Project Report PR-94-14
Community Structure of Fish and Macrobenthos at Selected Sites Fronting Sand Island, Oahu, Hawaii, in Relation to the Sand Island Ocean Outfall, Year 4, 1993
Richard E. Brock
Febuary 1994
ABSTRACT
This report provides the results of the fourth year of an annual quantitative monitoring (carried out on 7 – 8 September 1993) of shallow marine communities inshore of the Sand Island Ocean Outfall, Oahu, Hawaii. This monitoring effort focuses on benthic and fish community structure and is designed to detect changes in these communities. Marine communities offshore of Honolulu have received considerable perturbation for 100 years. Raw sewage was dumped in shallow water until 1978; however, point and nonpoint sources of pollution from both urban activities and industry continue. All of these disturbances may serve to obscure any impacts that may be caused by treated effluent discharge from the deep ocean outfall. The marine communities show a considerable range in development that is probably related to historical impacts. Stations have been located to take advantage of these gradients. Analysis of the Data for four years showed that there has been no statistically significant change in the biological measures (i.e., percent coral cover, number of coral species, number of invertebrate species, total number of invertebrates counted, number of fish species, total number of fishes counted, and the biomass of fishes present at each station) quantified in the study during this period. Hurricane Iniki, which occurred in September 1992, impacted marine communities along the south shore of Oahu. Coral communities received considerable damage, especially at the westernmost study station. Recovery in these communities was evident in the year following the storm.