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RAP Diver Disturbance Memo

Sanctuary Advisory Council
Research Activity Panel
Monterey Bay National Marine Sanctuary
299 Foam Street, Suite D.
Monterey, CA 93940
(408) 647-4213

August 24, 1998

Dr. Steve Webster, Chair
Sanctuary Advisory Council
Monterey Bay National Marine Sanctuary
886 Cannery Row
Monterey, CA 93940

The Research Activities Panel (RAP) has reviewed the report entitled, "Diver Disturbance in Kelp Forests," by Tim Schaeffer and Michael Foster. This short paper documents, for the first time, actual disturbance effects that SCUBA divers can have on kelp forest resources. The report further provides guidelines that could minimize potential impacts of divers on kelp forest resources.

Like all scientific work, the paper has strengths and weaknesses. Its strengths lie in its objective data collection and analysis, the measurement of actual events, and clearly stated questions and conclusions. Its weaknesses lie in its limited data set (42 divers), short time duration and limited set of environmental conditions in which the study was conducted. These are not criticisms. They are simply properties of this study that restrict the kinds of conclusions one can draw.

In view of the controversy surrounding recent discussions on regulating activities in nearshore kelp forests, we feel that it is important to emphasize what conclusions should and should not be drawn from this report. We also took the liberty of making our own recommendations based on our analysis of this report and of its recommendations. We offer this in the interest of informing the on-going discussions and debates about human impact of kelp forest resources.

What this report says: This report estimates the intensity of SCUBA diving activity in kelp forests habitats along Cannery Row, and quantitatively documents actual kinds of disturbance and frequency of disturbance of divers on marine life and the sea floor. The report further makes recommendations that could lead to reducing the frequency of disturbance by divers. The report focuses on SCUBA divers and not skin divers.

What this report does not say: While this report documents the proximate, direct impacts of SCUBA divers on selected marine resources, this report does not assess the long-term impacts or ecological effects of diver disturbance on marine resources. For example, while the report documents blade removal from attached kelp plants, it does not measure or extrapolate to the effect of blade removal on, say, plant growth or plant density. The report does not allow us to predict what kinds of changes we might expect given future patterns of diving intensity. And finally, the report does not compare the measured disturbance to disturbances from other phenomena, such as storms, boats, oceanographic events such as El Niño, etc.

Report Recommendations: The report makes the following recommendations to reduce diving disturbance: 1. Increase awareness by the diving industry of environmental consequences of careless SCUBA diving practices; 2. Improve diver training. Specifically, dive instructors should conduct dive training classes in areas that are least sensitive to diver disturbance; emphasize buoyancy control in diver training classes; teach divers to avoid entanglement with kelp and how to disentangle from kelp without breaking kelp fronds; encourage student divers to observe rather than touch marine animals. 3. Improved management of diving activities in marine parks and refuges. Any such management decisions must be based on better understanding of the direct impacts of SCUBA diving activities on marine resources and the long-term ecological effects. The report thus recommends further research on diver impacts, followed by management actions such as limiting numbers of divers in certain areas, designated training, entry and exit points, and underwater trails.

The RAP feels that education, rather than regulations that broadly restrict/control diving activity, is the most promising approach to minimizing potential impacts of SCUBA divers on kelp forest. With this in mind, we make the following recommendations:

1. Develop guidelines to minimize the impacts of SCUBA diving activity on kelp forest communities. Although further research (such as experimental diver exclusion zones) and more empirical data would provide a clearer picture of the short- and long-term effect of SCUBA divers on kelp forest communities, guidelines could and should be adopted now based on what we do know. These guidelines should be developed by a task force composed of kelp forest researchers, SCUBA instructors and managers of marine protected areas with diver management experience, under the guidance of the RAP. These guidelines could be published under the banner of the MBNMS and distributed to the national dive instructor organizations with a request that these guidelines be included in basic SCUBA training and in the specialty courses offered by these organizations. The guidelines should also be distributed to dive shops and hotels that cater to the SCUBA diving community as well as through other distribution venues. The Sanctuary Education Panel and the Sanctuary Public Relations office should certainly be involved.

2. Place signage at key diver entry and exit points that summarize the SCUBA diving guidelines. Exploit the sanctuary status of the area to emphasize the need for heightened awareness and sensitivity to the potential impacts of divers on marine resources.

3. Develop diver management guidelines for marine protected areas, and ensure these guidelines are considered in the current effort to evaluate the effectiveness of California's marine protected areas. Diving activities may be more manageable in marine protected areas, and resource managers should take advantage of this fact to minimize impacts of diving activities, and perhaps to empirically determine the actual impacts of diving activity on marine resources.

We hope that our review will be of interest the Sanctuary Advisory Council and of use in developing MBNMS education and outreach materials. Because it is a working group of the SAC, the RAP decided not to broadly circulate this information; however, we request that the MBNMS SAC considers forwarding this letter to the cities of Monterey and Pacific Grove.


Dr. Gregor Cailliet, Research Activities Panel Chair
Moss Landing Marine Laboratories
P.O. Box 450
Moss Landing, CA 95039

cc William Douros, MBNMS Superintendent

Reviewed: April 11, 2024
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