Kelp Forest Community Monitoring

Diver in front of towering blades of kelp, looking towards an outcrop of the ocean floor teeming with life. They hold calipers and a large board covered in written tallies and hand-drawn ruler markings along two sides.
Diver searching for invertebrates to measure as part of the kelp forest monitoring protocol. Measuring indicator species provides a more comprehensive understanding of the kelp forest structure and function, including more accurate biomass estimates.

NPS / Scott Gabara

Why We Care

The nearshore waters along the coastline southern California host one of the most productive marine ecosystems on earth, giant kelp forests (Macrocystis pyrifera). Like tropical rainforests, these towering seaweeds provide structure, food, and hiding places for more than 1,000 species of plants and animals, providing necessary habitat for species as diverse as giant black sea bass and tiny bluebanded gobies.

Kelp forests are influenced by both natural events and human activities. Strong storms associated with El Niño years and fluctuating water temperatures can cause dramatic changes in kelp forest communities. Human activities also affect the health and survival of kelp forests through coastal development, sedimentation, pollution, and, in particular, fishing. Removal of predators can alter predator-prey interactions. For example,with the elimination of sea otters and the overharvesting of spiny lobster and California sheephead, herbivore populations like purple sea urchins can decimate kelp beds through overgrazing. These areas quickly transition into "barren" landscapes supporting relatively few species and lower biomass. Loss of kelp beds also eliminates nursery grounds for many species whose young live in the kelp until they are large enough to venture into open waters. Without shelter and food from the kelp forest, these populations may be dramatically reduced.

How We Monitor

The Kelp Forest Monitoring Program was established by Channel Islands National Park in 1982 to collect baseline information about the kelp forest ecosystem in the Park. Each year the program collects size and abundance data for 70 categories (taxa) of algae, invertebrates, and fish that are indicators of ecosystem health. The current monitoring protocol was adopted in 1997.

Diver swimming through a kelp forest with 1m square PVC pipe quadrats and an oversized board and pen for recording data underwater.
Diver carries equipment for quadrat-based kelp forest monitoring program sampling methods. These methods allow the monitoring team to estimate species abundance, density, and distribution—more pieces of the puzzle for understanding the health of our kelp forests.

NPS / Scott Gabara

Diver in a dense kelp forest, moving along a yellow measuring tape stretched out in front of them.
A diver surveying a band transect, searching for various indicator species to better understand ecosystem health.

NPS / Scott Gabara

Our Goals

  • Determine the status and health of the islands' kelp forests
  • Document the types of changes occurring in the marine environment
  • Develop management strategies needed to protect the kelp forest ecosystem

Why It Matters for Park Managers

  • Park researchers have documented widespread and dramatic changes in the marine ecosystem around the Channel Islands since the program began, including declines in fished species like abalone and the loss of kelp beds around several of the islands.

  • Information from park monitoring was instrumental in establishing marine reserves, areas of the ocean granted complete protection from fishing and extractive activities, at the Channel Islands, placing nearly 20% of Park waters into state marine protected areas.
  • In 2008, a 5-year review of data collected by the Park and others demonstrated some positive trends in the new marine reserves including:
    • Greater overall biomass inside reserves
    • Larger average body size of some species like kelp bass and spiny lobster in unfinished reserves
    • Kelp beds around the Channel Islands have recently increased, after experiencing substantial declines in the 1980s and 1990s
A couple dozen silvery, mid-sized fish swim among towering blades of kelp.
School of blacksmith in giant kelp forest. Blacksmith are important prey fish in the kelp forest, providing food for many other species. They are one species whose presence indicates a healthy, productive kelp forest ecosystem.

NPS / Scott Gabara

For More Information

Download 1-2 page PDFs about the Mediterannean Coast Network's monitoring programs.

Source: Data Store Saved Search 3544. To search for additional information, visit the Data Store.

The Mediterranean Coast Network documents its findings in reports published in the NPS Natural Resource Publication Series.

Source: Data Store Saved Search 1508. To search for additional information, visit the Data Store.

Protocols describe in detail the procedures used to collect, manage, analyze and report monitoring data. They follow strict guidelines for content and format, and are reviewed and revised by subject-matter experts in each field.

Source: Data Store Saved Search 1520. To search for additional information, visit the Data Store.


Scott Gabara

Last updated: December 1, 2023