waste capture system - epa tasmania final...waste capture system: summary report 7 1 executive...

Waste Capture System: Summary Report 1

WASTE CAPTURE SYSTEM:

SUMMARY OF WATER AND SEDIMENT QUALITY MONITORING

Final Report to

Tassal

August 2018

www.marinesolutions.net.au www.aquenal.com.au


© Marine Solutions 2018. This document should only be used for the specific project and

purposes for which it was commissioned. 1

Version Author Date reviewed

Reviewed by

1 of 1 Annie Ford 16/8/2018 Joe Valentine (Aquenal Pty Ltd)

1 Cover photo, fish pens in Macquarie Harbour (photo by Marine Solutions, 2017).


TABLE OF CONTENTS

Table of Contents .......................................................................................................................................... 3

Table of Figures ............................................................................................................................................. 5

1 Executive Summary ............................................................................................................................... 7

1.1 Water Quality ................................................................................................................................ 7

1.2 Sediment Quality........................................................................................................................... 8

1.3 Overall Effect of WCS on Oxygen demand .................................................................................... 9

1.4 Summary ..................................................................................................................................... 12

2 Introduction ........................................................................................................................................ 13

2.1 Background ................................................................................................................................. 13

2.2 Purpose and Scope ...................................................................................................................... 14

3 Water Quality Monitoring ................................................................................................................... 15

3.1 Monthly Water Quality Monitoring ............................................................................................ 15

3.1.1 Methods .............................................................................................................................. 15

3.1.2 Results ................................................................................................................................. 19

3.2 Pelagic Oxygen Demand ............................................................................................................. 28

4 Benthic Monitoring ............................................................................................................................. 37

4.1 Sediment Sampling ..................................................................................................................... 37

4.1.1 Methods .............................................................................................................................. 37

4.1.2 Results ................................................................................................................................. 42

4.2 Benthic Oxygen Demand ............................................................................................................. 44

4.2.1 Methods .............................................................................................................................. 44

4.2.2 Results ................................................................................................................................. 46


5 Effects of WCS on Oxygen demand in Macquarie Harbour ................................................................ 48

5.1.1 Results ................................................................................................................................. 48

6 Discussion and Conclusions ................................................................................................................ 52

7 Appendices .......................................................................................................................................... 55

Appendix 1. Monthly water quality monitoring summaries ............................................................... 55

Appendix 2. Pelagic Oxygen Demand Study ....................................................................................... 55

Appendix 3. Sediment Quality Monitoring ......................................................................................... 55

Appendix 4. Benthic Oxygen Demand Study....................................................................................... 55

Appendix 5. Effect of WCS on Oxygen Demand .................................................................................. 55


TABLE OF FIGURES

Figure 1 Location of Marine Farming leases within Macquarie Harbour, Tasmania (LISTmap, 2017). ...... 13

Figure 2 Indicative fine-scale water quality sampling sites during October 2017, based on cage 13A being

the waste extraction cage. Map not to scale. ............................................................................................. 16

Figure 3 Broad scale water quality sampling locations ............................................................................... 17

Figure 4 Pre- and post-extraction dissolved oxygen profiles during fine-scale monitoring in a) July, b)

August and c) September 2017. .................................................................................................................. 21

Figure 5 Pre- and post-extraction dissolved oxygen profiles during fine-scale monitoring in d) October, e)

November and f) December 2017. ............................................................................................................. 22

Figure 6 Pre- and post-extraction dissolved oxygen profiles during fine-scale monitoring in g) January, h)

February and i) March 2018........................................................................................................................ 23

Figure 7 Turbidity, total nitrogen and total phosphorus concentrations over the WCS trial period in

surface, mid and bottom waters at site S5. ................................................................................................ 25

Figure 8 Dissolved oxygen profiles during broad-scale monitoring in a) August, b) September, c) October

and d) November 2017. .............................................................................................................................. 26

Figure 9 Dissolved oxygen profiles during broad-scale monitoring in e) December 2017, f) January 2018,

g) February 2018 and h) March 2018. ........................................................................................................ 27

Figure 10 POD sampling sites throughout Macquarie Harbour. The cage sampling site labeled in the

figure as “THC cages” indicate cages at Table Head Central Lease. “Tassal cages” indicate sampling sites

located on Tassal’s Gordon Lease. “BB cages” indicate cages at Bryan’s Bay Lease. ................................. 32

Figure 11 POD rates across all depths and sites from June to November 2017. Box plots show both mean

and median POD rates, as well as all data points collected. ...................................................................... 33

Figure 12 Harbour-wide POD in the photic zone from June to November 2017. ...................................... 34

Figure 13 1st Order DO consumption budget with depth from June to November 2017 in comparison to

previous POD campaigns. ........................................................................................................................... 35

Figure 13 POD with increasing depth under Gordon MF219 lease cages with WCS liners. Left column

represents POD with and without WCS extraction activities. Right column represents POD under cages

with and without WCS liners. ..................................................................................................................... 36


Figure 15 Schematic diagram illustrating fine scale survey design at the Gordon MF219 lease. Note map

not to scale. ................................................................................................................................................. 38

Figure 16 Schematic diagram illustrating fine scale survey design at the Middle Harbour MF214 lease.

Note map not to scale. ................................................................................................................................ 38

Figure 17 Middle Harbour (MF214) broad scale sediment sampling locations. ......................................... 39

Figure 18 Gordon (MF219) broad scale sediment sampling locations. Note that the northern and

southern transects were sampled by IMAS. ............................................................................................... 39

Figure 19 Location of sediment traps at Gordon (MF219) lease ................................................................ 41

Figure 20 Sample site locations for the 2018 BnOD Study. Detailed pen sampling on Gordon (MF219)

aquaculture lease is demonstrated in Figure 21 below. ............................................................................. 45

Figure 21 Sampling design for time series study around Gordon lease. Circles represent fish cage

positions, with red circles denoting no liners installed, orange denoting liners installed since October

2017, and purple denoting liners installed since June 2017. ...................................................................... 46

Figure 22 Benthic oxygen consumption with distance east of the edge of Gordon lease and at three

control sites north east of the lease. The red line indicates the mean oxygen consumption of control

sites (91.510 µmol m-2 h-1). ......................................................................................................................... 47

Figure 23 Benthic oxygen consumption at various cages in Gordon MF219 lease. Cages are ordered

based on installation date of waste liners. The solid red line indicated the mean oxygen consumption of

all cages (596.626 µmol m-2 h-1). ................................................................................................................. 48


1 EXECUTIVE SUMMARY

In June 2017, Tassal implemented a Waste Capture System (WCS) trial in Macquarie Harbour. The WCS

aimed to capture solid emissions from salmon farming operations beneath selected salmon cages at

Marine Farming leases MF214 (Middle Harbour) and MF219 (Gordon). This waste was collected in liners

installed beneath individual fish cages and was extracted from a sump, pumped to the surface and

stored for transport to shore.

Marine Solutions and Aquenal were contracted by Tassal to compile a summary report of water and

sediment quality monitoring conducted during the WCS trial. This report summarises 13 individual water

and sediment quality monitoring reports written by Marine Solutions, Aquenal and Aquadynamic

Solutions (ADS) during the trial period.

Water quality sampling was conducted each month throughout the trial period (July 2017 to March

2018), whereas sediment sampling was undertaken on two occasions (October 2017 and February

2018). Remotely Operated Vehicle (ROV) surveys of benthic habitats occurred on four occasions,

including October 2017, December 2017, February 2018 and April 2018.

Specifically, the purpose of this research was to:

Determine whether there were impacts to pelagic water quality from a) waste collection in the

sump, b) agitation of waste in sump during the waste removal process, and c) fish biomass

Determine if the waste capture system was effective in reducing impact to sediments and water

quality at the harbour bottom within lease area.

1.1 WATER QUALITY

Despite an increase in the fish biomass during the WCS trial, there were no identified changes in physical

parameters or increases in dissolved or particulate nutrient concentrations within the water column

adjacent to cages.

Water quality (physical, dissolved or particulate nutrients and Pelagic Oxygen Demand [POD]) adjacent

to cages installed with a WCS liner was comparable to the water quality adjacent to cages without a


WCS liner. Of the cages with a WCS liner installed, water quality in the adjacent water column was not

impacted during extraction (air lifting) processes. The absence of any notable changes in water quality

parameters at a fine-scale may indicate there were no detectable impacts of waste collection in the

sump or agitation of waste during extraction activities.

On a broader scale, water quality parameters measured throughout Macquarie Harbour were

comparable to sites adjacent to cages and the WCS. This pattern was observed in all water quality

parameters, including physical parameters, dissolved and particulate nutrients, and POD concentrations.

For example, dissolved oxygen concentrations did not significantly vary with increasing distance from

cages and dissolved oxygen profiles were generally typical of Macquarie Harbour.. An increase in bottom

water dissolved oxygen was recorded over the monitoring period and may be due to recharge events or

a reduction in organic matter on the seabed due to the installation of the WCS.

Similarly, the effect of the WCS on POD was insignificant, with a maximum reduction of 0.03% POD.

Levels of POD showed a closer relationship with general harbour background levels compared with

waste capture activities. Comparably, significant Gordon River inputs (freshwater and organic matter)

have a considerably greater influence on POD throughout Macquarie Harbour. In all seasons other than

summer, large inputs of organic matter from the Gordon River appeared to be responsible for variations

observed in oxygen consumption. In a system largely characterised by riverine influences, the oxygen

savings from WCS, while possible, is likely to lack significance.

Overall, the absence of any notable water quality elevations or changes indicates there were no impacts

attributable to the implementation of the WCS trial.

1.2 SEDIMENT QUALITY

With the exception of faeces and pellet quantities, the implementation of the WCS did not result in any

marked improvements in sediment quality. The installation of WCS liners resulted in a reduction of

faeces and pellet quantities at all adjacent sites. A relationship was also identified between an increase

in the duration of WCS liner installment and a reduction in the quantity of faeces and pellets.


Although sediment quality adjacent to WCS lined cages improved when assessed using visual methods,

no improvements were identified when assessing organic content, dissolved nutrient concentrations

and sedimentation rates. Organic content, dissolved nutrient concentrations and sedimentation rates

were highest closest to cages and decreased at sites 50m distance from cages. There were no discernible

differences detected between sites adjacent to lined or unlined cages.

Similar patters were observed in sediment chemistry, infauna and Benthic Oxygen Demand (BnOD),

where concentrations or communities were similar across cage sites, regardless of whether a liner was

present or not. On the lease, there were no distinct patterns in the rates of BnOD with respect to the

length of time cages had been lined. Notably, the highest rates of BnOD observed in 2018 were well

below the rates within the same lease reported in 2012 (see Appendix 2). This reduction in BnOD may

reflect a subtle cumulative effect of waste capture liners on seabed oxygen demand.

1.3 OVERALL EFFECT OF WCS ON OXYGEN DEMAND

Using results of field studies with pelagic and benthic oxygen demand experiments, ADS determined the

effect of the WCS on overall oxygen demand.

The ADS study addressed the key questions outlined below to assess the effectiveness of the WCS trial:

1. Determine the volume of the feed and faeces waste that is currently escaping pens without waste

capture systems;

Based on feed inputs a total of 963.2 tonnes of waste was generated between June 2017 and April 2018.

During the period Tassal was separating solids from their waste capture program (i.e. October 2017 to

April 2018) 632.2 tonnes of waste was generated, 219.3 tonnes of which was generated by fish and feed

over the biomass limit of 3,640 tonnes.

The waste mass of 219.3 tonnes represents the theoretical upper limit of waste collected by WCS in

excess of the biomass limit from October to April 2017. Tassal reported collecting 213.7 tonnes of wet

waste, and 81.8 tonnes of dry solids over this period. The 81.8 tonnes of dry waste should be considered

a minimum estimate of dry solid waste collected as it does not account for waste present in the effluent.


It was also not practical to accurately quantify dry solid waste due to variation in estimates of TSS and

moisture content of waste collected during the course of the trial.

2. Estimate waste that was captured expressed as a % of feed input;

Assuming 4,682.9 tonnes of feed was used on both the Middle Harbour and Gordon Leases between

October 2017 and April 2018 (1,624.5 tonnes was used to feed fish over the biomass limit), and

assuming that feed had a moisture content of 10% (total feed 4,214.6 tonnes, over-limit feed 1,462.1)

and 81.8 tonnes of dry solids were collected in waste capture systems, then approx. 1.9% of the total

feed inputs and 5.6% of the over-limit inputs were recovered in waste capture systems.

3. Estimate (reduction of) O2 demand assuming complete capture of all waste; and complete capture

of waste from feed over the biomass limit.

Discounting the likelihood that farm-derived wastes are buried upon reaching the seabed and assuming

all waste is collected by the WCS (963.2 tonnes of total waste generated from 7,135 tonnes of feed

assuming 10% moisture content), the waste could theoretically account for 291.9 to 514.4 tonnes of

organic carbon. If fully oxidized to CO2 this could remove 777.5 to 1,370.1 tonnes of dissolved oxygen.

The more likely estimate would be based on BOD5 from the raw waste resulting in 522.1 tonnes of

oxygen removed.

The solid waste generated from feed over the biomass limit from October 2017 to April 2018 (219.3

tonnes) would contain anywhere from 66.4 to 117.1 tonnes of organic carbon. If fully oxidized to CO2

this would require approx. 176.9 to 311.9 tonnes of dissolved oxygen over the growing season.

4. Calculate (reduction of) O2 demand based on waste actually captured.

The absolute DO demand of 81.8 tonnes of farm waste captured would range from 66.0 to 116.4 tonnes

of DO if all carbon were oxidized to CO2. Based on actual BOD5 measurements the captured waste would


require 44.3 tonnes of DO if that waste were exposed to the water column for 5 days. Because waste

sinks relative quickly (i.e. approx.15 min at the lease depths) it is likely buried quickly and can become

isolated from aerobic respiration.

Based on the standing stock of DO in the system (In June 2018 there was approx. 3,950 tonnes of DO in

the sub-halocline region of the water column). The best DO savings waste capture systems could offer

(i.e. if all farm-derived waste from June 2017 to April 2018 was oxidized to CO2) would be 2.9% of the

standing stock of DO in the harbour. Based on the relationship between BOD5 and TSS this value drops

to 1.1%. Based on comparisons of BnOD between MHDOWG 2014 and of ADS 2018 this value drops to

anywhere between 0.09% to 0.13%.

5. Determine the relative importance benthic oxygen demand and the waste capture systems on the

sub-halocline standing stock of O2 in Macquarie Harbour

Based on DO profiles taken at site C08 in June 2018, the amount of dissolved oxygen present in the

harbour below the halocline (assuming 15m depth) is approx. 3,950 tonnes. If all waste generated over

the biomass limit from October 2017 to April 2018 (219.3 tonnes) were captured (resulting in a savings

of 176.9 to 311.9 tonnes of dissolved oxygen) this would result in saving 4.5% to 7.9% of the sub-

halocline June 2018 DO budget (note these values are the standing stock and do not account for

recharge, vertical mixing, etc). Based on the oxygen demand estimates of the actual dry solids mass

collected by Tassal (66.0 to 116.4 tonnes of oxygen) WCS saved anywhere from 1.7% to 2.9% of the sub-

halocline June 2018 harbour DO budget.

System-wide DO demand in Macquarie Harbour is dominated by the water column and not the benthos.

The isolated portion of the water column (i.e. the sub-halocline water column) removes anywhere from

16.9 thousand tonnes to 33. 8 thousand tonnes of DO per month. Using the absolute maximum rate

observed during the ADS 2018 study, the Gordon and Middle Harbour Lease benthic DO demand only

removes 2.7 and 1.9 tonnes of DO per month respectively. The whole non-farmed portion the seabed


removes only 750 tonnes per month at best (according to rates reported in ADS 2018). The best

combined benthic DO savings due to waste capture systems would be 4.9 tonnes per month.

Even if every carbon atom captured by the waste capture systems were oxidized to CO2 (equivalent to

116.4 tonnes of DO) over the June 2017 to April 2018 waste capture period, it would only amount to

0.68% of the monthly pelagic oxygen demand during the lowest river loading period.

1.4 SUMMARY

Despite few measurable improvements in water and sediment quality during the WCS trial, a reduction

in feed and waste emitted to the surrounding water column and seafloor would have undoubtedly

resulted in reduced organic enrichment in the region of WCS lined cages over time. The inability to

identify a strong pattern was likely due to a number of confounding effects, including farming history,

sampling locations, variable feed inputs and farming practices, site specific environmental conditions

and lag effects.


2 INTRODUCTION

2.1 BACKGROUND

As part of Tassal’s Waste Capture System (WCS) development at Macquarie Harbour, solid emissions

from salmon farming operations were captured beneath selected salmon cages (using 900 gsm PVC

liners) at Marine Farming leases MF214 (Middle Harbour) and MF219 (Gordon; Figure 1). Waste

collected in the liners was extracted from a sump, pumped to the surface and stored in intermediate

bulk containers. Effluent was then transported to Tassal’s processing facility at Strahan for further

treatment.

Figure 1 Location of Marine Farming leases within Macquarie Harbour, Tasmania (LISTmap, 2017).

At the Gordon MF219 aquaculture lease, the number of waste capture liners increased from 2 in June

2017 to a maximum of 22 in February 2018 (prior to the removal of all liners in March 2018). Fewer

waste capture liners were installed at the Middle Harbour MF214 lease, where the number of liners

increased from 4 in September 2017 to a maximum of 10 from October 2017 to January 2018 (prior to


the removal of all liners in March 2018). From July 2017 to March 2018, a total of approximately 4.2 ML

of waste (including both liquid and solid emissions) was extracted out of waste capture liners at both

leases.

An environmental monitoring schedule was designed to align with Tassal’s Environmental Management

Plan (EMP) and to address the Environmental Protection Authority’s (EPA) Environmental Protection

Notice (EPN) 9702/1 issued under the Environmental Management and Pollution Control Act 1994.

Monitoring was aimed to assess the impacts of the WCS once the liners were installed and operational.

Where possible, monitoring methods were implemented in conjunction with routine compliance

monitoring conducted by Tassal and by the University of Tasmania’s Institute of Marine and Antarctic

Studies (IMAS).

2.2 PURPOSE AND SCOPE

Marine Solutions and Aquenal were contracted by Tassal to compile a summary report of water and

sediment quality monitoring conducted during the WCS trial in Macquarie Harbour. This report

summarises 12 individual water and sediment quality monitoring reports produced by Marine Solutions,

Aquenal and Aquadynamic Solutions during the trial period.

Specifically, the purpose of this summary report is to:

Determine whether there were impacts to pelagic water quality from a) waste collection in the

sump, b) agitation of waste in sump during the waste removal process, and c) fish biomass

Determine if the waste capture system was effective in reducing impact to sediments and water

quality at the harbour bottom


3 WATER QUALITY MONITORING

3.1 MONTHLY WATER QUALITY MONITORING

Monthly water quality monitoring was conducted by Marine Solutions and Aquenal. All methods, results

and discussions presented below have been summarised or reanalysed from full monthly reports (see

Appendix 1.a, Appendix 1.b, Appendix 1.c, Appendix 1.d, Appendix 1.e, Appendix 1.f, Appendix 1.g,

Appendix 1.h, Appendix 1.i).

3.1.1 Methods

During the WCS trial, water quality monitoring was conducted on both a fine-scale and broad-scale

within Macquarie Harbour. Fine-scale monitoring was conducted at the Gordon lease from July 2017 to

March 2018 and broad-scale monitoring was conducted north and south of the Gordon lease from

August 2017 to March 2018.

Fine-scale water quality sampling was conducted in two rounds within, and adjacent to, the Gordon

lease. The first round of sampling was conducted prior to extraction, and the second round of sampling

was conducted post-extraction. The post- extraction sampling round was commenced immediately after

the extraction was completed, in order to monitor any plume generated by agitating the waste during

collection. Waste extraction was facilitated by the vessel “Sea Hauler”.

The location of fine scale sampling sites was based on the location of the cage where extraction was

occurring, with monitoring sites radiating in a gradient north and south away from the cage (for example

of sampling sites in October 2017, see Figure 2). Water samples were taken at the surface, middle (20 m;

approximate liner depth) and 1 m above the seabed.


Figure 2 Indicative fine-scale water quality sampling sites during October 2017, based on cage 13A being the waste extraction cage. Map not to scale.

Broad scale water quality sampling was conducted at 9 sites throughout Macquarie Harbour to obtain

background data (Figure 3). Broad scale sampling was conducted at sites located approximately 500 m

from the nearest aquaculture lease. Water samples were taken from the surface, 15 m depth and 1 m

above the seabed.


Figure 3 Broad scale water quality sampling locations

Water sampling was conducted by grab-sampling from a research vessel. All surface grabs were

collected into a pre-washed and pre-flushed intermediate holding vessel, thus ensuring each subsample

for a given site was sampled from the same parcel of water, then transferred to the appropriate

subsample jar and chilled for transport to the laboratory. Mid-depth and bottom-depth samples were

collected using a pre-washed and pre-flushed Niskin sampler. A YSI 6920 V2 multi-

parameter water quality sonde was used for in situ water quality profile measurements, including

temperature, specific conductivity, salinity, pH, turbidity and dissolved oxygen. Water quality

parameters tested at each site are listed in Table 1.

Water samples were delivered to Analytical Services Tasmania within laboratory holding time

requirements.


Table 1 Water quality parameters measured during fine- and broad-scale sampling

Parameter Unit Location

Fie

ld

Temperature °C

Fine-scale and

broad-scale

Salinity PPT

Dissolved Oxygen %

pH La

bo

rato

ry

Turbidity NTU

Ammonia N mg/L

Total Nitrogen mg/L

Nitrogen Oxide mg/L

Total Phosphorus mg/L

Non-purgeable Organic Carbon (total) mg/L

Non-purgeable Organic Carbon (dissolved) mg/L

Total Suspended Solids mg/L

Biological Oxygen Demand mg/L Fine-scale

only


3.1.2 Results

3.1.2.1 Fine-scale Monitoring

There were no substantial changes in any parameters from pre-extraction sampling to post-extraction

sampling throughout the WCS trial period at the Gordon lease (Table 2). Any increases in parameter

concentrations were considered to be minor. No elevations in turbidity or total suspended solids during

the post-extraction round of fine-scale sampling indicated there was no detectable plume despite the

agitation of waste during collection.

Table 2 Range of particulate and dissolved nutrient parameter concentrations throughout the WCS trial at Site S5.

Depth Parameter Unit Pre-extraction Post-extraction

Lower limit Upper limit Lower limit Upper limit

Surface

Turbidity NTU

0.5 1.7 0.6 1.7 Middle 0.4 0.8 0.2 0.9 Bottom 0.3 1 0.3 0.9 Surface

Biological Oxygen Demand

mg/L


Dissolved oxygen concentrations, a key physical parameter of concern, did not change between pre- and

post-extraction sampling events (Figure 4; Figure 5; Figure 6). Dissolved oxygen concentrations

decreased rapidly from the surface to approximately 15 – 20 m depth. During the first half of the trial

(from July to November 2017), dissolved oxygen from 15 – 20 m depth to bottom waters either

continued to decrease steadily or remained consistent with increasing depth. During the second half of

the trial (December 2017 to February 2018), dissolved oxygen concentrations increased in bottom

waters (over 2 mg/L). Similar patterns were observed each month at broad scale monitoring (see Section

3.1.2.2),

Increases in bottom water dissolved oxygen concentrations may be associated with recharge events,

where an influx of seawater through the harbour mouth results in an increase in bottom water dissolved

oxygen concentrations.


Figure 4 Pre- and post-extraction dissolved oxygen profiles during fine-scale monitoring in a) July, b) August and c) September 2017.


Figure 5 Pre- and post-extraction dissolved oxygen profiles during fine-scale monitoring in d) October, e) November and f) December 2017.


Figure 6 Pre- and post-extraction dissolved oxygen profiles during fine-scale monitoring in g) January, h) February and i) March 2018.

Elevated ammonia was detected on two separate sampling events at the Gordon lease. In November

2017, an elevated ammonia concentration was detected in both pre- (0.066 mg/L) and post-extraction

(0.043 mg/L) sampling events. Elevations in ammonia during both rounds of sampling indicate a high

background level of ammonia rather than extraction activities causing elevations in concentrations. In

December 2017, a single elevation of 0.067 mg/L was detected during post-extraction sampling. This

elevation may be due to extraction activities, however ammonia concentrations returned to background

levels at all other sites and depths.


The absence of any notable changes in water quality parameters at a fine-scale indicates there were no

detectable impacts of waste collection in the sump or agitation of waste in the sump during extraction

activities.

The increase in fish biomass during the WCS trial at Gordon lease did not cause further increases in

dissolved or particulate nutrient concentrations or changes in physical parameters within the water

column. For example, Figure 7 demonstrates the variation in a selection of nutrient parameters,

including turbidity, total nitrogen and total phosphorus at site S5 prior to extraction activities.

Concentrations of all parameters were comparable across time, with the exception of total nitrogen

which recorded a substantial decrease in concentrations during September 2017. All other particulate

and dissolved nutrient parameters recorded similar patterns throughout the trial period.


Figure 7 Turbidity, total nitrogen and total phosphorus concentrations over the WCS trial period in surface, mid and bottom waters at site S5.


3.1.2.2 Broad-scale Monitoring

Dissolved oxygen profiles were comparable throughout the harbour, with a rapid decrease in

concentrations with increasing depth to approximately 15 m (Figure 8; Figure 9). Dissolved oxygen was

similar at deeper depths from August to November 2017 (Figure 8), however increased more in bottom

waters from December 2017 to March 2018 (Figure 9). These increases were consistent with those

observed at fine-scale monitoring sites during the same months (see Section 3.1.2.1).

Dissolved oxygen concentrations were generally comparable to those observed at fine-scale sampling

sites, with no notable differences in concentrations between sites.

Figure 8 Dissolved oxygen profiles during broad-scale monitoring in a) August, b) September, c) October and d) November 2017.


Figure 9 Dissolved oxygen profiles during broad-scale monitoring in e) December 2017, f) January 2018, g) February 2018 and h) March 2018.

Throughout the monitoring period, all parameters measured at broad-scale monitoring sites were

comparable to fine scale sites. The absence of any notable elevations or changes indicates there were

no impacts to water quality due to the implementation of the WCS trial.


3.2 PELAGIC OXYGEN DEMAND

Aquadynamic Solutions conducted a study to quantify the effectiveness of the WCS and determine its

impact on Pelagic Oxygen Demand (POD). Refer to Appendix 2 for full analysis and report.

3.2.1.1 Methods

The spatial variability of POD was assessed by measuring POD throughout Macquarie Harbour and

adjacent/downcurrent of cages with and without waste capture liners. The impact of WCS extraction

was also assessed by measuring POD concentration during the removal (extraction) of captured waste

under cages.

POD was assessed from June 2017 to November 2017. Samples were taken from three regions within

Macquarie Harbour including a southern transect, a central harbour region, and a northern transect (


Table 3; Figure 10). Each of these regions contained sites that were sampled at 4 depths below the

surface, including 2 meters (photic zone), 10 meters (halocline), 20 meters (subhalocline), and 2 meters

above the seabed (


Table 3). Samples from cage sites were collected adjacent or downstream of the most heavily stocked

cages. At sites where there was insufficient depth to collect samples from all depths, samples that were

possible were collected.


Table 3 - Locations of POD collection sites and depths sampled.


Figure 10 POD sampling sites throughout Macquarie Harbour. The cage sampling site labeled in the figure as “THC cages” indicate cages at Table Head Central Lease. “Tassal cages” indicate sampling

sites located on Tassal’s Gordon Lease. “BB cages” indicate cages at Bryan’s Bay Lease.

Samples were collected using a Niskin bottle and transferred into polycarbonate bottles using methods

that minimise the potential contaminations from air. For more complete details regarding methods see 0.


3.2.1.2 Results

There was harbour-wide increase in POD rates in August and September that coincided with increased

rainfall, snowmelt and organic loading from the Gordon River catchment during winter (Figure 11). This

was most obvious in the photic zone and is due to the respiration of catchment derived organic matter

transported to the harbour via the Gordon River (Figure 12).

Figure 11 POD rates across all depths and sites from June to November 2017. Box plots show both mean and median POD rates, as well as all data points collected.


Figure 12 Harbour-wide POD in the photic zone from June to November 2017.

In all seasons other than summer, inputs of organic matter into the southern end of Macquarie Harbour

was responsible for nearly 68% of variation in oxygen consumption in the photic zone. The impact of

organic matter input on POD increased with depth, with more than 92% of variation in oxygen demand

below the halocline due to organic inputs, and over 96% of variation in oxygen demand in the bottom

waters due to organic inputs (the layer of water most characterised by hypoxia; Figure 13).


Figure 13 1st Order DO consumption budget with depth from June to November 2017 in comparison to previous POD campaigns.

POD measured around the cages during the removal of waste showed no significant differences at any

depth in the water column, nor was there any significant differences in POD under cages with waste

capture systems or those without (Figure 14). Levels of POD showed a closer relationship with general

harbour background levels compared with waste capture activities during August and September 2017

(p = >1*10-14).


Figure 14 POD with increasing depth under Gordon MF219 lease cages with WCS liners. Left column represents POD with and without WCS extraction activities. Right column represents POD under cages

with and without WCS liners.


In summary, no significant differences could be identified between cages with and without waste

capture liners, nor were there any significant differences in benthic oxygen demand due to the length of

time waste capture liners had been installed.

4 BENTHIC MONITORING

4.1 SEDIMENT SAMPLING

Aquenal and Marine Solutions conducted fine scale and broad scale benthic monitoring during the WCS

trial at Middle Harbour and Gordon leases within Macquarie Harbour. See Appendix 3 for full analysis

and report.

4.1.1 Methods

Fine scale monitoring focused on comparison of seabed conditions beneath cages with waste collection

liners that had been installed for varying periods of time, including long term deployments, medium

term deployments and short term deployments. Samples were collected at the cage edge and 50 m

directly away from the cages (Figure 15; Figure 16).


Figure 15 Schematic diagram illustrating fine scale survey design at the Gordon MF219 lease. Note map not to scale.

Figure 16 Schematic diagram illustrating fine scale survey design at the Middle Harbour MF214 lease. Note map not to scale.

Broad scale sampling focused on benthic infauna and was included to provide an understanding of

broad scale infauna patterns in the vicinity of the Gordon and Middle Harbour leases over the duration

of the WCS trial. Samples were taken at 0 m (cage edge), 50 m, 100 m, 250 m and 500 m in a north, east,

south and west direction away from both leases (Figure 17, Figure 18).


Figure 17 Middle Harbour (MF214) broad scale sediment sampling locations.

Figure 18 Gordon (MF219) broad scale sediment sampling locations. Note that the northern and southern transects were sampled by IMAS.


Benthic monitoring included ROV surveys, sediment chemistry, sedimentation and infauna analysis. ROV

filming was conducted every two months as weather permitted, with benthic features (Table 4) scored

from when the ROV reached the seabed until the end of filming.

Table 4 Key features assessed during review of ROV footage.

Score

Category 0 1 2 3 4 5

Status Unlined Lined

Sediment colour

Normal

Few

black/grey

patches

Patchy

black/grey

throughout

Black/ grey

throughout

Gas bubbles No

Bubbling on

disturbance Free bubbling

Beggiatoa None Patchy Thick patches Thin mat Med mat Thick mat

Dorvilleids None Individuals Colonies Mixed

Dorvilleid count 0 1-30 31-100 101-300 301-1000 >1000

Fresh Pellets 0 1-30 31-100 101-300 301-1000 >1000

Fresh Faeces 0 1-30 31-100 101-300 301-1000 >1000

Sabellids/worm

tubes None Few Many

Heart urchins None Few Many

Nebalia None Few Many

Sediment cores were collected for analysis using a quad corer. Cores were tested for redox and sulphide

and described in terms of length, colour (using a Munsell soil chart), plant and animal life, gas vesicles,

and smell. At each site a separate core was collected for nutrients and organic content. The top 3 cm of

the core was used for these analyses.


Benthic fauna samples were collected using a Van Veen grab, with duplicate samples collected at each

of the fine scale sites and triplicate grab samples collected at each of the broad scale sites. Macrofauna

were identified to species level and numerated in the Aquenal laboratory.

Sedimentation was measured at fine scale monitoring sites by deploying duplicate sediment traps set 1

m above the substrate at Gordon lease for 3 weeks (Figure 19).

Figure 19 Location of sediment traps at Gordon (MF219) lease


4.1.2 Results

Sediment analysis found an improvement in sediment quality when assessed using visual methods,

however found no improvement when assessed using sediment chemistry and infauna.

In December 2017 the sites without liners installed recorded the highest average faeces score. The

sample sites with liners installed all saw reductions in average faeces score between October and

December 2017, while the faeces score at the unlined cage sites increased over the same period.

Patterns shifted in 2018, however these patterns are likely a result of destocking of cages. No faeces

were detected at the off-site controls.

Unlined and short-term lined cages recorded the highest average pellet scores in the October 2017

survey. During December 2017, pellet scores were much lower at cages with liners than cages without

liners. Cages with liners installed for the longest period had the lowest average pellets score in

December 2017. Similar to faeces, pellets were observed in reduced quantities in February 2018 and

completely absent in April 2018, reflecting destocking activities. No pellets were detected at the off

lease control sites.

Dorvilleid worms increased in density from 2017 to 2018, corresponding to a decrease in pellet and

faeces scores in these months. Densities were highest at lined cages. Numerous dorvilleids were also

detected at off lease control sites and were in greatest numbers in the October survey.

Beggiatoa was generally more prominent and mostly observed in medium/thick mats in the October

2017 and December 2017 surveys and decreased to become absent from a number of locations in the

February 2018 and April 2018 surveys. Small patches of Beggiatoa were detected at the off lease control

sites during the December 2017 and April 2018 surveys.

Redox potential was lowest at sites closest to cages, with no differences identified between liner or

unlined cage sites. Sulphide concentrations were highest in sediments closest to cages and generally

reduced with increasing distance from cages. Consistent with patterns described for redox potential,

there was no discernible differences in sulphide concentrations adjacent to lined or unlined cages.

Similarly, organic content and dissolved nutrient concentrations were higher in sediments closest to

cages, however no discernible differences were detected between concentrations adjacent to lined or


unlined cages. This trend was also observed in sedimentation rates, with highest sedimentation recorded

at sites closest to cages, and less captured sediments at sites 50 m distance from cages. There was no

discernible difference in accumulated sediment between lined and unlined cages.

There was no strong pattern in fine scale faunal abundance or diversity in relation to lined or unlined

cages. Animal abundance was generally low at cage sites, irrespective of whether they were lined or not.

Similarly, there were no clear patterns for broad scale macrofauna abundance or diversity across all

transect directions and distances. Notably, community structure at Middle Harbour changed from

Dorvilleids in October 2017 to Capitellids in February 2018, suggesting that the level of organic

enrichment had become too high for Dorvilleids to survive.

Overall, while positive benthic effects were identifiable from ROV surveys, other benthic sampling

activities did not show positive effects attributable to the WCS. Patterns of sediment chemistry,

deposition rates and infauna communities tended to be similar across cage sites, regardless of whether

a liner was present or not.

Despite benthic chemistry and infauna results not showing clear positive effects on benthic condition, a

reduction in feed and faeces on the seafloor would have undoubtedly resulted in reduced organic

enrichment levels beneath WCS cages over time. The inability to identify a strong pattern was likely due

to a number of confounding effects, including farming history, sampling locations, variable feed inputs

and farming practices, site specific environmental conditions and lag effects.


4.2 BENTHIC OXYGEN DEMAND

Aquadynamic Solutions conducted a benthic respiration study to quantify the effectiveness of the WCS

on mitigating excess Benthic Oxygen Demand (BnOD) resulting from fish farms. Refer to Appendix 4 for

detailed analysis and full report.

4.2.1 Methods

BnOD was assessed in two experiments, including 1) BnOD with increasing distance from cages, and 2)

BnOD variation over the duration WCS liners were installed under cages. The spatial variation in BnOD

was assessed by collecting triplicate sediment cores at sites increasingly further from WCS lined salmon

cages, including 100 m and 500 m east of the cages, and from 3 control sites east of the lease (Figure

20).


Figure 20 Sample site locations for the 2018 BnOD Study. Detailed pen sampling on Gordon (MF219) aquaculture lease is demonstrated in Figure 21 below.

Time series BnOD was assessed by collecting triplicate sediment cores adjacent to 1) cages that were not

lined, 2) cages that were lined since October 2017, and 3) cages that were lined since June 2017 (Figure

21).


Figure 21 Sampling design for time series study around Gordon lease. Circles represent fish cage positions, with red circles denoting no liners installed, orange denoting liners installed since October

2017, and purple denoting liners installed since June 2017.

Sediment cores were collected from the seabed using a KD Kajak corer with an 80 mm inner diameter

Perspex tube.

4.2.2 Results

The highest BnODs were observed under farm sites, with BnOD decreasing with increasing distance from

the cages (Figure 22). The high BnOD near salmon cages is likely due to the difference in the amount of

labile organic material deposited to the seabed from the cages.


Figure 22 Benthic oxygen consumption with distance east of the edge of Gordon lease and at three control sites north east of the lease. The red line indicates the mean oxygen consumption of control

sites (91.510 µmol m-2 h-1).

On the lease, there were no distinct patterns in the rates of BnOD with respect to the length of time

cages had been lined, nor were there any significant differences among cages (Figure 23). This is to be

expected given that farm-derived solids would have to fall to a seabed approximately 30 m deep and

would be subject to forces scattering the deposition away from its origin.

Notably, the highest rates of BnOD observed in 2018 were well below the rates within the lease

reported in studies conducted in 2012 (see Appendix 2). This reduction in BnOD may reflect the

cumulative effect of waste capture liners on seabed oxygen demand.


Figure 23 Benthic oxygen consumption at various cages in Gordon MF219 lease. Cages are ordered based on installation date of waste liners. The solid red line indicated the mean oxygen consumption

of all cages (596.626 µmol m-2 h-1).

5 EFFECTS OF WCS ON OXYGEN DEMAND IN MACQUARIE HARBOUR

Aquadynamic Solutions (ADS) used a combination of waste collection data and field studies to assess the

effects of WCS implementation on oxygen demand. Data sources included the volume and

characteristics of waste measured, along with pelagic oxygen demand (Appendix 2) and benthic oxygen

demand (BnOD; Appendix 4) studies. Refer to Appendix 45 for detailed analysis and the full report.

5.1.1 Results

The effectiveness of waste capture system on mitigating DO demand in Macquarie Harbour is at best a

localized phenomenon. Compared to the influence of the Gordon River on pelagic oxygen demand and

the area of the non-farmed seabed on the benthic oxygen demand, farm wastes in Macquarie Harbour

do not appear to be a major driver of DO dynamics in the system.

In short, this study’s main objectives and conclusions are summarised below:


1. Determine the volume of the feed and faeces waste that is currently escaping pens without waste

capture systems;

Based on feed inputs a total of 963.2 tonnes of waste was generated between June 2017 and April 2018.

During the period Tassal was separating solids from their waste capture program (i.e. October 2017 to

April 2018) 632.2 tonnes of waste was generated, 219.3 tonnes of which was generated by fish and feed

over the biomass limit of 3,640 tonnes.

The waste mass of 219.3 tonnes represents the theoretical upper limit of waste collected by WCS in

excess of the biomass limit from October to April 2017. Tassal reported collecting 213.7 tonnes of wet

waste, and 81.8 tonnes of dry solids over this period. The 81.8 tonnes of dry waste should be considered

a minimum estimate of dry solid waste collected as it does not account for waste present in the effluent.

It was also not practical to accurately quantify dry solid waste due to variation in estimates of TSS and

moisture content of waste collected during the course of the trial.

2. Estimate waste that was captured expressed as a % of feed input;

Assuming 4,682.9 tonnes of feed was used on both the Middle Harbour and Gordon Leases between

October 2017 and April 2018 (1,624.5 tonnes was used to feed fish over the biomass limit), and

assuming that feed had a moisture content of 10% (total feed 4,214.6 tonnes, over-limit feed 1,462.1)

and 81.8 tonnes of dry solids were collected in waste capture systems, then approx. 1.9% of the total

feed inputs and 5.6% of the over-limit inputs were recovered in waste capture systems.


3. Estimate (reduction of) O2 demand assuming complete capture of all waste; and complete capture

of waste from feed over the biomass limit.

Discounting the likelihood that farm-derived wastes are buried upon reaching the seabed and assuming

all waste is collected by the WCS (963.2 tonnes of total waste generated from 7,135 tonnes of feed

assuming 10% moisture content), the waste could theoretically account for 291.9 to 514.4 tonnes of

organic carbon. If fully oxidized to CO2 this could remove 777.5 to 1,370.1 tonnes of dissolved oxygen.

The more likely estimate would be based on BOD5 from the raw waste resulting in 522.1 tonnes of

oxygen removed.

The solid waste generated from feed over the biomass limit from October 2017 to April 2018 (219.3

tonnes) would contain anywhere from 66.4 to 117.1 tonnes of organic carbon. If fully oxidized to CO2

this would require approx. 176.9 to 311.9 tonnes of dissolved oxygen over the growing season.

4. Calculate (reduction of) O2 demand based on waste actually captured.

The absolute DO demand of 81.8 tonnes of farm waste captured would range from 66.0 to 116.4 tonnes

of DO if all carbon were oxidized to CO2. Based on actual BOD5 measurements the captured waste would

require 44.3 tonnes of DO if that waste were exposed to the water column for 5 days. Because waste

sinks relative quickly (i.e. approx.15 min at the lease depths) it is likely buried quickly and can become

isolated from aerobic respiration.

Based on the standing stock of DO in the system (In June 2018 there was approx. 3,950 tonnes of DO in

the sub-halocline region of the water column). The best DO savings waste capture systems could offer

(i.e. if all farm-derived waste from June 2017 to April 2018 was oxidized to CO2) would be 2.9% of the

standing stock of DO in the harbour. Based on the relationship between BOD5 and TSS this value drops

to 1.1%. Based on comparisons of BnOD between MHDOWG 2014 and of ADS 2018 this value drops to

anywhere between 0.09% to 0.13%.


5. Determine the relative importance benthic oxygen demand and the waste capture systems on the

sub-halocline standing stock of O2 in Macquarie Harbour

Based on DO profiles taken at site C08 in June 2018, the amount of dissolved oxygen present in the

harbour below the halocline (assuming 15m depth) is approx. 3,950 tonnes. If all waste generated over

the biomass limit from October 2017 to April 2018 (219.3 tonnes) were captured (resulting in a savings

of 176.9 to 311.9 tonnes of dissolved oxygen) this would result in saving 4.5% to 7.9% of the sub-

halocline June 2018 DO budget (note these values are the standing stock and do not account for

recharge, vertical mixing, etc). Based on the oxygen demand estimates of the actual dry solids mass

collected by Tassal (66.0 to 116.4 tonnes of oxygen) WCS saved anywhere from 1.7% to 2.9% of the sub-

halocline June 2018 harbour DO budget.

System-wide DO demand in Macquarie Harbour is dominated by the water column and not the benthos.

The isolated portion of the water column (i.e. the sub-halocline water column) removes anywhere from

16.9 thousand tonnes to 33. 8 thousand tonnes of DO per month. Using the absolute maximum rate

observed during the ADS 2018 study, the Gordon and Middle Harbour Lease benthic DO demand only

removes 2.7 and 1.9 tonnes of DO per month respectively. The whole non-farmed portion the seabed

removes only 750 tonnes per month at best (according to rates reported in ADS 2018). The best

combined benthic DO savings due to waste capture systems would be 4.9 tonnes per month.

Even if every carbon atom captured by the waste capture systems were oxidized to CO2 (equivalent to

116.4 tonnes of DO) over the June 2017 to April 2018 waste capture period, it would only amount to

0.68% of the monthly pelagic oxygen demand during the lowest river loading period.:


6 DISCUSSION AND CONCLUSIONS

There were no detectable water quality impacts associated with the installation of waste collection

liners, with water quality parameters remaining relatively stable throughout the WCS trial. Variations in

parameters were likely due to other factors, including seasonal variation and riverine inputs. For

example, POD was found to be largely influenced by inputs from the Gordon River rather than the

presence or absence of WCS liners.

Over the trial period, dissolved oxygen concentrations generally increased in bottom waters, with more

elevations in bottom water dissolved oxygen during the second half of the trial. Increases in dissolved

oxygen in bottom waters may be due to recharge events or a reduction in the organic waste that

consumes dissolved oxygen on the seabed due to the installation of the waste capture system.

There were no impacts to water quality attributable to the agitation of waste in the sump during

extraction activities. The absence of a waste plume during extraction activities may be due to the high

settling rate of waste or the effective extraction technique employed by Tassal. Alternatively, fine

spatial scale monitoring at the sump may better monitor plume generation, however any changes to

water quality are expected to be minor given the results obtained during the current trial.

Visual assessment of the sediments in the vicinity of lined cages found waste capture liners were

effective in preventing waste underneath cages. While positive benthic effects were identifiable from

ROV surveys, other benthic sampling activities did not show positive effects attributable to the WCS.

Despite benthic chemistry and infauna results not showing clear positive effects on benthic condition, a

reduction in feed and faeces on the seafloor would have undoubtedly resulted in reduced organic

enrichment levels beneath WCS cages over time. The inability to identify a strong pattern was likely due

to a number of confounding effects during the trial (see below).

Sediment studies indicate there is likely a large reduction in BnOD due to the WCS in comparison to

previous studies. Despite likely reductions, a clear spatial difference was observed in BnOD, with higher

oxygen demands closer to salmon cages. Because Gordon lease consists of cages both with and without

liners, however, any fine-spatial scale reductions in BnOD are likely masked due to sediment transport in

the water column and on the seabed.


Although no marked improvements in sediment quality was observed over the length of the waste

capture trial, sediment testing would likely reflect further reductions in farming-related impacts over

longer-term WCS liner installation. This is supported by the sheer quantity of waste removed from WCS

liners during the trial (approximately 213.7 tonnes), all of which would have previously been released

into the water column and onto the seabed.

A variety of confounding effects hindered the ability to assess the effectiveness of the WCS in reducing

impacts to sediments and water quality during the monitoring period. Confounding effects included

differences in farming history, cage arrangements, sampling locations, feed inputs, stocking densities,

environmental variation, lag effects and effectiveness of different survey methods. These confounding

effects are summarized below:

Farming history of the lease. Benthic condition in the vicinity of leases would likely reflect recent

farming history and the subsequent levels of organic enrichment. Benthic condition at the beginning

of the trial would therefore likely reflect previous farming history. Given that recovery of the benthos

can be very slow (even in the absence of farming activities), it is likely farming history has had a

strong influence on benthic patterns during the course of the trial.

Cage arrangement for experimental design, shadowing effects. The location of monitoring sites

was often constrained by logistical and operational factors. In many instances, unlined cages were

adjacent to lined cages. As a result, shadowing effects from nearby cages was likely to have influenced

analyses and could have potentially masked any positive effects of the WCS.

Sampling position. Due to practical constraints, the edge of the cage was sampled for water

quality and benthic analyses. Sampling at the cage edge potentially introduces the influence of

neighbouring cages (shadowing effect, described above), meaning that potential effects of the WCS are

likely to be more difficult to detect.

Feed inputs/farming practices. Variable feeding and stocking rates of cages during the trial

would have influenced the volume of waste reaching the seafloor, with flow on effects to water quality

and benthic condition. Given the complexities involved, it was beyond the scope of the current study to

consider how these factors may interact with the WCS and influence water and sediment quality.


Site specific environmental conditions and broad scale factors. Site specific differences in

environmental conditions (e.g. bathymetry, local current flow), both within and between leases, can

influence water and sediment quality. Within Macquarie Harbour, bottom water dissolved oxygen

concentrations, in particular, are known to have an overwhelming influence on benthic condition (Ross

and Macleod 2018). Any potential effect of the WCS system is likely to be strongly dependent on the

broad scale bottom water dissolved oxygen concentration at the time. For example, the very low

bottom water dissolved oxygen levels during the trial are likely to have had a strong influence on

benthic communities.

Lag effects. As described above, improvement or ‘recovery’ of benthic condition will depend on

organic enrichment levels and dissolved oxygen concentrations. A lag is expected between reduced

levels of accumulated feed and waste and subsequent improvement in benthic condition. It is likely the

restricted timeframe for assessing benthic condition was not sufficient to account for this potential time

lag in the current study. While speculative, it is possible that positive effects of the WCS on benthic

condition may have been evident with longer term monitoring of sample sites.

Scale. The scale of sampling is also an important consideration when interpreting results.

Alterations in water quality parameters due to extraction activities may have been on a finer

scale than that monitored. This may be accounted for in future monitoring by sampling within

the pens, rather than at the pen edge.

In conclusion, the implementation of the WCS did not result in any further elevations in nutrient

concentrations or changes in physical parameters despite increases in fish biomass throughout the trial

period. Benefits of the WCS to overall oxygen demand also appear to be low. Few measurable

improvements were identified in water and sediment quality during the WCS trial, however a reduction

in feed and waste emitted to the surrounding water column and seafloor would have undoubtedly

resulted in reduced organic enrichment in the region of WCS lined cages over time. The inability to

identify a strong pattern was likely due to the number of confounding effect or relatively short duration

of the WCS trial.


7 APPENDICES

Appendix 1. Monthly water quality monitoring summaries

a. Please see attached “A - Waste Capture WQ Data summary 31 July 2017.pdf”

b. Please see attached “B - Waste Capture WQ Data summary 30 August 2017 V1.0.pdf”

c. Please see attached “C - Waste Capture WQ Data summary September 2017 V1.0.pdf”

d. Please see attached “D - Waste Capture summary October 2017 V1.0.pdf”

e. Please see attached “E - Waste Capture summary November 2017 V1.0.pdf”

f. Please see attached “F - Waste Capture summary December 2017 V1.0.pdf”

g. Please see attached “G - Waste Capture summary January 2018 V1.0.pdf”

h. Please see attached “H - Waste Capture summary February 2018 V1.1.pdf”

i. Please see attached “I - Waste Capture summary March 2018 V1.2.pdf”

Appendix 2. Pelagic Oxygen Demand Study

Please see attached “Pelagic Oxygen Consumption in Macquarie Harbour, Tasmania.pdf”

Appendix 3. Sediment Quality Monitoring

Please see attached “Macquarie Harbour Waste Capture System: Summary of benthic monitoring

activities.pdf”

Appendix 4. Benthic Oxygen Demand Study

Please see attached “Waste Capture Systems and Benthic Oxygen Demand.pdf”

Appendix 5. Effect of WCS on Oxygen Demand

Please see attached “Effects of Pen Waste Capture Systems on Oxygen Consumption in Macquarie

Harbour, Tasmania.pdf””

waste capture system - epa tasmania final...waste capture system: summary report 7 1 executive...

Documents