Recreational diving and its impact in marine protected areas in eastern Australia.

TL;DR: In this article, the potential impacts of divers were assessed in underwater surveys at four major dive-sites in Eastern Australia, where recreational divers were followed for 30 minutes, and all contacts with and damage to the substratum or biota were recorded.

Abstract: Recreational scuba diving has generally been perceived as an activity with low environmental impact. With the rapid growth in popularity of diving, concerns have arisen that some heavily-dived sites may have diver visitation rates approaching the limit of ecological sustainability. The potential impacts of divers were assessed in underwater surveys at four major dive-sites in Eastern Australia. Recreational divers were followed for 30 minutes, and all contacts with and damage to the substratum or biota were recorded. Information on diver qualifications and experience was collected. The mean number of contacts with the substratum per 30 minute dive at each site ranged from 35 to 121, with a maximum of 304 in a single dive. The majority of contacts were made with fins. Breakage of coral ranged from an average of 0.6 per dive to 1.9 per dive. Most divers damaged no coral, but a small minority of divers broke between 10 and 15 corals each per 30 minute dive. The level of damage to the sites studied appeared to be sustainable at present levels of use by divers. However, at intensively dived, coral-dominated sites, the potential exists for considerable environmental impact as the number of recreational divers increases beyond present levels.