HAwAU-S-97-002 C2 AN ANALYSIS OF THE FISH AND MACROBENTHOS ALONG THE SAND ISLAND OCEAN OUTFALL USING REMOTE VIDEO: VII. 1996 DATA Richard E. Brock PROJECT REPORT PR-97-05 March 1997 WATER RESOURCES RESEARCH CENTER UNIVERSITY OF HAWAI'I AT MANOA Honolulu, Hawai'i 96822 AUTHOR: Dr. Richard E. Brock Associate Researcherand Fisheries Specialist Sea Grant Extension Service Marine Science Building 204 University of Hawai'i at Manoa Honolulu, Hawai'i 96822 Tel.: 808/956-2859 FAX: 808/956-2858 $5.00/copy Please make remittance in U.S. dollars from a U.S. bank or international money order to: ResearchCorporation of theUttiversity of Hawaii Mail to: Water Resources Research Center University of Hawai'i at M5aoa 2540 Dole St., Holmes Hall 283 Honolulu, Hawai'i 96822 ~ U.S,A. Attn: Publications Office NOTE: Pleaseindicate PR-97-05 on checkor moneyorder for our reference, <NISl-$EIIIiINII-TR - 9 i - 0 7 AN ANALYSIS OF THE FISH AND MACROBENTHOS ALONG THE SAND ISLAND OCEAN OUTFALL USING REMOTE VIDEO: VH. 1996 DATA Richard E. Brock Project ReportPR-97-05 March 1997 PREPARED FOR Departmentof WastewaterManagement City and County of Honolulu Project Report for "The Assessmentof the Impactof OceanSewer Outfalls on the Marine Environment off Oahu, Hawaii" ProjectNo.: C39805 Project Period: 1 January1995-30 September 1997 Principal Investigator: RogerS. Fujioka WATER RESOURCES RESEARCH CENTER University of Hawai'i at Manoa Honolulu, Hawai'i 96822 Any opinions, findings, and conclusionsor recommendationsexpressed in this publication are those of the author and do not necessarilyreflect the view of the Water ResourcesResearch Center. ABSTRACT Becausethe diffuser of the SandIsland OceanOutfall lies below safe diving depths,a remotely controlled video camerasystem was usedto determinethe statusof the fish and diurnally exposedmacrobenthos resident to the diffuser,The useof a remotelyoperated vehicle is stipulatedin the NationalPollutant Discharge Elimination System301 h! waiver permit for the Sand Island Wastewater Treatment Plant. Video reconnaissancewas completed over the entire 1,036 m length of the outfall diffuser. Five visual "transects," which "sampled" approximately41% of the total diffuser length, were establishedon the diffuser pipe. Video sampling of the diffuser marine communitieswas carried out annually from 1990 through 1996, Only a few species of diurnally exposed macroinvertebratesare evident on the videotapesof the diffuser; the numbersare insufficient for any meaningfulanalysis. In 1996, 29 fish species,931 individuals!having an estimated biomass ranging from 12to 293g/m2 incan 92 g/m>! were censused,In the 1991through 1995period the numberof fish species encounteredduring a surveyranged from 22 species in 1993!to 31 species in 1992!,the total number of individuals from 279 in 1993! to 2,936 in 1992!, and the mean biomass from 21 g/m2 in 1993!to 53 g/m2 in 1992!.Because the 1990video census covered only theterminal 183 m of the diffuser, whereas the later surveys were spread out along the entire diffuser length,a directcomparison cannot be madebetween the 1990data and the datafor subsequent years.The 1996census noted one new fish speciesfor every 15.3m of substratumsampled and one fish for every 0.7 m2. In the 1991 through 1996 period, measuresof the fish community numberof species,number of individuals,and biomass! have oscillated annually after an initial increase from 1991 to 1992 and a decrease in 1993. From a statistical perspective,changes in the meannumber of speciesper transectand the mean number of individual fishesper transectare significant Kruskal Wallis ANOVA!; changesin the biomass of fishes over the sameperiod are not significant. Thesechanges in the fish community are attributed to changesin the generalviewplane of the videotapesrecorded in 1994 and later years from that recordedin earlier years, as well as to a changein the resolution of the videotapefrom which the dataare derived.Poorer camera resolution results in lower counts; cameraresolution is affectedby local wind andcurrents interacting with the camera,tether, and support vessel,as well as by water visibility. Controlling thesesources of variation inherent with the use of the remotely operatedvideo systemis difficult if not impossible. Until an alternative can be found, the remotely controlled video system is the only low-cost means available to view the marine communities on the diffuser. Until a more accurate means of visual assessmentis available,the biological data generatedby the remotely operatedvideo camera shouldbe viewedas qualitative, with little statisticalrigor. CONTENTS INTRODUCTION . MATERIALS AND METHODS RESULTS .. DISCUSSION . 17 REFERENCES CITED .. 20 Figure l. Schematic of the 1,036-m-long Sand Island Ocean Outfall diffuser pipe showing the approximatelocations of the five transectsestablished in August 1991 and monitored annually using a remotely controlled video recording system. Tables 1. Family and species of fishes censused on five transects along the 1,036-m-longdiffuser pipe of the Sand!sland OceanOutfall as delineated using a remotely controlled video camera systemon 26 September1996.... 2. Summary of the diurnally exposedmacroinvertebrates censused on five video transectscarried out along the 1,036-m-longdiffuser pipe of the Sand Island Ocean Outfall on 26 September 1996 . 3. Summary of diurnally exposed macroinvertebrates censused on five transectsalong the 1,036-m-longdiffuser pipe of the Sand Island Ocean Outfall as delineated using a remotely controlled video camera system in the annual surveys from 1991 through 1995. 4. Summaryof the characteristicsof five transectscarried out at various points along the 1,036-m-longSand Island OceanOutfall diffuser, with data from the fish censuses camed out at each transect in September 1996... 10 5, Family and speciesof fishes censusedon five transectsalong the 1,036-m-longdiffuser pipe of the Sand Island OceanOutfall as delineated using a remotely controlled video camerasystem on 22 August 1991 6. Family and speciesof fishes censusedon five transectsalong the 1,036-m-longdiffuser pipe of the Sand Island OceanOutfall as delineated using a remotely controlled video camera system on 28 August 1992 7. Family and speciesof fishes censusedon five transectsalong the 1,036-m-longdiffuser pipe of the SandIsland OceanOutfall as delineated using a remotely controlled video camerasystem on 5 August 1993. 13 8. Family and speciesof fishes censusedon five transectsalong the 1,036-m-longdiffuser pipe of the Sand Island OceanOutfall as delineated using a remotely controlled video camerasystem on 10 August 1994 14 9. Family and speciesof fishes censusedon five transectsalong the 1,036-m-long diffuser pipe of the Sand Island Ocean Outfall as delineated using a remotely controlled video camerasystem on 16 November 1995.... 15 10. Comparativesummary of fish community developmentmeasured over six yearsat five locations along the 1,036-m-longSand Island Ocean Outfall diffuser, . 11. Summary of the nonparametricStudent Newman Keuls multiple rangetest on rankedvalues of parametersmeasured in the fish community at five permanenttransects along the 1,036-m-long Sand Island diffuser censusedannually from 1991 through 1996 . INTRODUCTION In recentyears controversy has arisen regarding the impactthat sewageeffluent from the Sand Island Wastewater Treatment Plant may have on marine communities resident to the receiving waters. The outfall was constructed in 1975, and screenedsewage has been dischargedsince 1976.The oceanportion of the outfall is comprisedof 2,780 m of 2,1-m- diameter reinforcedconcrete pipe that terminatesin a 1,036-m-longdiffuser. The diffuser is madeup of reinforcedconcrete pipe of three diameters:490 m of 2.1-m-diameterpipe, 271 m of 1,7-m-diameterpipe, and 275 m of 1.2-m-diameterpipe at the terminus.Along its length, the diffuser, which lies in waterfrom 68 to 73 m in depth,has 282 portsthat rangefrom 7.6 to 9 cm in diameter.The diffuser restson a gravelpad and has someballast rock placed at the junctures betweensections. Fishes and macroinvertebrateshave taken up residencealong most of the length of the deep oceanoutfall. This study has been undertakenin an attempt to semiquantitativelyascertain the impactsthat may be occurring to the communitiesresident to the dischargeport areasof the outfall. This report presentsa synopsisof the data from the seventhannual sampling effort carriedout on 26 September1996 and comparatively analyzes these data with information coUectedannually since 1991. MATERIALS AND METHODS A remotely controlledvideo camerawas usedto conductthe censusbecause the fish and diurnally exposedmacroinvertebrate communities of interest to this study reside in waters below safe diving depths.In addition,the systemwas usedbecause the waiver permit issued by the U.S. EnvironmentalProtection AgencyfHawai'i Departmentof Healthrequires the use of a remotelyoperated vehicle. There are a numberof drawbacksas well aspositive aspects to using a video camera system to visually census fishes and diurnally exposed macroinvertebrates.The drawbacksinclude problemswith cameraresolution, making species and size identificationsdifficult, andthe problemof adequatelycontrolling the camera to focus- in on rapidly fleeingfishes, adding further difficulty to identificationproblems. On the positive side, a permanentrecord of' the organismsin the pathof the camerais obtained.An additional benefit to using a videosystem is that it eliminatesthe needfor diving to greatdepths. There are somewelf-known problems