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Benthic Monitoring Report For the Period Year 2015
Subject Location The Open Ocean Mariculture Site Authorized by US Federal NPDES Permit HI 0021825 State of Hawaii CDUP HA-3497
Operated by Blue Ocean Mariculture
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Table Of Contents
Report Information Pg. 3
Site Image Pg. 4
General In-Situ Observations & Data Pg. 5
Benthic Sand Characterization Pg. 7
Chemical Analysis Pg. 15
Micromollusc Distribution Report Pg. 19
Chain of Custody Forms Pg. 27
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Benthic Monitoring Report For Blue Ocean Mariculture
Samples Collected At The Offshore Farm Site On: August 28th, 2015 By PlanB Consultancy Chief Scientist: John Burns
This report details the 2015 annual benthic monitoring for the Blue Ocean Mariculture fish pens off of Unualoha Point on the Kona Coast of Hawaii Island. All samples were collected with a ponar grab sampler lowered to the benthic substrate. Samples were collected from five survey locations used for benthic monitoring (Figure 1). The grab sampler was deployed and retrieved off of a boat with an electric winch. Upon retrieval the samples were transferred from the ponar grab sampler and placed in a receptacle along with the seawater collected with each sample.
The following parameters were assessed immediately for each sample: • General appearance • Macro fauna • Macro algae • Oxidation/Reduction Potential (ORP) readings
• Odor (presence of H2S)
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Sub-samples were collected from each sample in order to analyze the following parameters: • Total organic carbon (TOC) • Benthic sand characterization • Micromollusc characterization
Figure 1. Site image of Blue Ocean Mariculture fish pens. Orange triangles and star represent the locations utilized for benthic sampling.
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General In-Situ Sampling Observations and Data Description
During intial sampling the skies were clear. Winds were 1-2kts blowing from the northwest. There was a 3-4ft west swell, and a south current.
At approximatly 13:00 winds increased to 3-4kts from the southwest, and clouds developed in the skies.
The water was clear at each sampling location. There was no evidence of high turbidity, discoloration, visible sheen, foam, solids, or floating debris at any location during the benthic sampling.
Surface current from winds created difficult condictions for sediment collection, as the ponar sampler seemed to contact the benthos at an angle due to currents, and was unable to successfully grab enough sediment for the required analyses. Multiple deployments were conducted until enough sediment was collected for the required analyses.
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North Anchor 14:13 South Anchor 10:51
Appearance: Brown Appearance: Brown
Macro Fauna: None Macro Fauna: None
Macro Algae: Cladophora laetevirens Macro Algae: Cladophora laetevirens
ORP: 166.3 ORP: 136.4
Odor: None Odor: None
West Anchor 11:43 East Anchor 13:49
Appearance: Light Brown Appearance: Brown
Macro Fauna: None Macro Fauna: None
Cladophora laetevirens, Cladophora laetevirens, Macro Algae: Macro Algae: Halimeda kanaloana Halimeda kanaloana
ORP: 159.1 ORP: 118.1
Odor: None Odor: None
Under Cage 14:44
Appearance: Brown
Macro Fauna: None
Macro Algae: Cladophora laetevirens
ORP: 153.7
Odor: None
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Benthic Sand Characterization
Intro/Methods
Sediments play a significant role in the structure of benthic communities due to the fact that many organisms have grain size preferences, thus changes in sediment composition can affect organisms occupying the benthic habitat. Furthermore, sediment characteristics can provide useful information about source materials, the depositional environment (amount of energy in waves and currents), and other physical and chemical factors.
Sediment samples were collected in order to assess sediment composition. Three sub-samples from each site (North, East, West, South, Under Cages) were washed with fresh water to remove salt and then sun-dried. Sand grain size analysis was conducted using a set of 7 US Standard sieves (5,10,35,60,120,230, and Dust). Samples were processed through the sieves using a motorized shaker to adequately separate sand grains based on physical size. An electronic balance was used to measure the mass of each sample proportion that was isolated in the individual sieves. The average retained weights, and percentage of total weights, are presented in the data table below.
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Data/Results
North Anchor Mean Retained Mean Percentage of Mesh Size Weight (grams) Total 5 13.11 4.8% 10 33.99 11.0% 35 189.78 69.4% 60 51.89 16.8% 120 17.11 5.5% 230 2.92 0.9% Dust 0.19 0.1% TOTAL 308.99
South Anchor Mean Retained Mean Percentage of Mesh Size Weight (grams) Total 5 5.98 1.8% 10 18.75 5.5% 35 197.56 57.9% 60 79.84 23.4% 120 29.91 8.8% 230 8.01 2.3% Dust 1.31 0.4% TOTAL 319.12
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West Anchor Mean Retained Mean Percentage of Mesh Size Weight (grams) Total 5 49.87 18.9% 10 92.34 35.0% 35 106.59 40.3% 60 11.45 4.3% 120 2.47 0.9% 230 0.98 0.4% Dust 0.5 0.2% TOTAL 264.20
East Anchor Mean Retained Mean Percentage of Mesh Size Weight (grams) Total 5 6.72 1.9% 10 16.04 4.6% 35 153.94 43.9% 60 116.22 33.2% 120 42.87 12.2% 230 10.92 3.1% Dust 3.58 1.0% TOTAL 350.29
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Under Cages Mean Retained Mean Percentage of Mesh Size Weight (grams) Total 5 9.22 2.9% 10 25.34 7.9% 35 180.88 56.7% 60 82.51 25.9% 120 17.72 5.6% 230 3.15 1.0% Dust 0.3 0.1% TOTAL 319.12
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North Anchor 70.0%
60.0%
50.0%
40.0%
30.0%
20.0%
10.0% Percentage of Total 0.0% 5 10 35 60 Dust Mesh Size 120 230
South Anchor
70.0% 60.0% 50.0% 40.0% 30.0% 20.0% 10.0% Percentage of Total 0.0% 5 10 35 60 Dust Mesh Size 120 230
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West Anchor 70.0% 60.0% 50.0% 40.0% 30.0% 20.0% 10.0%
Percentage of Total 0.0% 5 10 35 60 Dust 120 230 Mesh Size
East Anchor 50.0% 45.0% 40.0% 35.0% 30.0% 25.0% 20.0% 15.0% 10.0% 5.0%
Percentage of Total 0.0% 5 10 35 60 Dust 120 230 Mesh Size
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Under Cages 60.0% 50.0% 40.0% 30.0% 20.0% 10.0%
Percentage of Total 0.0% 5 10 35 60 Dust 120 230
Mesh Size
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Summary The sediment compositions of the 2015 samples were similar to samples collected from previous years (Figure 2, 3). All samples were composed of primarily course sand, with minimal silt. There was no evidence of live coral or hard substrate from the collected samples, and this is to be expected considering the depth of the benthic environment at these monitoring sites (~60m). There was no macro fauna observed in any of the samples. Cladophora laetevirens was present in all samples, and Halimeda kanaloana was present in the West Anchor samples and East Anchor samples. The Halimeda kanaloana alga is very abundant at the West Anchor site. It appears to that the calcified blades of this alga species are one of the primary components of the sediment at this location (mesh size 10 & 35, see West Anchor graph above). Comparing these findings to those from previous years suggests the benthic sediment at this site has exhibited a similar sand composition over time, thus no effects induced by the fish cages are apparent. Currents in this area are known to run at speeds of up to 2 knots in various directions. The disruptive hydrology likely impedes settlement of detritus and facilitates the consistently similar benthic composition that has been observed in the annual benthic monitoring of this area. It is likely that any changes in composition observed among the monitored years is due to disturbances caused by the natural hydrological characteristics at this site.
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Figure 2. Sand characterization data from the East Anchor site (2007-2009). Note the similar composition to the 2015 samples.
All Sites 2014 70.0%
60.0% North Anchor 50.0% Under Cages South Anchor 40.0% East Anchor 30.0% West Anchor 20.0%
10.0% Percentage of Total 0.0% 5 10 35 60 Dust Mesh Size 120 230
Figure 3. Sand characterization data for all sites from 2014 benthic analysis.
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Chemical Analysis
Intro/Methods Chemical analyses were performed on samples collected from each monitored location. Sub-samples were properly stored and transported to the UH-Hilo EPSCoR Analystical Laboratory for Total Organic Carbon (TOC) analysis. Two sub-samples were analyzed for each location, and the average TOC values are presented in the tables and figures below. Samples where weighed, acidified, weighed again, and then the percentage of organic carbon was determined by processing the samples through a CHN analyzer. TOC (represented as a percentage of total dry sample weight) was calculated by multiplying the percentage of organic carbon by the mass of the acidified sample, and then this value was divided by the mass of the pre-acidified sediment sample. Oxidation/Reduction Potential (ORP) was measured immediately with an ORP meter upon sample retrieval while in the boat. Measuring the amount of TOC in benthic samples provides information on the amount of sample material that may be derived from decaying vegetation, bacterial growth, and metabolic activities of living organisms or chemicals. Levels of TOC can be indicative of contaminants from discharge, and therefore provides an important measure of the potential effects of industrial discharge on the environment and human health. TOC is a highly sensitive, and non-specific, measurement of all organics present in a sample. A low value of TOC can confirm the absence of potentially harmful organic chemicals in water exposed to any form of industrial discharge. ORP provides an indirect method to evaluate the level of biological activity in a benthic sample. This analytical technique also provides a measure of chemical exchange between the substrate and the water column. Low ORP values indicate a high amount of biological activity and an insufficient exchange for maintaining aerobic conditions. Readings below the value of 0 indicate anaerobic conditions. Anaerobic conditions typically occur when high levels of biological activity remove oxygen faster than it can be restored, thus creating an anaerobic environment. Aerobic and anaerobic
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conditions will determine the types of organisms that can inhabit the substrate and can cause a shift in the composition of the fauna and flora. Introduction of excess organic materials (fish feces, uneaten feed, or large amounts of bio-fouling material from cages) can be deposited on the substrate and result in anaerobic conditions. ORP therefore enables monitoring of the aerobic state of the substrate below the cages in order to ensure the fish farm is not affecting the biological composition of the sea floor.
Data/Results Site ORP Value North Anchor 166.3 South Anchor 136.4 West Anchor 159.1 East Anchor 118.1 Under Cages 153.7
Site TOC Value North Anchor 0.09 South Anchor 0.07 West Anchor 0.08 East Anchor 0.06 Under Cages 0.10
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300
250
200 North Anchor
150 South Anchor West Anchor 100 East Anchor Millivolts [mV]) Under Cages 50
0 Oxidation Reduction Potential (measured as Oxidation Reduction Potential (measured Jun-07 Jun-08 Jun-09 Jun-10 Jun-11 Jun-12 Jun-13 Jun-14 Jun-15 -50
Figure 3. Temporal comparison of ORP values measured at each monitoring location.
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0.35
0.3
0.25
North Anchor 0.2 South Anchor
0.15 West Anchor
East Anchor 0.1
Total Organic Carbon (TOC) Organic Total Under Cages [Percentage of total dry weight] [Percentage 0.05
0
Figure 4. Temporal comparison of TOC values measured at each monitoring location.
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Summary ORP readings taken over the last two years have consistently yielded values over 100 Millivolts (Figure 3). Despite high variability and apparently one case of anoxic conditions, among measurements taken between 2007 and 2009, there appears to be no current evidence of anoxic conditions in the substrate below any of the monitored stations. This is reflected in the color, presence of macro algae and micromolluscs, and lack of odor from the samples monitored this year. These findings provide evidence that the benthic substrate below the cages is aerobic and there appears to be no influence of fish-cage discharge on the oxidation-reduction potential of the benthic substrate. This is likely due in part to the hydrologic mixing induced by the strong currents that affect the benthic substrate in this area. TOC values (represented as a the percentage of total sample weight) exhibited minimal variation between the samples analyzed. The past several years have shown some variability, but in general samples have been more stable in comparison to values obtained between 2007 and 2009 (Figure 4). As suggested in previous benthic monitoring reports, this may be due to improvements in feeding technology and processes involved with waste management. Due to the high environmental variability at this site, in large part due to strong currents and depth, it is difficult to pinpoint one specific variable that may primarily drive the observed TOC values. It is worthwhile to note the sediment below the fish pens resides on top of solid basalt substrate, a characteristic common on the geologically young island of Hawaii. The depth of sediment is very shallow, and the composition is primarily inorganic and course (see sand characterization above). The lack of sediment depth, and constant mixing, may play a significant role in the consistently low observed TOC values. Ultimately, the values of the past two years fall below 0.25. These low values show no evidence of contaminants from discharge and are not considered problematic.
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Micromollusc Distribution Report for Keahole Point Fish Marta deMaintenon, UH Hilo Marine Science December 2015
Methods Sediment samples were taken from five stations (Cage, East, North, South, and West). Each sample (one per station) was rinsed in fresh water, dried, and three 15ml subsamples were taken. The subsamples were picked for mollusk shells using an Olympus SZX12 dissecting stereomicroscope. Fresh shells were picked from each sample, identified and counted. Bivalve halves were counted as whole individuals. Since it is not possible to identify shells that are truly freshly dead vs. dead for some time, the samples should be considered time-averaged. Identifications were primarily made using Severns (2011) and Kay (1979). Kay (1979) provides some information on habitat and ecology, and more was derived from Beesley et al. (1998).
Micromollusc diversity A total of 3678 individuals were found belonging to 116 taxa (Figure M1, Tables M1, M2). This is considerably more than previous years. Most were identified to species but some could not be. For instance, a number of sinistral juveniles were easily recognizable as triphorids, but not developed enough to identify to species; triphorids are highly diverse so these may represent a number of species. There were also many recently settled gastropods and bivalves too undeveloped to identify, so undoubtedly more than 116 species were represented. The larger numbers might suggest that too many poor quality specimens were kept, but I don’t think that’s the case. The number of individuals sampled was highest under the Cage, and progressively lower for East, North, South, and lowest for West (Figure M1, Table M1). Similar to previous years, West had fewer molluscs than the other four stations, and South was somewhat low again. The low numbers seen at West and South were likely due to the type of sediments sampled. West was almost entirely Halimeda plates, and South also had some of these this year, but not as many; thus both of these samples had lower abundance by weight.
Cage East North South West Total individuals: 945 892 767 603 471 Total species: 67 67 68 73 44 Shannon-Wiener Diversity (H’): 1.09 1.38 1.39 1.48 1.26 Hmax: 1.83 1.83 1.83 1.86 1.64 Evenness: 0.60 0.75 0.76 0.79 0.77 Table M1. Basic diversity indices for each station.
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The number of species (Table 1, Figure M2) was more constant; West had fewest (44), consistent with the lower overall abundance. Cage, North and East had 67 or 68, and South had the highest, 73, in spite of having lower abundance. Shannon-Wiener diversity was greatest at South, which had lower abundance but more species. It was lower under the cage, where the abundance was greatest, but several common species were present in greater numbers.
1000 Gastropods 900
Bivalves 800 Scaphopods 700 600
500
400 300 200
100
0 Cage East South West Figure M1. Mollusc abundance at each of the five stations for 2015.
80 Gastropods 70 Bivalves
60 Scaphopods 50
40
30
20
10
0 Cage East South West
Figure M2. Number of mollusc species at each of the five sampling stations for 2015.
In terms of molluscan taxa, gastropods were more abundant than bivalves as usual. Gastropods accounted for approximately 91 percent of the individuals in the samples (Table M2). Only one scaphopod species was collected, a cadulid, present in all but the Cage samples. Gastropods represented between 75 to 82 percent of the species sampled, with the most abundant species generally from the family Rissoidae. No bivalve species were
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present in high numbers. Bivalves were most prevalent in the East samples, and the most common species, as in previous years, were the infaunal semelid Rochefortina sandwichensis and the epifaunal mytilid Septifer cumingii.
Number of Number of Number of Number of Number of Number of gastropod bivalve scaphopod individual individual individual Station taxa taxa species gastropods bivalves scaphopods Cage 55 (82.1%) 12 (17.9%) 0 880 (93.1%) 65 (6.9%) 0 East 50 (74.6%) 16 (23.9%) 1 (1.5%) 791 (88.7%) 95 (10.6%) 6 (0.7%) North 54 (79.4%) 13 (19.1%) 1 (1.5%) 691 (90.1%) 73 (9.5%) 3 (0.4%) South 59 (80.8%) 13 (17.8%) 1 (1.4%) 554 (91.9%) 46 (7.6%) 3 (0.5%) West 36 (81.8%) 7 (15.9%) 1 (2.3%) 432 (91.7%) 38 (8.1%) 1 (0.2%) Total 95 (81.9%) 20 (17.2%) 1 (0.9%) 3348 (91.0%) 317 (8.6%) 13 (0.4%) Table M2. Overall abundance of each major molluscan class by individual and by species.
Numbers from this year were compared to those from the last four years; reports from previous years were not available. The number of individuals sampled (Figure M3) shows a different profile than usual, with the cage samples having much greater numbers than has been typical. The number of taxa sampled (Figure M4) varies from previous years in that the species richness at Cage and South increased impressively; East, North and West were more similar to previous years’ values.
1200
1000 ls
800 vidua
i
ind
600
of
er b 400 m
u N 200
Cage East South West Figure M3. Number of individual molluscs sampled at each station this year relative to the last four years.
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80
70
60
50
40
30
20
10
0 Cage East South West Figure M4. Number of molluscan taxa sampled at each station this year relative to the last four years.
Micromollusc feeding guilds
800 Cage 700
East ls 600 North
dua i 500 South
div
n i 400 West
of
r
e 300
200 Numb 100
0
Figure M5. Abundance of molluscs in specific feeding guilds at each site in 2015.
The feeding guilds represented among the molluscs (Figure M5, Table M4) were dominated by herbivores (microherbivores included). Cerithiids, dialids and rissoids were the most abundant herbivorous species, and these include most of the species with greatest overall abundance. These taxa were present at all sites, with their relative abundance similar to the overall pattern. The five most common species overall (Table M3: cerithiid Cerithidium perparvulum, rissoids Mellitestea scopulorum, Pusillina marmorata, Parashiela
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sp., and dialid Diala semistriata) all belong to this guild and are all micromolluscs as adults. One of the other most common taxa encountered was Scaliola sp., a small detritivore. This year the spongivorous triphorids (over 100 total) were also quite abundant, so I broke those out as a separate category. Parasites tended to be members of Eulimidae and Pyramidellidae; eulimids are frequently dermal parasites of holothurians, while pyramidellids parasitize a wide variety of taxa, most often polychaetes and other molluscs. These two groups were more or less equally abundant this year.
Table M3. The five most common molluscan species/ taxa at each station for 2015. Cage East North South West Cerithidium Mellitestea Cerithidium Mellitestea Cerithidium perparvulum scopulorum perparvulum scopulorum perparvulum Mellitestea Cerithidium Mellitestea Cerithidium Diala scopulorum perparvulum scopulorum perparvulum semistriata Diala Finella Diala Pusillina Scaliola sp. semistriata pupoides semistriata marmorata Pusillina Diala Pusillina Parashiela sp. Rissoina sp. 2 marmorata semistriata marmorata Diala Mellitestea Parashiela sp. Parashiela sp. Parashiela sp. semistriata scopulorum
Cage East North South West Total Carnivore 19 15 23 16 10 83 Chemosymbiont 11 11 6 8 3 39 Detritivore 27 100 21 41 6 195 Parasite 26 52 30 26 8 142 Herbivore 692 541 548 412 370 2563 Spongivores 43 15 38 21 14 131 Suspension feeder 47 46 53 29 35 210 Table M4. Individual abundance of each feeding guild at each station in 2015.
This year suspension feeders and detritivores were more common than in past years. Suspension feeders included mostly bivalves. Detritivores included mostly the scaliolid gastropods Finella pupoides and Scaliola spp., as well as the scaphopod Pulsellum. These were found in higher numbers at East. Finella is reported to be typically found in anaerobic conditions. It was present in higher numbers than usual, with 58 at East and one at Cage. Lucinids, bivalves that inhabit anoxic sediments high in sulfides, were not present in great abundance at any station; this would suggest that anaerobic conditions were not necessarily well-developed at East, though detritus was present in sufficient amounts to support detritivore populations.
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Carnivores this year included a large number of spongivorous triphorids, and relatively low numbers of a few other taxa. The most abundant non-spongivorous carnivore species was a very small marginellid, and these probably feed on sessile colonial invertebrates. One interesting pattern this year was a relatively large incidence of predation by naticid gastropods, infaunal predators that leave very recognizable round countersunk boreholes in mollusc shells. The overall incidence of naticid drill holes was about 5.6 %, but it was notably higher in the East samples, where over ten percent of the individual shells were drilled (and one ostracod). The species most frequently drilled by number were the common species Mellitestea scopulorum and Cerithidium perparvulum. This makes sense from the standpoint of those species being common and easily accessible. A few species were drilled in very high proportion, with most individual shells counted being drilled; this was the case for the bubble shell Pupa sp. (2 drilled of 3 counted), the bubble shell Atys semistriata (5 drilled of 8 counted), and oddly enough the naticids themselves, with 5 drilled of 11 counted.
Cage East North South West Total Number 29 102 37 27 12 207 Percentage 3.1 11.4 4.8 4.5 2.5 5.6 Table M5. Incidence of naticid predation by station
Habitat comparisons were not recorded for this year’s sample, however the fauna was almost entirely epifaunal. Some infaunal bivalves were found (lucinids, semelids and tellinids), and one scaphopod. Infaunal gastropods included a few carnivorous marginellids (20, more or less equally abundant at all stations) and naticids (11 total).
Overall, the data indicate a diverse and abundant molluscan fauna, with predominantly epifaunal gastropods displaying a variety of trophic levels. Herbivores were most abundant, followed by carnivores, detritivores, and suspension feeders. There were obviously more detritivores at one of the stations this year, but there were also more of everything; so that particular incidence does not seem likely to be indicative of any ill effect of the fish cages on the molluscan fauna – indeed the opposite seems to be true.
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Sources cited:
Beesley, P.L., Ross, G.J.B. & Wells, A. eds. 1998. Mollusca: the Southern Synthesis. Fauna of Australia. Vol. 5. CSIRO Publishing: Melbourne. Pt. A, xvi 563 pp. Part B viii pp. 565-1234.
Kawamoto, R. & Grasso, S. 2011. Micromollusk Distribution Report for Keahole Point Fish. Technical Report.
Kay, E.A. 1979. Hawaiian Marine Shells. Reef and Shore Fauna of Hawaii, Section 4: Mollusca. Bernice P. Bishop Special Publ. 64: 653 pp. Honolulu: Bishop Museum Press.
Severns, M. 2011. Seashells of the Hawaiian Islands – The Sea Shells. Conchbooks, Hackenheim, Germany. 564 pp.
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