Fish Distribution Study - Amazon Web Services...Two fish census techniques were used; underwater visual census (UVC) and baited remote underwater video stations (BRUVS). UVC was undertaken

HUNTER WATER

Fish Distribution Study

Burwood Beach WWTW

301020-03413 – 107

August 2013

Infrastructure and Environment

3 Warabrook Boulevard

Newcastle, NSW 2304 Australia

PO Box 814 NEWCASTLE NSW 2300

Telephone: +61 2 4985 0000

Facsimile: +61 2 4985 0099

www.worleyparsons.com

ABN 61 001 279 812

© Copyright 2013 WorleyParsons

HUNTER WATER

FISH DISTRIBUTION STUDY

BURWOOD BEACH WWTW

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SYNOPSIS

The aim of the Burwood Beach Fish Distribution study was to assess the abundance, richness and

diversity of reef fish assemblages at reefs with increasing distance from the Burwood Beach outfall in

order to establish whether an impact can be detected and, if so, the gradient of impact with distance

from the outfall. The study results can be used to assess any future impact associated with changes

to the volume and quality of effluent from the outfall.

Two fish census techniques were used; underwater visual census (UVC) and baited remote

underwater video stations (BRUVS). UVC was undertaken on four occasions (December 2011, April

2012, October 2012 and April 2013) at sites within three zones at increasing distance from the outfall:

outfall impact zone (< 50 m), mixing zone (~ 200 m) and reference zone (> 2,000 m). Within each

site, larger mobile fish were counted along four replicate 5 m x 25 m belt transects, and smaller,

cryptic fish species and sea urchins were counted along a parallel 1 m x 25 m belt transect. BRUVS

was undertaken by NSW Marine Parks (Port Stephens) on one occasion (December 2011) at five

locations, with three replicate deployments at each.

This study constitutes the first quantitative surveys of reef fish assemblages at the Burwood Beach

outfall, although there have been quantitative surveys elsewhere in the region, including at the

Boulder Bay outfall. While no quantitative studies of fish have been undertaken at Burwood Beach

outfall in the past, anecdotal evidence suggests that a higher abundance of fish occurs at the outfall

than at nearby rocky reefs.

The UVC data shows higher abundance of reef fish at the outfall sites followed by the mixing zone

and then the reference sites. There was greater fish abundance in the two April surveys than in the

October / December surveys, suggesting a seasonal variation. Univariate statistical analysis found

that there were significant differences in mean abundance between the four surveys and between

zones. In addition, there was a significant effect for the interaction of time by zone which shows that

there were inconsistent trends in fish abundance over the four survey events.

The trends in fish species richness in the UVC results were similar to those for mean abundance, with

higher richness values at the outfall sites followed by the mixing zone then reference sites. However,

as for abundance, small variations existed between survey events. Univariate analysis found that

there were significant differences in richness between sampling events and between zones. In

addition there was a significant interaction between time and zone. This demonstrates that the trend

of richness in different survey zones also differed over the surveys.

The Shannon Weiner Index of species diversity was determined for each site on the UVC data.

Higher species diversity indicates higher biodiversity / biological complexity at a given site / location.

Trends in species diversity were not as consistent as those seen for abundance and richness, with no

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zone having consistently higher or lower diversity. Univariate analysis found significant differences in

species diversity between survey events and zones. In addition, there were significant interactions of

time by zone and also time by site (zone), indicating that the trends were again inconsistent over

sampling events.

Overall, the UVC data showed much greater abundance of fish at the outfall sites. Approximately half

the fish observed were yellowtail. Even so, there was higher abundance of other fish species at the

outfall sites compared to the mixing zone or reference sites. The increase in fish abundance can be

attributed to several factors – the discharge may be a source of food, the outfall structures and the

rising plumes act as fish „attractants‟ and there is a larger area of reef at the outfall sites compared to

the mixing zone or reference sites.

Multivariate analysis of UVC data showed strong spatial and temporal trends. There were significant

differences in reef fish assemblages between sites within single surveys. In addition, when data from

all UVC surveys were analysed together, multivariate analysis indicated that there was a gradient of

impact on reef fish assemblages with distance from the outfall (the abundance of fish was highest at

the outfall and abundance decreased with distance from the outfall). Large temporal variation in

assemblages was also evident. When points on the MDS were represented by survey event or

season (i.e. cool or warm water) strong clustering between survey events and seasons was also

evident. In general, data from the two cool water surveys (December 2011 and October 2012) was

more similar to each other than data from the two warm water surveys (April 2012 and April 2013)

and a clear separation of reef fish assemblages between the cool and warm water seasons was also

observed.

In summary, the UVC results showed an impact of the outfall on fish abundance and richness – there

are more fish at the outfall sites than at the reference sites.

For the BRUVS survey, in contrast to the UVC results, fish abundance was higher at the outfall sites

in comparison to the mixing zone and reference reefs, but no significant difference was found.

Species richness measured using BRUVS data appeared to be lower at the outfall and increased with

increasing distance from the outfall (but no significant differences were found). Species diversity was

highest at the mixing zone sites and lowest at the outfall and northern reference sites. As the BRUVS

study only incorporated one sampling event it is difficult to make conclusive interpretations on the

findings.

No previous studies have quantitatively assessed fish abundance, richness or diversity for fish

assemblages at Burwood Beach. Therefore, no comparisons to previous site specific investigations

could be made. However, the high fish abundances recorded at the Burwood Beach outfall impact

zone sites compared to mixing zone and reference sites are in agreement with anecdotal evidence of

higher fish abundances at the outfall by local commercial and recreational fishermen and Hunter

Water divers. In addition, the UVC trends seen here are consistent with the findings of a number of

previous studies which have found greater abundance of fish at outfall sites.

There were significant differences in the results from the UVC and BRUVS techniques in terms of the

species and numbers of fish recorded. This is not surprising given that they employ very different

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methodologies and were undertaken on different days. The BRUVS data did not indicate a significant

effect of the outfall on fish numbers.

One of the objectives of this study was to make a judgment on the likely impact of future discharges

on reef fish assemblages at Burwood Beach. Burwood Beach WWTW is expected to have increased

flows in the future to accommodate an increasing population. While it is difficult to speculate on future

impacts (considering that the response of ecological communities to increased flows is not

necessarily going to be linear) in general, it would be hypothesised that with increasing future flows it

is likely that fish will continue to be more abundant at the outfall due to increased nutrient outputs.

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Disclaimer

This report has been prepared on behalf of and for the exclusive use of Hunter Water, and is

subject to and issued in accordance with the agreement between Hunter Water and

WorleyParsons. WorleyParsons accepts no liability or responsibility whatsoever for it in respect of

any use of or reliance upon this report by any third party.

Copying this report without the permission of Hunter Water or WorleyParsons is not permitted.

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Internal and Client Review Record

PROJECT 301020-03413 – BURWOOD BEACH FISH DISTRIBUTION STUDY

REV DESCRIPTION ORIG REVIEW WORLEY- PARSONS APPROVAL

DATE CLIENT APPROVAL

DATE

A Draft 1 issued for internal review

G Graham / Dr M Priestley

Dr K Newton 11 Jan 2012

B Draft 1 issued for internal review

Dr K Newton Dr K Stewart 18 Jan 2012

C Draft 2 issued for client review

Dr K Newton / Dr M Priestley

Hunter Water / CEE

23 Jan 2012

D Draft 2 issued for internal review

Dr K Newton / Dr M Priestley

Dr Kim Stewart

24 July 2012

E Draft 2 issued for internal review

Dr M Priestley M Holloway / Dr K Newton

7 Aug 2012

F Draft 2 issued for client review

Dr K Newton Hunter Water / CEE

15 Aug 2012

G Draft 3 issued for internal review

Dr M Priestley / Dr K Newton

M Holloway 10 Nov 2012

H Draft 3 issued for client review


14 Nov 2012

I Draft 4 issued for internal review

Dr M Priestley Dr K Newton / H Houridis

29 May 2013

J Draft 4 issued for client review


27 June 2013

K FINAL DRAFT Dr M Priestley/ Dr K Newton

EPA August 2013

L FINAL REPORT Dr K Newton

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CONTENTS

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

1.1 Burwood Beach WWTW ..................................................................................................... 1

1.1.1 Treatment Process ................................................................................................. 1

1.1.2 Environmental Protection Licence Conditions ....................................................... 1

1.1.3 Characteristics of Current Effluent and Biosolids Discharges ............................... 4

1.1.4 Effluent and Biosolids Flow Data ......................................................................... 12

1.1.5 Dilution Modelling / Dispersion Characteristics .................................................... 13

1.2 Burwood Beach Marine Environmental Assessment Program ......................................... 14

1.2.1 Initial Consultation ................................................................................................ 15

1.3 Study Area ........................................................................................................................ 15

1.4 Scope of Works / Study Objectives .................................................................................. 15

1.4.1 Null Hypothesis .................................................................................................... 16

1.5 Review of Previous Studies .............................................................................................. 16

1.5.1 Impacts of Sewage Discharges on Fish Assemblages ........................................ 16

1.5.2 Fish Distribution Studies at Burwood Beach ........................................................ 17

2 METHODS ........................................................................................................................ 19

2.1 Underwater Visual Census (UVC) .................................................................................... 19

2.1.1 Spatial and Temporal Replication ........................................................................ 20

2.2 Baited Remote Underwater Video Stations (BRUVS) ...................................................... 23

2.2.1 The BRUVS System ............................................................................................ 23

2.2.2 Spatial and Temporal Replication ........................................................................ 24

2.3 Data Analysis .................................................................................................................... 26

2.3.1 UVC Data – Fish Abundance, Richness and Diversity ........................................ 26

2.3.2 BRUVS Data – Species Richness and MaxN ...................................................... 27

2.3.3 Statistical Analysis ............................................................................................... 27

3 RESULTS: UNDERWATER VISUAL CENSUS ............................................................... 29

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3.1 Univariate Analysis ........................................................................................................... 29

3.1.1 Abundance of Fish and Sea Urchin Species ....................................................... 29

3.1.2 Species Richness................................................................................................. 34

3.1.3 Species Diversity.................................................................................................. 38

3.2 Multivariate Analysis ......................................................................................................... 41

3.2.1 December 2011.................................................................................................... 41

3.2.2 April 2012 ............................................................................................................. 43

3.2.3 October 2012 ....................................................................................................... 46

3.2.4 April 2013 ............................................................................................................. 48

3.2.5 Overall MDS Analysis .......................................................................................... 50

3.3 Power Analysis ................................................................................................................. 53

4 RESULTS: BAITED REMOTE UNDERWATER VIDEO STATIONS ............................... 55

4.1 Univariate Analysis ........................................................................................................... 55

4.1.1 Fish Abundance ................................................................................................... 55

4.1.2 Species Richness................................................................................................. 57

4.1.3 Species Diversity.................................................................................................. 58

4.2 Multivariate Analysis ......................................................................................................... 59

4.3 Power Analysis ................................................................................................................. 60

5 COMPARISON OF UVC AND BRUVS ABUNDANCE DATA .......................................... 61

6 DISCUSSION .................................................................................................................... 63

6.1 Underwater Visual Census ............................................................................................... 63

6.1.1 Trends in Abundance, Richness and Diversity .................................................... 63

6.1.2 Spatial and Temporal Variation ............................................................................ 64

6.1.3 Common / Abundant Fish Species ...................................................................... 66

6.2 Baited Remote Underwater Video Stations ...................................................................... 68

6.2.1 Trends in Abundance, Richness and Diversity .................................................... 68

6.2.2 Spatial Variation ................................................................................................... 69

6.2.3 Comparison to UVC ............................................................................................. 69

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6.2.4 Common / Abundant Fish Species ...................................................................... 70

7 CONCLUSIONS ................................................................................................................ 71

8 ACKNOWLEDGEMENTS ................................................................................................. 73

9 REFERENCES ................................................................................................................. 74

Figures

Figure 1.1 Location of Burwood Beach WWTW.

Figure 1.2 Burwood Beach WWTW and outfall alignment.

Figure 1.3 Effluent and biosolids flow data for the study period (July 2011 - May 2013).

Figure 2.1 Locations of UVC survey sites.

Figure 2.2 BRUVS setup used by the NSW Marine Parks Authority.

Figure 2.3 Locations of BRUVS deployments (sites).

Figure 3.1 Mean fish abundance for all survey events as recorded by UVC.

Figure 3.2 Photographs of some of the most abundant fish species surveyed by UVC.

Figure 3.3 Mean species richness for all survey events as recorded by UVC.

Figure 3.4 Mean species diversity (Shannon Weiner Index) for each UVC survey event.

Figure 3.5 MDS plot of reef fish assemblages for the December 2011 UVC surveys.

Figure 3.6 MDS plot of reef fish assemblages for the April 2012 UVC surveys.

Figure 3.7 MDS plot of reef fish assemblages for the October 2012 UVC surveys.

Figure 3.8 MDS plot of reef fish assemblages for the April 2013 UVC surveys.

Figure 3.9 MDS plot of reef fish assemblages for all events separated by site.

Figure 3.10 MDS plot of reef fish assemblages for all events separated by survey event.

Figure 3.11 MDS plot of reef fish assemblages for all events separated by season.

Figure 4.1 Mean fish abundance for the December 2011 BRUVS surveys or all sites at Burwood

Beach.

Figure 4.2 Abundance of the most abundant fish species surveyed using BRUVS at each site.

Figure 4.3 Mean species richness for the December 2011 BRUVS surveys for all sites at Burwood

Beach.

Figure 4.4 Mean species diversity (Shannon Weiner Index) for the December 2011 BRUVS surveys

for all sites at Burwood Beach.

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Figure 4.5 MDS analysis of reef fish assemblages for the December 2011 BRUVS surveys for all sites

at Burwood Beach.

Tables

Table 1.1 Load limits for effluent and biosolids discharges.

Table 1.2 Summary of physicochemical, metal/metalloid and organics data in effluent collected by

Hunter Water during 2006 - 2013.

Table 1.3 Summary of physicochemical, metal/metalloid and organics data in biosolids collected by

Hunter Water during 2006 - 2013.

Table 1.4 Effluent and biosolids flow data for the study period (July 2011 – May 2013).

Table 1.5 Classification of zones based on prior effluent dilution modelling.

Table 2.1 GPS co-ordinates and approximate depths of UVC survey sites.

Table 2.2 GPS co-ordinates of BRUVS survey sites.

Table 3.1 Mixed model nested ANOVA results for fish abundance measured by UVC.

Table 3.2 Mixed model nested ANOVA for species richness measured by UVC.

Table 3.3 Mixed model nested ANOVA for species diversity measured by UVC.

Table 3.4 Dissimilarity ranking, as determined by SIMPER and corresponding average abundance (in

brackets) of the fish species that contributed the highest dissimilarity to each survey site in December

2011.


brackets) of the fish species that contributed the highest dissimilarity to each survey site in April 2012.


brackets) of the fish species that contributed the highest dissimilarity to each survey site in October

2012.


brackets) of the fish species that contributed the highest dissimilarity to each survey site in April 2013.

Table 3.8 Overall PERMANOVA analysis of fish assemblages across all survey events.

Table 5.1 Comparison of UVC and BRUVS abundance data for December 2011.

Table 6.1 Effluent and biosolids flow data prior to and during UVC survey months.

Appendices

Appendix 1 – Fish Abundance (MaxN) from the UVC Surveys

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Appendix 2 – Fish Abundance (MaxN) from the BRUVS Surveys

Appendix 3 – Statistical Output: ANOVA and ANOSIM

Appendix 4 – Power Analyses

Abbreviations

ANOSIM Analysis of Similarities

ANOVA Analysis of Variance

BRUVS Baited Remote Underwater Video Stations

CEE Consulting Environmental Engineers

EPL Environmental Protection Licence

MDS Multi-dimensional Scaling

MaxN Maximum number of individual for a species

MEAP Marine Environmental Assessment Program

NSW New South Wales

UVC Underwater Visual Census

WWTW Wastewater Treatment Works

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1 INTRODUCTION

1.1 Burwood Beach WWTW

The Burwood Beach Wastewater Treatment Works (WWTW) is located on the Hunter Central Coast

of New South Wales (NSW), approximately 2.5 km south of the city of Newcastle (Figure 1.1). The

plant treats wastewater from Newcastle and the surrounding suburbs, servicing approximately

185,000 people and local industry. There is an average dry weather flow of 44 million litres of

wastewater (44 ML/d). Over the next 30 years these flows are expected to increase to 55 - 60 ML/d,

even with water conservation measures in place.

1.1.1 Treatment Process

The secondary treatment process at Burwood Beach consists of physical screening to remove large

and fine particulates, biological filtration and activated sludge processing including aeration and

settling stages. Secondary treated effluent from Burwood Beach WWTW is discharged to the ocean

through a multi-port diffuser which extends 1,500 m offshore, with diffusers at a depth of

approximately 22 m (Figure 1.2). Approximately 2 ML/d of activated sludge (i.e. biosolids), which is

surplus to treatment requirements, is also discharged to the ocean via a separate multi-port diffuser

that extends slightly further offshore than the effluent outfall. Both the effluent and biosolids outfalls

have been operating in their current configuration since January 1994.

1.1.2 Environmental Protection Licence Conditions

The Environment Protection Licence (EPL) for Burwood Beach WWTW specifies limit conditions for

the operation of the plant (latest version of licence is January 2012). These conditions provide an

indication of the characteristics of the effluent and biosolids discharged into the ocean. Condition L1

specifies that the operation of the outfall must not cause or permit waters to be polluted (i.e. the

licencee must comply with section 120 of the Protection of the Environment Operations Act 1997).

Condition L2 specifies limits relating to total loads discharged to the ocean (including both the effluent

and biosolids). These limits are provided in Table 1.1. Condition 3 specifies limits to concentrations

of suspended solids and oil / grease in the effluent discharged to the outfall. The three day geometric

mean concentration limit for suspended solids is 60 mg/L and for oil / grease is 15 mg/L. Condition 4

sets volume and mass limits of effluent and biosolids discharged via the outfalls. The limit for effluent

flow rate is 510 ML/d (to allow for higher flows in wet weather) and for biosolids the flow limit is

5 ML/d. Daily monitoring of flow is required.

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Figure 1.1 Location of Burwood Beach WWTW.

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Figure 1.2 Burwood Beach WWTW and outfall alignment.

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Table 1.1 Load limits for effluent and biosolids discharges.

Parameter Load Limits

kg/year kg/day

Total suspended solids 4,717,189 12,924

Biochemical oxygen demand - -

Total nitrogen 778,257 2,132

Oil and grease 341,290 935

Total phosphorus - -

Zinc 3,943 11

Copper 2,080 5.7

Lead 1,472 4.0

Chromium 224 0.61

Cadmium 124 0.34

Selenium 14 0.038

Mercury 9 0.025

Pesticides and PCBs 7 0.019

1.1.3 Characteristics of Current Effluent and Biosolids Discharges

The final treated effluent and biosolids from Burwood Beach WWTW has been monitored by Hunter

Water for physicochemical parameters and a suite of metals/metalloids and organic chemicals. A

summary of this data during the period 2006 - 2013 is provided in Tables 1.2 (effluent) and 1.3

(biosolids) (data provided by Hunter Water 2013).

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Table 1.2 Summary of physicochemical, metal/metalloid and organics data in effluent collected by Hunter Water during 2006 - 2013.

Group Parameter (units) Period N Median Mean Min Max Std

Error 75%ile 90%ile

Physicochemical Suspended solids (mg/L) 2006-13 449 27 33.6

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Error 75%ile 90%ile

Cadmium Cd-ICP (µg/L) 2006-13 59

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Error 75%ile 90%ile

α Chlordane (ug/L) 2006-13 90

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Error 75%ile 90%ile

Methoxychlor (µg/L) 2006-13 90

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Table 1.3 Summary of physicochemical, metal/metalloid and organics data in biosolids collected by Hunter Water during 2006 - 2013.


Error 75%ile 90%ile

Physicochemical

Total solids (%w/w) 2006-13 458 0.41 0.45 0.00 2.42 0.01 0.50 0.67

Volatile solids (%w/w) 2006-13 440 69.12 66.35 20.61 96.72 0.51 72.68 74.60

Ammonium N_Total (mg/L N) 2006-13 440 24.00 25.03 0.01 85.40 0.55 30.13 39.00

Grease – total low range (mg/L) 2006-13 440 153.5 172.0 1.0 841.0 5.5 230.0 328.2

Fluoride (mg/L) 2006-13 3 0.77 0.67 0.42 0.82 0.13 0.80 0.81

Metals / Metalloids

Silver-Ag-AASurnace (µg/L) 2006-13 152 22 23 4 63 1 29 40

Silver Ag-ICP (µg/L) 2006-13 279 11 12 0.5 38 0 15 18

Arsenic As-vga (µg/L) 2006-13 431 14.7 18.33 2.6 130 0.70 19.75 30.5

Cadmium Cd-furnace (µg/L) 2006-13 152 4 5.93 0.5 128 1.04 6 8

Cadmium Cd-ICP (mg/L) 2006-13 279 0.005 0.01 0.005 0.06 0.00 0.01 0.01

Chromium Cr VI-furnace (µg/L 2006-13 152 1 1.00 1 1 0.00 1 1

Chromium Cr_VIi-furnace (µg/L ) 2006-13 279 5 10 5 25 0.00 5 25

Chromium Cr-furnace (µg/L) 2006-13 152 46.5 68.16 1 750 7.41 68.5 105

Chromium cr- ICP (µgLl) 2006-13 279 30 50 5 3200 10 40 70

Copper Cu-furnace (µg/L) 2006-13 152 839 954 125 3930 42.8 1134 1426

Copper Cu-ICP (µg/L) 2006-13 279 830 880 5 3300 20 1000 1300

Mercury Hg- VGA ug/L) 2006-13 431 3.7 3.93 0.005 10.2 0.08 4.8 6.3

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Manganese Mn-furnace (µg/L) 2006-13 152 339 360 33 1270 13.73 446.25 512.5

Manganese -ICP (mg/L) 2006-13 279 0.39 0.41 0.06 1 0.01 0.47 0.57

Nickel Ni-furnace (µg/L) 2006-13 152 40 47.21 13 180 2.49 55 77.7

Nickel Ni-ICP (mg/L) 2006-13 279 0.03 0.04 0.005 0.33 0.00 0.05 0.07

Lead Pb-furnace (µg/L) 2006-13 152 187 224 13 900 11.37 269.25 375

Lead Pb ICP µg/L) 2006-13 279 120 130 10 450 0.01 150 212

Selenium Se-VGA (µg/L)) 2006-13 431 0.1 0.91 0.05 5.9 0.06 1.7 2.7

Zinc Zn (mg/L) 2006-13 152 2.4 3.03 0.78 15.6 0.16 3.515 5.39

Zinc Zn-ICP (mg/L) 2006-13 279 2.2 2.46 0.13 6.9 0.06 2.8 3.7

Organics

Aldrin (µg/L) 2006-13 96 0 0 0 0 0 0 0

α-BHC Bhc-a (µg/L) 2006-13 96 0 0 0 0 0 0 0

β-BHC-b (µg/L) 2006-13 96 0 0 0 0 0 0 0

α Chlordane (ug/L) 2006-13 96 0 0 0 0 0 0 0

Chlordane (ug/L) 2006-13 96 0 0 0 0 0 0 0

λ Chlordane- (µg/L) 2006-13 13 0 0 0 0 0 0 0

Chlorpyrifos (µg/L) 2006-13 96 0 0.003 0 0.239 0.003 0 0

DDT (uµ/L) 2006-13 96 0 0 0 0 0 0 0

DDD (µg/L) 2006-13 96 0 0 0 0 0 0 0

DDE (µg/L) 2006-13 96 0 0 0 0 0 0 0

Diazinon (ug/L) 2006-13 96 0 0 0 0 0 0 0

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Dieldrin (µg/L) 2006-13 96 0 0.006 0 0.315 0.004 0 0

Endosulfan-s (µg/L) 2006-13 96 0 0 0 0 0 0 0

Endrin (µg/L) 2006-13 96 0 0 0 0 0 0 0

HCB (µg/L) 2006-13 96 0 0 0 0 0 0 0

Heptachlor-epoxide (µg/L) 2006-13 96 0 0.0001 0 0.013 0.0001 0 2.8

Heptachlor (µg/L) 2006-13 96 0 0 0 0 0 0 0

Lindane (µg/L) 2006-13 96 0 0 0 0 0 0 0

Malathion (µg/L) 2006-13 96 0 0 0 0 0 0 0

Methoxychlor (µg/L) 2006-13 96 0 0 0 0 0 0 0

Parathion (ug/L) 2006-13 96 0 0 0 0 0 0 0

Total PCBs (µg/L) 2006-13 96 0 0 0 0 0 0 0

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1.1.4 Effluent and Biosolids Flow Data

Effluent and biosolids flow data for the study period was obtained from the Burwood WWTW. A

summary of flow data for the period July 2011 to May 2013 is provided in Table 1.4 and Figure 1.3.

Table 1.4 Effluent and biosolids flow data for the study period (July 2011 - May 2013).

Date

Rainfall (mm)

Secondary Flow (ML)

1

By-Pass Flow (ML)

2

Total Flow (ML)

WAS (ML)

3

July 2011 238.2 2068.14 777.24 2845.38 71.66

Aug 2011 47.8 1775.64 0 1775.64 87.73

Sep 2011 136.0 1731.62 205.9 1937.52 82.86

Oct 2011 161.4 1966.85 301.27 2268.12 94.93

Nov 2011 184.5 2004.51 465.58 2470.09 86.71

Dec 2011 110.8 1825.98 6.37 1832.35 92.83

Jan 2012 53.6 1481.64 22.32 1503.96 93.38

Feb 2012 336.7 2296.60 485.42 2782.02 89.47

Mar 2012 188.0 2083.66 403.74 2487.40 96.36

Apr 2012 174.0 1889.04 306.14 2195.18 88.98

May 2012 26.2 1470.51 0 1470.51 94.01

Jun 2012 188.0 2255.16 373.09 2628.25 95.01

Jul 2012 83.5 1839.45 24.17 1863.62 86.77

Aug 2012 71.0 1704.78 62.22 1767.00 93.44

Sep 2012 16.7 1305.15 0 1305.15 87.82

Oct 2012 13.5 1257.72 0 1257.72 76.17

Nov 2012 44.6 1201.80 0 1201.80 86.92

Dec 2012 114.2 1375.59 52.98 1428.57 98.06

Jan 2013 229.0 1488.58 322.25 1810.83 99.86

Feb 2013 175.0 1855.55 397.11 2252.66 87.39

Mar 2013 241.0 1954.00 629.58 2583.58 112.08

Apr 2013 94.5 1702.77 116.92 1819.69 102.98

May 2013 60.0 1538.14 55.7 1593.84 95.64

Note 1. Secondary Flow is total secondary treated flow through the plant (i.e. Total volume of screened and degritted sewage

into secondary plant over a 24 hour period from 12 midnight and discharged to ocean).

Note 2. By-Pass Flow is total volume of screened and degritted sewage which bypasses the secondary plant over a 24 hour

period from 12 midnight and is discharged to ocean.

Note 3. WAS is the volume of Waste Activated Sludge (i.e. biosolids) pumped from the clarifier underflow over a 24 hour period

from 12 midnight and is discharged to ocean.

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Figure 1.3 Effluent and biosolids flow data for the study period (July 2011 - May 2013).

1.1.5 Dilution Modelling / Dispersion Characteristics

Consulting Environmental Engineers (CEE 2007) calculated a predicted initial dilution for the Burwood

effluent outfall, assuming a discharge rate of 43 ML/d and all duckbill valves in operation. The model

predicted a typical dilution of 219:1 for the effluent field. Allowing for the reduction in dilution due to

the orientation of the diffuser ports parallel to the currents, initial dilution is expected to be in the range

of 180:1 to 220:1. The Water Research Lab (WRL 2007) also carried out field tests of effluent dilution

using rhodamine dye. The dilution of the surface field showed a typical dilution of 185:1. WRL (2007)

reported that the average near-field dilution was 207:1 and the 95th percentile minimum dilution was

78:1. CEE (2010) therefore considers it reasonable to base the environmental risk assessment of the

effects of effluent discharge on an effluent plume near the ocean surface with an initial dilution in the

range of 100:1 to 200:1.

The dilution of a combined biosolids and effluent discharge through the biosolids diffuser was also

calculated (CEE 2007). The CEE model predicted a typical dilution of 475:1 for discharged biosolids if

they rose to the ocean surface, or about 250:1 if trapped by stratification at mid-depth (CEE 2007).

The WRL hydrodynamic computer model showed a median dilution of 300:1, with a minimum dilution

of 100:1 when strong stratification decreases the rise and dilution of the small biosolids plumes, and a

maximum dilution at times of strong currents exceeding 1,000:1 (WRL 2007). The WRL model also

showed the biosolids plume is often trapped well below the surface by the natural stratification of the

ocean water column. WRL field tests of the biosolids plume, with dilution measured using rhodamine

dye, showed a typical dilution of 841:1. WRL reported that the average near-field dilution of the

biosolids plume was 268:1 and the 95th percentile minimum dilution was 205:1, for a submerged

plume (WRL 2007). Based on these results, it is considered reasonable to base the assessment of

the effects of biosolids discharge on two conditions; surface plume with an initial dilution of 300:1 and

submerged plume with an initial dilution of 200:1 (CEE 2010). WRL (1999) modelled the biosolids

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plume at 10 m depth and showed that at the centre of the plume, at about 10 m depth, the dilution

achieved is between 200:1 and 1,000:1. At a distance of 200 m from the diffuser, the dilution

exceeds 1,000:1 and increases further with distance travelled. The diluted biosolids extends to the

south of the diffuser, but would be indistinguishable except by the sensitive techniques used in the

field studies. Based on the field tests and dilution modelling undertaken by WRL (1999, 2007) and

CEE (2007), the following putative mixing zones (Table 1.5) were determined for reporting purposes

only.

Table 1.5 Classification of zones based on prior effluent dilution modelling.

Distance from Diffuser Zones

< 50 m outfall impact zone outfall impact

> 50 - 100 m

putative mixing zone

nearfield mixing zone

> 100 - 200 m midfield mixing zone

> 200 - 2,000 m farfield mixing zone

> 2,000 m reference zone reference

1.2 Burwood Beach Marine Environmental Assessment Program

A number of monitoring programs and studies have previously been undertaken to assess the impact

of treated effluent and biosolids discharge on the marine environment at Burwood Beach (e.g. NSW

Environment Protection Authority (EPA) 1994, 1996; The Ecology Lab 1996, 1998; Australian Water

Technologies (AWT) 1996, 1998, 200, 2003; Sinclair Knight Merz (SKM) 1999, 2000; Ecotox Services

Australasia (ESA) 2001, 2005; BioAnalysis 2006; Andrew-Priestley 2011; Andrew-Priestley et al.

2012). While providing a wealth of data on the marine environment here, it is considered that these

previous studies have not effectively assessed the spatial extent and ecological significance of the

outfalls impact (CEE 2010). The aim of the Burwood Beach Marine Environmental Assessment

Program (MEAP) was to establish the impact footprint of the existing outfall, establish the gradient of

impact with distance to the edge of the outfall and predict the potential footprint of future impacts.

The Burwood Beach Fish Distribution Study aimed to address one of the perceived knowledge gaps

by assessing the spatial and temporal distribution of reef fish assemblages along the effluent

dispersion pathway, as a function of distance from the outfall. Multiple survey sites located at a range

of distances north and south of the outfall were surveyed using a combination of Underwater Visual

Census (UVC) and Baited Remote Underwater Video Stations (BRUVS) techniques, over a two year

period.

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1.2.1 Initial Consultation

Prior to commencement of the Burwood Beach MEAP, details of the proposed sampling program and

survey methodology were discussed with Hunter Water, CEE and the NSW EPA (then the Office of

Environment and Heritage (OEH) on 10 October 2011. This initial consultation was undertaken to

ensure that the proposed MEAP was adequate in addressing the requirements of both the Client

(Hunter Water) and the Regulator (NSW EPA). During this meeting, concerns with the proposed

survey / sampling program were raised and where required the methodology was subsequently

altered accordingly. Consultation was also undertaken with the NSW Marine Parks Authority (Port

Stephens) regarding the MEAP, in particular the Burwood Beach Fish Distribution Study. It was at

this time that the NSW Marine Parks Authority suggested that the BRUVS survey method should be

incorporated into the study to contribute to the data set.

1.3 Study Area

Burwood Beach is located in Newcastle, on the Hunter Central Coast of NSW. It lies to the south of

Merewether Beach and to the north of Dudley Beach (refer to Figure 1.1). The seabed in the vicinity

of the outfall consists of small areas of low profile patchy rocky reef, which is subject to strong wave

action and periodic sand movement, interspersed between large areas of soft sediment (sandy)

habitat. These low profile reefs are emergent approximately 1 m above the sand. Water depth is

approximately 22 m at the outfall diffuser (refer to Figure 1.2). Fine mobile sandy sediments occur in

the gutters and low-lying seabed between reef patches. Extensive sandy beaches with intertidal

rocky reef habitats occur along the shoreline adjacent to the outfall.

1.4 Scope of Works / Study Objectives

Prior to commissioning this study, no quantitative assessment of fish assemblages around the

Burwood Beach outfall had been undertaken, so further studies were undertaken to assess the

relationship between fish abundance, richness and diversity and distance from the outfall diffuser.

Quantitative surveys would also check the anecdotal reports of higher fish abundance around the

outfall.

The objectives of the Burwood Beach Fish Distribution Study were to:

Assess the abundance, species richness and diversity of mobile and cryptic reef fish species

and sea urchins at rocky reef sites around the Burwood Beach outfall, and equivalent reef

sites with increasing distance from the outfall, using UVC and BRUVS methods.

Establish whether the characteristics of reef fish assemblages, including abundance, species

richness and diversity, differ between reefs around the Burwood Beach outfall in comparison

to equivalent reef habitats with increasing distance from the outfall.

Establish the zone in which the outfall discharge has a significant effect on fish populations.

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Extrapolate findings to make a judgment on the likely impact of future discharges on reef fish

assemblages at Burwood Beach.

1.4.1 Null Hypothesis

The null hypothesis of this study was:

There is no significant difference between the abundance, species richness or diversity of reef

fish and sea urchin species at the Burwood Beach outfall when compared to equivalent rocky

reef habitats with increasing distance from the outfall.

1.5 Review of Previous Studies

1.5.1 Impacts of Sewage Discharges on Fish Assemblages

Variables used in the monitoring of fish assemblages, such as species richness and diversity, can be

useful in the detection of impacts, both spatially and temporally (Guidetta et al. 2002). While coastal

fish species have also been described as a suitable indicator of the impacts of sewage effluent on the

receiving environment, the majority of scientific literature in environmental impact assessment

focuses on changes to soft bottom macrobenthic fauna (Warwick 1993). This may be attributed to the

difficulties associated with quantitative sampling of fish which include the ability to capture a dataset

that is representative of both conspicuous mobile and cryptic species (Warwick 1993).

Using fish to monitor environmental impacts can have advantages over assessments that rely on

other fauna assemblages. Fish have a comparatively easy taxonomy (Warwick 1993) and underwater visual methods (e.g. UVC) can be undertaken in-situ. Underwater visual methods are

considered to be a quick and efficient standard method for collecting quantitative fish data (Harmelin-

Vivien et al. 1985. In: Guidetta et al. 2002). However, fish mobility and visible distance may also

present bias in the assessment of anthropogenic impacts at the spatial scales at which many studies

are undertaken (Clarke and Warwick 1994). Therefore, using precise sampling methods and

determining appropriate communities and assemblages as a basis for monitoring are integral for

environmental assessment.

Several authors have detected a negative relationship between fish assemblage attributes (e.g.

abundance, richness and diversity) and / or populations and sewage outfalls. Sewage effluent

discharge has been shown to affect the diversity, abundance, mortality and fecundity of fish, causing

increased susceptibility to infection and parasitic invasion (e.g. Wharfe et al. 1984; Claridge et al.

1986; Gray 1989; Smith and Suthers 1999). Guidetta et al. (2002) assessed the impact of sewage

discharge on fish assemblages in the Mediterranean Sea, Italy. Multivariate Analysis of Similarities

(ANOSIM) demonstrated a significant difference between impact (outfall) and reference locations,

with fish abundance found to be higher at the sewage outfall in comparison to reference locations.

More locally, Smith et al. (1999) investigated spatial and temporal variations in fish assemblages

exposed to sewage in NSW, at the Boulder Bay WWTW. They detected differences between fish

assemblages at outfall and reference sites at the community and individual species levels during a

single sampling event. They observed significant effects of the outfall on the decline of the

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abundance of several common resident species of reef fish, and estimated a decrease of 33% of

species richness at the outfall location.

In comparison, other studies have detected impacts and found that fish abundance and diversity may

be higher at sewage outfalls in comparison to reference locations (e.g. Bell et al. 1982; Grigg 1994;

Hall et al. 1997; Guidetta et al. 2002, 2003). These patterns have been attributed to localised nutrient

enrichment caused by sewage effluent discharge, resulting in a higher density of plankton and

suspended organic matter (i.e. fish food) in the receiving environment of WWTW‟s. For example, Hall

et al. (1997) reported that at the Tyne Estuary in England, total fish abundance rose by 300% at the

WWTW outfall site and this variation was entirely due to small pelagic species. Bell et al. (1982) also

found that there was a higher abundance of planktivorous fish at a sewage outfall in Marseille,

France, in comparison to reference locations. In Hawaii, Grigg (1994) reported that while

planktivorous fishes and particulate organic matter feeders increased around the outfalls, species

richness was low. Similarly, Guidetta et al. (2002) and Guidetta et al. (2003) found (in separate

studies) that fish species richness was approximately 27% lower at a sewage outfall compared to the

reference location, but total fish abundance was 5 to 7 fold higher. Overall, these studies indicate that

while fish abundance may be higher at outfall locations, possibly due to the increased presence of

planktivorous species, species richness may be affected by the discharge of treated effluent.

Effects of sewage outfalls on fish assemblages may vary temporally and spatially. In Sydney, fish

assemblages were assessed before and after the commissioning of three deep-water sewage outfalls

(Otway 1995). While sustained impacts were detected at all three outfalls, they were not consistent

among outfalls and varied in their magnitude and direction, despite similar effluent quality and

treatment processes. The mean number of fish captured by long line increased for a short period

after the Malabar outfall was commissioned, whereas the mean abundance of longspined flathead

(Platycephalus longispinus) trawled near the Bondi outfall exhibited a sustained increase following

commissioning. Episodic impacts were only detected at the Malabar outfall and resulted in short-term

increases in abundance (Otway 1995). The majority of sustained impacts on commercially and

recreationally important fish at the North Head and Malabar outfalls included decreases in

abundance, whereas those at Bondi were mostly increases in abundance. The lack of consistency

and high variability in fish abundance between outfalls resulted in low statistical power to detect

impacts (Otway 1995) and raises doubt over the actual impacts of effluent discharge. This study

indicates the importance of power analysis in quantitative experimental designs to ensure that

adequate replication is employed for the detection of significant differences, should they be present.

1.5.2 Fish Distribution Studies at Burwood Beach

General qualitative descriptions of fish in the vicinity of the biosolids diffuser at Burwood Beach were

provided in an Environmental Monitoring and Performance Review (Hunter Water 2007). Following

the commissioning of the biosolids diffuser in 1994, monthly dive inspections were undertaken.

Divers reported that, “generally fish life in the vicinity of the diffuser has been…plentiful and abundant

throughout the period of inspections” (Hunter Water 2007 pg. 17). Species reported around the

diffuser included kingfish, yellow-tailed pike, blue groper, jewfish, blue morwong, red morwong,

bream, flathead, yellow tail trevally, small squire and wobbegong.

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However, there have been no quantitative assessments of fish assemblages undertaken at Burwood

Beach to date. A quantitative assessment of fish abundance, richness and diversity was therefore

commissioned to address this issue. An experimental design which assesses assemblage measures

at a number of zones with increasing distances from the outfall would check anecdotal reports of

higher fish abundance around the outfall and determine if species richness and diversity are affected.

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2 METHODS

Reef fish assemblages at Burwood Beach were assessed using a combination of two survey

methods; UVC and BRUVS. UVC is conducted in-situ and involves the use of divers to identify and

count fish species along underwater transects of a defined length. This survey method allows larger

mobile and smaller cryptic fish species, as well as larger marine invertebrate species such as sea

urchins, to be targeted in the field. The UVC surveys were undertaken using a gradient sampling

design, with the position of survey sites dependent on bottom type (i.e. the presence of rocky reef

habitat) and the dilution / dispersion modelling (refer to Section 1.1.5).

In comparison, BRUVS uses a remotely deployed (i.e. from a vessel) baited video system to attract

fish present in a given area, which are then captured on underwater video. This method may

therefore be biased towards fish species that are attracted to bait (Willis et al. 2000). The BRUVS

method has been shown to have the potential to attract rare larger predatory fishes and smaller

cryptic species, resulting in reduced sampling effort in comparison to UVC or un-baited video stations

(Watson et al. 2005; Malcolm et al. 2007). BRUVS techniques have been used successfully to

monitor fish recovery and assemblages in marine protected areas (Westera et al. 2003; Willis et al.

2003) and to assess spatial differences in fish assemblages (Stobart et al. 2007). The BRUVS

method is a non-destructive option for describing fish assemblages and is increasingly considered an

essential method for studies located within marine protected areas where conserving sensitive habitat

is a priority (Cappo et al. 2004).

For the current study it was considered that a combination of both survey methods would be ideal to

comprehensively assess fish assemblages at the Burwood Beach outfall and reference reefs.

However, due to the different sampling techniques and site locations required, the results from UVC

and BRUVS are analysed in this report as separate data sets / studies.

2.1 Underwater Visual Census (UVC)

Assessments of fish assemblages using UVC incorporated the following:

In-situ identification of all mobile and cryptic fish and sea urchin species present at the study

sites.

In-situ estimates of the abundance of all fish and sea urchin species present at the study

sites (i.e. fish counts).

An assessment of fish and sea urchin abundance, richness and diversity to determine any

differences in assemblages between reefs with increasing distances from the outfall.

For consistency, all UVC surveys were undertaken by a single observer and reef fish expert, Dr Tony

Ayling (Sea Research, Queensland). All surveys took place between 0900 and 1600 hours in

underwater visibility of > 5 m. A standardised transect length (25 m) and width (5 m) was used. The

observer swam at a height of 1 m to 2 m above the seabed, depending on underwater visibility at the

time of survey (i.e. the observer swam closer to the seabed in poor visibility conditions).

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2.1.1 Spatial and Temporal Replication

TEMPORAL REPLICATION

Underwater Visual Census (UVC) for the Burwood Beach Fish Distribution Study was undertaken four

times over a two year period, during cool and warm water periods, including December 2011 (cool),

April 2012 (warm), October 2012 (cool) and April 2013 (warm). Water temperature data can be found

in the Burwood Beach Water Quality Report (WorleyParsons 2013).

It must be noted that the underwater visibility encountered during the surveys differed quite

substantially between survey sites and events as listed below:

December 2011: 5 m

April 2012: 10 - 15 m

October 2012: 5 m

April 2013: 5 - 15 m

The underwater visibility encountered during all surveys was not prohibitive to the study except for at

one site (reference south) in October 2012 which could not be surveyed. However visibility was

noticeably higher during both the April surveys than in the October / December surveys.

SURVEY ZONES AND S ITES

Three survey zones (outfall impact, mixing and reference zones), located at various distances from

the outfall, were chosen for the UVC fish surveys for reporting purposes (refer to Section 1.1.5 for

further classification of zones). Within each of these zones, two sites were surveyed (one site located

to the north and one site located to the south of the outfall) (refer to Figure 2.1). GPS co-ordinates

and the approximate depths of each of the survey sites are provided in Table 2.1.

All fish surveys were undertaken over similar low profile rocky reef habitat, as is present around the

Burwood Beach outfall. Selection of fish survey sites was based upon the following:

Similarity to the reef type present at the Burwood Beach outfall (i.e. low profile rocky reef

with a lack of urchin barren habitat).

Similarity in depths to those encountered at the outfall (i.e. between 20 to 24 m).

Distance from the outfall (< 50 m, ~ 200 m and > 2,000 m north and south).

The three survey zones and six survey sites for UVC included the following:

1. Outfall impact zone (two sites were surveyed within 50 m of the outfall; north and south).

2. Mixing zone (two sites were surveyed ~ 200 m from the outfall; north and south).

3. Reference zone (two sites were surveyed > 2,000 m north (Merewether) and south

(Redhead) of the outfall).

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Table 2.1 GPS co-ordinates and approximate depths of UVC survey sites.

Zone Survey Site Latitude (S) / Longitude (E) Depth (m)

Outfall impact zone Outfall north 32°58.208' / 151°45.156' 22

Outfall south 32°58.272' / 151°45.119' 22

Putative mixing zone Mixing zone north 32°58.097' / 151°45.259' 21

Mixing zone south 32°58.323' / 151°45.080' 21

Reference Reference north (Merewether) 32°56.849' / 151°46.290' 23

Reference south (Redhead) 33°01.605' / 151°42.980' 23

W ITHIN S ITE REPLICATION

Within each survey site larger mobile fish were counted along four replicate 5 m x 25 m belt transects

while smaller, cryptic fish species and sea urchins were counted along a parallel 1 m x 25 m belt

transect (as per Smith 1989).

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Figure 2.1 Locations of UVC survey sites.

Outfall N

Outfall S Mixing zone S

Reference N

Mixing zone N

Reference S

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2.2 Baited Remote Underwater Video Stations (BRUVS)

Assessments of fish assemblages using BRUVS incorporated the following:

Identification of mobile fish species present at the outfall and reference locations using

remotely analysed video data.

Estimates of the abundance of all fish species present at outfall and reference locations (i.e.

fish counts) using remotely analysed video data.

An assessment of fish abundance, richness and diversity to determine any differences in fish

assemblages between outfall and reference reefs.

BRUVS surveys and video analysis were undertaken by NSW Marine Parks Authority (Port Stephens)

personnel to complement the UVC survey method.

2.2.1 The BRUVS System

Each BRUVS unit consisted of a high definition Canon HG21 (hard drive) video camera (with a wide

angle lens), contained in an underwater housing with an attachment frame, and a bait-pole with a

mesh flat-pack holder containing approximately 800 g of bait (Figure 2.2). The bait used to attract

fish was the Australian sardine or pilchard (Sardinops neopilchardus) which was contained within a

plastic mesh bait bag attached to the end of the bait-pole at a distance of approximately 1.5 m from

each camera. Each unit was attached to a rope and float system linking each BRUVS unit to the

surface. Housings consisted of a high-density polyethylene pipe with flat acrylic end-ports, bolted to

stainless steel frames so that fish could be viewed in a horizontal orientation to the benthos (Malcolm

et al. 2007). The field of view on the video was standardised to approximately 2 m behind the bait.

Figure 2.2 BRUVS setup used by the NSW Marine Parks Authority.

Source: NSW Marine Parks Authority, http://www.mpa.nsw.gov.au (2012).

Video camera

Bait on bait pole

http://www.mpa.nsw.gov.au/

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2.2.2 Spatial and Temporal Replication

TEMPORAL REPLICATION

One BRUVS survey was undertaken at 5 sites at Burwood Beach, with three replicates at each site,

during December 2011. After the initial sampling event, it was decided that no further BRUVS

surveys would be undertaken at this location. This decision was made by Hunter Water considering

advice from the NSW Marine Parks Authority indicating that the regularly poor visibility and the lack of

suitable reef offshore were problematic for this type of survey here.

SURVEY LOCATIONS AND S ITES

BRUVS was used to survey fish in three main zones including the Burwood Beach outfall impact zone

(< 50 m from outfall), mixing zone (> 200 m from the outfall to the north and south) and reference

zone (> 2,000 m from the outfall to the north and south). Five locations were sampled (outfall, north

1, south 1, north 2, south 2). BRUVS survey locations were selected by the NSW Marine Parks

Authority based on standard requirements for this survey method.

Three replicate deployments (i.e. survey sites) were undertaken at each location and these sites were

spaced at least 200 m from each other (a minimum distance of 200 m is required between sites to

avoid attracting and counting the same fish twice). The location of BRUVS deployments at Burwood

Beach are indicated in Figure 2.3 and the GPS co-ordinates of the sites are provided in Table 2.2.

The optimal soak time (i.e. time in which bait and video were deployed) was 30 minutes.

Table 2.2 GPS co-ordinates of BRUVS survey sites.

Zone Location BRUVS sites GPS co-ordinates

Outfall impact zone

Outfall

NC01 32°58.2290 / 151°45.1408

NC02 32°58.2433 / 151°45.0859

NC03 32°58.2894 / 151°45.1424

Mixing zone

North 1

NC04 32°57.4139 / 151°45.5752

NC05 32°57.5420 / 151°45.4998

NC06 32°57.3303 / 151°45.7637

South 1

NC12 32°59.4263 / 151°44.2212

NC13 32°59.5199 / 151°44.1556

NC14 32°59.5812 / 151°44.0597

Reference zone

North 2

NC07 32°57.4895 / 151°46.7046

NC08 32°57.3907 / 151°46.6874

NC09 32°57.1610 / 151°46.5399

South 2

NC15 33°00.4881 / 151°44.7859

NC17 33°00.5838 / 151°44.8236

NC18 33°00.5069 / 151°44.8580

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Figure 2.3 Locations of BRUVS deployments (sites).

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2.3 Data Analysis

Fish abundance, richness and diversity were calculated for both the UVC and BRUVS datasets

separately. A brief definition of each of these parameters is provided below:

Fish abundance: Relates to how common or rare a species is relative to other species in a

defined location or community. Abundance may be calculated for the total number of

individuals of a single species or the total number of individuals of all species present.

Species richness: A measure related to the total number of different species present within

a sample.

Species diversity: Species diversity accounts for the number of species and the evenness

of species giving a measure of the biodiversity and complexity of a population. Species

diversity consists of two components, species richness and species evenness. Species

richness is a simple count of species, whereas species evenness quantifies how equal the

abundances of the species are.

2.3.1 UVC Data – Fish Abundance, Richness and Diversity

Fish abundance, richness and diversity were calculated for the UVC data.

Total abundance (i.e. the total number of all fish species) was calculated for each site. Abundance of

each individual fish species was also determined.

Species richness was calculated for a) the total number of species at a site, and b) the mean number

of different species at a site.

Species diversity was calculated using the Shannon Weiner diversity index. This is calculated using

the equation:

S

H = Σ - (Pi * ln Pi)

i = 1

Where:

H = the Shannon diversity index

Pi = fraction of the entire population made up of species i

S = numbers of species encountered

Σ = sum from species 1 to species S

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2.3.2 BRUVS Data – Species Richness and MaxN

BRUVS video data was analysed remotely (i.e. analysed in the lab following field surveys). The field

of view on the video was standardised to approximately 2 m behind the bait. This was to reduce the

effects of underwater visibility on species richness and relative abundance measures (i.e. maximum

number (MaxN) of individual species).

BRUVS analysis was used to establish the zone in which outfall discharge has a significant effect (if

any) on fish populations. This was achieved through measurements of species richness (number of

different species in a given area) and MaxN (maximum number of individual fish of each species in

the frame at any one time during the 30 minutes, reducing the possibility of counting the same fish

twice). Fishes observed on the BRUVS video footage were counted by NSW Marine Parks Authority

personnel and all fish data was recorded using Event Measure Software (SeaGis).

2.3.3 Statistical Analysis

UNIVARIATE ANALYSIS

Univariate statistical analyses were performed using Statistica Version 7. Species richness (for large

fishes, smaller cryptic fishes and urchin species) and total abundance (MaxN) were examined for

normality, using a normal probability plot and homogeneity of variance, using a means versus

standard deviation test and the data transformed where applicable.

For analysis of UVC results, nested ANOVA was used to test for significant differences (p < 0.05) in

fish abundance, richness and diversity at the zone and site levels. There were eight replicates (i.e.

transects) per zone.

For the BRUVS results, a nested ANOVA could not be used as there was only one site available for

the outfall location (due to site distance requirements). Therefore all sites were compared using a

one-way ANOVA to test for significant differences (p < 0.05).

MULTIVARIATE ANALYSIS

Multi-dimensional scaling (MDS) plots were generated in PRIMER 6 to identify whether differences in

the abundance of fish assemblages were evident among zones. Ordination of parameters was

performed using MDS scaling in PRIMER 6, based on ranked matrices of dissimilarities between

samples, employing the square root transformation and Bray-Curtis distance, as a measure of

dissimilarity. Goodness of fit (stress) was assessed using Kruskal‟s stress formula and compared to

maximum values recommended by Sturrock and Rocha (2000).

POWER ANALYSIS

Power analysis can be used to identify a) the sample size required to detect a given effect size at a

given power and type 1 error rate or, b) the effect size that can be detected with a given sample size,

power and type 1 error rate. Sample size determination is usually most valuable as a design tool

prior to the commencement of an experiment using baseline or past studies to estimate the proportion

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of natural variability. This ensures that experiments are designed to have adequate replication to

detect significant differences between treatments, should differences be present.

However, for the current study no previous quantitative fish survey data were available to undertake

power analysis prior to the survey design so it was decided (during initial consultation with Hunter

Water and the NSW EPA) that power analysis would be undertaken after the first survey round and

changes to the survey methods made at that stage if required.

After a sampling program or survey has commenced the most powerful evidence of adequate sample

replication is the detection of significant differences. In the case that significant differences have

been detected, power analysis will only confirm that sample replication was sufficient to detect the

maximum significant difference between treatments.

Power analysis was undertaken on the first round of fish survey data in order to confirm that adequate

replication was being applied or to help design and modify, where applicable, future fish distribution

studies. A Type I error rate of 5% (0.05) was adopted, a Type II error rate of 20% (0.2, power 80%) is

considered acceptable and an effect size of 50% was adopted. Results of power analysis are

addressed in Section 3.

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3 RESULTS: UNDERWATER VISUAL CENSUS

In the following sections UVC fish data is analysed individually for each survey event, followed by an

overall analysis combining all surveys.

3.1 Univariate Analysis

3.1.1 Abundance of Fish and Sea Urchin Species

The abundance of various fish species and total fish abundance for each UVC survey and site are

detailed in the sections below. Figure 3.1 provides a graphical representation of fish abundance at

each site for each survey event. Images of some of the most common fish species recorded during

the four UVC surveys at Burwood Beach are provided in Figure 3.2.

3.1.1.1 DECEMBER 2011

The outfall impact zone sites had the highest total abundance of fish surveyed (388 fish) when

compared to the mixing zone sites (174 fish) and reference sites (37 fish). In addition, the northern

outfall impact zone site outfall N had considerably higher fish abundance than the southern site,

outfall S (Figure 3.1). Species that were most abundant included yellowtail (Trachurus

novaehollandiae), small scale bullseye (Pempheris compressa), bream (Acanthopagrus australis) and

Australian mado (Atypichthys strigatus) (see Appendix 1 for raw data).

The total combined abundance of fish at the putative mixing zone sites was second highest of the

three zones with 174 individuals. The majority of these fish were recorded from the site mixing zone

N (Figure 3.1). Similar to at the outfall impact zone, yellowtail (T. novaehollandiae) was highest in

abundance, followed by small scale bullseye (P. compressa) and flathead (Platycephalus bassensis).

The total abundance of fish at the reference zone sites was the lowest of all survey zones with just 37

individuals. Reference S had higher total fish abundance than reference N, as can be seen in Figure

3.1. It must be noted here that sand cover over the reef at reference N was considerable during this

December 2011 survey, potentially affecting the fish counts. Yellowtail (T. novaehollandiae) were the

most abundant species, however counts were low for all other species (i.e. < three individuals per

transect).

APRIL 2012

The data for this period showed similar trends to the December 2011 surveys with total fish

abundance being highest in the outfall impact zone (a combined site total of 2347 fish, with 1550

being yellowtail), followed by the mixing zone (combined total of 476 fish) and then the reference

zone (combined total of 189 fish). However, the number of species recorded and total fish

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abundance in each zone was higher during this warm water survey than the first cool water survey

(Figure 3.1).

At the outfall impact zone sites (i.e. outfall N and outfall S), species which were highest in abundance

were similar to in December 2011 and included yellowtail (T. novaehollandiae), spiny sea urchin

(Centrostephanus rodgersii), small scale bullseye (P. compressa) and bream (A. australis) (see

Appendix 1 for raw data). And similar to December 2011, total fish abundance was much higher at

outfall N than outfall S (Figure 3.1).

At the mixing zone sites (i.e. mixing zone N and mixing zone S), small scale bullseye (P. compressa)

was high in abundance, followed by yellowtail (T. novaehollandiae), silver sweep (Scorpis lineolatus)

and bream (A. australis). The northern site, mixing zone N, had higher fish abundance than the

southern site, mixing zone S, as was seen in December 2011 (Figure 3.1).

At the reference zone sites (i.e. reference N and reference S) yellowtail (T. novaehollandiae) had the

highest abundance followed by bream (A. australis), while all other species had an average

abundance of less than three. Total fish abundance was also similar, but slightly higher, at reference

N than reference S (Figure 3.1). Unlike during the December 2011 surveys, sand cover at the

northern reference site was minimal.

Overall, fish abundance was higher during the April 2012 warm water surveys than the previous

December 2011 cool water surveys, however, the trends observed between zones and sites for fish

abundance were quite similar. It should be noted that underwater visibility during the April 2012

survey was considerably higher (~ 10 m to 15 m) than in December 2011 (~ 5 m), which may be a

factor in the UVC results.

OCTOBER 2012

The second cool water UVC surveys (and third survey overall) was undertaken in October 2012.

Data exhibited similar trends to both previous surveys, especially to the first cool water survey of

December 2011. Again, fish abundance was highest in the outfall impact zone (a combined total of

811 individuals), followed by the mixing zone (combined total of 133) then the reference zone

(combined total of 16; but the southern reference site could not be surveyed during this round due to

very poor visibility). Overall, the number of different species and total fish abundance was lower than

in April 2012 but higher than in December 2011 (Figure 3.1).

At the outfall impact zone sites (i.e. outfall N and outfall S) species which were high in abundance

included yellowtail (T. novaehollandiae), small scale bullseye (P. compressa), bream (A. australis),

spiny sea urchin (C. rodgersii) and white ear (Parma microlepis) (see Appendix 1 for raw data).

However, in contrast to the two previous surveys, fish abundance was considerably higher at the

southern outfall impact zone site, outfall S, than at the northern site, outfall N (Figure 3.1).

At the mixing zone sites (i.e. mixing zone N and mixing zone S) bream (A. australis) was highest in

abundance, followed by big scale bullseye (Pempheris multiradiata) and yellowtail

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(T. novaehollandiae). In contrast to the previous two surveys, fish abundance was higher at mixing

zone S than mixing zone N (Figure 3.1).

At the reference zone sites (i.e. reference N and reference S) no individuals were detected at

reference S. This was because underwater visibility during the October 2012 survey at reference S

was too poor for the UVC survey to be undertaken. At reference N, flathead (P. bassensis) had the

highest abundance followed by white ear (P. microlepis). The northern reference site was again

found to have high sand cover during the October 2012 survey as it did in December 2011.

APRIL 2013

Fish abundance during the second warm water survey (and final UVC survey) undertaken in April

2013 showed similar trends to the past sampling events, particularly to the first warm water survey.

Combined fish abundance was highest at the outfall impact zone sites (combined total of 1684

individuals), followed by the mixing zone sites (318 individuals), then the reference zone sites (207

individuals) (Figure 3.1).

At the outfall impact zone sites (i.e. outfall N and outfall S), species that were highest in abundance

included yellowtail (T. novaehollandiae), bream (A. australis), big scale bullseye (P. multiradiata) and

Australian mado (A. strigatus) (see Appendix 1 for raw data). Similar to the findings of the December

2011 and April 2012 surveys, fish abundance was considerably higher at outfall N when compared to

outfall S (Figure 3.1).

At the mixing zone sites (i.e. mixing zone N and mixing zone S) bream (A. australis) was high in

abundance, followed by white ear (P. microlepis), Australian mado (A. strigatus) then big scale

bullseye (P. multiradiata). Fish abundance was similar at mixing zone S and mixing zone N (Figure

3.1).

At the reference zone sites (i.e. reference N and reference S), similar to the mixing zone, bream

(A. australis) was highest in abundance, followed by white ear (P. microlepis), Australian mado

(A. strigatus) and big scale bullseye (P. multiradiata). Fish abundance at the reference zone sites in

April 2013 was similar to that recorded during the first warm water survey in April 2012.

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Figure 3.1 Mean ±SE fish abundance for all survey events as recorded by UVC (Note: the site

reference S was not surveyed in October 2012 due to extremely low visibility). Different

colours indicate different distances (zones) from the WWTW outfall.

December 2011

April 2012

October 2012

April 2013

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Trachurus novaehollandiae (yellowtail)

Acanthopagrus australis (bream)

Pempheris compressa (small scale bullseye)

Atypichthys strigatus (Australian mado)

Platycephalus bassensis (flathead)

Figure 3.2 Photographs of some of the most abundant fish species surveyed by UVC.

Source: The Underwater Photo Gallery, www.daveharasti.com/, David Harasti (2012).

http://www.daveharasti.com/

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ALL SURVEYS

A mixed model nested ANOVA was used to assess whether there were significant differences in

mean fish abundance between the factors of time (December 2011 vs. April 2012 vs. October 2012

vs. April 2013), zone (outfall impact zone vs. mixing zone vs. reference zone) and site (nested within

zone), and to determine if there were any interactions between time by zone or interactions between

time by site (zone) (refer to Table 3.1 for ANOVA results).

Results of the analysis found that there were significant differences between time (i.e. between the

four survey events) and zones and there was also a significant effect for the interaction of time by

zone. This significant interaction was due to inconsistent trends in fish abundance over the four

survey events. The outfall impact zone had significantly higher fish abundance (in comparison to the

mixing zone and / or the reference zone) during the warm water surveys in April 2012 and April 2013,

but this was not consistent for the cool water surveys December 2011 and October 2012. In April

2012, there was significantly higher fish abundance at the outfall impact zone in comparison to the

putative mixing zone and reference zone. During April 2013, there was significantly higher fish

abundance at the outfall impact zone in comparison to the reference zone (Table 3.1).

Table 3.1 Mixed model nested ANOVA results for fish abundance measured by UVC.

Factor Effect (F/R) DF MS F p

Time Fixed 3 14.35 26.67 0.00**

Zone Fixed 2 54.32 82.92 0.00**

Site(Zone) Random 9 0.66 1.22 0.33

Zone*Time Fixed 6 1.53 2.84 0.03*

Site(Zone)*Time Random 27 0.54 0.33 1.00

Error

48 1.63

* p < 0.05, ** p < 0.01. Note: data was log transformed prior to analysis (ln(x+1).

3.1.2 Species Richness

Species richness refers to the number of different species recorded at a given site / location. Total

species richness (i.e. of all four transects per site) and mean species richness (i.e. average of four

transects per site) were measured using data from each UVC survey at the Burwood Beach outfall

impact zone, mixing zone and reference zone sites. Mean species richness data is presented in

Figure 3.3. Species richness for each survey event is discussed in the sections below.

DECEMBER 2011

During the cool water December 2011 UVC surveys species richness (total and mean) was higher at

the outfall impact zone sites than the mixing zone or reference sites. At the outfall impact zone sites

(i.e. outfall N and outfall S) total richness of 20 and 27 fish species was recorded. A total of nine and

20 fish species were present at the mixing zone sites, and at the reference zone sites (i.e. reference

N and reference S) nine and three different fish species were identified. Outfall impact S had higher

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average species richness than outfall impact N, while the mixing zone site, mixing zone S had similar

average species richness to outfall N. Mean species richness was found to be lowest overall at the

reference zone sites (Figure 3.3).

APRIL 2012

The April 2012 data showed a similar trend to December 2011, with overall higher mean species

richness at the outfall impact zone sites, however, mean species richness during this survey was also

high at the northern mixing zone site. Again, mean species richness was found to be lowest at the

reference zone sites (Figure 3.3). At the outfall impact zone sites (i.e. outfall N and outfall S), total

richness of 37 and 26 was recorded, at the mixing zone sites (i.e. mixing zone N and mixing zone S),

37 and seven different fish species were recorded and the total number of species present at the

reference zone sites (i.e. reference N and reference S) was very similar with 16 and 15 species

identified respectively. Overall, total and mean levels of species richness were higher in April 2012

than in December 2011 (Figure 3.3).

OCTOBER 2012

The second cool water UVC survey in October 2012 survey found similar trends to those seen in the

first cool water surveys of December 2011 (Figure 3.3). As for December 2011, outfall impact S had

the highest mean species richness, being higher than outfall impact N, and the mixing zone site

mixing zone S had similar mean species richness to outfall N. Mean species richness was low at

mixing zone N and reference N, while no data could be analysed for reference S due to the extremely

poor visibility during the survey (Figure 3.3). Total species richness at the outfall impact zone sites

(i.e. outfall N and outfall S) was 31 and 54 respectively. At the mixing zone sites, (i.e. mixing zone N

and mixing zone S) seven and 30 different species were recorded and at the reference zone sites (i.e.

reference N and reference S) there were seven different species recorded at reference N but no

individuals were detected at reference S.

APRIL 2013

The final warm water UVC survey in April 2013 found that while mean species richness was higher at

the outfall impact zone, the difference (in comparison to the mixing zone and reference zone) was

much less pronounced than for previous surveys. Mean species richness was similar at the reference

N site and the outfall impact sites (Figure 3.3). Total richness values at the outfall impact zone sites

(i.e. outfall N and outfall S) were 51 and 53 different species respectively. At the mixing zone sites

(i.e. mixing zone N and mixing zone S), 36 and 21 different species were recorded and at the

reference zone sites (i.e. reference N and reference S), 45 and 26 different species were recorded

respectively.

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ALL SURVEYS

A mixed model nested ANOVA was used to assess whether there were significant differences in

species richness between the factors of time (December 2011 vs. April 2012 vs. October 2012 vs.

April 2013), zone (outfall impact zone vs. putative mixing zone vs. reference zone) and site (nested

within zone) and to determine if there were any interactions between time by zone or between time by

site (zone) (refer to Table 3.2 for ANOVA results).

Results of the analysis found that there were significant differences in richness between sampling

events (time) and between zones, in addition there was a significant interaction between time by

zone. This demonstrates that the trend of richness in different survey zones differed over the

surveys. This was due to a significant difference between richness at the outfall impact zone in

comparison to the reference zone during October 2012, but not during the other sampling events.

Table 3.

Documents

Fish Distribution Study - Amazon Web Services...Two fish census techniques were used; underwater visual census (UVC) and baited remote underwater video stations (BRUVS). UVC was undertaken