Bare, A. Y., Grimshaw, K. L., Rooney, J. J., Sabater, M. G., Fenner, D., Carroll, B.

Mesophotic communities of the insular shelf at Tutuila, American Samoa

2010

Coral Reefs

29

2

369-377

"An investigation into the insular shelf and submerged banks surrounding Tutuila, American Samoa, was conducted using a towed camera system. Surveys confirmed the presence of zooxanthellate scleractinian coral communities at mesophotic depths (30-110 m). Quantification of video data, separated into 10-m-depth intervals, yielded a vertical, landward-to-seaward and horizontal distribution of benthic assemblages. Hard substrata composed a majority of bottom cover in shallow water, whereas unconsolidated sediments dominated the deep insular shelf and outer reef slopes. Scleractinian coral cover was highest atop mid-shelf patch reefs and on the submerged bank tops in depths of 30-50 m. Macroalgal cover was highest near shore and on reef slopes approaching the bank tops at 50-60 m. Percent cover of scleractinian coral colony morphology revealed a number of trends. Encrusting corals belonging to the genus Montipora were most abundant at shallow depths with cover gradually decreasing as depth increased. Massive corals, such as Porites spp., displayed a similar trend. Percent cover values of plate-like corals formed a normal distribution, with the highest cover observed in the 60-70 m depth range. Shallow plate-like corals belonged mostly to the genus Acropora and appeared to be significantly prevalent on the northeastern and eastern banks. Deeper plate-like corals on the reef slopes were dominated by Leptoseris, Pachyseris, or Montipora genera. Branching coral cover was high in the 80-110 m depth range. Columnar and free-living corals were also occasionally observed from 40-70 m. "

10.1007/s00338-010-0600-y

FY2010 CRCP Project ID 1084; Project Title: Benthic Habitat Mapping and Characterization - American Samoa and the U.S. Pacific Remote Island Area; Principal Investigator: John Rooney