Power analysis of the intertidal monitoring programs at Channel Islands National Park and the Bureau of Ocean Energy Management

Raimondi, Peter; Ammann, Karah; Gilbane, Lisa; Whitaker, Stephen; Ostermann-Kelm, Stacey

The rocky shores of the west coast of North America are home to dynamic, highly diverse biological communities that are subject to dramatic changes due to natural phenomena and human activity. Channel Islands National Park (CHIS) and the Bureau of Ocean Energy Management (BOEM) have responsibilities to monitor biological resources on rocky shores in adjacent areas of southern California, predominantly within and surrounding the Santa Barbara Channel (Figure 1). For over 20 years, CHIS and BOEM have been committed to a partnership through the Multi-Agency Rocky Intertidal Network (MARINe) to monitor rocky shore biological resources using the same methods and to share data and goals. Periodic assessment of program protocols and sampling designs is required by CHIS and BOEM to ensure that they meet benchmark goals. This report is a statistical assessment of both agencies’ rocky intertidal monitoring programs. MARINe is a partnership of federal, state, and local government agencies in collaboration with many nonprofit groups, universities, and volunteers committed to the long-term study of selected rocky intertidal species primarily in California, Oregon, and Washington. Established in 1997, MARINe conducts long-term monitoring at more than 116 locations along the northeast Pacific coast from Alaska to Baja California, Mexico. Protocols were adopted from the CHIS Rocky Intertidal Monitoring Program, which was initiated in 1982 to assess seasonal and annual changes in populations of intertidal organisms as a result of natural and anthropogenic influences within the five northern Channel Islands offshore of California. Over 20 years later, both BOEM, CHIS, and 15 other groups collecting data all follow identical field protocols and share data publicly as a part of MARINe. Monitoring along the mainland of Santa Barbara County, California, began in 1991 with a project funded jointly by the BOEM, formerly the Minerals Management Service, and the County of Santa Barbara. The priority for BOEM monitoring has always been to document baseline conditions of rocky intertidal biological resources to assess possible injury from an oil spill or chronic oil and gas activity in state and federal waters. Results from power analyses indicate that CHIS and BOEM protocols are meeting individual program goals. In other words, both programs have sufficient power to detect relatively small changes in populations of targeted organisms with current levels (biannual sampling) of survey effort. Moreover, given the extensive temporal scales of the two datasets, analyses revealed that it is possible for both programs to reduce survey effort by half (annual sampling) and experience minimal losses in power to detect significant population impacts. Analyses were performed independently for the two programs and therefore each is presented separately in this report. In the face of budget cuts requiring reduced staffing and impaired ability to access sites, as well as the desire to implement additional protocols designed to supplement current data collection, CHIS and BOEM independently proposed several options to reduce program costs. These proposals and questions regarding consequences and benefits of modifying temporal and spatial sampling designs are addressed in individual Conclusions and Recommendations sections for the two agencies.

Power analysis of the intertidal monitoring programs at Channel Islands National Park and the Bureau of Ocean Energy Management

Series