Post on 15-Feb-2020
Westhaven Pile Berth
Redevelopment - Marine Ecological
Assessment
April 2018
Consulting Biologists – Established 1972
P.O. Box 2027, Auckland 1140. New Zealand
www.Bioresearches.co.nz
P O Box 2027, Auckland 1140. Telephone: (09) 379-9417, Website: www.Bioresearches.co.nz 18020 Westhaven Biota final report.docx Final 4 April 2018
i
Westhaven Pile Berth Redevelopment - Marine Ecological
Assessment
April 2018
DOCUMENT APPROVAL
Document title: Westhaven Pile Berth Redevelopment - Marine Ecological Assessment
Prepared for: Pānuku Development Auckland
Version: Final
Date: 4 April 2018
Document name: 18020 Westhaven Biota final report.docx
Authors: Simon West
Senior Marine Ecologist M.Sc (Hons)
Reviewer: Jessica Feickert
Ecologist M.Sc (Hons)
Approved for release: Graham Don
Senior Ecologist M.Sc (Hons)
REVISION HISTORY
Rev. No. Date Description Author(s) Reviewer Approved
1
2
Reference: Bioresearches (2018). Westhaven Pile Berth Redevelopment - Marine Ecological
Assessment. Report for Pānuku Development Auckland. pp 38
Cover Illustration: Westhaven Marina (Simon West, 3 December 2017)
P O Box 2027, Auckland 1140. Telephone: (09) 379-9417, Website: www.Bioresearches.co.nz 18020 Westhaven Biota final report.docx Final 4 April 2018
ii
CONTENTS
1. Introduction ...........................................................................................................1
2. Western Entrance ...................................................................................................1
2.1 Results............................................................................................................................. 2
2.2 Discussion ....................................................................................................................... 4
3. Dredge area Sediment quality .................................................................................6
3.1 Results............................................................................................................................. 8
3.2 Discussion .....................................................................................................................10
3.2.1 Total Recoverable Metals ................................................................................10
3.2.2 Tributyl Tin Compounds ...................................................................................10
3.2.3 Polycyclic Aromatic Hydrocarbons ..................................................................11
3.2.4 Other Semivolatile Organic Compounds .........................................................11
3.2.5 Total Petroleum Hydrocarbons ........................................................................11
3.2.6 Particle Size ......................................................................................................11
3.2.7 Elutriation ........................................................................................................11
4. Biota adjacent to dredge area ............................................................................... 13
4.1 Results...........................................................................................................................13
4.2 Discussion .....................................................................................................................15
5. Conclusions and recomendations .......................................................................... 16
6. References ............................................................................................................ 17
7. APPENDICES ......................................................................................................... 18
Appendix 1 Breakwater Photographs. ...................................................................19
Appendix 2 Laboratory Results ..............................................................................26
Westhaven Pile Berth Redevelopment - Marine Ecological Assessment 18020 Westhaven Biota final report.docx Final 4 April 2018 1
1. INTRODUCTION
With Westhaven Marina operating at full capacity, there is a growing demand for new berths. One of the
solutions outlined in the Westhaven Plan in 2012 is the Pile Mooring development, which will see the
creation of new modern marina berths in the water space currently occupied by the pile berths in the
north eastern corner of the marina.
To achieve this, the current proposal includes an extension for the western breakwater to connect to the
eastern breakwater to provide public open space and parking. The public open space has been designed
in conjunction with local iwi. The proposal also includes the conversion of existing pile moorings to pile
berthage. A small amount of dredging is required as outlined in section 3 and it is likely this material will
be used in the reclamation of the Western entrance.
This report contains information on the biota in the vicinity of the proposed reclamation of the Western
entrance of Westhaven Marina, and adjacent to the area to be dredged. It also contains information on
the quality of the sediments in the area to be dredged. It provides comment on the likely effects and
impacts of the dredging and reclamation. The Western entrance surveys were conducted in March 2016
and the dredging area assessments were conducted in February 2018.
2. WESTERN ENTRANCE
The proposed closure by reclamation of the Western entrance will impact the biota present on the
seafloor of the entrance and have potential impacts on the biota currently present on the inner and outer
seawalls through realignment and remedial works.
In order to evaluate the biota present on the Western entrance seafloor, three sampling stations were
located within the footprint of the proposed reclamation of the Western entrance of Westhaven Marina
as indicated in Figure 2.1. A single sample was collected using a stainless steel box dredge sampler
operated from a boat. Each sample of 180 x 280 mm area (approximately 6 L), was sieved wet through a
0.5 mm mesh sieve fresh and all material retained on the sieves was preserved with a 10% glyoxal, 70%
ethanol sea water solution. In the laboratory the samples were rinsed with freshwater and placed in a
white sorting tray. Any organisms were picked out of the samples and placed in a labelled vial of 70%
isopropyl alcohol solution prior to taxonomic identification and enumeration, to the lowest possible level.
Benthic biota samples were collected on 15 March 2016.
The intertidal biota of the rocky breakwaters either side of the Western Entrance were surveyed on 11
March 2016. Sampling consisted of intertidal transects at four locations, two inside the marina and two
outside the marina, as indicated in Figure 2.1. At each location the intertidal zonation and species present
were photographed and described.
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Figure 2.1 Location of Benthic Biota Stations and Intertidal Biota Transects within and Adjacent to the Westhaven Marina Western Entrance, showing concept reclamation area. ( Benthic biota, Intertidal biota)
2.1 Results
The benthic biota data from the three samples taken under the footprint of the proposed reclamation are
presented as Table 2.1.
A photographic record of the intertidal habitats either side of the sea wall and entrance are presented in
Appendix 1. Species present on the intertidal transect locations are summarised in Table 2.2.
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Table 2.1 Semi Quantitative Benthic Biota Data, 15 March 2016 (Dredged Samples)
Taxa Sites
Channel BWI W BWI E
PHYLUM ANNELIDA
CLASS POLYCHAETA Aglaophamus ?macroura 1 1 Aonides trifida 1 Balanoglossus australiensis 2 5 Boccardia sp. 4 5 3 Cirratulidae 2 1 1 Cossura consimilis 6 Glycera americana 2 4 Glycinde (Goniada) trifida 1 Hesionidae 2
Heteromastus filiformis 15 15 Lumbrinereis sp. 2 Maldanidae 1
Nicon aestuariensis 2 Paraonidae 4 Phylo novaezealandiae 1 Pelogenia antipoda 1 Prionospio aucklandica 1
Sphaerosyllis sp. 1 Syllidae 1 Trichobranchidae 1 6
PHYLUM NEMERTEA Nemertian 3
PHYLUM SIPUNCULA
Sipunculid worm 8 2
PHYLUM MOLLUSCA
CLASS GASTROPODA Nassarius (Plicarcularia) burchardi 1 4 CLASS BIVALVIA
Corbula zelandica 1 Lasaea sp. 1 Mactra discors 2 3
Modiolus areolatus 1 Purpurocardia purpurata 1
Theora lubrica 13 17 83 Unident. Bivalve juvenile 3 CLASS AMPHINEURA
Unidentified juvenile 1
PHYLUM ARTHROPODA CLASS CRUSTACEA
ORDER AMPHIPODA Ampeliscidae 1
Paradexamine pacifica 1 ORDER DECAPODA Alpheus sp. 1 1
Halicarcinus cookii 1 ORDER LEPTOSTRACA Nebalia sp. 1
ORDER OSTRACODA Ostracod A 1 1 Ostracod C 2 ORDER TANAIDACEA Tanaid species B 2
PHYLUM COELENTERATA CLASS ANTHOZOA
Edwardsia sp. 1
PHYLUM ECHINODERMATA CLASS HOLOTHUROIDEA
Trochodota dendyi 2 3 CLASS OPHIUROIDEA Amphiura sp. 10
PHYLUM CHORDATA CLASS ASCIDIACEA
ORDER STOLIDOBRANCHIA Botrylloides leachii 18
Total Number of Species / Taxa 18 28 14 Total Number of Individuals 65 90 127
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Table 2.2 Biota Present on Intertidal Transects Adjacent to the Westhaven Marina Western Entrance, 11 March 2016 (Breakwater Wall Samples)
Taxa Site
BW Inner BW Outer CP Inner CP Outer
Low Mid Upper Low Mid Upper Low Mid Upper Low Mid Upper
PHYLUM ARTHROPODA CLASS CRUSTACEA ORDER DECAPODA
Petrolisthes elongatus P ORDER CIRRIPEDIA
Elminius modestus P C A A C
PHYLUM MOLLUSCA CLASS AMPHINEURA
Sypharochiton pelliserpentis C C C P P CLASS GASTROPODA Austrolittorina antipodum C A A Cabestana spengleri R Cellana ornata P P
Dicathais orbita R P P Diloma aethiops C C C Haustrum scobina C P P
Nerita melanotragus C P C C C Onchidella nigricans P Turbo smaragdus C A C A
CLASS BIVALVIA Crassostrea gigas A A A A R A P A
Mytilus edulis R
PHYLUM ECHINODERMATA CLASS ASTEROIDEA
Patiriella regularis R
PHYLUM PORIFERA CLASS DEMOSPONGIAE
ORDER HADROMERIDA Cliona sp. R
Tethya burtoni R
PHYLUM CHLOROPHYTA CLASS BRYOPSIDOPHYCEAE
Codium fragile R
PHYLUM OCHROPHYTA CLASS PHAEOPHYCEAE
Carpophyllum flexuosum R P Carpophyllum maschalocarpum C C
Colpomenia sinuosa P R Ecklonia radiata C P Hormosira banksii C P P P C C
PHYLUM RHODOPHYTA CLASS FLORIDEOPHYCEAE
Gelidium sp. R R Corallina officinalis R C P A
Total Number Of Species/Taxa 12 5 3 12 9 4 3 0 0 12 6 3
Key:
A = Abundant (> 25 specimens) C = Common (10 - 24 specimens) P = Present (3 - 10 specimens) R = Rare (1 or 2 specimens)
2.2 Discussion
The diversity of the benthic biota present in the seabed in the Western entrance and along the inside of
the breakwater to the east was relatively high with a total of 43 taxa, but not particularly abundant with
an abundance of 1,865 individuals per m2. Species composition indicates some stress possibly related to
sediment quality. The dominance of the polychaete worm Heteromastus and the lower occurrence of the
polychaete worms Lumbrineris, Maldanidae, and Terebellidae have been identified as indicators of
environmental stress (Dean, 2008). The bivalve Theora is a non-indigenous invasive species which can
rapidly multiply to plague proportions and is indicative of soft muddy organically enriched habitats. None
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of the species present indicate that the habitat is of significant value. The biota present under the
proposed reclamation footprint are not of high value and are common in the nearby environments.
The steep (45 degree slope) artificial, basalt boulder rocky intertidal habitat located east and west of the
western entrance on the outside of the breakwater supports a typical moderately rich diversity of species.
The zonation of the species up and down the shore is well defined and typical, with the upper tidal area
including the barnacle Elminius, snails, Austrolittorina and Nerita. The mid shore is dominated by Pacific
oyster Crassostrea, with a range of typical rocky shore species including the molluscs Cellana ornata,
Diloma aethiops, Haustrum scobina, Nerita, and Sypharochiton, and barnacle Elminius; the seaweed
Hormosira is present in the lower mid tide of the outside shore east of the western entrance. The lower
shore was boarded by subtidal beds of seaweeds including Ecklonia, Carpophyllum flexuosum and C.
maschalocarpum which are typical of north-eastern New Zealand. Just above these low water seaweed
beds is a band of the seaweed Hormosira and patches of the coralline turf algae, Corallina. Within the
algae the grazing mollusc Turbo was abundant. Also found in the low tide area were the larger predatory
molluscs Cabestana and Dicathais. The undersides of some of the larger boulders created habitat suitable
for sponges.
The inner side of the breakwater east of the Western entrance was equally steep and constructed. The
biota present were generally similar however diversity was lower in the mid and upper shore. Species
composition was marginally different between inner and outer shores with the limpet, Cellana not present
on the inner side but the sea slug, Onchidella was present on the lower shore as was the occasional blue
mussel, Mytilus. The low tide algal community was less diverse with the absence of the kelp, Ecklonia,
seaweed C. maschalocarpum. The coralline turf, Corallina was rare in its abundance as was the seaweed,
Carpophyllum flexuosum. The green seaweed, Codium was found in small patches. The lower shore was
coated in a thin layer of fine muddy sediments in places which was absent on the outer shore. The inner
shoreline on the western side of the western entrance was almost entirely overhung by concrete walkway,
and covered in a thicker layer of fine muddy sediment. The only species observed were oysters,
Crassostrea, the seaweed, Hormosira and one starfish, Patiriella.
The rocky shore habitats on the outside of the breakwater are common all along the outside of the
breakwater and any disturbance or newly created basalt boulder rocky shore will be colonised over time
with similar communities expected to establish. Colonisation by biota will be staged, with some species
colonising almost immediately but other species taking longer to establish. The newly established
communities will be well on the way to being similar to those recorded previously, within the first 1 – 3
years. At present the eastern breakwater does not have land access and has had limited human harvesting
pressure, however the difference in populations of significant edible shellfish such as oysters is negligible,
so the creation of access is not expected to have adverse effects.
The inner shore west of the western entrance is of low value due to the overhanging walkway and siltier
habitat. The inner shore east of the western breakwater will in part be reclaimed and moved south and
modified with an overhanging walkway thus creating similar low value, species poor habitat along the
inside of the reclamation to that current west of the western entrance. East of the reclamation the inner
breakwater habitat is unlikely to change significantly as a result of the closing of the western entrance.
A hydraulic modelling study (BECA, 2015) suggests that predictably the tidal flow through the marina will
be decreased by closing the western entrance. The flushing time of the marina will increase, but is still
Westhaven Pile Berth Redevelopment - Marine Ecological Assessment 18020 Westhaven Biota final report.docx Final 4 April 2018 6
expected be within acceptable limits to maintain good water quality. Sedimentation within the marina is
expected to decrease as the main source of sediment is from the harbour water and less of this will be
entering the marina. This may result in less silty habitats along the inside of the breakwater; however it
is not expected to greatly change the habitat values if the inner shore is overhung with a walkway.
Modelling has shown the potential addition of the ferry and fishing industry relocation facility at the
eastern entrance of the Westhaven marina as part of the Americas Cup 36 redevelopments is likely to
increase currents in the eastern entrance (Beca, 2018). The model also predicted that the flushing of the
marina water would be slightly reduced. However, this model assumed that the western entrance
remained open. To date the model has not been run with the ferry and fishing industry relocation facility
and the western entrance closed.
Ecologically the predicted changes in flows and flushing rates are not expected to change the water quality
sufficiently to have adverse effects on the benthic and shoreline biota. It is possible during storm events
that the surface water quality in the marina could show reduced salinity, which in turn, depending on the
frequency and extent, could have effects on fouling biota on the floating pontoons.
3. DREDGE AREA SEDIMENT QUALITY
The pink area marked on Figure 3.1 shows the proposed area to be dredged to a depth of 4.0 m water
depth. Current water depths are approximately 3.5 m so this equates to a dredging depth of
approximately 0.5 m, and dredging volume of approximately 2,500 m3.
Four sediment samples were collected on 12 February 2018, at sites as shown in Figure 3.1 by yellow
circles and labelled M1 to M4. The samples were collected using a petite Ponar Grab sampler. The entire
sample was homogenised and subsamples taken for metals and grain size analysis. Equal portions from
each of the four samples were combined and analysed for organics constituents (total organic carbon,
tributyl tin compounds, total petroleum hydrocarbons, SVOC and ammonia). Each of the four metals
samples were subjected to elutriate analysis for metals availability.
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Figure 3.1 Dredging Area Sediment quality and Biota sample locations
All samples were double bagged in clean zip lock plastic bags, with a waterproof label between the two
bags. The labels specify site, date, and analysis required. All samples were prevented from warming after
collection in chilly bins. Samples for chemical analysis were returned to the laboratory and frozen before
dispatch to the analytical laboratory. Samples for particle size were treated in the same way but
refrigerated until delivery to the laboratory. The samples were dispatched to the analytical laboratory as
soon as practical. The samples were accompanied by a custody sheet specifying sample date, site,
analysis, practical quantification limits requirements1 and storage details1. All chemical analysis was
conducted by the New Zealand accredited laboratory, Hill Laboratories in Hamilton. Sediment grain size
analysis were conducted via Hill Laboratories in Hamilton. The laboratory accreditation details are
specified on their website2.
1 if different from the laboratory standard 2 https://www.hill-laboratories.com/page/pageid/2145845622/Accreditations
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3.1 Results
Raw sediment quality data are attached in Appendix 2 and are summarised and compared with sediment
quality guidelines in Table 3.1.
The results for tributyl tin compounds, antifouling co-biocides and polycyclic aromatic hydrocarbons, in
Table 3.1 have been normalized to 1 % organic carbon, which is required for comparison with the ANZECC
ISQG (ANZECC, 2000) guidelines. Note if the sediment total organic carbon content is less than 0.2
percent, then ANZECC suggest normalisation is not appropriate.
Raw particle size data for each of the four sites are attached in Appendix 2 and summarised in Table 3.2.
Raw water and elutriate quality data are attached in Appendix 2 and are presented and compared with
water quality guidelines in Table 3.3.
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Table 3.1 Sediment Total Recoverable Metals and Polycyclic Aromatic Hydrocarbons Data (dry weight)
Tests Site ANZECC ISQG
1 2 3 4 Composite Low High
Dry Matter (g/100g) - - - - 40
Ammonium (mg/kg dry wt) - - - - 9
Total Organic Carbon (g/100g dry wt) - - - - 1.2
Total Recoverable Heavy metals (mg/kg dry wt)
Arsenic 7.5 7.5 7.8 7.4 - 20 70
Cadmium 0.043 0.051 0.037 0.049 - 1.5 10 Chromium 24.0 25.0 26.0 23.0 - 80 370
Copper 21.0 27.0 36.0 25.0 - 65 270
Lead 26.0 27.0 26.0 27.0 - 50 220
Mercury 0.216 0.170 0.199 0.182 - 0.15 1
Nickel 7.4 7.8 8.2 7.7 - 21 52 Zinc 88.0 97.0 98.0 93.0 - 200 410
Tributyl Tin (1% TOC) (ug Sn/kg dry wt)
Dibutyltin - - - - < 0.005 99999
Monobutyltin - - - - < 0.007 99999
Tributyltin - - - - < 0.004 9 70 Triphenyltin - - - - < 0.003 99999
Polycyclic Aromatic Hydrocarbons (1% TOC) (ug/kg dry wt)
Acenaphthene * - - - - < 83.3 16 500
Acenaphthylene * - - - - < 83.3 44 640 Anthracene * - - - - < 83.3 85 1100
Fluorene * - - - - < 83.3 19 540
Naphthalene * - - - - < 83.3 160 2100
Phenanthrene * - - - - 141.7 240 1500
Low Molecular Weight PAHs * - - - - 558 552 3160
Benzo[a]anthracene * - - - - 133.3 261 1600
Benzo[a]pyrene (BAP) * - - - - 183.3 430 1600
Benzo[b]fluoranthene + Benzo[j] fluoranthene *
- - - - 166.7
99999
Benzo[g,h,i]perylene * - - - - 133.3 99999
Benzo[k]fluoranthene * - - - - < 116.7 99999
Chrysene * - - - - 125 384 2800
Dibenzo[a,h]anthracene * - - - - < 116.7 63 260 Fluoranthene * - - - - 250 600 5100
Indeno(1,2,3-c,d)pyrene * - - - - 125 99999
Pyrene * - - - - 258.3 665 2600
High Molecular Weight PAHs * - - - - 1608 1700 9600
Total PAHs * - - - - 2167 4000 45000
Total Petroleum Hydrocarbons (mg/kg dry wt)
C7 - C9 - - - - < 15
C10 - C14 - - - - < 30
C15 - C36 - - - - < 60
Total hydrocarbons (C7 - C36) - - - - < 110 280 550
* = normalised to 1 % total organic carbon
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Table 3.2 Sediment Grain Size Data (Percentage by Weight)
Grain size Site
(mm) Class M1 M2 M3 M4
> 3.35 Gravel 0.0 0.0 0.0 0.0
3.35 - 2.00 Granules 0.0 0.0 0.0 0.0
2.00 - 1.18 Very Coarse Sand 0.0 0.0 0.0 0.0
1.18 - 0.600 Coarse Sand 0.1 0.6 0.0 0.1
0.600 - 0.300 Medium Sand 2.6 3.4 0.7 1.9
0.300 - 0.150 Fine Sand 8.1 7.7 3.6 6.1
0.150 - 0.063 Very Fine Sand 22.3 19.2 14.2 18.5
0.063 - 0.0313 Coarse Silt 13.4 12.6 15.5 13.8
0.0313 - 0.0156 Medium Silt 10.5 11.3 14.9 12.6
0.0156 - 0.0078 Fine Silt 13.1 14.2 17.2 15.6
0.0078 - 0.0039 Very Fine Silt 12.7 13.6 15.5 14.2
< 0.0039 Clay 17.2 17.4 18.4 17.3
< 0.063 Silt and Clay 66.9 69.1 81.5 73.4
Mean Size 0.022 0.021 0.015 0.019
Grain size description sZ sZ sZ sZ
Table 3.3 Sediment Elutriation Data (µg/L)
Sample Arsenic Cadmium Chromium Copper Lead Mercury Nickel Zinc
ANZECC Trigger
values for marine water
Level of protection (% species)
99% ID 0.7 0.14 0.3 2.2 0.1 7 7
95% ID 5.5 4.4 1.3 4.4 0.4 70 15
90% ID 14 20 3 6.6 0.7 200 23
80% ID 36 85 8 12 1.4 560 43
USEPA CMC 69 33 1100 4.8 210 1.8 74 90
CCC 36 7.9 50 3.1 8.1 0.94 8.2 81
Elutriate Water < 4.20 < 0.21 < 1.10 4.9 < 1.10 < 0.08 < 7.00 6.3
Site M1 extract 4.5 < 0.21 < 1.10 1.3 < 1.10 < 0.08 < 7.00 < 4.20
Site M2 extract 10.2 < 0.21 < 1.10 < 1.10 < 1.10 < 0.08 < 7.00 < 4.20
Site M3 extract 5.6 < 0.21 < 1.10 < 1.10 < 1.10 < 0.08 < 7.00 < 4.20
Site M4 extract 5.3 < 0.21 < 1.10 1.2 < 1.10 < 0.08 < 7.00 < 4.20
3.2 Discussion
3.2.1 Total Recoverable Metals
The concentrations of arsenic, cadmium, chromium, copper, lead, nickel and zinc in sediment, were all
below the ANZECC ISQG low trigger values. The concentration of mercury exceeded the ANZECC ISQG
low value of 0.15 mg/kg dry weight in all samples and ranged from 0.17 to 0.22 mg/kg dry weight.
3.2.2 Tributyl Tin Compounds
Tributyl tin, historically used in antifouling paints, degrades in the marine environment to dibutyl and
monbutyl tin. Tributyl tin is compared with a revised ANZECC ISQG low value of 9.0 µg Sn/kg dry weight
for tributyl tin (Simpson, Batley, & Chariton, 2013) in Table 3.1. No guidelines are presented or published
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for the degraded tin compounds, however, as tributyl tin degrades the toxicity progressively reduces
(ANZECC, 2000).
The concentrations of monobutyl, dibutyl, tributyl tin and triphenyl tin were less than the detection limit
in the Composite sample collected from the dredge area, and below the revised ANZECC ISGQ Low trigger
value.
3.2.3 Polycyclic Aromatic Hydrocarbons
Of the individual PAHs tested in the Composite sample, the low molecular weight Phenanthrene was detected at a low concentration. The majority of the higher molecular weight PAHs tested in the composite sample were detected at low concentration with only Benzo[k]fluoranthene and Dibenzo[a,h]anthracene below detection limits.
The 1% total organic carbon corrected maximum concentrations of all of the individual PAHs detected
were below the available individual ANZECC ISQG low trigger values. In order to calculate the total
concentration values a conservative approach was taken. Where results were shown as less than
detection limits, these were summed at the detection limits rather than halving the value. The total
concentration of low molecular weight PAHs was < 558 µg/kg dry weight, which exceeded the ANZECC
ISQG low trigger value of 552 µg/kg dry weight. However, this was largely the result of the summation of
higher detection limit values for some of the individual PAHs. The total concentration of high molecular
weight and total PAHs, 1608 and 2167 µg/kg dry weight respectively.
3.2.4 Other Semivolatile Organic Compounds
No organic pesticides, chlorophenols, plasticisers, halogenated compounds were detected, as shown in
the raw data presented in Appendix 2.
3.2.5 Total Petroleum Hydrocarbons
A revision of the ANZECC sediment quality guidelines was published in 2013 (Simpson, Batley, & Chariton,
2013) proposed ISQG values for TPHs, as shown in Table 3.1.
No petroleum hydrocarbons were not detected in the Composite sample tested from the proposed
dredge area. The detection limits for TPHs were lower than the ANZECC ISQG low trigger value, hence
the ANZECC ISQG low value was not exceeded.
3.2.6 Particle Size
Surface sediments at sites M1, M2 and M4 contained moderate to high proportions (50 - 75%) of silt and
clay, while Site M3 had a high proportion (75 - 100%). The sediment at all sites were described as sandy
Silt (sZ).
3.2.7 Elutriation
Results from the background elutriate water sampled on 12 February 2018 showed the concentrations of
arsenic, chromium, cadmium, lead, mercury and nickel, were below the level of detection and below the
ANZECC water quality trigger values for the protection of aquatic life in typical ‘slightly-moderately’
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disturbed habitats as indicated by the grey guideline values in Table 3.3. The concentration of zinc was
below the ANZECC water quality trigger value for the protection of aquatic life in typical ‘slightly-
moderately’ disturbed habitats of 15 µg/L. Copper was detected at 4.9 µg/L which was greater the 90%
ANZECC water quality trigger value.
Elutriation of the sediment samples from Site M1 to M4 resulted in detectable changes in the
concentrations of arsenic, copper and zinc. The most notable of these was that in all samples the
concentration of arsenic increased from < 4.2 to between 4.5 and 10.2 µg/L. This indicates that the arsenic
is not strongly bound to the sediments but that the amount released is not likely to cause adverse effects
as the resultant concentrations are less than USEPA chronic criterion, or Criterion Continuous
Concentration (CCC) of 36 µg/L (USEPA, 2017). The ANZECC guidelines do not contain guidelines for
arsenic in seawater, hence the use of the USEPA guidelines. The concentration of copper decreased in all
samples from 4.9 to between < 1.1 and 1.3 µg/L. At these concentrations copper is equal to or below the
ANZECC water quality trigger value for the protection of aquatic life in typical ‘slightly-moderately’
disturbed habitats. The concentration of zinc decreased in all samples from 6.3 to < 4.2 µg/L.
All other elutriation results remained below the detection limits, these together with the copper and zinc
results indicate that the metals are strongly bound to the sediment and unlikely to result in adverse water
quality effects as a result of dredging and disposal. The fine clay sized particles found in the marina basin
sediments often have an ionic charge, resulting in them attracting oppositely charged ions such as metals.
The result is that metals stay bound to the sediment particles when mixed with water.
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4. BIOTA ADJACENT TO DREDGE AREA
The pink area marked on Figure 3.1 shows the proposed area to be dredged to a depth of 4.0 m water
depth. Dredging will have significant impact on the biota in the dredge area, but also has the potential to
cause effects on the biota adjacent to the dredge area though spread and settlement of disturbed
sediments. The biota adjacent to the dredging area were sampled in February 2018 at five sites
approximately 50 m outside the dredging area. Five single samples were collected at sites as shown in
Figure 3.1 by orange circles and labelled B1 to B5. The samples were collected using a petite Ponar Grab
sampler.
The petite Ponar Grab sampler was lowered to the bottom on a rope and then raised and its contents
poured into a clean bucket, labelled and then sieved as soon as practicable by washing each whole sample
through 0.5 mm mesh sieves with sea water. Each sample was a minimum of 2 L in volume. All samples
were sieved within three hours of collection. The material retained on the sieves was transferred to a
fresh clean polyethylene zip lock bag, and preserved with a 10% glyoxal, 70% ethanol and sea water
solution, sealed, placed in a second clean polyethylene zip lock bag and packed into a labelled plastic
container for transportation to the laboratory.
In the laboratory, the samples were rinsed with fresh water and placed in a white sorting tray where any
organisms were picked out of the samples and placed in a labelled vial of 70% isopropyl alcohol solution
prior to taxonomic identification to the lowest possible level.
Seabed photographs were taken at the five biota sites (B1 - B5), however under water visibility was less
than 0.5 m at the seabed and insufficient for the camera to produce useable images.
4.1 Results
The results of the benthic biota sampling are presented in Table 4.1.
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Table 4.1 Quantitative Benthic Biota Data, 12 February 2018 (Grab Samples)
Taxa Sites Average
/m2 B1 B2 B3 B4 B5
PHYLUM ANNELIDA
CLASS POLYCHAETA Aonides trifida 21 32 18 6 42 1030.1
Boccardia sp. 9 11 1 1 4 225.1
Capitella capitata 11 9 10 50 865.7
Cirratulidae 2 1 1 1 54.1
Cossura consimilis 3 8 11 1 6 251.0
Glycera americana 2 1 64.9
Heteromastus filiformis 5 14 9 11 14 458.8
Lumbrinereis sp. 1 43.3
Nereidae 8 3 6 3 4 207.8
Orbiniidae 2 3 7 3 162.3
Paraonidae 5 3 2 144.3
Polynoidae 1 1 43.3
Prionospio sp. 2 7 4 5 10 242.4
Scolelepis sp. 2 86.6
Syllidae 1 1 2 4 86.6
PHYLUM NEMERTEA
Nemertian 1 43.3
PHYLUM HEMICHORDATA
CLASS ENTEROPNEUSTA
Acorn Worm 2 86.6
PHYLUM MOLLUSCA
CLASS BIVALVIA
Nucula hartvigiana 5 1 129.8
Theora lubrica 22 52 19 120 48 2259.3
PHYLUM ARTHROPODA
CLASS CRUSTACEA
ORDER AMPHIPODA
Unidentified species 2 2 4 6 7 181.8
ORDER DECAPODA
Alpheus sp. 1 43.3
Austrohelice crassa 2 1 64.9
ORDER CUMACEA
Cumacean sp. 2 1 1 57.7
ORDER MYSIDACEA
Mysid 2 86.6
ORDER OSTRACODA
Ostracod 3 4 1 5 6 164.5
CLASS MAXILLOPODA
Copepod 1 43.3
Total Number Of Species/Taxa 15 14 16 17 20 26
Total Number Of Individuals 84 155 98 182 207 7127.2
Shannon Wiener Diversity 2.170 2.080 2.367 1.492 2.172 2.471
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4.2 Discussion
The benthic biological community found around the dredging area was relatively diverse and abundant,
with a total of 26 taxa recorded and an average abundance of 7127 individuals per square metre.
The benthic biological communities found were numerically dominated by the bivalve Theora lubrica
(2,259 /m2) and polychaete worms, particularly Aonides trifida (1,030 /m2), Capitella capitata (866 /m2)
and Heteromastus filiformis (459 /m2), all of which are relatively tolerant of fine sediments.
Theora lubrica is a small bivalve with an almost transparent shell. The shell is very thin, elongated and
has fine concentric ridges. Theora lubrica is native to the Japan and China Seas. It was been introduced
to the New Zealand in the early 1970s. Theora lubrica typically lives in muddy sediments from the low
tide mark to 50 m. In many localities, Theora lubrica is an indicator species for eutrophic and anoxic areas.
Aonides trifida is a small (<100mm) thin active spionid polychaete worm, with a pointed head and two
pairs of eyes. They burrow in fine intertidal and subtidal sands, preferring low mud content, to 10 cm
sediment depth. They are found New Zealand wide. Aonides trifida is a surface deposit feeder and
bioturbator and a prey for fish and birds. Aonides trifida tolerates a sediment mud content up to 80%,
but has an optimum range of 0-5%. Accordingly, Aonides trifida is most abundant in sandy habitats.
Aonides trifida is also sensitive to copper contamination. Where the sediment becomes muddier,
exceeding its optimum range, and/or polluted, particularly with copper, the abundance of Aonides trifida
generally declines thus their presence indicates lower copper concentrations.
Capitellid worms (Capitella capitata and Heteromastus filiformis) are long, thin and fragile worms. They
have no head appendages or other distinguishable characteristics. Adults can grow up to 50mm long.
Capitellids prefer a muddy sand habitat in estuaries and harbours where they can burrow deeply into the
sediment up to about 10 cm. They are tolerant of and sometimes flourish in organically-enriched
environments. Capitellids are subsurface deposit feeders and bioturbators and are prey for fish and birds.
Capitellids tolerate a sediment mud content of up to 95%, with an optimum range of 10-40%. Therefore
they are usually found in moderately muddy habitats.
Biota in the dredge area are expected to recover via colonisation to be similar to those communities
recorded around the dredge area, within the first 1 – 2 years.
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5. CONCLUSIONS AND RECOMENDATIONS
The ecological effects of reclamation of the western entrance will have adverse effects on the immediate
area to be reclaimed. However the area affected is relatively small, impacted by current environmental
stresses, and not greatly different from adjacent habitats; therefore the effects of the reclamation overall
are considered to be no more than minor.
The changes in the hydrodynamics of the marina as a result of the closing of the western entrance are not
expected to result in adverse effects to the ecology of the marina, nor is the potential restriction of the
eastern entrance by the construction of the ferry and fishing industry relocation facility as part of the
Americas Cup 36 redevelopments.
Where possible the use of similar rock size and rock type should be used to maintain habitat type, in the
areas of new rock wall enclosing the western entrance reclamation.
Disturbance of the rock wall either side of the western entrance should be kept to a minimum. If so it is
expected that the ecology of the disturbed rock walls will start once work finishes and be well on the way
to being fully recovered by 3 years.
The sediment analysis within the dredge area showed only mercury exceeded the ANZECC ISQG low
trigger values. Mercury is generally slightly elevated in the lower Waitematā Harbour. Elutriation water
quality data shows dredging of the seabed from the marina’s main channel is unlikely to release significant
quantities of contaminants that could adversely affect biota in the marina and on the adjacent seabed.
The overall low concentration of contaminants in the sediment to be dredged, suggests its use as
reclamation material is unlikely to have adverse effects on biota. The biota adjacent to the dredge area
are typical of the marina basin sea bed. The dominant biota species are tolerant of fine sediment and
contaminants hence the redistribution of a very small volume of sediment during dredging is unlikely to
have adverse effects.
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6. REFERENCES
ANZECC (2000)
Australian and New Zealand Guidelines for Fresh and Marine Water Quality, Volume 1, The Guidelines (Chapters 1-7). Australian and New Zealand Environment and Conservation Council (ANZECC) and Agriculture and Resource Management Council of Australia and New Zealand (ARMCANZ). Paper No. 4 - Volume 1 (Chapters 1-7) October 2000.
BECA (2015)
Westhaven Marina - Hydraulic Modelling Report. Prepared for Auckland Waterfront Development Agency by Beca Ltd. 20 April 2015. pp 167.
BECA (2018)
America’s Cup 36, Auckland 2021, Hydraulic Modelling Report for Resource Consent Application, Wynyard Basin and Ferry & Fishing Industry Relocation Facility. Prepared for Panuku Development Auckland (Panuku) by Beca Ltd. January 2018.
Dean, H.K. (2008)
The use of polychaetes (Annelida) as indicator species of marine pollution: a review. Rev Biol Trop, 56(4), 11-38.
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7. APPENDICES
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Appendix 1 Breakwater Photographs.
Figure 7.1 Breakwater Inner (BWI) Low Tide Photographic Quadrats, 11 March 2016.
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Figure 7.2 Breakwater Inner (BWI) Mid Tide Photographic Quadrats, 11 March 2016.
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Figure 7.3 Breakwater Outer (BWO) Low Tide Photographic Quadrats, 11 March 2016. (note photo labels incorrect)
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Figure 7.4 Breakwater Outer (BWO) Mid Tide Photographic Quadrats, 11 March 2016. (note photo labels incorrect)
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Figure 7.5 Car Park Breakwater Outer (CPO) Low Tide Photographic Quadrats, 11 March 2016.
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Figure 7.6 Car Park Breakwater Outer (CPO) Mid Tide Photographic Quadrats, 11 March 2016.
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Figure 7.7 Car Park Breakwater Inner (CPI) Low Tide Photographs, 11 March 2016.
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Appendix 2 Laboratory Results
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