makara estuary baseline and construction monitoring plan …€¦ · erosion of the estuary/river...

Makara Estuary Baseline and

Construction Monitoring Plan (MEBCMP)

Prepared for Meridian Energy Ltd

eCoast Ltd Marine Consulting and Research PO Box 151 Raglan New Zealand Telephone: +64 21 423 224 Email: [email protected]

MEBCMP

i

Contents

1 INTRODUCTION ...................................................................................................................................... 1

1.1 THE SITE ...................................................................................................................................................... 1

2 METHODOLOGY ...................................................................................................................................... 3

2.1 PROPOSED LOCATIONS OF MONITORING ............................................................................................................ 3

2.2 BIOLOGICAL DATA COLLECTION ........................................................................................................................ 4

2.3 BIOLOGICAL DATA ANALYSIS ............................................................................................................................ 6

2.4 SEDIMENT DEPOSITION DATA COLLECTION ......................................................................................................... 9

3 REPORTING ........................................................................................................................................... 10

4 REFERENCES ......................................................................................................................................... 11

APPENDIX 1 – MAKARA ESTUARY BASELINE AND CONSTRUCTION MONITORING PLAN ................................ 13

APPENDIX 2 – EXPERT WITNESS EVIDENCE OF SHAW MEAD FOR MILL CREEK ENVIRONMENT COURT

PROCEEDINGS ................................................................................................................................................ 15

List of Figures Figure 1.1. Locality map of Makara Estuary (Source: Google Earth). ....................... 2

Figure 2.1. Sampling locations for the MEBCMP. Site 1 also includes cobble habitat

monitoring (blue box). ................................................................................................. 8

Figure 2.2 A plate being buried on a tidal flat (http://www.geog.sussex.ac.uk, 2004). 9

MEBCMP

1

1 Introduction

The Makara Estuary Baseline and Construction Monitoring Plan (MEBCMP) has

been prepared on behalf of Meridian Energy Ltd (MEL) for one of the Conditions of

Consent for the Mill Creek:

“The consent holder shall engage an appropriately qualified and

experienced estuarine ecologist to prepare and submit a Makara Estuary

Baseline and Construction Monitoring Plan ("the MEBCMP") to the

Manager, Environmental Regulation, Wellington Regional Council, for

approval at least 20 working days prior to the proposed start date of the

baseline water quality monitoring programme site.”

The condition specifies that the baseline monitoring shall commence at least 6

months prior to bulk earthworks. At this stage, dry-season (March 2012) and wet-

seaon (September 2012) baseline monitoring is proposed to time with the

commencement of constrution in October 2012.

The MEBCMP has been developed using the details provided in the condition –

attached as Appendix 1. Appendix 2 is the Environment Court Evidence for the Mill

Creek Resource Consent for Environment Court compiled by Dr. Shaw Mead, which

includes the lastest of a series marine and estuarine investigations associated with

Project Westwind “State of the Environment Assessment for Makara Beach, Makara

Estuary, Ohau Bay and Oteranga Bay – Wellington coast 2010” compiled by Dr.’s

Mead and Haggitt (the ecologists engaged by MEL), and list the previous 5

investigations dating back to 2004. CV’s of Dr’s Shaw Mead and Tim Haggitt, the

ecologists engaged to undertake the MEBCMP, accompany this document.

1.1 The Site

The entrance to Makara Estuary is located at the northern end of Makara Beach

(Ohariu Bay), west of Wellington (Figure 1.1), and is fed by the Makara River. The

estuary proper is bounded by the seaward entrance and the location where highest

MEBCMP

2

spring tides encroach up river (approximately 1.5 km). The estuary is approximately

80 m wide at its widest point near the entrance and narrows to 20 m wide 1 km from

the entrance. It incorporates 2-3ha of saltmarsh, and is mostly 1-3 m deep. The

estuary margins are modified and vegetated with various scrub species, saltmarsh,

terrestrial grass and weed, which provide reasonable habitat for whitebait spawning

(Taylor and Kelly, 2001).

Figure 1.1. Locality map of Makara Estuary (Source: http://mapping.gw.govt.nz/gwrc/).

Makara Estuary

MEBCMP

3

2 Methodology

The monitoring methodology will expand on the sampling undertaken at Makara

Estuary in February 2010 (Appendix 2). Monitoring will target macro and meio-fauna

abundance and diversity, and sediment deposition rates. Monitoring will be

undertaken every 6 months. At this stage, the base-line monitoring data will be

collected for the dry-season (March 2012) and wet-seaon (September 2012) in order

to time with the commencement of construction in October 2012. Six-monthly data

collection will be undertaken for the duration of construction and for 12 months

following construction.

2.1 Proposed Locations of Monitoring

Three locations within the estuary will be monitored (Figure 2.1):

1. the inner entrance (previously sampled in 2010);

2. 400 m upstream of the entrance, and;

3. 800 m upstream of the entrance.

At each site, biological and physical sampling will be undertaken. A table of GPS

positions for each sample location will be provided with the first report (Baseline

Monitoring Report I).

In addition, general environmental health of the estuary will be recorded with

photography and described during each monitoring visit. For example, details of any

particular characteristics that are noted during monitoring which may influence the

results e.g. activities or incidents occurring in the Makara Catchment, any changes to

the extent of the saltmarsh, presence of seagrass, erosion of the banks, stock

encroachment, etc.

Erosion of the estuary/river banks has been observed to be a contributor to sediment

inputs (Section 30, Appendix 2). The banks of the estuary will be video-surveyed

along its 1.5 km length. Areas of active erosion (e.g. near the Opau Road

intersection) will be measured to easily identified benchmarks (e.g. fence posts,

MEBCMP

4

large trees, road edge, etc.). Both the video-survey and benchmarking will provide

information of additional sediment inputs directly into the estuary.

Further data is also available to assess environmental characteristics that my

influence the results – the Baseline Aquatic Monitoring. This monitoring has been

undertaken for up to 5 years in some locations and includes macro-invertebrates,

temperature, dissolved oxygen, pH, suspended sediments, NTU and visual clarity

assessments at 16 sampling sites throughout the catchment. Rain gauges at Mill

Creek and West Wind will provide additional information and any "observations" of

activities occurring within the catchments which may contribute to deposition of

sediment in the estuary between monitoring regimes1 will be recorded as part of the

Baseline Aquatic Monitoring Plan (BAMP) for Mill Creek.

2.2 Biological Data Collection

Monitoring of species composition has regularly been used to consider

sedimentation-related effects in estuaries; this is often in association with specific

events or modifications to the estuary or catchment, as is the potential in the present

case (e.g. (Turner & Riddle, 2001; Gibbs and Hewitt 2004). Different species are

associated with different types of sediment, especially infaunal species such as

bivalves and polycheates (marine worms). Thus, by assessing the biological

community composition and how it changes (or does not change) with time,

sedimentation rates/impacts can be evaluated. Data collection will be the same as

used at other GWR estuaries (e.g. Robertson and Stevens, 2008), with respect to

numbers of replicates (n=12), size of quadrats (0.25 m2), and sediment sample

collection (250 gms from the top 20 mm of sediment cores).

The general sampling protocol will:

1. Establish what species and communities are present at each of the three

locations within the Makara Estuary (baseline data for dry and wet seasons)

prior to the proposed works being undertaken;

1 The BAMP includes water quality monitoring after every rainfall event exceeding 20 mm over 24 hours and 3 monthly for macro-invertebrates.

MEBCMP

5

2. Determine what species and communities are of value to employ as indicator

species;

3. Develop “effect thresholds” that will constitute an “effect” (defined as percent

change) for those indicator species and communities;

4. Undertake temporal sampling during and following the construction phase of

the proposed works, and;

5. Undertake analysis of temporal data following each sampling period to gauge

magnitude and direction of effects (if any) through time associated with the

proposed works.

Note: Due to the unavailability of a comparable control location within the general

region of Makara Estuary or along the southern NW coast, (see Robertson and

Stevens 2007) the focus of the sampling design will be to measure possible changes

through space and time before and after the proposed works only within the Makara

Estuary. However, based on the methodology proposed we feel that detection of

environmental effects will be possible.

To obtain data on species abundance, composition and diversity, at each of the

three locations, 12 core samples (130 mm diameter 150 mm deep) will be collected

from predetermined sampling site within. This will be achieved by dividing up each

site into 12 blocks (done in GIS) and selecting random sample sites (Coordinates)

within each block. Such an approach is necessary to: 1) achieve adequate

dispersion across each sampling location; 2) reduce the possible influence of

previous sampling events (this will become increasingly important as sampling

progresses); 3) reduce spatial autocorrelation (Thrush et al., 1988). Further,

individual core samples will not be positioned within a 4 m radius from one another

during a sampling event or from any core samples collected over the previous 12

months.

Individual core samples will be rinsed through a 0.5 mm sieve with residues stained

in rose Bengal and then preserved in 70% isopropyl alcohol in seawater. Samples

will be identified to the lowest possible taxonomic level, counted and sorted in 50%

isopropyl alcohol at the Leigh Marine Laboratory. In addition to core samples,

observations of the sediment surface ecology and sediment characteristics will also

MEBCMP

6

be made. As the estuary sediments were found to be extremely anoxic (Mead and

Haggitt, 2010), to evaluate the depth of the sediment anoxic layer at each site, 1

clear plastic graduated cylinder, 50 mm diameter will be driven into the sediment to a

depth of 150 mm. The cylinder will then be removed and the origin (depth) of the

sediment anoxic layer (generally visible as a dark black (anoxic) zone, relative to

lighter oxygenated sediment) measured.

250 gms of sediment from the top 20 mm of each core will be collected at archived

for future reference with respect to particle size measurement. Particle size is a

useful parameter with respect to variability in invertebrate abundance and

distribution. However, previous site visits have indicated homogeneous substrate,

and so, particle size analysis would provide little benefit with respect to explaining

variability. The future requirements for particle size measurement will be assessed

from the baseline surveys and results; even so, sediment samples will be collected

during each monitoring event.

Epifauna will be assessed from 12 random 0.25 m2 quadrats within the 4 m radius of

each of the 12 core samples. All animals observed on the sediment surface will be

identified and counted, and any other observations will be noted (e.g. development

of microalgal mats). Photographs of the quadrats will be taken for future reference.

In addition to infaunal sampling of the soft sediments, the cobble habitat at Site 1 will

be surveyed. Twelve haphazardly placed 0.25m2 quadrats will be surveyed. All

organisms occurring within each quadrat will be identified to species level and

counted. Individual cobbles will also be turned over (and replaced) to investigate the

presence of organisms beneath.

2.3 Biological Data Analysis

The majority of data analysis will be undertaken using either Primer-E, of R statistical

software.

The initial baseline data will be analysed and presented to show:

MEBCMP

7

1. Species abundance;

2. Size distribution (e.g. for bivalves);

3. Biodiversity (e.g. using standard biodiversity indices such as Species

Richness and the Shannon-Weaver Diversity Index and other measures

presented in the ‘Diverse” routine available in Primer-E (Clarke and Warwick

2001)), and;

4. Community variability among locations and between wet and dry seasons (if

any).

In addition, based on the findings of the first sampling regime (March 2012), key

indicator species will be selected (e.g. bivalve and polycheate species) and focussed

on throughout the remainder of the monitoring programme. At this point in time we

will also determine what “effect thresholds“ (per cent change) will be desirable to

assign to individual species and communities.

It is anticipated that both multivariate (many species) and univariate (single species)

data will be analysed over the course of the monitoring programme. Both principal

coordinate analysis (PCO; metric MDS) and PERMANOVA analysis (Anderson et al.,

2008) will be used to visualise and statistically evaluate any differences in

community structure and variability among the three locations within Makara Estuary

before and after the proposed works and through time. PERMANOVA will also be

used to statistically evaluate any differences in univariate data among the three

locations within Makara Estuary before and after the proposed works and through

time. Univariate data analyses using PERMANOVA will be run on Log (x+1)

transformed data using an Euclidean distance measure (which is equivalent to

traditional ANOVA (see Anderson et al., 2008), whereas multivariate analyses using

PERMANOVA will be likely run on square-root transformed data and a Bray-Curtis

similarity measure.

In combination, these data analyses will provide information on the state of and

changes to the ecological communities of the Makara Estuary while construction of

the Mill Creek is undertaken.

MEBCMP

8

Figure 2.1. Sampling locations for the MEBCMP. Site 1 also includes cobble habitat monitoring (blue box).

200 m 100 m 0 m

Site 1

Site 2

Site 3

MEBCMP

9

2.4 Sediment Deposition Data Collection

An efficient and accurate method of measuring bed elevation, which is currently used

in other parts of New Zealand, is to measure the amount of sediment over a buried

level plate. Once a plate has been buried and the elevation below the surrounding

sediment is measured, probes are pushed into the sediment until they hit the plate

and the penetration depth is measured. A number of measurements within the plate

are averaged to take into account irregular sediment surfaces.

Care is needed to position the plates to ensure that they are not disturbed and to

ensure that changes in sediment elevation can be identified that are not associated

with natural sedimentation such as meandering channels. Two 40 cm x 40 cm

stainless steel plates will be placed at each of the three monitoring sites. Positions

will be close to spring low tide, noting that river flow will need to be considered for re-

sampling, and levelled with a builder’s level. The locations will be selected during

the baseline data collection and recorded by GPS as well as a set of measurements

from prominent local features that will be photographed. Depth of sediment above

the plates will be measured during every monitoring visit (i.e. every 6 months).

Figure 2.2 A plate being buried on a tidal flat (http://www.geog.sussex.ac.uk, 2004).

Sediment depths will be collated, averaged and graphically presented for each of the

6 sample sites (i.e. 2 per Site).

MEBCMP

10

3 Reporting

Reports will be generated every 6 months following each monitoring event. The

State of the Environment report in Appendix 2 provides an example of a similar type

of report that will be produced. The reports will include:

1. Methods and locations of data collection.

2. Results of the monitoring undertaken including data analysis and

presentation.

3. Discussion of the findings including:

a) Identification of the taxa being surveyed and their relevance/tolerance

in association with the health of the estuarine system;

b) Comparisons of monitoring results over time and what this indicates in

regards to the health of the estuarine system in each particular

monitoring location and as a whole system;

c) Rates of sediment deposition and;

d) Details of any particular characteristics that were noted during

monitoring that may influence the results e.g. activities or incidents

occurring in the Makara Catchment, including correlation to historic

rainfall records.

MEBCMP

11

4 References

Anderson, M.J., 2003. PCO: a FORTRAN computer program for principal coordinate

analysis. Department of Statistics, University of Auckland, New Zealand

Anderson, M.J. 2005. PERMANOVA: a FORTRAN computer program for

permutational multivariate analysis of variance. Department of Statistics,

University of Auckland, New Zealand.

Anderson, M.J., Gorley, R.N., Clarke, K.R. 2008: PERMANOVA+ for PRIMER: Guide

to Software and Statistical Methods. PRIMER-E: Plymouth, UK 217 pp.

Clarke, K.R., Warwick, R.M. 2001: Change in marine communities: an approach to

statistical analysis and interpretation. Natural Environment Research Council,

Plymouth.

Gibbs, M., Hewitt J. 2004: Effects of sedimentation on macrofaunal communities: a

synthesis of research studies for ARC. Auckland Regional Council Technical

Publication 264. 48 pp.

Mead S.T., and T. Haggitt, 2010. State of the Environment Assessment for Makara

Beach, Makara Estuary, Ohau Bay and Oteranga Bay – Wellington coast 2010.

Report prepared for Meridian Energy Limited.

Robertson, B., Stevens, L. 2007: Kapiti, Southwest and South Coasts and Wellington

Harbour. Risk Asessment and Monitoring Recommeendations. A report to

GWRC by Wriggle Ltd. 68pp.

Robertson, B., Stevens, L. 2008: Porirua Harbour Fine Scale Monitoring 2007/2008.

A report to GWRC by Wriggle Ltd.

Taylor, M.J. & Kelly, G.R., 2001. Inanga spawning habitats in the Wellington Region,

and their potential for restoration. NIWA, report prepared for Wellington

Regional Council.

Thrush, S.F., Pridmore, R.D., Hewitt, J.E., Roper, S.D. (1988) Design of an

ecological monitoring programme for the Manukau Harbour. NIWA report to the

Auckland Regional Water Board. Water Quality Centre Consultancy Report No.

7099.

Turner, S. and Riddle, B. 2001: Estuarine Sedimentation and Vegetation –

Management Issues and Monitoring Priorities. Environment Waikato Internal

Series 2001/05. Document #: 686944

MEBCMP

12

MEBCMP

13

Appendix 1 – Makara Estuary Baseline and Construction

Monitoring Plan

6. The consent holder shall engage an appropriately qualified and experienced estuarine ecologist to prepare and submit a Makara Estuary Baseline and Construction Monitoring Plan ("the MEBCMP") to the Manager, Environmental Regulation, Wellington Regional Council, for approval at least 20 working days prior to the proposed start date of the baseline water quality monitoring programme site. (Note: Council will notify the consent holder in writing within ten working days if the 20 working day period cannot be achieved). The ecologist that the consent holder engages shall be to the approval of the Manager, Environmental Regulation, Wellington Regional Council. No bulk earthworks or monitoring shall commence until the MEBCMP is approved. Purpose of the MEBCMP The purpose of the MEBCMP is to monitor the environmental effects of the discharges on the Makara Estuary receiving environments during the construction phase of the of the wind farm. This requirement continues until 12 months after the site is completely stabilised in order to assess any recovery to those environments. Commencement of monitoring The baseline monitoring shall commence at least 6 (six) months prior to bulk earthworks commencing on the Core Site. The MEBCMP must be approved prior to any monitoring commencing. Details to be included in MEBCMP The MEBCMP shall include but not be limited to:

a) A scaled plan(s) that show the following: � the proposed location(s) of monitoring;

� the areas that monitoring will be undertaken over;

b) Details of the following:

� the parameters that will be measured. These parameters shall result in,

at a minimum:

• baseline macrofauna abundance and diversity; • select key taxa being identified from baseline for longer term study

over the remainder of the monitoring period; and • sediment deposition rates i.e. from core or metal plate sampling.

MEBCMP

14

� the technique that will be used to measure the parameters;

� the frequency and duration of monitoring for baseline monitoring and

details of how long it will take to identify the select key taxa;

� the frequency and duration of monitoring once bulk earthworks commence on site;

� the frequency and duration of monitoring once the site is stabilised;

� the overall timeline of monitoring and when this will commence using the above; and

� what details will be provided in a report, prepared by a qualified estuarine ecologist, which is to be submitted to the Manager, Environmental Regulation, Wellington Regional Council. The report shall include, but not be limited to:

• Results of the monitoring undertaken; • Identification of the taxa being surveyed and their relevance/tolerance

in association with the health of the estuarine system; • Comparisons of monitoring results over time and what this indicates in

regards to the health of the estuarine system in each particular monitoring location and as a whole system; and

• Details of any particular characteristics that were noted during monitoring that may influence the results e.g. activities or incidents occurring in the Makara Catchment.

c) How often the reports required above will be submitted to the Manager, Environmental Regulation, Wellington Regional Council.

15

Appendix 2 – Expert Witness Evidence of Shaw Mead for Mill Creek

Environment Court Proceedings

BEFORE THE ENVIRONMENT COURT

AT WELLINGTON ENV-2009-WLG-000060, 61, 62, 63, 65, 67

IN THE MATTER of the Resource Management Act 1991

AND

IN THE MATTER of appeals pursuant to Section 120 of the Act

BETWEEN Meridian Energy Limited

(ENV-2009-WLG-000060)/Applicant

Ohariu Preservation Society

(ENV-2009-WLG-000061)

R P Harley

(ENV-2009-WLG-000062)

A & J Tolo

(ENV-2009-WLG-000063)

Makara Guardians Incorporated Society

(ENV-2009-WLG-000065)

Ngati Wai O Ngati Tangata Whenua

(ENV-2009-WLG-000067)

AND WELLINGTON CITY COUNCIL

First respondent

WELLINGTON REGIONAL COUNCIL

Second respondent

POURIRUA CITY COUNCIL

Third Respondent

STATEMENT OF EVIDENCE OF SHAW TREVOR MEAD ON BEHALF OF

MERIDIAN ENERGY LIMITED

2 JUNE 2010

1

QUALIFICATIONS AND EXPERIENCE

1 My full name is Shaw Trevor Mead .

2 I hold BSc and MSc (Hons) degrees from the University of Auckland (School of Biological Sciences), and a PhD degree from the University of Waikato (Earth Sciences). I am currently an environmental scientist and Managing Director at ASR Ltd, which is a marine consulting and research organisation. I have 15 years experience in marine research and consulting, have 36 peer-reviewed scientific papers, and have solely or jointly produced over 150 technical reports pertaining to coastal oceanography, marine ecology and aquaculture. I have undertaken over a thousand research and consulting SCUBA dives around the coast of New Zealand and led many comprehensive field investigations that have addressed metocean, biological and chemical components of the coastal environment. I am affiliated to the New Zealand Marine Science Society and the New Zealand Coastal Society (IPENZ).

3 I have a background in coastal oceanography, marine ecology and aquaculture. I studied for my MSc degree at the University of Auckland’s Leigh Marine Laboratory, undertaking subtidal research there from 1994 to 1996 directed at the fertilisation success of sea urchins as a basis for the sustainable management and development of the commercial market. The marine ecological components of my Doctorate were directed towards subtidal habitat enhancement of marine structures, while the physical oceanography component was focussed on understanding the effects of coastal bathymetry on wave breaking characteristics using field measurements and hydrodynamic numerical modelling. More recently, I have been involved in a wide range of coastal consulting and research projects that have included the design of coastal structures and developments, and assessments and monitoring of physical and ecological effects of marine construction, coastal erosion control, marine reserves, dredging, outfalls, oil industry, aquaculture ventures and various other coastal and estuarine projects that have included hydrodynamic (waves and currents), sediment transport and dispersion (contaminants, suspended sediments, freshwater, hypersaline water, nutrients, petro-chemicals, etc) modelling.

4 Work I have undertaken of particular relevance with respect to the matters currently before the Court includes:

a) In 2004 and 2005, together with Dr. Tim Haggitt, I undertook ecological and physical process assessments of Oteranga Bay and Ohau Bay as part of the AEE investigations into the construction of landing structures at either of the bays for the delivery of large wind turbine components for Project West Wind. Five technical reports were produced:

• Mead, S. T., and T. Haggitt, 2004. Assessment of Marine

Ecological Effects of the Construction of an Access Berthing Structure at Oteranga Bay, Wellington. Prepared for Meridian Energy Ltd, May 2004.

2

• Mead, S. T., and B. Scarfe, 2004. Assessment of Physical Effects of the Construction of a Jetty at Oteranga Bay, Wellington. Prepared for Meridian Energy Ltd, July 2004

• Mead, S. T., A. Moores and T. Haggitt, 2005. Assessment of Marine Ecological Effects of the Construction of an Access Berthing Structure at Ohau Bay, Wellington. Prepared for Meridian Energy Ltd, May 2005.

• Mead, S. T., K. P. Black, D. Johnson and A. Moores, 2005. Physical Process Investigation and Breakwater Design for Ohau Bay, Wellington: Numerical modelling, Wave Climate Hindcasting and Physical Impact Assessment. Prepared for Meridian Energy Ltd, July 2005.

• Mead, S. T., 2005. Barge Operation Limitations within Ohau Bay. Prepared for Meridian Energy Ltd, July 2005.

The evidence presented at the 2005 hearings (WCC SRN: 131428 GWRC Ref: WGN060001) describes the findings of the marine investigations undertaken at these two bays and present the findings and conclusions obtained from this work.

b) In September 2008, Dr. Haggitt and I repeated a marine ecological survey of Oteranga Bay using the same methodology as used in 2004, so that the results could be compared to the work undertaken pre-Project West Wind construction, with particular emphasis on the ecological health and indications of siltation and impacts caused by silt run-off, as well as a basic assessment of the ecological health of the Makara Estuary mouth. These surveys were undertaken during heavy rain events. However, repeat surveys could not be undertaken in Ohau Bay due to high sea conditions. During the site visit we were also able to make some observations around the existing sediment sources and conditions of the waterways leading to the estuary. The findings of these surveys are presented in Dr. Haggitt’s evidence presented in the 2008 Mill Creek hearings (Haggitt, 2008).

c) In February this year, Dr. Haggitt and I undertook a State of the

Environment assessment of marine communities adjacent to Meridian Energy’s wind farm. The focus of the assessment was to identify any impacts to the communities that may have occurred as a result of sedimentation/silt run-off during the construction phase of the wind farm, located in the adjacent hill country or in the same catchments to these sites.

SUMMARY OF APPROACH TO EVIDENCE TO BE PRESENTED

5 ASR Ltd was retained by Meridian Energy Ltd to undertake marine ecological surveys at four sites located along the southern and western coast situated directly adjacent the hill country (Quartz Hill and Terawhiti Station) that occupies the West Wind wind farm. These sites included Oteranga Bay, Ohau Bay, Makara Beach, and Makara Estuary.

3

6 The aim of the recent surveys was to provide a “State of the Environment” assessment of these locations and, in so doing, identify any impacts to the marine communities associated with the construction phase of Project West Wind, i.e., primarily sedimentation-related impacts from silt-run off (terrigeneous-derived suspended sediment). The point of this assessment was to determine whether or not there is potential for the Mill Creek proposal to adversely impact on the health and functioning of these potential receiving environments.

7 In my evidence I will summarize the findings of the February 2010 marine surveys, and relate these findings to previous surveys of the area and evaluate the biodiversity of the site to a relatively pristine marine environment in New Zealand. The findings of the recent marine surveys are presented in detail as Attachment 1 of this evidence. An important factor that influences the marine ecological communities of these coastal areas is the metocean conditions, i.e. the waves, winds and tides. These have been previously detailed in reports and evidence, and I reiterate them here as they have a profound effect on the findings.

8 I have read the Environment Court’s Code of Conduct for Expert Witnesses and agree to comply with the Code when presenting evidence to the Court. I confirm that the matters addressed in this brief of evidence are within my area of expertise. I can confirm that I have not omitted to consider material facts known to me, which might alter or detract from my opinions expressed within this evidence.

PREVIOUS MARINE SURVEYS

9 Both Oteranga Bay and Ohau Bay were surveyed previously (in 2004 and 2005 respectively) as part of an assessment of potential environmental effects in relation to construction of a temporary berthing structure, also part of Project West Wind. Oteranga Bay was resurveyed again in 2008 during the construction phase of the wind farm to evaluate whether the construction of wind turbines and associated structures were negatively impacting nearshore marine communities through silt run-off.

10 The 2004 and 2005 surveys of Oteranga Bay and Ohau Bay indicated that intertidal regions were composed of mixed shingle/sand with low biological diversity. Large piles of decaying beach-cast algae were present in the higher intertidal and foreshore areas, occupied amphipods, isopods, and kelp flies. Nearshore subtidal cobble and boulder habitat at Oteranga Bay were found to support red turfing algae and coralline paint, whereas larger platform reef habitat supported mixed algal stands. Ohau Bay was found to support similar marine communities to that of Oteranga Bay. Subtidal soft sediment habitat at the two locations was generally species depauperate.

11 The 2008 survey at Oteranga Bay found no evidence of sedimentation-related impacts to the marine communities attributable to silt run-off associated with the construction phase of the wind farm, with no change to the marine communities surveyed between 2004 (pre-construction) and 2008

4

(construction phase) (Haggitt, 2008). It was concluded that the absence of any impact was likely attributable to the physical nature of the marine environment (high currents and wave action) coupled with sediment control practices used during the construction phase.

2010 STATE OF THE ENVIRONMENT MARINE SURVEYS

12 The focus of the recent study was to resurvey marine sites at Oteranga Bay and Ohau Bay where quantitative and qualitative information existed, but also to intensify the sampling of rocky reef habitats as biological communities occupying rocky reefs can be particularly sensitive to sedimentation from silt run-off (Airoldi 2003). For Makara Beach and Makara Estuary no historical data were available, thus the survey represents the first assessment of the ecological state at these locations.

13 Terrigeneous derived sediment entering the marine environment can affect rocky coast organisms and/or assemblages in multiple ways or degrees of severity, including changes in species composition and distribution, inhibition of settlement and recruitment, reduced species diversity/monopolisation of space and weakened competition and/or predation (Airoldi 2003). Thus, concerns that increased run-off due to the construction of the wind farm could have impacted on the local marine ecological communities are valid.

14 The 2010 survey had two main aims:

a) Provide information on the current State of the Environment at Makara Beach, Makara Estuary, Ohau Bay and Oteranga Bay, and;

b) Compare the current survey data with that of previous surveys conducted at Ohau Bay and Oteranga Bay (pre-project West Wind) to identify any impacts to the marine communities that may have occurred.

Methodology

15 At the beach locations, the survey methodology previously employed in 2004, 2005 and 2008 was repeated i.e. quantitative and qualitative data collection in the subtidal and intertidal areas, diver transects and photographic/video recordings. In addition, to provide a finer scale assessment of rocky reef communities that can be adversely affected by silt run-off (e.g. Airoldi 2003; Ford and Anderson; 2005), a sampling technique using 1m2 quadrats was employed. This approach had the added advantage of enabling us to compare the data obtained in the current study to that of other surveys that have been undertaken in the Wellington area, i.e. at sites well outside of the works area (Shears and Babcock, 2003), and to a location that is considered as pristine - Great Barrier Island – (Haggitt and Mead, 2008). Identical sampling techniques to that used at Oteranga Bay and Ohau Bay were also employed at Makara Beach. Details of sampling methods are provided in Attachment 1 and the previous investigations listed above.

5

16 In Makara Estuary, the two main areas of the lower estuary were sampled; the main channel and the intertidal cobble. Five core samples were taken of the soft sediment in the main channel, while 0.25 m2 quadrat samples were sampled in the cobble area. General observations of the upper reaches of the estuary and the Makara River between Makara Beach and Makara Township were also made as part of the assessment.

17 A variety of data comparisons and statistical analysis were applied to the data collected during the recent surveys. At all marine locations surveyed, the biological communities were typical of shallow-water rocky reef communities that have been surveyed elsewhere in the Wellington region (Shears and Babcock 2004) and share commonality with Great Barrier Island (Haggitt and Mead 2008). Subtidal and intertidal soft sediment communities at Ohau Bay and Oteranga Bay in 2010 were also similar to that of surveys undertaken pre Project West Wind, characterised by low taxa diversity.

18 Considering the indicators of sedimentation-related impacts (outlined in detail in Attachment 1) relative to the data collected in 2010 (all locations), 2008, 2005 (Ohau Bay) and 2004 (Oteranga Bay) there is no compelling evidence that marine communities have been affected by terrigeneous derived sediment as:

• Negligible sediment cover was recorded on the rocky reef habitats surveyed out to 6 m deep;

• There was no visible evidence of damage attributable to siltation and smothering of marine communities;

• Macroalgae occurred at high to moderate biomasses at all locations surveyed forming enclosed canopies;

• Macroalgal communities were analogous to that surveyed elsewhere in the Wellington Region and from a pristine shallow-water location at Great Barrier Island, north-eastern New Zealand;

• There were a high density of grazers, particularly paua, at Makara Beach and Ohau Bay;

• Overall there was high biological biodiversity of macroalgae and sessile invertebrates at all locations, and;

• There was no visible change to subtidal soft sediment communities at Oteranga Bay or Ohau Bay between surveys.

19 If sedimentation-related impacts were an issue, it is conceivable that the rocky reef habitats would be characterised by low macroalgal cover, low biological diversity and a high percent cover of sediment on the reefs surveyed. However, this is not the case.

6

20 When undertaking State of the Environment assessments it is important to place biological measurements and observations within the context of the physical environment, as biological communities are strongly influenced by abiotic parameters (currents, wave action, turbidity, etc).

Subtidal and Inter tidal areas

21 As documented in previous reports, the exposed nature of the Wellington Peninsula (specifically the coast of Quartz Hill and Terawhiti Station coast regions) to both waves and wind and the close proximity of the high velocity tidal currents of the Cook Strait combine to suspend and remove any fine silts that may enter the marine environment (which could potentially smother marine life), and maintain a relatively healthy marine biota on the rocky reef in the area. Fine sediments can only settle and smother marine life in sheltered areas, since waves quickly suspend fine sediments (out to hundreds of metres deep when the wave period is long) and currents move the suspended sediments.

22 The regular wave action from both the north and south due to local strong winds that are compressed and accelerated through the Cook Strait, as well as longer period swells from distant sources, prevent the settlement of fine sediments in the bays investigated. For example, at Ohau Bay, the diver survey in 2005 found coarse sands at 14 m deep out near the mouth of the bay. In simple terms, the normal sorting process pushes coarse sediment (i.e. sand and gravel) towards the beach, while fine sediments are moved offshore to settle in deeper water. However, due to the presence of the Cook Strait, the tidal currents are too strong for fine sediments to settle in deeper water off the coast. For example, current speeds of over 5 knots regularly occur off of Oteranga Bay (the Karori Current), and very strong currents also exist off the entrance of Ohau Bay (whirlpools and disturbed waters can be visually observed at this location).

23 While the input of fine sediments into the marine environment from any source is unwanted, due to the exposed nature of the area (to both waves and wind) and the close proximity of the high velocity currents of the Cook Strait, which combine to suspend and remove fine silts which can smother marine life, the rocky reef habitats in the area maintain a relatively healthy marine biota.

24 Another factor to consider is the type of disturbance. Disturbances (such as sediment run-off) are often referred to as either ‘pulse’ or ‘press’ disturbances, with the former occurring intermittently and the latter being a constant disturbance. A second potentially negative impact of water discolouration due to run-off is the lowering and/or prevention of light penetration into the water, which is required for photosynthesis of marine algae (both phytoplankton and seaweeds), which are the primary producers of the marine food web. A permanent flow of discoloured water into the marine environment would result in the reduction of algae in the area and an associated decrease in the biodiversity of marine organisms associated with the reefs. The discharge events are pulse events generally associated with rainfall and are less likely to cause long-term damage.

7

25 The local geology must also be considered to put the potential impacts of wind farm construction into context. As previously described in Dr. Haggitt’s (2008) evidence, in reference to Mr. Mikoz’s “The Dirt Behind Wind Turbines” article where he quotes G. R. Stevens in his book the Rugged Landscape, local “natural” sediment inputs are substantial. Quartz Hill is described as “… the largest relatively uneroded peneplain remnant in the Wellington Region” He continues, “However, many of the minerals in the greywacke rock (called feldspar and micas) are relatively soft and readily decompose to form mud”. This describes the natural erosion that occurs on the Wellington Peninsula, which was evident in areas that have not been recently disturbed by earth works – during the rainfall last week (11 September 2008), muddy water was observed running off these areas (e.g. from the undisturbed land along the Transpower access road to Oteranga Bay). Indeed, analysis of historical aerial photographs of Ohau Bay indicate that on the Western side of the bay, some 270,000 m3 of sediment has been eroded since 1941 (or some 4,300 m3/year). When this kind of erosion rate is applied to the whole of the greywacke Wellington Peninsula, it is clear that very large amounts of sediment are naturally entering the marine environment each year. The pooled silt in the streams observed at both Oteranga Bay and Ohau Bay in 2004/2005 (i.e. pre-project) is also an indicator of the natural erosion of the Peninsula. As stated earlier, while the input of fine sediments into the marine environment from any source is unwanted, as a result of the conditions in this area, the reefal communities maintain a relatively healthy marine biota.

26 When the exposed nature of the marine environment in the area, the pulse nature of sediment inputs and the local erosive geology of the area are considered together, it becomes clear as to why there has been no measureable impact on the marine ecology due to the development of the wind farm on the Wellington Peninsula.

Makara Estuary

27 While subtidal and intertidal marine locations at Makara Beach showed no evidence for sedimentation-related impacts, the same could not be said for Makara Estuary. At the mouth of the Makara Estuary, fragments of drift algae were apparent on the immediate substratum. Directly beneath the drift algae the sediment was extremely anoxic down to a depth of >25cm. In the middle of estuary proper, the substratum was composed of extremely fine anoxic mud that extended to a depth of >30 cm. In the shallows of the estuary, the anoxic mud layer was approximately 20 cm deep with small cobbles/pebbles occurring directly beneath.

28 Marine taxa were extremely sparse within the estuary. Oligochaete tube worm mats were conspicuous covering large areas of the substratum in the main channel of the estuary, and small shrimp (unidentified) were also observed. No other organisms were sampled or observed in the estuary channel, nor were any fish encountered. The shallow intertidal cobble region of the estuary supported mats of Ulva spp and the occasional porcelain half crab Petrolisthes elongatus. This region of the estuary also had very low biological diversity.

8

Slabs of concrete and plastic litter were also a feature of the foreshore at the mouth of the estuary.

29 The low biological diversity, extremely deep sediment anoxic layer within the main channel and shallower regions and overall appearance of this estuary - typified by eroding banks and exotic weeds - suggests it is a heavily impacted ecosystem. The depth of the anoxic sediment layer alone indicates that sedimentation has been an issue in the estuary for some considerable time. As stated above, the only dominant taxa were Oligochaete worm mats that covered large areas of the main channel. Patterns of this nature are indicative of polluted/impacted ecosystems, i.e., dominance of one or several taxa and low biological diversity (Gibbs and Hewitt 2004). There was no evidence of any shellfish or gastropod taxa common to estuarine systems (Morton and Millar 1968), nor were there any shell remnants in sediment samples that would suggest the estuary supported such taxa in the past.

30 Observations made in 2008 (during construction of the wind turbines) indicated that the catchments that lead to the Makara Estuary were highly modified, there was very little native vegetation or riparian vegetation of any type, the banks of the estuary and Makara River were actively eroding and in many areas livestock were grazing up to the water’s edge. These observations still hold true for the current state of the estuary. Moreover, riparian plantings observed in 2008, and viewed as a positive initiative, are now covered in weeds and many plants are in a poor state.

31 Monitoring of the Makara River, which feeds directly into the Makara Estuary, is routinely undertaken by the Greater Wellington Council as part of their State of the Environment Monitoring. It is worth noting that for the 2000/2001 survey, well before construction of any wind turbines or associated infrastructure, the Makara River was classified as moderately polluted, with the Regional Freshwater Plan suggesting the river needed enhancement (GWRC 2001). In 2008/2009 based on Water Quality Index grades, the Makara River was described as having “fair” water quality, but was considered degraded because the median value of at least one of the six physico-chemical or microbiological variables tested exceeded ANZECC 2000 guideline values (GWRC 2009). For the Makara River site these were E-coli, water clarity, and dissolved reactive phosphorus (DRP). These results indicate that multiple activities are impacting the river and ultimately the Makara Estuary.

32 Attributing the current state of the estuary as being due to a single activity such as the construction of the wind farm is questionable at best because of:

a) the degraded nature of the estuary which was evident in 2008 during construction of the wind farm;

b) construction of the wind farm required sediment control and was the only activity in the receiving catchments where sediment control was employed;

c) there was no sign of shellfish or shellfish remnants in sediment samples that would indicate that sedimentation was a recent impact, and;

9

d) there are myriad activities, due to their proximity to the estuary and Makara River that are likely to have impacted the estuary through space and time (farming and associated erosion, stock wandering through waterways, reclamation, forestry etc).

SUMMARY

33 State of the Environment assessments made for Makara Beach, Makara Estuary, Ohau Bay and Oteranga Bay presented in this report provide a snap-shot of the current ecological state of these locations, particularly as temporal monitoring data are generally lacking. Fortunately much of the data collected in this survey could be compared to other studies providing a broader evaluation of the ecological state. Data suggests that there has been no impact to the marine communities from construction of Meridian Energy’s West Wind wind farm. While not a necessity, it would be desirable to repeat the marine surveys again (i.e., in 12 months time) if only to compare temporal trends and build on the data collected to date should the site be developed further.

34 The survey of the Makara Estuary revealed that it is a heavily impacted system and in a very poor state. Repeat surveys undertaken by the Greater Wellington Council indicate that the Makara River feeding into the estuary is also degraded and was well before construction of the wind farm commenced. In light of this information, together with the fact that construction of the West Wind wind farm required sediment control and much of the farmland surrounding the estuary and Makara River is actively eroding it is very unlikely that the degraded nature of the estuary is due to the construction of the wind farm. Due to the absence of any monitoring within the estuary proper it is not possible to comment on the temporal pattern of degradation that has taken place. Given the depth of the sediment anoxic layer, very low biological diversity and absence of any marine taxa such as shellfish and gastropods including shell remnants within the estuary, it is likely that this has been a lengthy process that has occurred over a number of decades.

35 Given the severely degraded nature of the Makara Estuary it is presently considered pointless to undertake monitoring unless a concerted effort is made to enhance the estuary and waterways leading to it. This could begin through intensive riparian planting followed by better land use practices, as has occurred elsewhere in New Zealand. Because water quality monitoring indicates that multiple activities have in the past and continue to impact the Makara River and ultimately the estuary, this would require a concerted effort across multiple sectors.

Shaw Mead

2 June 2010

1

Attachment 1

State of the Environment Assessment for Makara Beach, Makara

Estuary, Ohau Bay and Oteranga Bay – Wellington coast 2010

Prepared by

Shaw Mead BSc, MSc (Hons), PhD

Tim Haggitt BSc, MSc (Hons) PhD (Coastal and Aquatic Systems Ltd)

1

Executive Summary

• A State of the Environment assessment of marine communities was undertaken in February 2010 at Makara Beach, Makara Estuary, Ohau Bay, and Oteranga Bay on the southern and western Wellington coast. The focus of the assessment was to identify any impacts to the marine communities that may have occurred as a result of sedimentation/silt run-off during the construction phase of Meridian Energy’s wind farm (Project West Wind), situated in the adjacent hill country to these locations. Both Ohau Bay and Oteranga Bay had been surveyed previously prior to the construction of the wind farm.

• The survey placed a strong emphasis on quantifying rocky reef communities, as these are likely to be strongly impacted by silt-run-off (suspended sediments) and due to the depauperate nature of the soft sediments in the Bays. Rocky reef habitats surveyed at each location was characterised by rich macroalgal assemblages and diverse sessile and mobile invertebrate communities, showing similarity to other parts of the Wellington coast and pristine locations such as Great Barrier Island (north-eastern New Zealand).

• Subtidal soft sediment and intertidal soft sediment communities had low biological diversity, reflecting the exposed nature of the locations and matching the findings of earlier studies.

• There was no evidence that subtidal marine communities at Makara Beach, Ohau Bay, or Oteranga Bay have been affected by terrigeneous-derived sediment. This is likely due to the physical nature of the marine environment at these locations (high currents and wave action) coupled with sediment control practices employed during the construction phase of Project West Wind.

• The survey of the Makara Estuary revealed that it is heavily impacted by sedimentation and consequently extremely degraded with low biological diversity and deep (> 30 cm) anoxic sediments present throughout the estuary.

• Attributing the impacted state of the estuary to construction of the wind farm is considered tenuous as: there is extensive erosion surrounding both the estuary and Makara River that feeds into the estuary; the depth of the anoxic sediment suggests that sedimentation has been impacting the estuary for some time (years); the Makara River has been classified as degraded well before the construction of the wind farm; and, sediment control practices were employed during the construction phase of the wind farm. In addition,

2

observations during heavy rainfall in September 2008 (i.e. during the wind farm construction phase) indicated that heavy silt loads were being delivered from the northern catchment rather than those incorporating the wind farm.

31266078:616093

Preamble ASR Ltd was commissioned by Meridian Energy Ltd to undertake marine ecological surveys at four locations situated along the southern and western coast situated directly adjacent the hill country (Quartz Hill and Terawhiti Station) that occupies the Meridian Energy wind farm. These locations included Oteranga Bay, Ohau Bay, Makara Beach, and Makara Estuary. The aim of the survey was to provide a “State of the Environment” assessment of these locations and, in so doing, identify any impacts to the marine communities that could be associated with the construction phase of Project West Wind, i.e.,- primarily sedimentation-related impacts from silt-run off (terrigeneous-derived sediment). Previous surveys Both Oteranga Bay and Ohau Bay have been surveyed previously (in 2004 and 2005 respectively), as part of an assessment of potential environmental effects in relation to construction of a temporary berthing structure, also part of Project West Wind (Mead and Haggitt 2004, Mead et al. 2005). Oteranga Bay was resurveyed again in 2008 during the construction phase of the wind farm to evaluate whether the construction of wind turbines and associated structures were negatively impacting nearshore marine communities through silt run-off (Haggitt 2008). The 2004 and 2005 surveys of Oteranga Bay and Ohau Bay indicated that intertidal regions were composed of mixed shingle/sand with low biological diversity with large piles of decaying beach-cast algae present in the higher intertidal and foreshore areas supporting amphipods, isopods, and kelp flies. Neashore subtidal cobble and boulder habitat at Oteranga Bay supported red turfing algae and coralline paint, whereas larger platform reef habitat supported mixed algal stands (Mead and Haggitt 2004). Ohau Bay was typified by similar intertidal and subtidal biological communities to that of Oteranga Bay (Mead et al. 2005). Subtidal soft sediment habitat at the two locations was generally species depauperate with amphipods the most abundant taxa. . The 2008 survey at Oteranga Bay found no evidence of sedimentation-related impacts to the marine communities attributable to silt run-off associated with the construction phase of the Wind Farm with no change to the marine communities surveyed between 2004 (pre-construction) and 2008 (construction phase) (Haggitt 2008). It was concluded that the absence of any impact was attributable to the physical nature of the marine environment (high currents and wave action) coupled with sediment control practices used during the construction phase. Current survey

Meridian Energy Ltd has commissioned the present study in order to determine the current state of the marine environments at Makara Beach and Makara Estuary, Ohau Bay, and Oteranga Bay and to identify any potential impacts post Project West Wind. The focus of the study was to resurvey marine sites at Oteranga Bay and Ohau Bay where quantitative and qualitative information existed, but also to intensify the sampling of rocky reef habitats, primarily as biological communities occupying rocky reefs can be particularly sensitive to sedimentation from silt run-off (Airoldi 2003). For Makara Beach and Makara Estuary no historical data were available, thus the current survey represents the first assessment of the ecological state of the marine communities at these locations.

Methodology The 2010 survey had 2 main aims:

1) Provide information on the current State of the Environment at Makara Beach, Makara Estuary, Ohau Bay and Oteranga Bay.

2) Where possible, compare the current survey data with that of previous surveys conducted at Ohau Bay and Oteranga Bay (pre Project West Wind) to identify any impacts to the marine communities that may have occurred resulting from construction of the wind farm.

Oteranga Bay, Ohau Bay, Makara Beach On 24 February 2010, similar surveys were undertaken within Oteranga Bay and Ohau Bay to that of Mead and Haggitt (2004) and Mead et al. (2005) consisting of intertidal and subtidal qualitative and quantitative sampling (Fig. 2.1a-c). To provide a finer scale assessment of rocky reef communities, which can be adversely affected by silt run-off (see Airoldi 2003, Ford and Anderson 2005), an additional sampling technique using 1m2 quadrats was employed. This approach had the added advantage of enabling us to compared the data obtained in the current study to that of other marine community surveys that have been undertaken in the Wellington area, i.e., well outside of the works area (Shears and Babcock 2004) and to a location that is considered as pristine - Great Barrier Island – (Haggitt and Mead 2008, www.arc.govt.nz 2009). Identical sampling techniques to that used at Oteranga Bay and Ohau Bay were also employed at Makara Beach; however no historical survey data exist for this location.

Subtidal sampling To mirror the surveys done in 2004, 2005 and 2008 (Oteranga Bay only), a total of three subtidal transects were sampled at both Oteranga Bay and Ohau Bay. All sampling was carried out using SCUBA. Along each transect details of the substrate and presence of any conspicuous surface dwelling invertebrates and fish species were recorded. In addition, observational dives were recorded with underwater video and camera around the greater area of Ohau Bay and Oteranga Bay (Fig. 2.1). For any rocky reef habitat encountered the presence of conspicuous macroalgae and invertebrate taxa were recorded. At Makara Beach three subtidal transects were also sampled (as above).

Soft sediment sampling A total of 9 soft-sediment subtidal samples were collected via SCUBA using a 410 x 410 x 200 mm deep stainless steel sampler (approximately 1/6 m2 surface area). All living species found within the quadrat were recorded. Representative specimens were then preserved in 5% buffered formalin in seawater and sent to Leigh Marine Laboratory for identification. In the

laboratory, samples were rinsed through a 0.5 mm sieve and allowed to de-gas overnight. Specimens were then identified to the lowest taxonomic group possible, and stored in 70% ethanol. Note: Investigating offshore impacts (e.g., the suggestion of smothering of deep-water shellfish beds) were outside the scope of our investigations.

Additional rocky reef sampling Because we would expect that largest impacts from sedimentation/silt run-off would be evident within rocky reef communities (see Airoldi 2003) further quadrat sampling was undertaken on this habitat type at Ohau Bay, Oteranga Bay and Makara Beach (Fig. 2.1a-c). Sampling followed the general methodologies of Shears and Babcock (2004) for rocky reef community sampling using a 1m2 quadrat. Each quadrat was sampled by counting and measuring all large brown macroalgae and invertebrate taxa occurring within (see below).

Macroalgae All large brown macroalgae and turfing algal species within each quadrat were counted, measured, and their percent cover estimated. The total length of all brown algae was measured to ± 5 cm and individual measurements of stipe length and primary lamina length were made to ± 5 cm for the laminarian algae Ecklonia radiata and Lessonia variegata. Macroalgal length measurements were then converted to biomass based on length-dry weight relationships presented in Shears (2003) and Shears and Babcock (2004) (see Table 2.1). Table 2.2 . Algal species and functional groups used in analysis along with length-weight and/or percent cover-weight relationships for biomass estimates. y = dry weight (g), x = total length (cm), SL = stipe length (cm) and LL = laminae length (cm). Data are compiled from Shears (2003); Shears and Babcock (2004).

Brown algae

Carpophyllum angustifolium y = 0.068x – 0.27

C. maschalocarpum ln(y) = 1.764ln(x) – 4.311

C. plumosum ln(y) = 1.472ln(x) – 3.850

C. flexuosum ln(y) = 2.049ln(x) – 5.251

Xiphophora chondrophylla y = 1.786x – 4.171

Ecklonia radiata – Stipe ln(y) = 1.671ln(SL) –3.787

– Laminae ln(y) = 1.177ln(SL × LL) – 3.879

Sargassum sinclairii y = 0.075x + 0.124

Landsburgia quercifolia ln(y) = 1.971ln(x) – 5.058

Lessonia variegata ln(y) = 1.677ln(x) - 5.537

Small brown algae ln(y) = 2.587ln(x) – 6.443

e.g. Zonaria turneriana 1% = 2.5 g

Carpomitra costata ln(y) = 1.735ln(x) - 5.856

Brown turf, e.g. Distromium, Dictyota spp. 1% = 1.5 g

Brown encrusting, e.g. Ralfsia 1% = 0.1 g

Red algae

Osmundaria colensoi ln(y) = 1.720 ln(x) – 3.379, 1% = 22.9 g

Pterocladia lucida ln(y) = 1.963 ln(x) – 5.076 0., 1% = 10.0 g

Melanthalia abscissa ln(y) = 1.775 ln(x) – 4.247

Red foliose, e.g. Plocamium spp. ln(y) = 2.649 ln(x) – 8.812

Red turfing (< 5 cm), e.g. Champia spp. 1% = 1.7 g

Coralline turf, e.g. Corallina officinalis 1% = 4.5 g

Crustose corallines 1% = 0.1 g

Red encrusting 1% = 0.1 g

Green algae

Caulerpa flexilis 1% = 4.7 g

Codium convolutum 1% = 4.7 g

Others, e.g. Ulva sp. 1% = 1.7 g

Filamentous algae 1% = 0.2 g

Encrusting species

The primary (substratum) percent cover of foliose algae, turfing algae, encrusting algal species, encrusting invertebrates (e.g., sponges and ascidians) as well as sediment and sand cover were recorded in each 1m2 quadrat using a visual estimation technique (see Shears and Babcock 2004). Briefly, quadrats were divided into quarters (1/4 =25 %) to assist in estimating covers of dominant forms, while the covers of minor forms were estimated on the basis that a 10 x 10 cm area equates to 1 % cover. This technique is considered to be the most suitable for this study as it is efficient and ensures that the cover of all minor forms are recorded, unlike point-intercept methods. Sub-samples of any unidentifiable species were taken, preserved, and then identified at the Leigh Marine Laboratory.

Urchins All urchins occurring within each 1m2 quadrat were counted and their test diameter measured to the nearest 5 mm.

Molluscs All molluscs on the substratum and on macroalgae within each 1m2 quadrat were counted and the largest shell dimension (width or length) for each species measured. For example, shell width was measured for Cookia sulcata, whereas shell height was measured for Cantharidus purpureus and total length was measured for paua (Haliotis species).

Environmental variables The percent cover of selected environmental variables including rock type (see below) and the percent cover of sand/shingle and sediment were also recorded.

Rock type The nature of the rock type within each permanent quadrat was recorded based on 5 categories:

• Low lying platform reef; • Boulder reef; • Platform and boulder reef mix; • Cobbles; • Complex platform reef characterised by overhangs and crevices.

Note: All animal taxa enumerated in the survey were checked using ASR Ltd identification guides and the New Zealand Inventory of Biodiversity (Gordon 2009).

Intertidal sampling Intertidal sampling was undertaken at 5 sites at Oteranga Bay and 5 sites at Ohau Bay in the general vicinity of previous sampling events. At Makara Beach 5 sites adjacent the estuary mouth extending in a southern direction were also sampled (Fig. 2.1a-c). At each site, one 410 x 410 x 200 mm deep, sample was taken and processed (as above). Data analysis Unless otherwise stated, means of dominant taxa are given ± their associated standard error (SE). The biodiversity of rocky reef habitats sampled within a location was measured based on taxa richness, i.e., the total number of

species in a given sample or area. Comparisons of macroalgal biomasses and macroalgal community structure are also made with data collected from Wellington by Shears and Babcock (2004).

Multivariate ordination Variation in macroalgal species composition based on biomasses among quadrats for each location was investigated using principal coordinates analysis based on fourth-root transformed data and Bray-Curtis similarities using the PCO program of Anderson (2003). Data from a pristine location on Great Barrier Island, north-eastern New Zealand (Haggitt and Mead 2008) were analysed in the same way to use as a reference point. Differences in algal communities among locations were also tested using non-parametric multivariate analysis of variance (PER-MANOVA) (Anderson, 2005) based on fourth-root transformed data and Bray-Curtis similarities. The factor “Location” was treated as a random factoring the analysis. Pair-wise a posteriori comparisons were also made to investigate which locations were statistically different from each other. Makara Estuary Two main regions of the Makara Estuary, the main channel region and intertidal cobble region (Fig. 2.1d) were sampled on 24 February 2010. For the main channel region 5 core samples (50 mm diameter down to a depth of 10cm) were taken. Samples were rinsed through a 0.5 mm sieve were then preserved in 5% buffered formalin in seawater and sent to Leigh Marine Laboratory for identification. In addition to core samples, observations of the sediment surface and sediment characteristics were also made. As the estuary sediments were found to be extremely anoxic, the depth of the anoxic layer was routinely measured using a stainless steel ruler (50 cm length). The cobble habitat characteristic of the foreshore of the estuary was sampled with five haphazardly placed 0.25m2 quadrats. All organisms occurring within each quadrat were recorded. Individual cobbles were also turned over (and replaced) to investigate the presence of organisms beneath. General observations of the upper reaches of the estuary and the Makara River between Makara Beach and Makara Township were also made as part of the assessment.

Figure. 2.1a Sample areas at Makara Beach. White lines denote observational transects and soft sediment sampling transects; blue box denotes wider observational survey area; red oval denotes rocky reef survey area (adjacent to the Estuary entrance); orange points denote intertidal sampling sites.

Figure. 2.1b Sample areas at Ohau Bay. White lines denote observational transects and soft sediment sampling transects; blue box denotes wider observational survey area; red oval denotes rocky reef survey area; orange points denote intertidal sampling sites.

Figure. 2.1c Sample areas at Oteranga Bay. White lines denote observational transects and soft sediment sampling transects; blue box denotes wider observational survey area; red oval denotes rocky reef survey area; orange points denote intertidal sampling sites.

Figure. 2.1d Sample areas at Makara Estuary. Blue box denotes intertidal cobble sampling area; red oval denotes main subtidal channel sampling area. Orange points denote sites where core samples were taken.

RESULTS General descriptions Makara Beach Subtidal rocky reef The rocky reef habitat on the northern side of Makara Beach consisted of cobble and small boulder habitat extending approximately 15-20m in a south-west direction before terminating in sand and mixed gravel habitat in approximately 4-5m depth (MLWS). Sand was common to all quadrats (Fig. 2.1), but was generally < 2 % of the total area and fine sediment that would be attributable to silt run-off was negligible. The macroalgal community at Makara Beach, reflected in biomasses (Fig. 3.1), was dominated by Carpophyllum maschalocarpum intermixed with sporadic Carpophyllum flexuosum and Lessonia variegata. Sub-canopy macroalgal species included Carpomitra costata, Glossophora spp., Codium convolutum, Padina australis, Ralfsia sp, Pterocladia lucida, Gigatina spp, articulated coralline turf, crustose coralline algae (CCA), and Zonaria turneriana. Of all taxa quantified, CCA and coralline turf had the highest percent covers (Fig. 2.1). Mats of the green alga Caulerpa flexis were also observed at the reef/soft-sediment interface, but were not enumerated in sample quadrats. Mobile invertebrates on the substratum were typified by the common urchin Evechinus chloroticus, the eleven arm starfish Coscinasterias muricata, the catseye gastropod Turbo smaragdus, the cooks turban Cookia sulcata, the green topshell Trochus viridis, paua Haliotis iris, the wandering anemone Phlyctenactis tuberculosa, cushion starfish Patiriella regularis, the black chiton Scutus breviculus, and the dahlia anemone Isocradactis magna. Of these taxa, paua were particularly abundant occurring at approximately 8 individuals per m2 (Fig. 2.2). Size frequency data (Fig. 2.3) indicate that the sample population was comprised of both sub-legal (< 120 mm) and legal-sized individuals (>120 mm), indicative of a healthy population. Common fish taxa associated with rocky reef habitat included the eagle ray Myliobatis tenuicaudactus, sweep Scorpis lineolatus, hiwihiwi Chrironemus marmoratus, banded wrasse Notolabrus fucicola, spotty Notolabrus celidotus, variable triplefin Forsterygion varium, and the common triplefin Forsterygion lapillum. Mullet were observed in the sandy shallows between rocky reef habitat and the estuary mouth at high tide. Subtidal soft sediment The subtidal soft sediment habitat sampled was generally species depauperate with 4 out of 9 samples containing living organisms. Of these, three samples contained lysianassid amphipods and ceramcaens. The remaining sample, taken close to the reef edge, contained 2 hermit crabs (Appendix 1).

Intertidal soft sediment Intertidal soft sediment samples were all species depauperate, with no living organisms occurring. In all samples an anoxic layer of sediment was encountered at varying depths (5-10 cm) below the sediment surface. Large piles of beach-cast algae were observed on the beach. Common taxa included Carpophyllum maschalocarpum, Carpophyllum flexuosum, Lessonia variegata, Ecklonia radiata, and Durvillea antarctica. Amphipods and isopods were associated with these beach-cast piles as was the kelp fly Chaetocoelopa spp.

Site

Makara Beach Ohau Bay Oteranga Bay

Alg

al b

iom

ass

(g m

-2 +

SE

)

0

200

400

600

800

EckloniaC. maschalocarpumC. flexuosumLandsburgiaLessoniaCaulerpa

Site


Sus

trat

um c

over

(%

m-2

+S

E)

0

5

10

15

20

25

30

35

40

45

50

55

60

65

70 CCACoralline turfRedsGreensSmall brownBareSpongeAscidianSand

A

B

Figure. 3.1 Patterns in rocky reef benthic community structure at Makara Beach, Ohau Bay

and Oteranga Bay based on: A) Macroalgal biomasses; and, B) percent cover of dominant sub-canopy algae and algal groups (Reds, Greens, Small brown), sessile invertebrate groups (Sponge and Ascidian), and physical variables (sand and bare rock).

Figure 3.2. Abundance of paua (Haliotis iris) at Makara Beach, Oteranga Bay and Ohau Bay.

Haliotis iris (Paua)

02468

1012141618

Fre

quen

cy

02468

1012141618

Size (mm)

40 50 60 70 80 90 100 110 120 130 140

02468

1012141618

Makara Beach

Ohau Bay

Oteranga Bay

n=79

n=50

n=35

Figure 3.3. Size frequency distribution of paua (Haliotis iris) at Makara Beach, Ohau Bay and

Oteranga Bay.

Ohau Bay Subtidal rocky reef Rocky reef habitat at the northern end of Ohau Bay was comprised of small cobbles and low lying platform reef that terminated in sand at approximately 5m depth (MLWS). Sand patches within quadrats were < 2% of the total quadrat area (Fig. 3.1) and sediment/silt levels were negligible. Based on biomasses, the fucalean algae Carpophyllum flexuosum and Carpophyllum maschalocarpum were the dominant canopy species (Fig. 3.1) with Lessonia variegate patchily distributed. Understory algal assemblages were particularly diverse being comprised of large mats of Caulerpa racemosa and Caulerpa flexilis and smaller patches of Carpomitra costata, Glossophora spp., Codium convolutum, Padina australis, Ralfsia sp., Pterocladia lucida, Gigatina spp, crustose coralline algae (CCA), Zonaria turneriana, and Plocamium spp. Both CCA and coralline turf had the highest percent cover of all understorey taxa (Fig. 3.2). Sessile invertebrate taxa were particularly diverse within Ohau Bay. Common sponge taxa included the golfball sponges Tethya ingalli, Tethya aurantium, the boring sponge Cliona celata, Polymastia granulosa, Ciocalypta polymastia and Dysidea sp. Ascidians were represented by Chemidocarpa biocornuta, Asterocarpa coerulea, and patches of Aplidium spp. Anemones were characterised by Isocradactis magna, Actinthoe albocincta, and the jewel anemone Corynactis haddoni. The bryozoan Catenicellidae spp. was also abundant in several quadrats. As for Makara Beach, paua (Haliotus iris) were the numerically dominant mollusc taxa occurring at approximately 6 individuals per m2 with sub-legal and legal-sized individuals present (Fig 3.2 & 3.3). Gastropods were represented by Cookia sulcata, Turbo smaragdus, and Trochus viridis. A similar suite of reef fish occurred at Ohau Bay to that of Makara Beach. Common taxa included banded wrasse Notolabrus fucicola, spotty Notolabrus celidotus, the variable triplefin Forsterygion varium, the common triplefin Forsterygion lapillum, the oblique-swimming triplefin Oliquichthys maryannae and red moki Cheilodactylus spectabilis. Subtidal soft sediment Lysianassid and Phoxocephalid amphipods were the dominant taxa occurring in 5 of the 9 samples (5-10 individuals per sample). Other taxa included the polychaete worms Orbina papillosa (2 individuals in 1 sample) and Scolplos cylindifer (1 individual in 1 sample) and the gastropod Cominella glandiformis (1 individual in 2 samples) (refer to Appendix 1 for taxa lists). In subtidal soft sediment areas the eagle ray Myliobatis tenuicaudactus and the short-tailed stingray Dasyatis brevicaudata were very common. A large school of tarakihi Nemadactylus macropterus were observed in deeper water (approximately 9m depth MLWS) adjacent low-lying reef.

Intertidal soft sediment Intertidal soft-sediment samples were, as for Makara Beach, species depauperate with no living organisms occurring. Similarly, an anoxic sediment layer occurred in all soft-sediment samples - between 5 to 15 cm depth from the sediment surface. Comparison between surveys The subtidal and intertidal surveys undertaken in the current survey for the most part matched the survey undertaken in 2005 (Mead et al. 2005) with a similar suite of taxa occurring on the rocky reef substratum and within the subtidal soft sediment habitat (see Appendix 1). Several subtidal soft sediment taxa that were enumerated in 2005 were not present in the 2010 survey including the amphipod Ampithoe hinatore, Orbinid and Spinoid polychaete worms and the gastropods Diloma subrostratum and Cantharidella sp. The presence/absence of certain species between surveys is likely to reflect the variable nature of soft sediment macrofaunal communities in general, which are notoriously patchy over small spatial scales (Morrisey et al. 1992). Oteranga Bay Subtidal rocky reef Subtidal rocky reef at the western end of Oteranga Bay was characterised by extensive cobble habitat in the nearshore which gave way to more-stable low-lying platform reef further offshore. Cobble habitat was characterised by thick covers of brown algae including Cystophora torulosa, Halopteris spp, and Zonaria turneriana intermixed with green algal mats comprised of Ulva spp, Caulerpa flexis, Caulerpa racemosa, and Chaetomorpha spp. On the stable low-lying platform reef different macroalgal assemblages occurred to that of the nearshore cobble habitat. These were largely mixed algal mosaics comprised of canopy forming Carpophyllum maschalocarpum, Carpophyllum flexuosum, Cystophora torulosa, Lessonia variegata, Marginariella spp, Sargassum sinclairii, and Landsburgia quercifolia. Common understory taxa were Zonaria turneriana, Glossophora spp, Pterocladia lucida, Codium convolutum, Padina australis, Dictyota sp, Ralfsia sp, Gigatina spp, and Caulerpa flexis. As for Makara Beach and Ohau Bay crustose coralline algae (CCA) had the highest percent cover of all taxa (Fig. 3.1). Sponges, ascidians, anemones and bryozoans were only encountered on the platform reef characteristic of deeper-water, highlighting the unstable nature of the cobble habitat within the bay being unable to support these type of communities. Common taxa were the sponges Tethya ingalli, Tethya aurantium, and Dysidea sp and ascidians Chemidocarpa biocornuta, Asterocarpa coerulea, and Aplidium spp. Anemones were represented by Isocradactis magna, and Actinthoe albocincta.

Fish taxa associated with rocky reef showed commonality with Makara Beach and Ohau Bay with hiwihiwi Chrironemus marmoratus, banded wrasse Notolabrus fucicola, red moki Cheilodactylus spectabilis, spotty Notolabrus celidotus, and the variable triplefin Forsterygion varium all common. On the sand habitat in the middle of the bay a large school of trevally Psuedocaranax dentex were observed. The eagle ray Myliobatis tenuicaudactus were common adjacent reef habitat. Subtidal soft sediment samples A total of 6 out of 9 soft sediment subtidal samples contained living organisms. These were numerically dominated by Lysianassid and Phoxocephalid amphipods and cermaceans, that occurred in all 6 samples. One sample contained 2 individuals of the polychaete worm Orbina papillosa and 1 brittle star (Ophiuroidea) (Appendix 1). Intertidal soft sediment Mirroring the intertidal environment of Makara Beach and Ohau Bay, and past surveys at Oteranga Bay, intertidal soft sediment samples contained no living taxa. Again an anoxic layer was present in all samples varying in depth among samples (5-15 cm depth below the surface). Beach-cast seaweed was also abundant within the intertidal region typified by taxa found in the subtidal survey. Comparison between surveys As for Ohau Bay, the subtidal and intertidal surveys undertaken in 2010 at Oteranga Bay were analogous to the 2004 survey (Mead and Haggitt 2004) with the same taxa occurring on the rocky reef substratum and broadly similar taxa occurring within the subtidal soft sediment habitat (see Appendix 1). Subtidal soft sediment taxa that were enumerated in 2004 that were not present in the 2010 survey included the amphipod Ampithoe hinatore, the pea crab Pinnotheres spp and the gastropod Diloma subrostratum. Similarly, several taxa were present in the 2010 survey that were not encountered in the 2004 survey including brittlestars and cermaceans. Again these differences are most-probably reflective of the variable nature of soft sediment macrofaunal communities in general. Comparison among locations Macroalgae Multivariate analysis, represented by a PCO ordination based on macroalgal biomasses (22 taxa) for Makara Beach, Ohau Bay, and Oteranga Bay is presented in Figure 3.4. The ordination indicates that while the macroalgal assemblages within individual quadrats share some commonality among the locations (e.g., O9, Ot8 and M8) differences are also apparent. For example, sample quadrats for Makara Beach and Ohau Bay generally appear to the left of the ordination negatively associated with PCO axis 1 and positively associated with PCO axis 2. Oteranga Bay quadrats were generally located to middle of the ordination. Of particular note are the Oteranga Bay quadrats

Ot1, Ot2 and Ot3 which all group to the right of the ordination away from the main cluster of points. These sites were all cobble habitat and reflect the difference in macroalgal assemblages associated with this habitat type.

PCO Axis 1 (27.74 %)

-40 -20 0 20 40

PC

O a

xis

2 (1

9.87

%)

-40

-20

0

20

40

O1

O2

O3 O4

O5

O6

O7

O8

O9

Ot1

Ot2

Ot3

Ot4Ot5

Ot6

Ot7

Ot8Ot9

M1

M2

M3

M4

M5 M6

M7

M8

M9

GB1

GB2GB3GB4

GB5GB6

GB7

GB8GB9

GB10

Makara Beach (M)Ohau Bay (O)Oteranga Bay (Ot)Great Barrier Island (GB)

Figure 3.4. Principal coordinates analysis of macroalgal community structure based on

22 taxa (fourth root transformed biomass) for Makara Beach (M), Ohau Bay (O), Oteranga Bay (Ot), and Great Barrier Island (GB). Data for GB are from Haggitt and Mead (2008). Points denote individual quadrats for each location surveyed.

Comparison with the south Wellington Coast (Shears and Babcock 2004) Macroalgal assemblages (Fig. 3.1) showed general commonality with that of Shears and Babcock (2004) for the southern Wellington coast (Fig. 3.5). In that study, macroalgal assemblages at < 2m depth and between 4-6m depth (depth ranges comparable to this study) were typified by mixed algal stands by Carpophyllum maschalocarpum, Ecklonia radiata, Lessonia variegate, Marginariella spp, Landsburgia quercifolia and Caulerpa flexis. Crustose coralline algae and coralline turf were also dominant components of the understorey (Fig.3.5). When placed in a biogeographical context Shears and Babcock (2004) suggest that the algal communities of the south coast of Wellington share a number of similarities with northern North Island locations, but tend to be more similar to southern localities, particularly Kaikoura.

Figure 3.5. Patterns in rocky reef benthic community structure in Wellington. Source:

Shears and Babcock (2004).

GBI

Alg

al b

iom

ass

(g m

-2 +

SE

)

0

100

200

300

400

500

EckloniaC. maschalocarpumC. flexuosumLandsburgiaLessoniaCaulerpa

Site

GBI

Sus

trat

um c

over

(%

m-2

+S

E)

0

5

10

15

20

25

30

35

40

45

50

55

60

65

70

75

CCACoralline turfRedsGreensSmall brownBareSpongeAscidianSand

A B

Figure 3.6. Patterns in rocky reef benthic community structure at Great Barrier Island.

Source: Haggitt and Mead (2008).

Comparison with Great Barrier Island (Haggitt and Mead 2008) Algal communities between 2- 4 m depth at Waikaro Point (north), Great Barrier Island (GBI) (Easting 2730501.3; Northing 6562748.9), a pristine location, is also presented in Fig. 3.4. The spread of quadrats from GBI sit amongst the general spread of quadrats between Makara Beach and Oteranga Bay and there are clear similarities among these locations. Further analysis with PERMANOVA indicated a statistically significant difference among locations (Table 3.1). Pair-wise a posteriori comparisons (Table 3.2) revealed that Ohau Bay was statistically different to all other locations and Oteranga Bay was marginally statistically different to Makara Beach, but not Great Barrier. The macroalgal assemblage at Great Barrier Island was only statistically different to Ohau Bay. Table 3.1 Results from PERMANOVA (degrees of freedom, F ratios and P values from

permutation) for biomass of 22 macroalgae taxa from quadrat sampling at Makara Beach, Ohau Bay, Oteranga Bay and Great Barrier Island.

Source df F P (perm)

Location Residual Total

3 32 35

3.5795 0.0001

Table 3.2 Tests among levels of the factor “Location” based on biomass of 22 macroalgae

taxa from quadrat sampling at Makara Beach, Ohau Bay, Oteranga Bay and Great Barrier Island (GBI).

Groups t P (perm) Oteranga Bay, Ohau Bay Oteranga Bay, Makara Beach Oteranga Bay, GBI Ohau Bay, Makara Beach Ohau Bay, GBI Makara Beach, GBI

2.19 2.18 2.38 1.74 1.42 1.41

0.0001 0.0081 0.0006 0.0314 0.0974 0.0772

Biodiversity Biodiversity of rocky reef communities based on taxa richness for macroalgae and sessile invertebrates was highest for Ohau Bay (Fig. 3.7) with similar richness occurring between Makara Beach and Oteranga Bay. Taxa richness of mobile invertebrates was broadly similar among locations (refer to Appendix 1 for taxa lists).


No.

of s

peci

es (

+SD

)

0

2

4

6

8

10

12

14

16

18

MacroalgaeSessile InvertebratesMobile Invertebrates

Figure 3.7. Mean taxa richness for macroalgae, sessile invertebrates and mobile

invertebrates on rocky reef habitat at Makara Beach, Ohau Bay and Oteranga Bay. Subtidal soft sediment communities Subtidal soft sediment taxa were low in both diversity and abundance across locations; reflecting the patchy nature of soft sediment fauna in general and matching patterns observed at Ohau Bay and Oteranga Bay in previous surveys (see Appendix 1). The low diversity likely reflects the exposed nature of the locations and the mobile nature of the sand and single habitat characteristic of all locations which make it a very difficult place for marine organisms to exist. Lysianassid and Phoxocephalid amphipods were the common taxa among locations and the polychaete worm Orbinia papillosa was present in samples at Ohau Bay and Oteranga Bay for both the current and previous surveys. Due to the low biological diversity and abundance of many of the soft sediment taxa, no formal statistical analysis was undertaken to compare patterns among locations.

Makara Estuary At the mouth of the Makara Estuary, fragments of drift algae (Ecklonia radiata, Lessonia variegate, and Carpophyllum species) were apparent on the immediate substratum. Directly beneath the drift algae the sediment was extremely anoxic down to a depth of > 25cm. In the middle of estuary proper, the substratum was composed of extremely fine anoxic mud that extended to a depth of > 30 cm. In the shallows of the estuary, the anoxic mud layer was approximately 20 cm deep with small cobbles/pebbles occurring directly beneath. Marine taxa were extremely sparse within the estuary. Oligochaete tube worm mats were conspicuous covering large areas of the substratum in the main channel of the estuary, and small shrimp (unidentified) were also observed. No other organisms were sampled or observed in the estuary channel, nor were any fishes encountered. The shallow intertidal cobble region of the estuary supported mats of Ulva spp and the occasional porcelain half crab Petrolisthes elongatus. This region of the estuary also had very low biological diversity (Appendix 1). Slabs of concrete and plastic litter were also a feature of the foreshore at the mouth of the estuary. Tracking back along the estuary towards the Makara Stream, erosion where farmland met the estuary banks was very obvious. This was also apparent further upstream towards the Makara Township (also see Haggitt 2008). Riparian planting observed in 2008 on the western side of the Makara Estuary and also investigated in this study revealed that the various groupings of native plants were generally covered in weeds and many plants were unfortunately in a poor state.

Discussion Makara Beach, Ohau Bay, Oteranga Bay The purpose of this study was to undertake a State of the Environment assessment of four locations Makara Beach, Makara Estuary, Ohau Bay and Oteranga Bay situated immediately adjacent to the hill country occupying Meridian Energy’s wind farm. The primary focus of the survey was to identify impacts associated with sedimentation from silt run-off and where possible compare current data with that from previous surveys undertaken at Ohau Bay and Oteranga Bay and similar surveys in the Wellington region. Data were also compared to a pristine shallow-water site surveyed at Great Barrier Island in 2008. At all marine locations surveyed the biological communities were typical of shallow-water rocky reef communities that have been surveyed elsewhere in the Wellington region (Shears and Babcock 2004) and share commonality with Great Barrier Island (Haggitt and Mead 2008). Subtidal and intertidal soft sediment communities at Ohau Bay and Oteranga Bay in 2010 were also similar to that of surveys undertaken pre Project West Wind, characterised by low taxa diversity. Terrigeneous derived sediment entering the marine environment can affect rocky coast organisms and/or assemblages in multiple ways or degrees of severity, including changes in species composition and distribution, inhibition of settlement and recruitment, reduced species diversity/monopolisation of space and weakened competition and/or predation (Airoldi 2003). In a comprehensive review on the effects of sedimentation on rocky reef assemblages Airoldi (2003) suggests:

(1) Rocky coast organisms that persist by sexual reproduction appear to be more vulnerable to the presence of sediments than organisms that propagate vegetatively, probably because larvae and propagules require stable substrata for settlement, and/or juvenile stages are more sensitive to smothering by sediments than adult stages;

(2) There seems to be a trend in sediment affected areas for the

prevalence of species with sediment-trapping morphologies, opportunistic, vegetative propagating or migratory life histories and physiological and morphological adaptation to withstand stressful physical and chemical conditions during burial. Many of these species can probably be characterised as “sand-tolerant” species, for which negative effects due to the presence of sediments are possibly compensated for by indirect advantages, including reduced competition and predation.

(3) Low density of grazers and concomitant dominance of turf-forming

and/or opportunistic foliose algae frequently characterise rocky coasts affected by sediments, suggesting that sediments may control rocky coast vegetation through inhibition of grazing.

(4) Areas affected by sediments appear to be frequently characterised by a

low diversity of species, often because of the prevalence of space-monopolising forms. At the same time, however, variable patterns of sediment deposition and movement may be important sources of spatial and temporal heterogeneity in the structure and dynamics of affected assemblages, sometimes promoting diversity.

(5) There seem to be trends in areas with high human perturbations,

including high sediment load, for the decline in cover of erect, canopy-forming algae and increased abundance of turf-forming algae. It can be further speculated (but evidence either supporting or refuting this hypothesis is limited) that assemblages dominated by canopy-forming and turf-forming algae might represent alternative stable states in shallow temperate rocky reefs, and that sediments might be one of the factors triggering the shift in balance between those two states.

Considering the indicators of sedimentation-related impacts (outlined above) relative to the data collected in 2010 (all locations), 2008, 2005 (Ohau Bay) and 2004 (Oteranga Bay) there is no compelling evidence that marine communities have been affected by terrigeneous derived sediment considering that:

• Negligible sediment cover was recorded on the rocky reef habitats surveyed out to 6 m deep;

• There was no visible evidence of damage attributable to siltation and smothering of marine communities;

• Macroalgae occurred at high to moderate biomasses at all locations surveyed forming enclosed canopies.

• Macroalgal communities were analogous to that surveyed elsewhere in the Wellington region and from a pristine shallow-water location at Great Barrier Island, north-eastern New Zealand,

• There were a high density of grazers, particularly paua, at Makara Beach and Ohau Bay;

• Overall there was high biological biodiversity of macroalgae and sessile invertebrates at all locations;

• There was no visible change to subtidal soft sediment communities at Oteranga Bay or Ohau Bay between surveys;

If sedimentation-related impacts were an issue, it is conceivable that the rocky reef habitats would be characterised by low macroalgal cover, low biological diversity and a high percent cover of sediment on the reefs surveyed. When undertaking State of the Environment assessments it is important to place biological measurements and observations within the context of the physical environment, as biological communities are strongly influenced by abiotic parameters (currents, wave action, turbidity etc). As documented in

previous reports, the exposed nature of the Wellington Peninsula (specifically the coast of Quartz Hill and Terawhiti Station coast regions) to both waves and wind and the close proximity of the high velocity tidal currents of the Cook Strait combine to suspend and remove any fine silts that may enter the marine environment (which could potentially smother marine life), and maintain a relatively healthy marine biota on the rocky reef in the area. Fine sediments can only settle and smother marine life in sheltered areas, since waves quickly suspend fine sediments (out to 100’s of meters deep when the wave period is long) and currents move the suspended sediments. The regular wave action from both the north and south due to local strong winds that are compressed and accelerated through the Cook Strait, as well as longer period swells from distant sources, prevent the settlement of fine sediments in the bays investigated. For example, at Ohau Bay, the diver survey in 2005 found coarse sands at 14 m deep out near the mouth of the bay. In simple terms, the normal sorting process pushes coarse sediment (i.e. sand and gravel) towards the beach, while fine sediments are moved offshore to settle in deeper water. However, due to the presence of the Cook Strait, the tidal currents are too strong for fine sediments to settle in deeper water off the coast. For example, current speeds of over 5 knots regularly occur off of Oteranga Bay (the Karori Current), and very strong currents also exist off the entrance of Ohau Bay (whirlpools and disturbed waters can be observed at this location) and Makara Beach. While the input of fine sediments into the marine environment from any source is unwanted, due to the exposed nature of the area (to both waves and wind) and the close proximity of the high velocity currents of the Cook Strait, which combine to suspend and remove fine silts which can smother marine life, the rocky reef habitats in the area maintain a relatively healthy marine biota. Makara Estuary While subtidal and intertidal marine locations at Makara Beach showed no evidence for sedimentation-related impacts, the same could not be said for Makara Estuary. The low biological diversity, extremely deep sediment anoxic layer within the main channel and shallower regions and overall appearance of this estuary - typified by eroding banks and exotic weeds - suggests it is a heavily impacted ecosystem. The depth of the anoxic sediment layer alone indicates that sedimentation has been an issue in the estuary for some time. The only dominant taxa were Oligochaete worm mats that covered large areas of the main channel. Patterns of this nature are indicative of polluted/impacted ecosystems, i.e., dominance of one or several taxa and low biological diversity (Gibbs and Hewitt 2004). There was no evidence of any shellfish or gastropod taxa common to estuarine systems (Morton and Millar 1968), nor were there any shell remnants in sediment samples that would suggest the estuary supported such taxa in the past.

Observations made in 2008 (during construction of the wind turbines) indicated that the catchments that lead to the Makara Estuary were highly modified, there was very little native vegetation or riparian vegetation of any type, the banks of the estuary and Makara River were actively eroding and in many areas livestock were grazing up to the water’s edge. These observations still hold true for the current state of the estuary. Moreover, riparian plantings observed in 2008, and viewed as a positive imitative, are now covered in weeds and many plants are in a poor state. Monitoring of the Makara River, which feeds directly into the Makara Estuary, is routinely undertaken by the Greater Wellington Council as part of their State of the Environment Monitoring. It is worth noting that for the 2000/2001 survey, well before construction of any wind turbines or associated infrastructure, the Makara River was classified as moderately polluted, with the Regional Freshwater Plan suggesting the river needed enhancement (GWRC 2001). In 2008/2009 based on Water Quality Index grades, the Makara River was described as having “fair” water quality, but was considered degraded because the median value of at least one of the six physico-chemical or microbiological variables tested exceeded ANZECC 2000 guideline values (GWRC 2009). For the Makara River site these were E-coli2, water clarity3, and dissolved reactive phosphorus (DRP)4. These results indicate that multiple activities are impacting the river and ultimately the Makara Estuary. Attributing the current state of the estuary as being due to a single activity such as the construction of the wind farm is questionable at best because of: 1) the degraded nature of the estuary which was evident in 2008 during construction of the wind farm; 2) construction of the wind farm required sediment control and was the only activity in the area where sediment control was employed; 3) there was no sign of shellfish or shellfish remnants in sediment samples that would indicate that sedimentation was a recent impact and, 4) there are myriad activities, due to their proximity to the estuary and Makara River that are likely to have impacted the estuary through space and

2 E. coli bacteria have been used as an indicator of the human health risk from harmful micro-organisms present in water, for example from human or animal faeces (www.mfe.govt.nz).

3 Reduced clarity may be a consequence of poorly managed farmland (for example, the collapse of unprotected stream banks and sediment run-off from paddocks). Urban development and harvesting of plantation forestry can also produce high volumes of sediment run-off. Natural factors can also determine clarity caused by the geology of the catchment. Sandstones, mudstones and gravels are easily eroded, which leads to high-suspended sediment loads (www.mfe.govt.nz).

4 The main sources of DRP, which is the dissolved form of phosphorus that is available for plant growth are from fertilisers applied to land to enhance plant growth, which can then dissolve in rain and flow into rivers. There is strong evidence regionally and nationally that the levels of dissolved reactive phosphorus in rivers increase in proportion to the levels of agricultural activity in river catchments (www.mfe.govt.nz).

time (farming and associated erosion, stock wandering through waterways, reclamation, forestry etc). Concluding comments State of the Environment assessments made for Makara Beach, Makara Estuary, Ohau Bay and Oteranga Bay presented in this report provide a snap-shot of the current ecological state of these locations, particularly as temporal monitoring data are generally lacking. Fortunately much of the data collected in this survey could be compared to other studies providing a broader evaluation of the ecological state. Data suggest that there has been no impact to the marine communities from construction of Meridian Energy’s wind farm. While not a necessity, it would be desirable to repeat the marine surveys again (i.e., in 12 month time) if only to compare temporal trends and build on the data collected to date should the site be developed further. The survey of the Makara Estuary revealed that it is a heavily impacted system and in a very poor state. Repeat surveys undertaken by the Greater Wellington Council indicate that the Makara River feeding into the estuary is also degraded and was well before construction of the wind farm commenced. In light of this information, together with the fact that construction of the wind farm required sediment control and much of the farmland surrounding the estuary and Makara River is actively eroding it is very unlikely that the degraded nature of the estuary is due to the construction of the wind farm. Due to the absence of any monitoring within the estuary proper it is not possible to comment on the temporal pattern of degradation that has taken place. Given the depth of the sediment anoxic layer, very low biological diversity and absence of any marine taxa such as shellfish and gastropods including shell remnants within the estuary, it is likely that this has been a lengthy process that has occurred over a number of decades. Given the severely degraded nature of the Makara Estuary it is presently pointless to undertake monitoring unless a concerted effort is made to enhance the estuary and waterways leading to it. This could begin through intensive riparian planting followed by better land use practices, as has occurred elsewhere in New Zealand e.g., Raglan Harbour. Because water quality monitoring indicates that multiple activities have in the past and continue to impact the Makara River and ultimately the estuary, this would require a concerted effort across multiple sectors.

REFERENCES Airoldi, L. (2003) The effects of sedimentation on rocky coast assemblages.

Oceanography and Marine Biology: an Annual Review 41:161-236 Anderson, M.J. (2003). PCO: a FORTRAN computer program for principal

coordinate analysis. Department of Statistics, University of Auckland, New Zealand

Anderson, M.J. 2005. PERMANOVA: a FORTRAN computer program for permutational multivariate analysis of variance. Department of Statistics, University of Auckland, New Zealand.

Gibbs, M., Hewitt, J. (2004) Effects of sedimentation on macrofaunal communities: A synthesis of research studies for ARC. NIWA report to the ARC. Auckland Regional Council Technical Report 2004/264

Gordon, D.P. (2009) New Zealand Inventory of Biodiversity Vol 1 Kingdom Animalia. Canterbury University Press 566 pp.

GWRC (2009) Annual freshwater quality monitoring report for the Wellington region, 2008/09. Environmental Monitoring and Investigations Department. Greater Wellington Regional Council Report 46 pp.

GWRC (2001) Annual Freshwater Quality Report 2000-2001. Resource Investigations Section Wairarapa Division August 2001 Publication No. WRC\RINV-G 01/34 69 pp.

Haggitt, T. (2008) Statement of Evidence of an application by Meridian Energy Limited for resource consents to establish, operate and maintain a wind farm at Mill Creek, Quartz Hill, and Terawhiti Station [Project West Wind].

Haggitt, T., Mead, S.T. (2008) Great Barrier Island (Aotea) Benthic Monitoring Programme: May 2008 Survey. CAS Ltd report prepared for The Department of Conservation- Auckland Conservancy 41pp

Mead, S.T., Haggitt, T. (2004). Assessment of Marine Ecological Effects of the Construction of an Access Berthing Structure at Oteranga Bay, Wellington. Prepared for Meridian Energy (Project West Wind), May 2004. 21pp

Mead, S.T., Moores, A., Haggitt, T. (2005) Assessment of Marine Ecological Effects of the Construction of an Access Berthing Structure at Ohau Bay, Wellington. Prepared for Meridian Energy (Project West Wind), May 2005. 40 pp

Morton, J. E., Miller, M.C. (1968) The New Zealand Seashore. William Collins Sons and Co. Ltd, Glasgow, Great Britain.

Shears, N.T. (2003) Ecological response of shallow subtidal reef communities to marine reserve protection in northeastern New Zealand. Unpublished PhD Thesis – University of Auckland 195 pp.

Shears, N. T., Babcock, R. C. 2004. Quantitative description of mainland New Zealand’s shallow subtidal reef communities. Department of Conservation. Science for Conservation 280 - 123pp

APPENDIX 1

Table A1. Presence (+) of algal taxa pooled across quadrats for Oteranga Bay, Ohau Bay, and Makara Beach in 2010. * denotes presence of that taxa observed, but not measured during the survey.

Taxa Oteranga

Bay Ohau Bay

Makara Beach

Ecklonia radiata + + + Carpophyllum maschalocarpum

+ + +

Carpophyllum flexuosum + + + Landsburgia quercifolia + + + Lessonia variegata + + + Sargassum sinclairii + + + Marginariella spp + + + Zonaria turneriana + + + Cystophora torulosa + + + Cystophora retroflexa + Dictyota sp + + + Halopteris spp + Carpomitra costata + + + Glossophora spp + + + Padina australis + + + Ralfsia sp + + + Osmundaria colensoi + Melanthalia abscissa + Pterocladia lucida + + + Plocamium sp. + + Gigatina + + + Coralline turf + + + Crustose coralline algae (CCA)

+ + +

Ulva spp + + + Codium convolutum + + + Chaetomorpha spp + Caulerpa flexis + + * Caulerpa racemosa + + * Table A2. Presence (+) of mobile invertebrates pooled across quadrats for Oteranga

Bay, Ohau Bay, and Makara Beach in 2010. * denotes presence of that taxa observed, but not measured during the survey.

Taxa Oteranga Ohau Makara

Bay Bay Beach Turbo smaragdus + + + Cookia sulcata + + + Trochus viridis + + + Cantharidus purpureus + Calliostoma tigris + Buccinulum linea + + Haliotis iris + + + Xymenella sp1 (red foot) + + + Xymenella sp2 (orange foot) + + + Cominella virgata + + + Scutus breviculus + + + Evechinus chloroticus * + + Stichopus mollis * + * Patiriella regularis + + + Coscinasterias muricata + + + Ceratosoma amoena + + + Aplysia dactylolmela + + Cryptoconchus porosus + + Table A3. Presence (+) of sessile invertebrate across quadrats for Oteranga Bay, Ohau

Bay, and Makara Beach in 2010. * denotes presence of that taxa observed, but not measured during the survey.

Taxa Oteranga

Bay Ohau Bay

Makara Beach

Tethya aurantium + + + Tethya ingalli + + + Cliona celata + + * Polymastia sp. + Ciocalypta polymastia + Dysidea sp. + + + Chemidocarpa bicornuta + + + Asterocarpa coerulea + + + Aplidium adamsi + + + Catenicellidae sp. + Monomyces rubrum + + Isocradactis magna + + + Actinthoe albocincta + + Corynactis haddoni + + Phlyctenactis tuberculosa + + + Table A4. Presence (+) of fish taxa for Oteranga Bay, Ohau Bay, and Makara Beach in

2010. * denotes presence of that taxa observed, but not measured during the survey.

Taxa Oteranga

Bay Ohau Bay

Makara Beach

Hiwihiwi Chrironemus marmoratus + + + Banded wrasse Notolabrus fucicola + + + Red moki Cheilodactylus spectabilis, + + Spotty Notolabrus celidotus + + + Trevally Psuedocaranax dentex + Common triplefin Forsterygion lapillum + + +

Variable triplefin Forsterygion varium + + Oblique-swimming triplefin Oliquichthys maryannae

+

sweep Scorpis lineolatus + + + Eagle ray Myliobatis tenuicaudactus + + * Short-tailed stingray Dasyatis brevicaudata + Yellow-eyed mullet Aldrichetta forsteri + Tarakihi Nemadactylus macropterus + Table A5. Presence (+) of subtidal soft sediment taxa for Oteranga Bay (2010, 2004),

Ohau Bay (2010, 2005) and Makara Beach (2010). Common name Taxa Oteranga Bay

2010 Oteranga Bay 2004

Amphipod Phoxocephalid + + Amphipod Lysianassid + + Amphipod Ampithoe hinatore + Pea crab Pinnotheres spp + Topshell/gastropod Diloma subrostratum + Polychaete Orbinia papillosa + + Brittlestar Ophiuroidea + Curmacean + Common name Taxa Ohau Bay 2010 Ohau Bay 2005 Amphipod Phoxocephalid + + Amphipod Lysianassid + + Amphipod Ampithoe hinatore + Polychaete Worm Orbinia papillosa + +

Polychaete Worm Scolplos cylindifer + +

Polychaete Worm Orbinid +

Polychaete Worm Spinoid +

Polychaete Worm Neried/Nicon complex

* +

Topshell Diloma subrostratum

+

Topshell Diloma sp. +

Topshell Cantharidella sp. +

Topshell Cominella glandiformis

+

Common name Taxa Makara Beach

2010 Amphipod Phoxocephalid + Amphipod Lysianassid + Curmacean + Hermit crab Paguridae +

Table A6. Presence (+) of sediment taxa within Makara Estuary (2010). Common name Taxa Makara Beach

2010 Polychaete +

Shrimp Unidentified + Curmacean + Porcelain crab Petrolisthes elongatus + Algae Ulva spp +

makara estuary baseline and construction monitoring plan …€¦ · erosion of the estuary/river...

Documents