Hawai'i Coral Reef Network

DIVER Impacts on 
coral reefS at Kealakekua BaY, Hawai’i


The study was conducted in 1996-1997 at Kealakekua Bay. Four 50m transects were established at 3-6 m depths: two in areas of high diver activity, the impact site (directly in front of the Capt. Cook Monument and in the area where the diver boat moor) and two in areas of low to no diver activity, the control site located about 1km south of the impact site (Figures 1 & 2).  

Data were collected using photographs taken with a Nikonos V camera with a 15mm lens attached to a PVC quadrat covering an 0.50m2 area (Figure 3). On each transect 18 photographs were taken at randomly selected coordinators along the transect lines at all study sites both at the beginning and end of the study (Figure 4). Percent cover estimates were made of all living and non-living substratum in each photograph by projecting the slide over a series of 50 random coordinates and recording the observed substratum under each point. In addition, the percent cover of bleached and broken coral was estimated for each slide. Bleached coral was noted as unusually pale portions of the coral colony, typically located at the tips or edges of coral colonies. Broken coral was identified as recently damaged coral fragments. A single observer was used to analyze all of the photographic data in order to minimize observer bias.

Figure 1. Location of impact transects.

Figure 2. Location of control transects.

Figure 3. Diver using photoquadrat to 
collect reef images.

Figure 4. Example of photoquadrat image.



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Last update: 1/25/2005