Figure 1.
Map showing the location of the survey sites.
As part of the NOAA Pacific Reef Assessment and Monitoring Program, 240 sites were selected using a random depth-stratified design over hardbottom substrate in depths of 1–30-m. At each site the fish community was surveyed by means of a stationary point count method and the benthic composition examined via a photo-transect.
Figure 2.
Variation in the benthic composition around islands in American Samoa by depth zone.
The mean percentage cover (standard error (SE) bars) of encrusting macroalgae, hard coral, fleshy macroalgae and turf algae. Mean cover was calculated by pooling sites surveyed per depth zone per island. Depth zone ranges were shallow: 0–6-m, mid-depth: 6–18-m and deep: 18–30-m).
Figure 3.
Variation in the biomass of functional groups of herbivorous reef fishes in American Samoa.
The mean biomass (gm−2) (SE) of A) browsers, B) grazers/detritivores, C) large excavators/bio-eroders and D) scrapers/small excavators per island. Mean biomass per groups was calculated by pooling all sites surveyed per island. Ofu & Olo = Ofu & Olosega.
Table 1.
Variance explained in benthic variables by herbivorous fish in American Samoa.
Figure 4.
The relationship between the percentage cover of benthic categories with the biomass of herbivorous fish.
The best fit relationships identified between (A) encrusting algae and grazers/detritivores (solid points, solid line), (B) fleshy macroalgae and grazers/detritivores (solid points, solid line), (C) hard coral and large excavators/bio-eroders (hollow points, dashed line), and (D) turf algae and grazers/detritivores (solid points, solid line) and large excavators/bioeroders (hollow points, dashed line).