Sanctuary Integrated Monitoring Network
Monitoring Project

Reef Check California: Statewide Subtidal Monitoring Network of the Nearshore Rocky Reefs

Principal Investigator(s)

  • Gregor Hodgson
    Reef Check
Start Date: July 26, 2006

Stretching over 1,100 miles, California’s coastline is the gateway to a unique and seldom seen marine ecosystem. Offshore, just below the surface, kelp forests and rocky reefs are home to a myriad of marine life supporting a diverse array of consumptive and non-consumptive human uses. Unfortunately, similar to reefs around the world, the rapid growth of California’s population, coastal development, pollution, and overfishing have placed increasing demands on our nearshore resources. Many organisms that were previously common in high numbers, like abalone, are now nearly gone in certain regions.

Reef Check California (RCCA) is currently monitoring 64 kelp forest sites statewide, and continues to expand their monitoring network as more funds and trained divers become available. Of those sites 16 are found within the Monterey Bay National Marine Sanctuary (Figures 1 and 2). Sites are surveyed at least once per year with around 15% designated as index sites, which are surveyed twice per year to measure within year variability. RCCA monitoring fills large gaps within existing academic and institutional monitoring programs. Through long term monitoring of sites patterns of natural variation of important species’ population parameters can be measured and tracked over time. Site placement allows for the contrast of both habitats and indicator species between geographic regions and areas experiencing varied human-induced pressures.

RCCA data are available to all interested parties approximately one month after collection. The data can be accessed through the user friendly Nearshore Ecosystem Database (NED). Sites and summarized data can be viewed with an interactive Map Viewer. A link to download the entire database (MS Access format) can be found on NED as well: NED

A report of the first two years of data (2006-2007) is available for download (RCCA Reports) in entirety or as an Executive Summary. A four year report on data collected 2006-2009 will be available summer 2010.

Summary to Date

In its first four years, Reef Check California trained and certified 505 volunteer divers. This group of citizen scientist divers was comprised of a diverse array of ocean users including recreational divers, commercial urchin fishermen, port police and college students. These dedicated volunteers have completed 247 surveys at 64 sites along California’s coast (Figures 1 and 2) and counted over 450,000 individual organisms including:
• 113,436 fishes
• 281,724 invertebrates
• 92,637 seaweeds

The ability of Reef Check California divers to collect high quality scientific data has been
especially timely on the central coast where a new network of Marine Protected
Areas (MPAs) went into effect on September 21, 2007. Many of the new
MPAs in the central coast MLPA region were surveyed by Reef Check California
teams in both 2006 and 2007 and have continued to be monitored in subsequent years. These data, along with data collected at Reef Check California sites around the state, will
be crucial for evaluating the effectiveness of MPAs and other marine management measures as well as informing the on-going siting of MPAs in California.

Study Parameters

  • Non-indigenous species
  • Diversity
  • Habitat
  • Dispersal & Recruitment
  • Range/Biogeography
  • Density
  • Abundance
  • Distribution
  • Size structure
  • Sex ratio
  • Stock assessment
  • Substrate characterization

Study Methods

RCCA protocol uses visual diver surveys of the benthos. Four types of 30m transects are employed: Fish, Invertebrates, Algae, and Substrate Characterization using uniform point contact (UPC). During fish surveys divers measure the density, sizes, and sexes (when applicable) of target organisms in 30m x 2m x 2m swaths. During invertebrate and kelp surveys divers measure density and sizes (when applicable) of target organisms within 30m x 2m swaths. A site consists of 6 "core" transects and 12 "fish-only" transects (Figure 3). A "core" transect is one 30m transect upon which first fish, then invertebrates, then algae are counted, and then substrate is characterized using UPC.

A detailed description of the protocol and layout of a site can be viewed at this link:

Figures and Images

Figure 1. Reef Check sites found within the MBNMS.

Figure 2. Close-up of Reef Check sites around the Monterey Bay Peninsula.

Figure 3. Schematic of transect layout within an idealized survey site.