WRRCTR No.132 Benthic Ecosystem and Fish Population off the Mokapu Outfall: A Second Postinstallation Ecological Study

dc.contributor.author Russo, Anthony R. en_US
dc.contributor.author Dollar, Steven J. en_US
dc.contributor.author Kay, E. Alison en_US
dc.date.accessioned 2008-08-08T21:23:03Z
dc.date.available 2008-08-08T21:23:03Z
dc.date.issued 1980-05 en_US
dc.description.abstract An ecological study of the benthic and fish populations at Mōkapu, O’ahu, Hawai’i was completed in the summer of 1979. This is the second post-installation study of the Mōkapu Outfall area since the commencement of effluent discharge in December 1977. An initial baseline survey was completed in 1975 (Russo et al. 1977, 1979). Data were obtained from five stations between Mōkapu Point on the northeastern tip of O’ahu to Alāla Point approximately 6 034 m (3.75 miles) south, at depths of 6 to 24 m (20-80 ft) in all surveys. Results show little or no effect from the operation of the outfall on the benthic and fish communities two years after commencement of discharge. There are no significant differences in abundance, diversity or composition of fishes from 1975 to 1979 except over the outfall site where fish abundance increased significantly especially over the diffuser where the snapper Lutjanus kasmira was counted in large numbers (>500). The relative abundance of herbivorous fishes (acanthurids) increased near the outfall. This may be commensurate with an increased coverage of a fine microalgal mat and an increase in the biomass of Lyngbya, a blue-green alga near the outfall site. The biomass of dominant macroalgae did not significantly change at any of the five areas surveyed. Between the 1975, 1978, and present (1979) studies, there are some differences in coral cover which are attributed to patchy substrata distribution rather than stress from the sewer outfall. In comparison with the samples of 1975 and 1978, the 1979 transect D samples and that from the diffuser show a lower, overall abundance in micromolluscan assemblages than was recorded in either 1975 or 1978, and that Tricolia, Vitricithna, Rissoina miltozona, and Bittium increased in relative proportions at the 18 to 16 m (60-80 ft) depth levels and at the diffuser. The differences reflect increasing numbers of micromollusks more usually associated with depths of less than 15 m (50 ft) at greater depths and of species associated with frondose algae and substrata. This trend was noted in 1978 and is apparent again in 1979. Large differences among some of the 1979 samples and between the 1979 and other year samples reflect the patchiness of the substratum and cannot be attributed to effects of the sewer outfall. en_US
dc.description.sponsorship Department of Public Works, City and County of Honolulu Grant/Contract No. F-637-78 en_US
dc.format.extent viii + 45 pages en_US
dc.identifier.citation Russo AR, Dollar SJ, Kay EA. 1980. Benthic ecosystem and fish population off the Mokapu outfall: a second postinstallation ecological study. Honolulu (HI): Water Resources Research Center, University of Hawaii at Manoa. WRRC technical report, 132. en_US
dc.identifier.uri http://hdl.handle.net/10125/2266
dc.language.iso en-US en_US
dc.publisher Water Resources Research Center, University of Hawaii at Manoa en_US
dc.relation.ispartofseries WRRC Technical Report en_US
dc.relation.ispartofseries 132 en_US
dc.subject fish populations en_US
dc.subject coral en_US
dc.subject mollusks en_US
dc.subject marine algae en_US
dc.subject effluent discharge (water) en_US
dc.subject baseline surveys en_US
dc.subject benthic fauna en_US
dc.subject Hawaii en_US
dc.subject micromollusks en_US
dc.subject macroalgae en_US
dc.subject Mokapu outfall en_US
dc.subject Shannon-Wiener diversity index en_US
dc.subject Morisita similarity index en_US
dc.subject Sorensen similarity index en_US
dc.subject Oahu en_US
dc.subject.lcsh Benthos -- Hawaii -- Oahu. en_US
dc.subject.lcsh Fish populations -- Hawaii -- Oahu. en_US
dc.subject.lcsh Marine animals -- Effect of water pollution on. en_US
dc.subject.lcsh Marine ecology -- Hawaii -- Oahu. en_US
dc.subject.lcsh Mokapu Peninsula (Hawaii) en_US
dc.subject.lcsh Ocean outfalls -- Environmental aspects -- Hawaii -- Oahu. en_US
dc.subject.lcsh Sewage disposal in the ocean -- Environmental aspects. en_US
dc.title WRRCTR No.132 Benthic Ecosystem and Fish Population off the Mokapu Outfall: A Second Postinstallation Ecological Study en_US
dc.type Report en_US
dc.type.dcmi Text en_US
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