Technical Report No. 122
ECOLOGICAL OBSERVATIONS OFF THE MOKAPU, O’AHU, OCEAN OUTFALL A POST-INSTALLATION STUDY
Anthony R. Russo, Steven S. Dollar, E. Alison Kay
February 1979
ABSTRACT
An ecological study of the benthic and fish communities at Mokapu, Oahu, was completed in the summer of 1978 approximately 1 yr subsequent to the installation of a submarine outfall by the City and County of Honolulu. Data were obtained from five transects between Mokapu Point on the northeastern tip of Oahu to Alala Point, approximately 6 034 m (3.75 miles) south, at depths of 6 to 24 m (20-80 ft). This study is subsequent to an initial survey completed in 1975 prior to outfall construction.
Results show little or no effect from the operation of the outfall on the benthic and fish communities. There are not significant differences in the abundance, diversity, or composition of fishes from 1975 to 1978 except at the outfall site where new substrate was formed by construction. Between the 1975 and 1978 studies there are some differences in coral species cover indices, which are attributed to patchy substrate distribution rather than stress from the sewer outfall. Differences in species composition and distribution of micromolluscan assemblages may also be explained, at least in part, by patchy distribution of the substrate.