National Park

The mission of the National Park Service is to preserve, unimpaired, the natural and cultural resources of the National Park System. But what happens when resources are impaired? Well, our goal is to restore those resources back to their unimpaired state.

The next time you visit your favorite National Park take a close look and you may see rangers or volunteers putting plants in the ground. They may be restoring the population of a single, important native species, or they may be adding several native species in hopes of restoring an entire ecosystem.

Tending to and restoring native ecosystems is no small task; but what if the ecosystem you were trying to restore was underwater half of the time? Well, the task just got a little more complicated.

When the tide recedes and the intertidal system is exposed to the air, plants and animals look for ways to avoid desiccating in the relatively warm, dry air. Rockweed, with its thick, dense canopy, provides refuge for an entire suite of species seeking out relief as they wait for the tide to roll back in.

NPS / Michael Ready

At Channel Islands National Park, marine ecologists are working with local scientists to understand the best methods to restore a key intertidal seaweed commonly called rockweed (Silvetia compressa). Rockweed is considered a foundational species, meaning that its presence is so important that without it the entire ecosystem would change radically. Imagine removing giant sequoia trees from a sequoia grove. You might still have a forest but it would look and behave much differently than it would in their presence.

The same thing can be said for rockweed in the intertidal zone. When the tide recedes and the intertidal system is exposed to the air, plants and animals look for ways to avoid desiccating in the relatively warm, dry air. Rockweed, with its thick, dense canopy, provides refuge for an entire suite of species seeking out relief as they wait for the tide to roll back in. This is what makes rockweed such an important piece to the intertidal in coastal California.

Since the early 2000s, ecologists who monitor rocky intertidal ecosystems each year have noted declines in rockweed. It could simply be a natural oscillation that occurs over long periods of time, but we are beginning to suspect that extreme heat during Santa Ana wind events have caused portions of the rockweed populations to wither and vanish. While we can’t prevent Santa Ana wind events from occurring, we can help restore these depleted rockweed communities.

Working with scientists at University of California-Santa Barbara, the National Park Service is translocating patches of rockweed from areas that have been unaffected and remain healthy to areas where it has gone missing. This arduous process sometimes requires multi-day trips across rugged remote islands in order to slowly piece the system back together.

In addition to providing hands-on assistance in the effort to rebuild rockweed “forests”, the Southern California Research Learning Center is developing a comprehensive science communication story (coming soon!) about the process. We are also providing opportunities for young scientists in the Smithsonian Scholars Program to work side-by-side with our partner scientists where they will learn more about re-building underwater ecosystems.

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A Publication of the Southern California Research Learning Center

The Southern California Research Learning Center is one of 18 Research Learning Centers across the country. These centers strive to increase scientific activity in the national park system, to communicate research that supports stewardship and to make science part of the visitor experience. By working with a variety of partners, we aim to support science-based decision-making, increase science literacy and promote a conservation ethic within the Santa Monica Mountains National Recreation Area, Channel Islands National Park, and Cabrillo National Monument.