Intertidal Communities

Technician standing in intertidal zone looking through a PVC frame to take a picture of a rock in the intertidal zone.
Intertidal sampling at Redwood National and State Parks

The coastline of northern California is home to a diverse array of nearshore habitats that contain a wide variety of species. Geographic location, habitat diversity, and complex oceanographic patterns contribute to the diversity of marine life in this area. The northern coastline of Redwood National and State Parks is composed of rocky intertidal areas dominated by boulders and rocky bench areas.

Population monitoring within the rocky intertidal zone provides information needed to study the effects of natural disturbances such as severe storms, flood events, and tsunamis, as well as man-made disturbances such as visitor use impacts and oil spills. Monitoring also provides basic ecological knowledge of how systems are changing.

Since 2006, the Klamath Network has been monitoring three intertidal sites in Redwood National and State Parks. These sites contribute to the MARINe (Multi-Agency Rocky Intertidal Network) program, where over 200 sites are monitored from Mexico to Alaska, allowing direct comparison of results to these other sites.

Objectives are to:

  • Monitor the temporal dynamics of target invertebrate and algae species, and surfgrasses.
  • Determine status, trends, and effect sizes through time for morphology, color ratios, and other key parameters describing population status of intertidal organisms.
  • Integrate with and contribute to a monitoring network spanning a broad geographic region, in order to evaluate trends at multiple scales, from the park to regionwide, taking advantage of greater sample sizes at broader scales.
  • Detect and document invasions, changes in species ranges, disease spread, and rates and scales of processes affecting the structure and function of rocky intertidal populations and communities to better understand normal limits of variation.

We measure:

  • Percent cover of sessile invertebrates and algae using fixed plots (photoplots) as reference.
  • Percent cover of organisms within select fixed plots.
  • Abundance of mobile invertebrates (sea stars, snails, chitons, limpets, and crabs) in fixed plots.
  • Cover of surfgrass along fixed point-intercept transects.
  • Size and bed/patch thickness of mussels using fixed plots.
  • Sea surface temperature.
  • Site information including weather, birds, marine mammals, humans, trash, and presence/absence for a set list of species.

Monitoring Documents

Monitoring Reports

Source: Data Store Saved Search 613. To search for additional information, visit the Data Store.

Monitoring Protocol

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Last updated: July 24, 2018