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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

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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)

http://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

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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

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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.


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.


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


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


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


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.


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

https://www.hill-laboratories.com/page/pageid/2145845622/Accreditations


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.


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


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


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’


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.


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.


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


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.


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.


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.

18020 Westhaven Biota final report.docx 4 April 2018


7. APPENDICES


Appendix 1 Breakwater Photographs.

Figure 7.1 Breakwater Inner (BWI) Low Tide Photographic Quadrats, 11 March 2016.


Figure 7.2 Breakwater Inner (BWI) Mid Tide Photographic Quadrats, 11 March 2016.


Figure 7.3 Breakwater Outer (BWO) Low Tide Photographic Quadrats, 11 March 2016. (note photo labels incorrect)


Figure 7.4 Breakwater Outer (BWO) Mid Tide Photographic Quadrats, 11 March 2016. (note photo labels incorrect)


Figure 7.5 Car Park Breakwater Outer (CPO) Low Tide Photographic Quadrats, 11 March 2016.


Figure 7.6 Car Park Breakwater Outer (CPO) Mid Tide Photographic Quadrats, 11 March 2016.


Figure 7.7 Car Park Breakwater Inner (CPI) Low Tide Photographs, 11 March 2016.


Appendix 2 Laboratory Results

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