Rocky shorelines are highly variable and are affected significantly by natural and anthropogenic sources. This makes developing standardized bioindices of health especially challenging. Several objectives are being pursued by the sub-committee members to develop these parameters.

1) Determine if a group of experts, given a set of raw data from a couple of dozen sites, in a blind test, will rank the sites in similar order from healthy to unhealthy.

The concept is that if experts intuitively agree on the criteria, we should be able to define them. Conversely, if there is wide divergence at this level, it will be even more difficult to arrive at a set of standard bioindices.

Dr. Steve Weisberg conducted a similar blind data test when developing bioindices for soft bottom benthic communities and found that this approach helped the scientists develop criteria. In Fall 2008, Dr. Pete Raimondi and Dr. Steve Murray put together a set of MARINe site data and sent it to a group of recognized rocky intertidal experts for their consideration. The experts and members of the Subcommittee met at Catalina Island to discuss their results. There were two important conclusions reached. First, all the experts agree that bioindices can be developed which are credible. Second, the group determined that they need to break down rocky intertidal into habitat subsets in order to develop these indices. For example, a sand scoured flat rocky bench such as the site at Coal Oil Point looks very different than an open coast, high relief site such as those found along the Central Coast. Organisms that tolerate sand scour may be considered part of a “healthy” ecosystem at Coal Oil Point, but would not be at the other sites.

New subtypes are being developed and the data will be resent to the experts to evaluate using these criteria. The group of experts plans to meet again once that has been completed.

2) Examine the concept of disturbance.

Determine what constitutes a “disturbance”; decide what a “healthy” disturbance is vs. an “unhealthy” disturbance; and, identify those factors that demonstrate its origin.

A “healthy disturbance” sounds like an oxymoron but disturbance such as the creation of bare rock, is a natural process in a rocky intertidal community which increases biodiversity and improves the health of the community.

The issue of disturbance is further complicated by the fact that in a rocky intertidal community, the same type of disturbance can be made either by an anthropogenic source or natural and the effects may be similar. For example, sand causes smothering and scouring in the rocky intertidal community. Significant amounts of sand can be placed in intertidal beds during storm events and from natural seasonal oceanographic processes. Sand can also enter rocky intertidal habitats from man-made activities such as road-building and beach replenishment projects. Is either or both unhealthy? Or healthy?

The group has conducted a literature search of studies which look at disturbances to refine these parameters for use in developing indices of health.

3) Define health.

What is “Health” anyway?  Health is a term that makes scientists cringe because it means something different to each person, and often is the unexplained composite of many different factors. Yet managers confronted with decisions about the coast, and public citizens interested in the ocean often want to know about a communities’ “health”. 

A working definition of health has been developed and is being modified for use in this effort.

4) Determine if bioindices have been developed internationally which could aid in the discussion.

A literature search found a few pertinent approaches in other habitat types. However, it seems that this effort by the Rocky Intertidal Health Sub-Committee will be one of the only attempted for rocky intertidal.