BIOLOGICAL MONITORING OF THE CHEVRON DIFFUSERBARBERS POINT, OAHU --- 2005

Steven Kolinski, Ku‘ulei Rodgers, Regina Kawamoto and E. Alison Kay,Dept. of Zoology, University of Hawaii

Honolulu, Hawaii 96822

Summary

Surveys of corals, micromollusks and fishes were conducted at permanent monitoring areas on 23 August 2005 in compliance with the requirements of a Zone of Mixing Permit issued by the Hawaii State Department of Health to the Chevron Oil Refinery. Additional measurements of corals and fishes were made along bench substrate in the Pipeline and Control areas. Here we report the following:

No new corals recruited to monitored saddle tops. Coral saddle-top population mortality averaged 21 %, and populations on average declined 21 %. The decline was heavily influenced by mortality on a single saddle, but was consistent with a gradual downward trend in coral numbers. Two recruits from 2004 survived to 2005. Corals measured in 2004 grew an average 176 cm2 by 2005, which did not differ significantly from previously measured growth rates. Four previous measured colonies suffered significant partial (n = 2) or total (n = 2) mortality. Three new colonies were selected for monitoring of growth.

Micromollusk abundance showed a minor increase and species numbers a decrease in 2004 compared to 2003. In 2004, a total of 4,772 micromollusks belonging to 151 mollusk taxa were collected. Species indicative of habitat degradation were not found in the vicinity of the pipeline. Isognomon, a genus characteristic of lowered salinity conditions, were present at T2, T3, and the Control site in extremely low numbers. At all four stations, pyramidellids and infaunal bivalves (indicators of enriched conditions) were present but in extremely low numbers.

Although total number of fishes was lower, number of fish species was higher compared to 2004. A higher number of individuals and species were identified at the Pipeline compared to the Control. Biomass estimates of fishes were made, and ordination analysis suggested that the Pipeline and T3 differed substantially from T2 and the Control sites based on fish assemblage characteristics, numerical abundance and biomass densities. No evidence of negative impacts to fish populations due to the Pipeline or effluent was found.

Additional coral and fish surveys were conducted on bench habitat 10 m north of the Pipeline and within the Control region to ascertain sample sizes needed for evaluating impacts. Power analysis suggested from 34 to 60 samples would be needed per site to gain 70 % to 90 % confidence that Type II error was not occurring, due to similarity in average coral density values and relatively high variability within sites. Modification of transect lengths and numbers, and the addition of stations more representative of the diversity of community

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structure found within the stated ZID, may be needed to make control comparisons practicable.

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Introduction

The Chevron monitoring program at Barbers Point, Oahu, was initiated in 1982 to comply with the requirements of a Zone of Mixing Permit issued by the Hawaii State Department of Health. Censuses of corals on the pipeline saddle, micromollusks from sediments near the discharge pipe, and fishes in the vicinity of the pipeline have been conducted yearly with the exception of an 18-month (1983 – 1984) and 16-month (1999 – 2000) hiatus. In 1996 the zone of mixing was expanded and two additional sites within the zone and an outside control site were added to the surveys (Figure 1). We report here measured parameters of coral growth and population dynamics for pipeline saddle-top populations, and micromollusk and fish counts for all surveyed sites for the year 2005. Additional measurements of corals and fish are reported for bench habitats adjacent to the pipeline and within the control region.

Site DescriptionPipeline

The pipeline (Figure 1) carrying the effluent discharge extends a distance of 364 m (1200 ft.) from shore to a depth of 7 m (23 ft.). The discharge consists of process effluent and once-through brine cooling water with temperatures 3 to 4o above ambient, and DO’s and pH slightly different from ambient (Kay and Smalley 1982). The discharge is rapidly diffused and the receiving water falls well within ambient limits within a few seconds of discharge (Kay 1981).

The pipeline sits on a topographically homogeneous limestone shelf which experiences continuous surge varying in intensity (relative to surf conditions) and a long shore current that frequently changes speed and direction. The shelf is subject to continual sand abrasion and the water to relatively high turbidity, with visibility typically from 1.5 to 5 m because of the sediment load in the water column.

The diffuser is anchored by eight large concrete saddles (approximately 1.5 m x 1.5 m x 1.5 m) through which the pipeline passes. The seaward-most saddle site is in 7 m (23 ft.) of water and the other saddles are in progressively shallower water as the pipe approaches shore. Approximately 50 m shoreward of the end of the diffuser several bags of concrete (ca 75 pounds) have been dumped under and around the pipe. The pipe, saddles, and concrete bags significantly increase the structural complexity of an otherwise two-dimensional habitat.

The macrobiota reflects the physical conditions of the environment. The limestone shelf is interrupted by pockets and crevices, some with sand, and is covered by a sparse algal turf. Scattered encrusting Porites and Montipora corals are present, along with low-level branching colonies of Pocillopora meandrina. Corals are present on the pipeline itself, with the dominant species being Pocillopora meandrina. Other obvious components of the biota are several species of fish and sea urchins (Echinometra) that are found around the pipeline.

Experimental SitesIn 1996, two additional experimental sites (T2 and T3, Figure 1) within an expanded zone

of mixing (ZID) were designated. Location, proximity and greatest similarity to the pipeline in terms of topographic relief and macrobiota were the basis for the selections (Kay et al. 1996). T2 is approximately 600 m northwest of the pipeline, and roughly 250 m southeast of the Barbers Point Harbor. It consists of approximately 40 - 70% living coral cover in the form of large colonies of Porites lobata (and possibly some P. evermanni) along with P. compressa and

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various Montipora spp. Massive three-dimensional colonies and accretions provide complex habitat for fishes that is reasonably comparable to the saddle structures of the diffuser pipeline, given the limitations of habitat within the ZID.

Figure 1. Map of biological monitoring stations (T1 – T3, Control) for the Chevron Refinery wastewater outfall.

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The second site, T3, is approximately 600 m south of the diffuser pipeline in 9-11 m of water and consists of fractured and contoured limestone shelf with an abrupt 2 m drop and gradual rise, and several large apparently carbonate boulders. Coral cover, although estimated at less than 20%, is greater than that found in the inshore area surrounding the pipeline. Poriteslobata (including several large lobate heads) and Pocillopora meandrina are the most common species. Numerous encrusting corals, including Montipora patula, M. flabellate, M. verrucosa, and Pavona varians are also present. The area appears impacted by occasional heavy swell that may serve to limit expansion of coral cover and upright growth of all but the P. meandrina and P. lobata heads.

Control SiteA control site (Figure 1) outside the zone of mixing was also established in 1996. The site

is approximately 600 - 700 m north of the Barbers Point Harbor entrance and 400-500 m south of the Ko‘Olina Resort, at a fairly consistent depth of about 8 m. The bench is topographically complex, with numerous caves, caverns, crevices and an apparent spur and groove network. The proximate grooves are estimated to be 2-4 m wide, with an abruptly vertical northernmost wall approaching 3 m in height and a southernmost wall sloping more gradually to the bench above. Each groove contains scattered sand deposits. Live coral cover in the area is estimated to be less than 10%. Prevailing species included Pocillopora meandrina and Porites lobata (including both encrusting and large lobate heads). Other scleractinians included Pavona varians, Montipora verrucosa, M. flabellata, and Cyphastrea ocellina (all encrusting).

Methods and MaterialsTransects

The permanent monitoring locations (Pipeline [T1], T2, T3 and Control) were relocated using GPS and surveyed on 23 August 2005. Fish surveys and sediment collections occurred along a 50 meter transect line laid perpendicular to shore at T2, T3 and the Control site. Pipeline between and including the four outermost (ocean side) saddles served as the permanent transect for surveys of coral and fish and sediment sampling at T1.

Additional coral and fish surveys were conducted along bench substrate at 10 m north of the pipeline and roughly 100 m west of the Control site to investigate an alternate methodology for statistically evaluating potential impacts to corals in the region. These surveys may form the basis for comparative long-term coral monitoring as pipeline saddle top coral populations continue to decline in the absence of comparative controls (Kolinski et al. 2003, 2004). Wave heights did not exceed 0.4 m. Visibility ranged from 5 to 15 m.

Corals

Saddle Top Measurements

Three replicate length (the longest curved dimension of live coral colony skeletal structure in a direction perpendicular to the pipeline) and width (the longest curved width of live coral colony skeletal structure in a direction parallel to the pipeline) measurements were made using a flexible measuring tape on 11 colonies of Pocillopora meandrina on the tops of the four outermost saddles of the diffuser pipeline (T1). This included eight previously (2004) measured

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colonies (one to three on a saddle) and three new colonies (on saddles 1, 2 and 3) to replace those suffering from high levels of partial or total mortality. Coral recruits (new colonies of larval origin and those expanding from saddle sides into saddle top monitoring zones) and the positions of all live and dead colonies on each saddle top were mapped.

Bench Measurements

Corals were identified to species and numbers recorded with 0.5 m of two (first and last) 10 m sections of two 25 m transects laid perpendicular to shore (i.e., four 10 m2 replicates) in the pipeline and control regions. Individual corals were assigned to a size class based on greatest linear diameter (1 to < 2 cm; 2 to < 5 cm; 5 to < 10 cm; 10 to < 20 cm; 20 to < 40 cm; 40 to < 80 cm; 80 to < 160 cm; > 160 cm). Detached corals were noted, counted and sized, as was fission for attached colonies. Rugosity (an indicator of topographic complexity) was measured using a 15 m fine linked chain (1.3 cm links) draped to conform to the topographic structure of the reef under each 25 m transect line (rugosity = fully extended chain length/transect section length; McCormick 1994). Colonies were collectively analyzed as densities m-2 or as arcsine square root transformed proportion values.

MicromollusksMicromollusks (mollusks with shells less than 10 mm in greatest dimension) were

sorted from sediments collected from sand-accumulations within 3 m of each of the four saddles on limestone bench adjacent to the pipeline. Sediments were also collected within 3 m of the 0, 17, 34 and 50 m marks on the transect lines demarcating sites T2, T3, and the Control site. The sediments were put through two 75% alcohol washes, air dried, and only fresh shells were removed from aliquots of 25 ml by sorting under a dissecting microscope. The shells were identified to the lowest taxonomic level possible using Kay (1979). The shells were counted and counts were analyzed for abundance, habitat and trophic information (Kay 1979, Beesley et al. 1998).

FishesVisual fish surveys were conducted 2 m on each side and above each transect at each site,

which, at the pipeline included under the pipeline and within the concrete stanchions. All fish were identified to lowest possible taxon and sizes were estimated for calculations of fish biomass.

Four additional transects were surveyed in 2005. Two 25 m transects 5 m apart were positioned 10 m to the north and parallel to the first concrete stanchion of the Pipeline (T1-1, T1-2). Two additional 25 m transects were positioned near the Control site (C1, C2). Site selection of these transects were based on depth and substrate similarity within the immediate vicinity.

ResultsSaddle Top Corals

Summary data from the 23 August 2005 survey of corals on diffuser pipeline saddle tops are shown in Table 1. Appendix 1 presents measurement data for individual colonies and a sketch of the 23 August 2005 saddle top populations. Pocillopora meandrina was the only species observed and measured on the cement saddle tops.

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Table 1. Number of recruits, recruit survival and colony mortality, % change in population numbers.

Saddle 1 Saddle 2 Saddle 3 Saddle 4 Mean . No. Recruits 2005 0 0 0 0 0

Recruits Surviving 04-05 1 of 1 0 of 0 1 of 1 0 of 0 100%

Mortality 04-05 1 of 6 5 of 9 1 of 8 0 of 7 21.2%

Change in No. Colonies - 16.7 - 55.6 - 12.5 0 -21.2%

Recruitment. No new corals were observed to have recruited to the pipeline saddle tops by settlement or colony expansion from saddle sides. The two previous recruits from 2004 were alive in 2005 and displayed no evidence of partial mortality. The average percent survival of new recruits in following year surveys from 1996 to present is 80.7 % ( 7.7 S.E., n = 20). Recruitment has declined significantly since being recorded in 1996 (Linear Regression: No. Recruits = 538.48 – 0.2686 x Year; R2 = 0.30, df = 35, F = 14.59, P = 0.001).

Mortality. The percent of saddle top colonies that died between November 2004 and August 2005 averaged 21.2 % ( 12.0 S.E., Table 1). This did not differ significantly from average annual mortalities observed since 1997 (One-way ANOVA of arcsine-square root transformed proportions, df = 31, F = 0.84, P = 0.563). Similar to previous observations, levels of colony mortality varied between saddle tops, ranging from 0 to 55.6 % for saddle top corals in 2005. New or additional partial mortality was observed in 4 of 23 colonies. Partial mortality occurred on average in 31.4 % ( 12.0 S.E.) of saddle top colonies.

Population Status. Coral numbers on sampled saddle tops continued to decline as shown in Figure 2. The decline in 2005 appears to have been heavily influenced by the loss of 5 of 9 colonies on Saddle 2. Colony numbers declined an average 21.2 % ( 12.0 S.E.; 1.8 colonies 1.1 S.E.) from 2004 (Table 1). The number of 2005 corals averaged 55.6 % ( 15.3 S.E.) that of 1997 highs, a reduction of nearly 45 % (5.6 colonies 2.0 S.E. per saddle). Average colony numbers in 2005 were significantly lower than those of 1997 (Repeated Measures ANOVA, df = 8, F = 4.06, P = 0.004, Tukey HDS test P = 0.007) but did not differ statistically from those of 2004 (P = 0.922). The continuing population trend towards lower coral numbers on the pipeline saddle tops is reflective of a system that is failing to provide new recruits at a pace consistent with older colony mortality. The decline (as reflected in average numbers) is gradual.

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Figure 2. Mean number of saddle top colonies over time ( 1 S.E.)

Colony Growth. Four of the previously measured corals experienced significant partial (n = 2) or total (n = 2) mortality. The mean annual growth rate (increase in area of an ellipse in cm2) of colonies was 176 cm2 40 S.E. (n = 5; only colonies with no or minor tissue mortality included as major tissue mortality may be the result of senescence). Growth (standardized by initial colony size) did not differ between 2004 and 2005 (Two-sample T-test, df = 12, T = -0.66, P = 0.521). No significant trends in growth have been evident since monitoring in 1996.

Corals on Bench SurveysTwo-hundred-and-sixty-seven coral colonies representing 9 species were observed along

pipeline transects, and 317 colonies representing 11 species were identified along control area transects (Table 2). The control area displayed slightly higher diversity (Shannon index = 1.64) and equability (0.68) than within the pipeline area (Shannon index = 1.30, equability = 0.59). Total colony densities m-2 did not differ significantly (Two-sample T-Test, df = 6, T = 0.84, P = 0.433); however, percent number of colonies did differ significantly between size categories (Table 3), and for the 2 to < 5 cm category between sites (Pipeline = 0.50 0.09 S.E., Control = 0.22 0.09 S.E.; Tukeys HSD test, P = 0.0001). Colonies < 5 cm in diameter (considered relatively “recent” recruits) were over double in average number at the pipeline compared to the control site, but did not differ significantly (Two-sample T-Test, df = 6, T = 1.74, P = 0.132). Colonies > 5 cm diameters were more prevalent at the control site (average = 73 13 S.E. vs. 48

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8 S.E.) suggesting greater area cover by live coral tissue, but the means also did not differ significantly between sites (Two-sample T-Test, df = 6, T = 1.78, P = 0.126). No coral fragments were found, suggesting high wave energy exposure. Percent colonies separated by fission (arcsine square-root transformed) did not differ significantly between the two sites (Two-sample T-Test, df = 6, T = 1.25, P = 0.259). Rugosity was much higher at the control site (1.54, 1.61) than on the pipeline bench (1.17, 1.18).

Table 2. Total numbers and average densities ( S.E.) of corals by species.Pipeline Control

SpeciesTot. No.

Colonies m-2

No. recent (1 to < 5 cm)

visual recruits m-2

Tot. No.

Coloniesm-2

No. recent(1 to < 5 cm)

visual recruits m-2

Cycloseris sp. 1 0.03 0.03 0.03 0.03Leptastrea purpurea 1 0.03 0.03 0Montipora capitata 154 3.85 0.48 0.80 0.12 113 2.83 0.85 0.23 0.13Montipora flabellate 16 0.40 0.16 0.14 0.06 7 0.18 0.14 0Montipora patula 27 0.68 0.48 0.10 0.07 60 1.50 0.20 0.10 0.10Montipora studeri 1 0.03 0.03 0Palythoa cesia 1 0.03 0.03 0Pavona duerdeni 4 0.10 0.06 0Pavona varians 9 0.23 0.13 0Pocillopora eydouxi 1 0.03 0.03 0Pocillopora meandrina 13 0.33 0.08 0.05 0.03 21 0.53 0.14 0.05 0.03Porites compressa 3 0.08 0.05 0Porites evermannii 4 0.10 0.07 0 9 0.23 0.10 0Porites lobata 50 1.25 0.16 0.22 0.10 89 2.23 0.45 0.25 0.22

Total 267 6.68 0.79 1.32 0.23 317 7.93 1.26 0.63 0.33

Table 3. Two-way factorial ANOVA of percent colonies (arcsine square-root transformed) per size category for pipeline and control areas. Source df SS MS F PSite 1 0.0048 0.0048 0.4826 0.491Size Category 6 1.4938 0.2490 24.7809 0.000Site x Size Category 6 0.2445 0.0408 4.0566 0.003Error 42 0.4219 0.0100

Power analysis for Bench SurveysThe power of the Two-sample T-Test to reject a false null hypothesis (i.e., statistics

suggest no significant site difference when one exists) at α = 0.05 for coral densities was very low (0.114, a probability of 11.4 %). Approximately 60 ten meter samples would needed per siteto increase power to 0.9 at α = 0.05. Management decisions might more realistically be based on a level of power approaching 0.70 (see Wilkinson 1993). At α = 0.05, 34 samples per site would be needed. Sample size would be adjusted only slightly by increasing the probability of Type I

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error (α; probability of rejecting a true null hypothesis). This situation is forced by having similar average site density values and high natural variability.

MicromollusksThe micromollusks in the Chevron biomonitoring samples were representative of

various habits and habitats. A total of 4,772 micromollusks were collected, belonging to 151 mollusk taxa (Appendix 2). Similar to 2003, Gastropods comprised 93% of the micromollusk abundance at all sites. The high proportion of gastropods: low bivalve proportion is said to be due to lack of expanses of nutrient-rich, silty sand ocean substrata (Kay 1967). Overall abundance was similar to that of 2003 (4,763 micromollusks with 171 taxa), although number of taxa was lower. Abundance and species composition are shown in Appendix 1. The highest abundance of micromollusks was at T2 (2,916), followed by T1 pipeline (884), T3 (756), and Control sites (216). The dominant species were Rissoina cerithiiformis (1,123), Tricolia variabilis (371), and species in the genus Leptothyra and families Rissoidae and Cerithiidae.

For all taxa present at T1, T2, T3, and Control, epifaunal species (i.e. species associated with rocks, gravel, or other hard substrates; 89.7% of total) made up 90.9% (T2), 90.2% (T3), 88.0% (Control), and 85.6% (T1 pipeline) of the micromollusk numbers observed. Detritivores made up a major portion of the epifauna: 50.2% (T1 pipeline); 43.6% (Control); 42.1% (T3) and 33.1% (T2). Infaunal (6.2%), parasitic (2.7%) and commensal (1.3 %) micromollusks made up remaining numbers by habit.

In all, at T1, detritivores (46.9%) were followed by herbivores (24.9%), filter feeders (12.8%), parasitic mollusks (8.8%), carnivores (4.2%), and foragers (2.0%). For T2, herbivores (46.4%) were more abundant than detritivores (33.6%). They were followed by filter feeders (8.1%), carnivores (7.4%), parasitic mollusks (3.5%) and foragers (0.9%). At T3, detritivores (40.7%) were followed by herbivores (35.4%), filter feeders (8.1%), parasitic mollusks (6.6%), carnivores (6.3%) and foragers (2.2%). At the Control Site, herbivores (22.7%), filter feeders (19.4%), parasitic mollusks (11.6%), carnivores (2.3%), and foragers (0.9%) followed detritivores (43.1%). Species in the family Rissoidae feed on diatoms and algal filaments. The rissoid, Rissoina cerithiiformis (1,123) was the most abundant species present, with T2 at 972, T3 at 111, T1 at 35 and the Control at 5. The herbivore, Tricolia variabilis (371), followed with T2 (132), T1 (115), T3 (97), and Control (27). The sponge feeding triphorids (Wells 1998) were most abundant at T2 (135).

The classic model of pollution or of deleterious effects of land-based outfalls predicts a decline in species richness at the impact site and/or an increase in abundance of a few pollution tolerant organisms. The pipeline T1 has a low species richness value of 100, but is higher than the Control (48), and its value has increased since the year 2002. Finella pupoides, characteristic of anoxic conditions were not recorded at the pipeline T1 for 2004. At T1, pyramidellids (2) and infaunal bivalves (23) indicative of enriched conditions, were recorded but at very low numbers. Mollusk species in the genus Planaxis, characteristic of lowered salinity, were not present. A few juvenile shells of the genus Isognomon, also characteristic of lowered salinity conditions, were present at station T2 (7), T3 (4), and Control (1), with none identified at the pipeline T1.

Fish

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Numbers of individual fish by species are shown in Appendix 3. Total fish numbers in 2005 were lower than in 2004 at the previous measurement sites, although not statistically different from the prior 8 years of census data (545 versus an average of 732; Table 4) due to high variability. Species richness was slightly lower than the average for the previous 8 years (51 versus an average of 56 across all sites; Appendix 4, Table 4). However, total abundances and species richness were not significantly different from previous surveys (Single Specimen Compared to a Sample, P > 0.05 for all sites).

Table 4. Comparison of 2005 fish data with earlier data.

Total Number of Individuals:Date Pipeline (T1) T2 T3 Control

Aug 96 369 246 229 134Aug 97 386 209 174 126Aug 98 364 134 82 86Sep 99 274 81 143 290Apr 01 197 97 121 113Apr 02 344 172 228 128Aug 03 142 116 56 87Nov 04 202 131 201 94Aug 05 170 175 129 71

Total Number of Species:Date Pipeline (T1) T2 T3 Control

Aug 96 38 44 26 24Aug 97 35 26 39 21Aug 98 28 23 20 17Sep 99 32 21 31 22Apr 01 26 23 28 17Apr 02 30 23 26 19Aug 03 24 21 16 18Nov 04 14 17 24 16Aug 05 25 27 20 15

As in previous years, there was significantly higher number of fishes at the Pipeline than at the Control site. Species richness followed this trend in 2005 as in previous years. Fish biomass at the Pipeline (9.8 Kg) and T3 (6.4 Kg) was higher than T2 (2.1 Kg) and the Control site (1.2 Kg). The arrangement of the eight sites in multi-dimensional space for the 2005 survey show the Pipeline (T1) and T3 to cluster separately from T2 and the Control site based on fish assemblage characteristics, numerical abundances and biomass densities (Figure 3). The ordination suggests substantial differences in fish parameters between these and the other sites.

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Chevron Fish AssemblagesA

xis

2

Axis 1

T1

T1-1

T1-2T2

T3C

C1

C2

Figure 3. Multivariate ordination of fish assemblage characteristics for eight Chevron sites(including the new benthic stations T1-1, T1-2 and C1, C2).

Ten species counted during 2005 were not seen on previous transects and included species that normally occur in low numbers, such as Plagiotremus goslinei and Canthigaster epilampra. Two species of butterflyfishes, Chaetodon unimaculatus and C. fremblii, were also recorded in 2005 that had not previously been seen on transects. Three Caranx ignobilis (papio) not reported in 2004 were included in 2005 surveys. Eight species that were recorded in 2004 were not seen in 2005. No evidence of the rare appearance of a large recruitment of Priacanthus meeki (āweoweo) in 2004 at the Pipeline and T3 was seen in 2005. The majority of the fish species (48) are either endemic or indigenous, while three of the species recorded, Lutjanus fulvus (to‘au), L. kasmiras (ta‘ape) and Cephalopholis argus (roi), were introduced to Hawai‘i.

Rugosity was much higher at the two additional Control transects (C1, C2) (1.54,1.61) than at the added Pipeline transects (T1-1, T1-2) (1.18, 1.17). This is reflected in the higher mean numbers of individuals and species richness at the Control transects (77, 14) as compared to the Pipeline transects (53, 7).

DiscussionCorals

The gradual decline in mean coral numbers on T1 saddle tops has continued with a nearly 45 % reduction from an observed high in 1997. Significantly different rates of colony mortality

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have not been observed over time and have lacked consistency amongst saddles within a given year; however, a general decline in recruitment has been evident.

Coral recruitment in Hawaii a highly variable phenomenon (Kolinski 2004). Ascertaining causes for temporal decline where appropriate substrate is available is difficult. Evidence of relatively recent recruitment to bench substrate 10 m north of the pipeline was found, with mean densities twice as high as that observed in limited samples within the control region. However, recent benthic recruitment of Pocillopora meandrina in both the pipeline and control regions appears to have been extremely low (Table 2), suggesting a regional phenomenon of low species recruitment. Continued monitoring of saddle top populations is warranted as a change in trend could signify natural variability in population dynamics.

The application of benthic surveys in both pipeline and control regions appears useful, even at low power, when information is combined with saddle top population monitoring. However, preliminary analysis suggests sample sizes would need to be very large to gain high confidence in a conclusion of no difference between sites. Variation in the level of ecologicaldevelopment is evident throughout the region. An increased number of replicates of reduced length (5 m), and benthic surveys at T2 and/or T3 (which may increase the differences between mean values), may allow for adequate comparison of a select range of habitats found within Chevron’s ZID to the control. In evaluating benthic data, alternative hypotheses other than effluent impact, such as natural variation in community structure, might best be addressed through the addition of one or more stations representing the greater diversity of community structure that occurs within the ZID.

Kolinski et al. (2004) proposed monitoring of bench habitats be initiated in 2006 (if saddle top population declines continued) to determine analytical power to detect differences. We propose that evaluation of benthic monitoring sample sizes continue in 2006, with additional or expanded comparisons in 2007 if warranted by data interpretation and management agency recommendation (as previously proposed).

MicromollusksThe slight increase in micromollusk species numbers, absence of species indicative

of anoxic conditions, and low numbers of species indicative of nutrient rich conditions, along with the high proportion of gastropods: low bivalve proportion, strongly suggest effluent released at the pipeline T1 is not negatively impacting or shifting micromollusk communities in the region. High species numbers and abundance at T2 and T3, in comparison to the Control populations, support this conclusion

FishTotal numbers of fishes and species varied, but did not differ statistically from estimates

made over the past eight years. Variation in numbers can be attributed to differences in visibility and natural fluctuations that are typically observed in temporally spaced censuses of highly mobile reef organisms. Species richness and fish numerical and biomass abundance at the Pipeline were higher than at the Control site in 2005. The Pipeline appears to attract and retain fish in the area, which is likely the result of higher topographic complexity due to the concrete stanchions that provide additional protection from predators. T2 was the only station with higher fish values. The results of this survey do not indicate that the Pipeline or effluent negatively impact fish populations (as measured) within the ZID.

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Higher topographic relief is correlated with greater fish densities. The pipeline and stanchions and sites with large coral colonies provide additional substrate for fishes. Since the spatial configuration at the Pipeline is unique, even the high rugosity at the additional Control transects (C1, C2) are not comparable in fish populations to the Pipeline.

Prior research has recognized the importance of topographic relief in the structure of fish assemblages throughout the world and in Hawai‘i. It is evident that fish populations are highly associated with spatial relief for several reasons.

Increased substrate provides habitat for benthic invertebrates, which serve as the main diet of many species of fishes, which in turn are utilized at other trophic levels.

Increase in coral cover associated with rugosity feed obligate corallivores. Spatial complexity increases habitat heterogeneity, providing increased areas of

refuge for fish populations from predation and competition. Topographical relief can expand the availability of resources and their production

rate. Increased rugosity results in higher heterogeneity, creating habitat complexity that

increases fish diversity. The additional four transects were included to address the repeated decline of coral

colonies at the Pipeline. Rugosity measurements were taken to verify habitat similarity between sites. Although the use of a rugosity index can not substitute as a proxy for fish abundance data, it can serve as a relative indicator of differences in fish assemblages, benthic complexity and coral communities between sites. These transects were found to be very different from the Pipeline area in fish community characteristics Figure 3).

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Kay, E.A. 1967. The composition and relationships of the marine molluscan fauna of the Hawaiian Islands. Venus 25: 96-104.

Kay, E.A. 1979. Hawaiian Marine shells. Reef and Shore Fauna of Hawaii, Section 4: Mollusca. BPBM Spec. Publ. 64(4): 653 pp.

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Kay, E.A. and T. Smalley. 1982. Biological monitoring of the Chevron diffuser pipeline.Barbers Point, Oahu -- 1982. Typescript.

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Kay, E. A., S. Kolinski, M. Mohlmann and R. Kawamoto. 2002. Biological monitoring of the Chevron diffuser. Barbers Point, Oahu – 2002. Typescript.

Kolinski, S. P. 2004. Sexual reproduction and the early life history of Montipora capitata in Kaneohe Bay, Oahu, Hawaii. Ph.D. Dissertation, University of Hawaii, 152 pp.

Kolinski, S., F. Cox, R. Kawamoto and E. A. Kay. 2003. Biological monitoring of the Chevron diffuser. Barbers Point, Oahu – 2003. Typescript.

Kolinski, S., K. Rodgers, R. Kawamoto and E. A. Kay. 2004. Biological monitoring of the Chevron diffuser. Barbers Point, Oahu – 2004. Typescript.

McCormick, M. 1994. Comparision of field methods for measuring surface topography and their associations with a tropical reef fish assemblage. Marine Ecology Progress Series 112: 87-96.

Wells, F. E. 1998. Family Triphoridae. Pp. 809 – 811, in Beesley, P.L., Ross, G.J.B. & Wells, (eds.) Molluscas: The Southern Synthesis. Fauna of Australia. Vol. 5. CSIRO Publishing: Melbourne, Part B viii 565 - 1234 pp.

Wilkinson, C. R. 1993. Coral reefs of the world are facing widespread devastation: can we prevent this through sustainable management practices. Proceedings of the Seventh International Coral Reef Symposium, Guam 1: 11-21.

16

APPENDIX 1

17

APPENDIX 2

Benthic Survey Coral Size Distribution Data

Pipeline Species

Pipeline Transect Section

0 to < 2 cm

2 to < 5 cm

5 to < 10 cm

10 to < 20 cm

20 to < 40 cm

40 to < 80 cm

80 to < 160 cm

Montipora capitata 1 1 6 9 12 5 6 3Montipora patula 1 1Montipora studerii 1 1Pocillopora meandrina 1 2Porites evermannii 1 3Porites lobata 1 2 2 5

Cyphastrea sp. 2 1Montipora capitata 2 1 4 10 8 8 5 1Montipora flabellata 2 1 1 1Montipora patula 2 3 4 5 5 3 1Pocillopora meandrina 2 1 2 1 1Porites lobata 2 2 4 5 2 1

Montipora capitata 3 2 8 7 6 3Montipora flabellata 3 3 1 3Montipora patula 3 1 1Palythoa cesia 3 1Pocillopora meandrina 3 2Porites lobata 3 1 4 3 3

Montipora capitata 4 2 23 13 5 5 1Montipora flabellata 4 2 2 1 1Montipora patula 4 2 1Pocillopora meandrina 4 2 2Porites evermannii 4 1Porites lobata 4 4 6 5 1

Control Species

Control Transect Section

0 to < 2 cm

2 to < 5 cm

5 to < 10 cm

10 to < 20 cm

20 to < 40 cm

40 to < 80 cm

80 to < 160 cm

Montipora capitata 1 2 6 12 7 8Montipora patula 1 3 4 3 3Pavona duerdeni 1 1 1Pocillopora meandrina 1 1 1 4Porites compressa 1 2Porites evermannii 1 2 1 1Porites lobata 1 3 2 3 1

Montipora capitata 2 1 2 6 2 5

18

Montipora patula 2 4 6 4 5 2Pavona varians 2 1 5Pocillopora eydouxi 2 1Pocillopora meandrina 2 1 2Porites evermannii 2 1 1 2Porites lobata 2 9 8 6 2 1 1

Leptastrea purpurea 3 1Montipora capitata 3 1 5 19 13 7 4Montipora flabellata 3 2 2 2Montipora patula 3 1 4 5 3 1Pavona varians 3 1 1Pavona duerdeni 3 2Pocillopora meandrina 3 4 2 3Porites compressa 3 1Porites evermannii 3 1Porites lobata 3 1 6 15 7

Montipora capitata 4 4 7 2Montipora flabellate 4 1Montipora patula 4 4 6 1 1Pavona varians 4 1Pocillopora meandrina 4 1 2Porites lobata 4 6 11 5 1 1

19

APPENDIX 3

Micromollusk species, numbers, habit and trophic level at T1-T3 and Control Sites, 2004

No. of Individuals

Station

Taxon Habit Trophic Control T1 T2 T3 Totals

BIVALVIA

Arcidae spp. Epifaunal Filter 1 1 2

Barbatia divaricata Epifaunal Filter 2 11 13 3 29

Barbatia nuttingi Epifaunal Filter 4 22 33 9 68

Brachidontes crebristriatus Epifaunal Filter 1 1

Cardita spp. Epifaunal Filter 1 1

Carditella hawaiensis Infaunal Filter 4 4

Chlamydella sp. A Epifaunal Filter 1 1 2

Crenella sp Epifaunal Filter 1 3 4

Ctena bella Infaunal Filter 1 1 2

Cuspidaria spp. Infaunal Carnivore 1 1

Dendostrea sandvicensis Epifaunal Filter 2 28 3 33

Epicodakia sp. Infaunal Filter 1 1 2

Ervilia bisculpta Infaunal Detritus 1 1

Fragum mundum Infaunal Filter 7 25 1 33

Haumea juddi Epifaunal Filter 1 1

Hiatella arctica Infaunal ? 3 3

Isognomon perna Epifaunal Filter 1 7 4 12

Kellia hawaiensis Commensal Filter 29 11 17 57

Kona symmetrica Epifaunal Filter 1 1

Leiochasmea elongata Commensal Filter 1 1

Malleus regula Epifaunal Filter 4 4

Malleus sp. Epifaunal Filter 4 4

Nucula hawaiensis Infaunal Filter 1 1 13 3 18

Ostreidae spp. Epifaunal Filter 4 4

Rochefortina sandwichensis Infaunal Filter 6 12 2 20

Scintilla hiloa [c] Commensal Filter 2 2

Septifer bryanae Infaunal Filter 5 24 2 31

Bivalvia spp. 2 1 3

GASTROPODA

Acteocina sp. Infaunal Carnivore 1 1

Alcyna ocellata Epifaunal Detritus 8 6 91 9 114

Alcyna subangulata Epifaunal Detritus 8 2 10

Alvania isolata Epifaunal Detritus 3 3 6

Antisabia foliacea Epifaunal Parasitic 8 38 26 23 95

20

Atys semistriata Infaunal Carnivore 2 3 1 6

Balcis brunnimaculata Parasitic Parasitic 3 2 5

Balcis spp. Parasitic Parasitic 2 3 15 20

Barleeia labiosa Epifaunal Detritus 12 9 1 22

Bittium impendens Epifaunal Detritus 1 7 108 7 123

Brookula iki Epifaunal Detritus 6 6

Caecum arcuatum Infaunal Detritus 7 15 41 7 70

Caecum glabriformis Infaunal Detritus 1 1

Carinapex minutissima Epifaunal Carnivore 2 12 58 15 87

Carinapex papillosa Epifaunal Carnivore 1 1

Cerithidium diplax Infaunal Detritus 1 1 4 1 7

Cerithidium perparvulum Epifaunal Detritus 6 50 7 63

Cerithiopsis spp. Epifaunal Carnivore 1 1

Cerithium columna Epifaunal Detritus 1 9 1 11

Cerithium egenum Epifaunal Detritus 8 30 6 44

Cerithium interstriatum Epifaunal Detritus 45 2 47

Cerithium nesioticum Infaunal Detritus 2 15 31 10 58

Cerithium rostratum Epifaunal Detritus 4 4

Cerithium zebrum Epifaunal Detritus 3 46 61 38 148

Cerithium sp. Epifaunal Detritus 5 8 1 14

Cheilea equestris Epifaunal Filter 1 1

Clavus mighelsi Epifaunal Carnivore 1 1

Clavus spp. [c] Epifaunal Carnivore 1 5 6

Collonista candida Epifaunal Forage 1 14 15 10 40

Crepidula aculeata Epifaunal Filter 1 1 2

Cyclostremiscus emeryi Epifaunal Detritus 2 7 5 8 22

Dendropoma spp. Epifaunal Filter 31 13 30 6 80

Dentimargo pumila Epifaunal Forage 1 1

Diala semistriata Epifaunal Detritus 3 4 7

Diodora granifera Epifaunal Herbivore 4 2 6

Eatoniella janetaylorae Epifaunal Detritus 7 3 10

Epitonium spp. Parasitic Parasitic 1 1 2

Erato sandwicensis Parasitic Parasitic 1 1

Etrema acricula Epifaunal Carnivore 2 1 3

Euchelus gemmatus Epifaunal Herbivore 1 11 9 5 26

Eulimidae sp. Parasitic Carnivore 2 2

Euplica livescens Epifaunal Carnivore 1 1

Evalea peasei Epifaunal Detritus 2 2

Gibbula marmorea Epifaunal Herbivore 7 4 18 2 31

Granula sandwicensis Epifaunal Forage 1 3 7 4 15

Granulina vitrea Epifaunal Forage 1 2 2 5

Herviera gliriella Parasitic Parasitic 7 18 1 26

Herviera patricia Parasitic Parasitic 3 2 5

21

Hinemoa indica Parasitic Parasitic 4 3 1 8

Hipponix australis Epifaunal Detritus 1 5 6

Hipponix pilosus Epifaunal Filter 1 2 9 2 14

Ittibittium parcum Epifaunal Detritus 4 73 25 31 133

Julia exquisita Epifaunal Herbivore 1 5 7 2 15

Kermia aniani Epifaunal Carnivore 2 2

Kermia pumila Epifaunal Carnivore 1 1 4 6

Leptothyra rubricincta Epifaunal Detritus 22 20 10 52

Leptothyra verruca Epifaunal Detritus 3 19 33 28 83

Lophocochlias minutissimus Epifaunal Detritus 3 9 45 15 72

Lophocochlias sp. A Epifaunal Detritus 27 14 20 61

Lovellona peaseana Epifaunal Carnivore 1 1

Merelina granulosa Epifaunal Detritus 2 2 1 5

Merelina hewa Epifaunal Detritus 4 2 102 7 115

Merelina wanawana Epifaunal Detritus 17 8 8 33

Miralda paulbartschi Epifaunal Parasitic 1 4 11 7 23

Miralda scopulorum Parasitic Parasitic 11 8 8 9 36

Mitra sp. Epifaunal Carnivore 2 2

Mitrella margarita Epifauna Detritus 2 2

Mitrella rorida [c] Epifauna Detritus 1 1

Mitrolumna metula Epifaunal Detritus 1 1

Mitrolumna sp. Epifaunal Detritus 2 2

Modulus tectum Epifaunal Detritus 3 3

Muricidae spp. Epifaunal Carnivore 1 1 2

Naticidae spp. Infaunal Carnivore 1 1

Odostomia gulicki Parasitic Carnivore 1 1

Odostomia stearnsiella Parasitic Parasitic 5 5

Odostomia sp. Parasitic Parasitic 2 3 5 4 14

Orbitestella regina Epifaunal Detritus 2 2 25 4 33

Orbitestella sp. B Epifaunal Detritus 1 1

Parashiela beetsi Epifaunal Detritus 2 25 5 32

Peristernia chlorostoma Epifaunal Detritus 1 1 1 3

Phenacolepas scobinata Epifaunal Herbivore 1 1

Philippia oxytropis Parasitic Parasitic 1 1

Plesiotrochus luteus Epifaunal Detritus 3 1 4

Pusillina marmorata Epifaunal Herbivore 18 149 30 197

Pyramidellidae sp. B Infaunal Parasitic 1 1

Pyramidelloides gracilis Epifaunal Parasitic 2 4 6

Pyramidelloides miranda Epifaunal Parasitic 1 1

Rissoella longispira Epifaunal Parasitic 1 1 1 3

Rissoidae spp. Epifaunal Detritus 4 3 7

Rissoina ambigua Epifaunal Detritus 1 28 22 24 75

Rissoina cerithiiformis Epifaunal Herbivore 5 35 972 111 1123

22

Rissoina costata Epifaunal Detritus 5 17 12 12 46

Rufodardanula sp. Epifaunal Detritus 4 1 1 6

Sansonia kenneyi Epifaunal Filter 1 1 9 4 15

Scalenostoma carinata Parasitic Parasitic 1 1

Scaliola spp. Epifaunal Detritus 1 4 5

Schwartziella ephamilla Epifaunal Detritus 3 49 5 57

Schwartziella triticea Epifaunal Detritus 4 22 28 18 72

Scissurella pseudoequatoria Epifaunal Detritus 2 1 6 2 11

Seminella peasei Epifaunal Detritus 5 3 8

Seminella smithi Epifaunal Detritus 2 2 4

Sinezona insignis Epifaunal Herbivore 3 2 9 4 18

Stosicia hiloense Epifaunal Detritus 8 4 21 6 39

Strebloceras subannulatum Infaunal Herbivore 1 2 1 4

Styliferina goniochila Infaunal Detritus 2 26 3 31

Synaptocochlea concinna Epifaunal Herbivore 2 8 3 13

Tricolia variabilis Epifaunal Herbivore 27 115 132 97 371

Triphora spp. Epifaunal Carnivore 2 17 135 23 177

Trochus intextus Epifaunal Herbivore 6 6

Turbo sandwicensis Epifaunal Herbivore 11 6 3 20

Turbonilla spp. Parasitic Parasitic 1 1

Turridae sp. Parasitic Forage 1 1

Vanikoro sp. Epifaunal Detritus 2 1 3

Vermetidae sp. Epifaunal Filter 2 1 3

Vexillum tusum Epifaunal Carnivore 1 1

Vexillum spp. Epifaunal Carnivore 1 1

Volvarina fusiformis Epifaunal Carnivore 2 2

Williamia radiata Epifaunal Herbivore 4 14 18

Zebina bidentata Epifaunal Herbivore 2 1 14 3 20

Zebina spp. Epifaunal Herbivore 7 7 14

Gastropoda sp. A 3 1 4

Gastropoda sp. 2 2

POLYPLACOPHORA:

Polyplacophora spp. Epifaunal Herbivore 1 1 6 8

Total No. of Individuals 216 884 2916 756 4772

Total No. of Individuals/cm3 2.16 8.84 29.16 7.56 11.93

Total No. of Taxa 48 100 123 89 151

23

APPENDIX 4

Numbers of individual fish by species at T1 – T3 and Control sites, 2004

SpeciesPipeline

(T1)T1-1

(Benthic)T1-2

(Benthic) T2 T3 ControlC1

(Benthic)C2

(Benthic)AcanthuridaeA. blochii 2 20A. nigrofuscus 37 37 7 22 17 15A olivaceous 30 12 4 12 3A. tristegus 24 24 42A. leucopareius 4Ctenochaetus strigosus 1 36 7 3 1 7Naso lituratus 1Zebrasoma flavescens 4 1BalistidaeMelichthys niger 1 2Sufflamen bursa 1 1 5 3 1Rhinecanthus rectangulus 2 4ChaetodontidaeC. fremblii 2C. lunulatus 1 2C. quadrimactlatus 1 1 3C. multicinctus 8 2 2C. ornatissimus 4 1 2C. miliaris 2C. unimaculatus 1 4CirrhitidaeParacirrhites arcatus 1 1 1LabridaeCoris gaimard 1Bodianus bilunulatus 1 1H. ornatissimus 1Gomphosus varius 2 2Labroides phithrophigus 1Stethojulis balteata 1 1Thallasoma duperrey 9 24 9 10 17 15 7 15T. purpureum 1T. trilobatum 1LutjanidaeLutjanus kasmira 1 21L. fulvus 5Monocanthidae 1Cantherhines sandwichensis 1 1MullidaeMulloides flavolineatus 10Parapeneus bifasciatus 1 1P. multifasciatus 8 2 5 1 1Ostraciidae

24

Ostracion melagris 1PomacentridaeAbudefduf abdominalis 3 3Chromis vanderbilti 29 50 20C. agilis 2Dacyllus albicella 3Plectroglyphidodon imparipenis 3 6 3 2

1

P. johnstonianus 1 2 4 4Stegastes fasciolatus 1 1BlennidaePlagiotremus goslinei 1ScaridaeScarus sp. 3 2 5 2 2SerranidaeCephalopholis argus 1 1TetraodontidaeCanthigaster jactator 1 1 2 8 1 6 2 2C. lampra 1ZanclidaeZanclus cornutus 1 2CarangidaeCaranx ignobilus 1 2

Total per site 170 89 17 129 175 71 57 97Number of species 25 8 6 20 27 15 15 13