Groundwater Interception Potential Impacts on Migratory and Threatened Shorebird Communities in Botany Bay
October 2004
Report prepared by: Avifauna Research & Services
Avifauna Research & Services Groundwater Interception - Potential Impacts on Migratory and Threatened Shorebird Communities in Botany Bay
Contents
Executive Summary …………………………………………………………………….. 1
Shorebird habitat at Penrhyn Estuary and Foreshore Beach ……………………………… 2
Availability of prey ………………………………………………………………………. 4
Changes in groundwater flows 4
Changes to invertebrate populations ………………………………………………………4
Changes to saltmarsh communities ………………………………………………………. 5
Likelihood of impact ………………………………………………………………………4
Avifauna Research & Services ii Groundwater Interception - Potential Impacts on Migratory and Threatened Shorebird Communities in Botany Bay
Executive Summary
Shorebird species that were once abundant in the north of Botany Bay have declined over the past 60 years as a result of habitat loss and are now restricted to a small area of intertidal habitat at Penrhyn Estuary. Most shorebird species feed on invertebrates found in tidal mud and sand flats on the falling tide and to a lesser extent on the rising tide. During high tide when feeding habitat is covered shorebirds roost (rest) at suitable locations.
Little is known about the influence on invertebrates as a result of alterations to groundwater flows, and therefore indirect impacts on shorebird populations, however it is likely that species diversity and abundance will change with changes in salinity. Any changes to the number of invertebrates or species composition of invertebrates at Penrhyn Estuary may have an effect on shorebirds in the estuary, however it is known that shorebirds are readily able to switch prey due to their migratory nature.
Invertebrate populations are currently under severe stress as a result of contaminants in the mudflats at Penrhyn Estuary. The proposed groundwater interception will reduce the risk of further contamination and risk to the estuary and its fauna and flora allowing the levels of contaminants to decline over time.
Roost sites used by shorebirds are usually areas that have an open aspect to allow an all-round view for potential predators either saltmarsh habitat with low vegetation or open sand spits or beaches. The level at which saltmarsh grows depends on a number of factors including tide heights and freshwater runoff, including groundwater flows. Cessation of groundwater flows may result in a change in saltmarsh distribution, influenced by tide heights alone.
The proposed expansion of Port Botany will to some extent override the effect of groundwater interception in that that proposal includes the establishment of additional saltmarsh habitat, much larger than the that currently existing. If the port expansion proceeds the remediation measures planned by SPC would complement those of Orica in providing and improved roosting and foraging habitat for migratory and non-migratory shorebirds within the estuary.
Foreshore Beach currently provides very little shorebird feeding habitat. However the proposed port expansion would result a modification of the beach and protection from wave action. This is likely to increase the area of shorebird feeding habitat if the slope of the beach is lowered. This would also be compatible with the Proposal by Orica, providing a wider area of tidal flats and minimising the effect of groundwater interception.
Key issues
The retention of the existing mudflats at Penrhyn Estuary is essential to the long-term survival of shorebirds currently using the site.
Actions to prevent toxic chemicals entering the estuary should be taken to protect shorebirds, their habitats and prey at the earliest opportunity.
Regular, monthly, monitoring of the site will be essential to determine in any changes to the nature of the foreshore as a result of the proposal. Although it is likely that invertebrate populations and saltmarsh would adjust, it may be advantageous to carry out landscaping,
Avifauna Research & Services 1 Groundwater Interception - Potential Impacts on Migratory and Threatened Shorebird Communities in Botany Bay including the addition of appropriate soils to enhance and expand the area of saltmarsh and therefore shorebird habitat. Recent successes in the establishment or enhancement of saltmarshes in Sydney have clearly demonstrated the feasibility to manage saltmarsh in modified habitat.
Ongoing management of the site may be necessary to prevent invasion shorebird habitat by mangroves including the ‘weeding’ of mangrove seedlings on an annual basis.
Avifauna Research & Services 2 Groundwater Interception - Potential Impacts on Migratory and Threatened Shorebird Communities in Botany Bay
Shorebird habitat at Penrhyn Estuary
Since the 1940s the gradual loss of shorebird habitat has resulted in a substantial decline in the numbers of shorebirds found in the northern part of Botany Bay. Penrhyn Estuary now provides the only shorebird feeding habitat and roosting sites in the north of the Bay. Although shorebird habitat exists along the southern shores of the bay it is not suitable for most of the shorebirds found at Penrhyn Estuary. Twenty four species of resident and migratory shorebirds and seabirds, listed under the Threatened Species Conservation Act (TSC Act) and/or the Environment Protection and Biodiversity Conservation Act (EPBC Act), are known to occur or have previously been recorded at Penrhyn Estuary. Of these seven are listed as Vulnerable and one, the Little Tern, as Endangered under the TSC Act, 22 are listed under international agreements (JAMBA and CAMBA) and 23 under the Bonn Convention of Migratory Animals (see Table 1).
The most productive shorebird feeding habitat appears to be the silts in the delta area formed by Springvale and Floodvale Creeks as shown clearly in the airphoto taken at low tide (Figure 1).
Figure 1. Penrhyn Estuary at low tide showing silt deltas formed by Springvale and Floodvale Creeks
Shorebirds feed almost exclusively on invertebrates found in the substrate of wetlands, especially coastal estuaries. These habitats provide exposed mudflats in a relatively sheltered environment. Estuarine habitats are complex and rely on river flows, daily tidal cycles, groundwater runoff and the presence of organic material which support invertebrate populations. Although groundwater plays an important role in the formation and health of some saltmarsh plant communities it is not known how important groundwater is to maintaining
Avifauna Research & Services 3 Groundwater Interception - Potential Impacts on Migratory and Threatened Shorebird Communities in Botany Bay invertebrate populations on tidal mudflats given that frequent freshwater flows occur at Penrhyn Estuary from surface runoff of local catchments.
A reduction in groundwater flows into Penrhyn Estuary is likely to result in the change in species composition and numbers of some invertebrates. However it is known that shorebirds are readily able to switch prey due to migratory nature feeding in a variety of habitats from freshwater bogs to hyper saline saltpans and can adjust to a wide variety of invertebrate prey.
Figure 2: Available shorebird feeding habitat at Penrhyn Estuary (outlined in orange)
Avifauna Research & Services 4 Groundwater Interception - Potential Impacts on Migratory and Threatened Shorebird Communities in Botany Bay
Availability of prey
Studies of invertebrate populations at Penrhyn Estuary (The Ecology Lab Pty Ltd 2004, Botany Groundwater Clean-up, Aquatic Ecology Component 18/0405A) have indicated that characteristics indicative of this community include reduced species richness, community structure dominated by a few taxa, a paucity of small crustaceans such as amphipods, dominance of a few families of polychaete worms, and dominance by species with small body size and short life spans that retain (by various means) offspring in the immediate vicinity of parents or within the parental habitat.
The current population of shorebirds at Penrhyn Estuary have developed in the presence of the current levels of contaminants in the estuary as well as levels of a level of toxins in the tissues of their prey. Any changes to invertebrate populations could influence the species diversity and population density of shorebirds. Improvement in the level of contaminants in the mudflats at Penrhyn Estuary, through the prevention of further contamination of the site, should in the long term provide a healthier environment for shorebirds by improving the diversity and health of their invertebrate prey. The effect of groundwater interception on invertebrates cannot be determined specifically (The Ecology Lab Pty Ltd 2004, Botany Groundwater Clean-up, Aquatic Ecology Component 18/0405A) but may result in a change in species composition. Any such changes may require a switch in prey species by shorebirds, provided the density of available prey is not reduced on the whole, most shorebird species should be able to adapt to these.
Changes in groundwater flows
The effects of changes to groundwater flows into the estuary as a result of works carried out by Orica are not likely to have any direct impacts on shorebirds as these species frequent a variety of habitats of varying salinity levels in the space of a single day. Any impact on shorebirds is likely to be as a result of changes in vegetation composition and prey (i.e. invertebrates) availability addressed elsewhere in this document.
Changes to invertebrate populations
Invertebrate populations appear to be under stress due to the current state of the tidal flats at Penrhyn Estuary, including high levels of contaminants. However it would be logical to assume that the shorebird species composition and numbers at Penrhyn Estuary are as a result of the current degraded state. Any reduction on contaminant levels would presumably result in an increased shorebird population and increased health of the birds.
Any changes to invertebrate populations at Penrhyn Estuary is likely to affect shorebird populations. An overall reduction in numbers of invertebrates may result in a decline in the numbers of shorebirds while the change in invertebrate species composition may affect one or two species of shorebirds that feed on these, although it is known that most shorebirds are able to readily switch prey.
Changes of saltmarsh communities
Shorebirds at Penrhyn Estuary spend most to the time during high tide roosting (resting) on sand spits or saltmarsh habitat while waiting for the tide to recede. Roost sites used by shorebirds at Penrhyn Estuary include saltmarsh during neap tides and sand spits or beaches
Avifauna Research & Services 5 Groundwater Interception - Potential Impacts on Migratory and Threatened Shorebird Communities in Botany Bay during spring high tides. Saltmarsh, in particular Sarcocornia sp., provide protection from adverse weather for some of the small shorebirds while enabling them to see over the top of the vegetation for potential predators. However key saltmarsh roost sites used by shorebirds, such as the Pacific Golden Plover, have been lost at Penrhyn Estuary due to invasion by mangroves and these birds have been forced to roost elsewhere. Some species of shorebirds, notably the Sharp-tailed Sandpiper, feed on invertebrates including insects and benthic animals found in saltmarshes at Penrhyn Estuary.
Sarcocornia exists in a wide variety of wetland habitats ranging from daily inundated estuaries to rarely flooded saltmarshes in coastal, as well as inland wetlands.
Changes in flows of groundwater at Penrhyn Estuary could result in a change to the nature of the saltmarsh community and may result in some sections dying. However saltmarsh species are likely to adapt to a new regime of flooding. If appropriate soils are available a healthy saltmarsh is likely to result although these may be perched at different levels to the existing saltmarsh. Any management of the site should aim at favouring relatively short vegetation such as Sarcocornia sp. in preference to tall vegetation such as Suaeda sp. or mangroves in order to provide favourable habitat for shorebirds. An ongoing monitoring program may be necessary, including the ‘weeding’ of mangrove seedlings and management of soil supplements to improve Sarcocornia growth.
Flooded saltmarsh habitats are used by many shorebird species at night, however these conditions do not occur and Penrhyn Estuary and shorebirds abandon the site at night to roost elsewhere.
Likelihood of impact
Assessments of the potential impacts of the proposal conclude that no threatened species, populations or ecological communities of birds are likely to be significantly affected as listed under the TSC Act. There is therefore no requirement for a SIS under the EP&A Act. No species listed under international agreements would be significantly affected to warrant a referral to the Department of Environment and Heritage with regard to species listed under the EPBC Act.
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TABLE 1 TSC Act Migratory/non JAMBA CAMBA Bonn (E=Endangered migratory V=Vulnerable) Species listed under EPBC Act Species Scolopacidae Curlew Sandpiper XXXX Calidris ferruginea Common Sandpiper XXXX Actitis hypoleucos Eastern Curlew XXXX Numenius madagascariensis Sanderling VXXXX Calidris alba Sharp-tailed Sandpiper XXXX Calidris acuminata Great Knot VXXXX Calidris tenuirostris Common Greenshank XXXX Tringa nebularia Grey-tailed Tattler XXXX Heteroscelus brevipes Bar-tailed Godwit XXXX Limosa lapponica Black-tailed Godwit VXXXX Limosa limosa Broad-billed Sandpiper VXXXX Limicola falcinellus Marsh Sandpiper XXXX Tringa stagnatilis Red Knot XXXX Calidris canutus Red-necked Stint XXXX Calidris ruficollis Ruddy Turnstone XXXX Arenaria interpres Terek Sandpiper VXXXX Xenus cinereus Whimbrel XXXX Numenius phaeopus
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TABLE 1 TSC Act Migratory/non JAMBA CAMBA Bonn (E=Endangered migratory V=Vulnerable) Species listed under EPBC Act Species Pied Oystercatcher V Haematopus longirostris Charadriidae Grey Plover XXXX Pluvialis squatarola Pacific Golden Plover XXXX Pluvialis fulva Greater Sand Plover VXXXX Charadrius leschenaultii Lesser Sand Plover VXXXX Charadrius mongolus Double-banded Plover X Charadrius bicinctus Laridae Little Tern EXXXX Sterna albifrons
Avifauna Research & Services 8 Report to: URS Australia Pty Ltd
Botany Groundwater Clean-up Aquatic Ecology Component
FINAL November 2004
Botany Groundwater Clean-up Aquatic Ecology Component
November 2004
Report Prepared for: URS Australia Pty Ltd Level 3, 116 Miller Street North Sydney, NSW 2060
Report Prepared by: The Ecology Lab Pty Ltd 4 Green Street Brookvale, NSW, 2100 Phone: (02) 9907 4440
Report Number – 18/0405A Report Status – Final, 10 November 2004
© This document and the research reported in it are copyright. Apart from fair dealings for the purposes of private study, research, criticism or review, as permitted under the Copyright Act 1968, no part may be reproduced by any process without written authorisation. Direct all inquiries to the Director, The Ecology Lab Pty Ltd at the above address. Botany Groundwater Clean-up – Aquatic Ecology Component Final, November 2004
TABLE OF CONTENTS Summary ...... i 1.0 Introduction ...... 1 1.1 Background...... 1 1.2 Aims...... 1 2.0 Existing Information...... 2 2.1 Description of the Environment...... 2 2.1.1 Penrhyn Estuary...... 2 2.1.2 Foreshore Beach...... 2 2.2 Contamination in Penrhyn Estuary...... 3 2.3 Groundwater Behaviour and Contaminant Plumes ...... 4 2.4 Biota ...... 4 2.4.1 Invertebrate Fauna - Meiofauna...... 5 2.4.2 Invertebrate Fauna - Macrofauna ...... 6 2.4.2.1 Intertidal Fauna ...... 6 2.4.2.1 Subtidal Fauna...... 7 2.4.3 Saltmarsh and Mangroves ...... 8 2.4.4 Seagrasses and Algae...... 9 2.4.5 Fish and Mobile Invertebrate Communities in Shallow Subtidal Habitats...... 9 2.4.6 Bioaccumulation in Fish and Oysters...... 11 3.0 Brief Description of the Proposal...... 14 4.0 Assessment of Impacts ...... 16 4.2 Groundwater Interception Alternative...... 21 4.2.1 “High Level” Range of Responses to Groundwater Interception...... 22 4.2.2 “Low Level” Range of Responses to Groundwater Interception...... 25 4.3 Conclusions...... 27 4.4 Cumulative Impacts...... 27 5.0 Mitigation Measures...... 29 6.0 Acknowledgements ...... 30 7.0 References ...... 31 Figures ...... 34
The Ecology Lab Pty Ltd – Marine and Freshwater Studies Botany Groundwater Clean-up – Aquatic Ecology Component Final, November 2004
SUMMARY Orica Australia Pty Ltd has been issued a Notice of Clean Up Action (NCUA) by the Department of Environment and Conservation (DEC, formerly NSW EPA). Contaminated groundwater from the Orica site is migrating toward Penrhyn Estuary and Foreshore Beach, within Botany Bay. If unmitigated, the contaminated groundwater would arrive at the bay in early 2006, with the potential to affect aquatic biota there. Orica has devised a Groundwater Cleanup Plan (GCP) as required by DEC which consists of pumping and treating contaminated plumes of groundwater downgradient of the Botany Industrial Park (BIP).(i.e. between BIP and Botany Bay). Hydraulic containment of the existing contaminant plumes and their source areas would be achieved by means of groundwater interception bores along strategically placed containment lines. The pumping of groundwater would reduce the total groundwater discharge to Botany Bay, from all aquifers, by 15% and is expected to continue for 30 years, with extraction rates being adjusted to cater for the changing level of contaminants in the groundwater. The groundwater interception would prevent groundwater from entering Springvale and Floodvale drains, which flow into Penrhyn Estuary. This would result in no surface or groundwater flow to Penrhyn Estuary, except in the case of local rainfall. The contaminated groundwater plumes contain volatile and semivolatile hydrocarbons. The primary contaminants of concern include 1,2-dichloroethane (EDC) , vinyl chloride (VC), trichloroethene (TCE), tetrachloroethene (PCE), carbon tetrachloride (CTC) and chloroform (CFM), hexachlorobutadiene (HCBD), collectively referred to here as CHCs. In addition to the plumes, there is historical contamination of sediments in Penrhyn Estuary as a result of activities in the catchment. These include nutrients, metals (especially mercury and chromium) and some hydrocarbons especially hexacholobenzene, (HCB). These will continue to be an issue within Penrhyn Estuary, irrespective of the arrival of groundwater contaminated with CHCs. The Ecology Lab Pty Ltd was engaged by URS Australia on behalf of Orica to assess the effects of the proposal on the aquatic ecology of Penrhyn Estuary and the south-eastern end of Foreshore Beach. These areas are part of an estuarine ecosystem that includes fringing saltmarsh and mangrove habitats, subtidal seagrass beds and intertidal and subtidal sand and mudflats that support invertebrates living at the surface or within the upper layers of sediment (benthos). A range of fish species use the estuary to feed and shelter and, during low tide, a variety of shorebirds (some protected under international agreements) feed on invertebrates in the mudflats and roost on sand flats and in low saltmarsh vegetation. The reduction of groundwater discharge and surface flows via Springvale and Floodvale drains may alter the nature of the intertidal and subtidal habitats and, as a consequence, the biota they contain. Because these invertebrates provide food for fish and birds, changes to the abundance of benthos may flow on to fish and shorebird populations. Direct changes to saltmarsh, mangrove and seagrasses habitats could also affect the quality and quantity of shelter and food they provide for fish and shorebird populations. Overall there is very little information on the effects of reductions in groundwater flow to estuarine ecosystems. Saltmarshes, mangrove and seagrasses have been mapped, but no studies of their associated fauna have been undertaken. Little information exists on benthic communities in Penrhyn Estuary, with insufficient information to confidently establish spatial or temporal patterns of distribution. The relative contributions of various factors known to affect the abundance and distribution of benthos (e.g. salinity, water quality, sediment particle size distribution, particulate organic input, etc.) and local conditions (e.g. The Ecology Lab Pty Ltd – Marine and Freshwater Studies Page i Botany Groundwater Clean-up – Aquatic Ecology Component Final, November 2004 contamination) are unknown. Furthermore, there is an absence of relevant, field-based scientific research on these interacting factors which would form the basis of predictions of the effects on estuarine flora and fauna of the withdrawal of groundwater. Assessments of impacts on estuarine biota, therefore, are presented as a range of scenarios based on extremely limited information. Assessment of Impacts The assessment of impacts considered two alternative conditions: • Do nothing: there is no interception of groundwater; hence no remediation and plumes of contaminated groundwater migrate to Botany Bay. • The Proposal: all contaminated groundwater is intercepted, treated to remove CHCs and appropriately used or disposed of. In this case, no groundwater would enter Penrhyn Estuary or the south-eastern end of Foreshore Beach. If nothing is done to intercept the flow of CHCs to the bay (i.e. “Do Nothing”), there will be a risk of mortality to intertidal and subtidal benthos due to toxic effects of the CHCs. Whilst levels of acute toxicity to high concentrations of CHCs are not known for the benthos, a precautionary approach would indicate that the risk is high. Similarly, seagrass, saltmarshes and invertebrates would also suffer mortality due to exposure to CHCs in the levels indicated in the Central Plume (maximum EDC level in Central plume predicted to be in the order of 5000 ugL-1). Shorebirds may suffer mortality as a result of direct exposure to volatile CHCs, or may increase dietary exposure to Hg present in sediment-ingesting benthos in the short term, and decreased food availability in the longer term. If saltmarsh plants also die, shorebirds would loose important roosting habitats. Overall the estuarine ecosystem may degrade significantly, with potential long-term residual effects, but it is not possible to quantify the magnitude of effects or their duration beyond the period of flow of contaminated groundwater into the bay. Recovery time for the ecosystem would be linked to the severity of the response by various ecosystem components and the time required for the plume to dissipate into the waters of Botany Bay. The bores that would be excavated to intercept groundwater would be located along Foreshore Road, well back from Botany Bay; hence excavation would not directly affect aquatic biota, provided that safeguards are put in place to ensure no turbid water, drilling mud, etc, enters the bay. Similarly, any noise that could affect shorebirds would be attenuated by distance and other background noise. The treated water would be discharged into Botany Bay at Brotherson Dock, via the discharge point at Bunnerong Canal. Impacts of this discharge have been assessed directly by URS, hence this assessment of impacts focuses on the effects of groundwater interception on aquatic habitats and biota in Penrhyn Estuary and the south-eastern end of Foreshore Beach. In the “High Level” response scenario to the groundwater interception proposal, intertidal benthos are predicted to reduce in abundance and species richness, assuming that long-term reduction in sediment water content during low tide would cause mortality. Effects would be greater during spring low tides due to increased evaporation of residual saline pore water. While some types of intertidal benthos are resistant to desiccation being protected by shells (e.g. gastropods and bivalves) or hard body coverings (e.g. crabs and amphipods), these types of benthos are less common in the estuary than the soft-bodied animals such as polychaetes that may have a greater response to desiccation. Effects on subtidal benthos are expected to be less extreme, because sediments are not predicted to dry during low tides; however subtidal benthos would be exposed to more variable salinity. The long-term
The Ecology Lab Pty Ltd – Marine and Freshwater Studies Page ii Botany Groundwater Clean-up – Aquatic Ecology Component Final, November 2004 response to the interaction of new factors (increase in salinity during low tide, decrease in dissolved nutrients and particulate organic matter input) with current conditions (presence of metals such as Hg and Cr in sediment) is unknown. Flow-on effects to shorebirds are predicted to be related to the level of response of invertebrates. Reduced populations of invertebrates would result in less food for shorebirds, although they may respond by using similar habitats elsewhere in Botany Bay (e.g. Quibray Bay). Saltmarsh habitats would become more saline, potentially killing some plants or altering the assemblage in favour of salinity–tolerant species. Shorebirds may benefit from this shift, as one of their preferred roosting habitats, saltmarshes comprising Sarcocornia quinqueflora, is tolerant of more saline habitats, but potentially at the cost of loss of food items in the saltmarsh sediment. In the short term fish would continue to bioaccumulate metals in benthic food items at the same or lower levels as at present, but in the longer term would shift to other more abundant food sources. The direct effects of withdrawal of groundwater on seagrass beds is unknown, but the beds in outer Penrhyn Estuary and off Foreshore Beach are subtidal, patchy in nature and provide relatively low quality habitat due to their short, sparse morphology compared to seagrasses elsewhere in Botany Bay. The single intertidal bed in the inner estuary is short and sparse, and may be at risk due to desiccation. The “Low-Level” response scenario to groundwater interception predicts smaller magnitudes of response by invertebrates and saltmarsh plants, with reduced flow-on effects to fish and shorebirds. In this scenario, abundance of intertidal benthos abundance may reduce only slightly, but may become dominated by smaller bodied meiofauna that are too small for shorebirds to eat. The altered intertidal community may display a spatial shift with the centre of their population displaced towards the subtidal zone. Subtidal benthic communities may respond by altering community structure in favour of assemblages adapted to increased salinity, decreased dissolved nutrients and decreased amount of particulate organic matter entering the estuary. This shift may also be accompanied by a reduction in overall abundance, with flow on effects to fish and shorebirds as previously described. In the context of the effects on Botany Bay, Penrhyn Estuary represents a relatively small area. The loss of some benthos, seagrasses and mangroves are not likely to have a major effect on the productivity or diversity of the large bay ecosystem. Impacts on shorebirds that feed and roost in the estuary may of greater significance due to the protected status of some of species and due to the dwindling habitat in the Sydney region. Similarly, impacts on saltmarshes would be significant because these habitats too are decreasing in Botany Bay and the Sydney region generally. However, as elsewhere in the region, the increase in the extent of mangrove in Penrhyn Estuary threatens saltmarsh habitats there. Removal of groundwater may actually create conditions more favourable to the expansion of saltmarsh over mangrove habitat. Cumulative Impacts As the current proposal would result in a decrease in water-borne contaminants in Penrhyn Estuary and Botany Bay, and no change in existing levels of sediment contamination, the cumulative effects of the proposal with respect to levels of contamination is considered to decrease future levels of contamination in Penrhyn Estuary and Botany Bay. The Port expansion is predicted to have little effect on groundwater and hence the cumulative effects of the port expansion proposal on changes to groundwater levels are considered negligible. The cumulative impacts of the interception of groundwater and the predicted increase in water depth due to global warming would have the effect of making Penrhyn Estuary a
The Ecology Lab Pty Ltd – Marine and Freshwater Studies Page iii Botany Groundwater Clean-up – Aquatic Ecology Component Final, November 2004 more saline environment, becoming more similar to those that occur in Botany Bay. The predicted increased frequency of storms and variability in rainfall would not counteract this shift because during groundwater interception all but local rainfall would be intercepted by wells extracting the upper layer of groundwater. Mitigation The objective of the proposal is to intercept and treat contaminated groundwater for up to 30 years. Because the proposal would operate over a decade time horizon, it is important to ensure that impacts to the aquatic habitats and biota in Botany Bay are understood and distinguished from other anthropogenic and natural causes of change. There are three possible areas where mitigation should be considered: 1. If independent studies (e.g. toxicology) indicate that CHCs have limited toxicity on aquatic biota (including shorebirds), the interception of groundwater could be terminated or scaled down. 2. If concentrations of CHCs in groundwater plumes as they enter the bay are found to be highly variable, there may be periods when partial interception of groundwater might be feasible (and cost effective). 3. Reintroduction of treated groundwater to the estuary should be considered. If groundwater was only partially reintroduced, or applied locally as surface water, this may serve to mitigate the impacts of the proposal. Impacts on the estuarine ecosystem may vary greatly in magnitude and could affect several ecosystem components. Because the magnitude of effects on fish and birds flow on from the magnitude of impacts on benthic invertebrates, it is essential that the abundance and spatial distribution of the benthos be monitored before, during and after groundwater interception. It is recommended that a program of monitoring be developed in negotiation with the relevant government agencies and initiated as soon as possible to enable the effects of groundwater interception to be measured. Components of monitoring that should be considered include habitat mapping and surveys of benthos, shorebirds and fish using, wherever appropriate, control locations to provide a measure of natural variability. In addition, it is suggested that toxicological studies of CHCs be initiated using a range of indicator species (individually and as assemblages), preferably using Direct Toxicity Assessment.
The Ecology Lab Pty Ltd – Marine and Freshwater Studies Page iv Botany Groundwater Clean-up – Aquatic Ecology Component Final, November 2004
1.0 INTRODUCTION
1.1 Background Orica Australia Pty Ltd has been issued a Notice of Clean Up Action (NCUA) by the Department of Environment and Conservation (DEC, formerly NSW EPA). Contaminated groundwater from the Orica site is migrating within “plumes” toward Penrhyn Estuary and Foreshore Beach, within Botany Bay. If unmitigated, the contaminated groundwater would arrive at the bay in early 2006, with the potential to affect aquatic biota there. Orica has devised a Groundwater Cleanup Plan (GCP) as required by DEC which consists of pumping and treating contaminated plumes of groundwater downgradient of the Botany Industrial Park (BIP) (i.e. between BIP and Botany Bay) of its premises at Botany NSW. Hydraulic containment of the existing contaminant plumes and their source areas would be achieved by means of groundwater interception bores along strategically placed containment lines. The pumping of groundwater would reduce the total groundwater discharge to Botany Bay by 15% (Merrick 2004) and is expected to continue for 30 years, with extraction rates being adjusted to cater for the changing level of contaminants in the groundwater. The groundwater interception would prevent groundwater from entering Springvale and Floodvale drains, which flow into Penrhyn Estuary. This would result in no surface or groundwater flow to Penrhyn Estuary except in the case of local rainfall. The reduction of groundwater discharge and surface flows via Springvale and Floodvale drains may alter the nature of aquatic habitats, and, as a consequence, the biota they support. Changes in the populations of invertebrates living in aquatic habitats may in turn affect the populations of shorebirds that feed on them.
1.2 Aims The Ecology Lab Pty Ltd was engaged by URS Australia on behalf of Orica to assess the effects of the proposal on the aquatic ecology of Penrhyn Estuary and the south-eastern end of Foreshore Beach. The overall aim of this report is to fulfil the requirements for an Environmental Impact Statement (EIS) on the effects of groundwater extraction on the aquatic ecology of Penrhyn Estuary and nearby areas in the intertidal and subtidal habitats of Foreshore Beach. The specific aims of this report are to: • Identify, and if possible review of existing information on the habitats and biota that may be affected, • Summarise the project with respect to potential effects on aquatic ecology of the study area, • Assess impacts of the project on the aquatic ecology of Penrhyn Estuary and subtidal and intertidal habitats near Foreshore Beach, focussing on the populations of invertebrates living in subtidal and intertidal habitats, • Define testable predictions about changes likely to occur to habitats and biota, • Suggest measures that could be taken to mitigate and, if warranted, monitor the impacts identified.
The Ecology Lab Pty Ltd – Marine and Freshwater Studies Page 1 Botany Groundwater Clean-up – Aquatic Ecology Component Final, November 2004
2.0 EXISTING INFORMATION
2.1 Description of the Environment
2.1.1 Penrhyn Estuary Penrhyn Estuary is bounded by Foreshore Road to the north, Penrhyn Road to the east and the Port Botany container terminal to the south. The estuary was formed as a result of development in Botany Bay in the 1970s. It is about 30 ha in size and characterised by intertidal and subtidal sand and mud flats. The topography of the area is low lying with sand dunes reaching 2.5 m to 3 m in elevation. Parts of Springvale Drain have been colonised by mangroves, which have increased through time and are now also present near the outlet of Floodvale Drain. The total area currently occupied by mangroves is approximately 1.0 ha. Vegetation on the fringes of the estuary includes a saltmarsh community occupying approximately 0.71 ha. Species present include Suaeda australis, Sarcocornia quinqueflora and Juncus kraussii. The estuary has two basins, a triangular “inner estuary” connected to an “outer estuary” via a narrow channel formed by sand accreted from Botany Bay and adjacent dunes (Figure 1). The bed of the inner estuary is dominated by muddy sand, exposed at low tides and features two incised channels ~ 1 m wide. A deeper pool exists in the inner estuary at the confluence of Floodvale and Springvale drains, just north of the old boat ramp. The inner estuary is subject to virtually no wave action and is a low energy, depositional environment. In fact, the old boat ramp was closed due to shallowing within the inner estuary as a result of sedimentation. A new boat ramp was consequently built in the outer estuary. The majority of the outer estuary bed is subtidal and comprised of a higher percentage of sand particles and shell debris compared with the inner estuary. A large sandflat forms the southern edge of the outer estuary. Approximately 10 small seagrass beds comprised of Zostera capricorni grow on the fringes of the outer estuary from about the low tide mark. Four beds occur in the vicinity of the new boat ramp off Penrhyn Road ranging in size from 48 to 300 m2. Based on observations in the intertidal saltmarsh west of the estuary, acid sulphate soils may potentially underlay the estuary bed, although potential acid sulphate soils have not been tested in the area (URS 2003). The estuary receives flow from Floodvale Drain from the north-west and Springvale Drain from the north east as well as groundwater discharge to intertidal areas. The drains currently carry shallow groundwater to the estuary as well as stormwater during rainfall.
2.1.2 Foreshore Beach Foreshore Beach is approximately 1.5 km long and forms the north-eastern shoreline of Botany Bay west of Penrhyn Estuary to the mouth of the Mill Stream. Like Penrhyn Estuary, it was created as part of local development by reclaiming the shoreline in the late 1970s to build Foreshore Road. The eastern end of the beach is currently eroding with sand migrating to the north west and depositing at the mouth of the Mill Stream. It is estimated that groundwater interception would affect approximately 470 m of the beach and foreshore area, equivalent to the parallel distance between the eastern end of the ponds in Sir Joseph The Ecology Lab Pty Ltd – Marine and Freshwater Studies Page 2 Botany Groundwater Clean-up – Aquatic Ecology Component Final, November 2004
Banks Park and the derelict groyne and jetty which marks the outer margin of Penrhyn Estuary. A fringing bed of seagrass (Zostera capricorni) is present seaward of Foreshore Beach in water depths of -2.658 m LAT to 0.45 m LAT and is located approximately 95 m offshore. Smaller patches of Zostera also occur between the fringing bed and Foreshore Beach in water depths of approximately 0.34 m LAT. The seagrass Posidonia australis does not occur off the south- eastern end of Foreshore Beach, but several small patches occur towards the north-western end (The Ecology Lab 2003). Three patches kelp (Ecklonia radiata) are located off the derelict groyne and jetty that marks the outer margin of Penrhyn Estuary (The Ecology Lab 2003).
2.2 Contamination in Penrhyn Estuary Water quality in the Penrhyn Estuary is dependant on tidal water circulation and input to the estuary via groundwater and Springvale and Floodvale Drains. There are a number of studies on water quality in Penrhyn Estuary (AGC Woodward-Clyde 1990, URS 2003, 2004). Chemicals of Potential Concern (based on the ANZECC (2000) water quality guidelines for recreational purposes and the Orica risk assessment studies) present in estuarine water have been summarised by URS (2002) and include: • Mercury in Springvale Drain (max 2 µgL-1) • Sulphide in Penrhyn Estuary and Floodvale and Springvale Drains (max 700 µgL-1) • Semivolatile organic compound: o Benzene in Floodvale and Springvale Drains (max 20 µgL-1) • Volatile organic compounds including: o 1,2 dichloroethane (EDC) in Floodvale and Springvale Drains (max 2000 µgL-1) and Penrhyn Estuary (max 100 µgL-1) o Vinyl chloride (chloroethane) (VC) in Penrhyn Estuary, Springvale and Floodvale Drains (range of values as of June 2004: 0.114 mgL-1 to 2.89 mgL-1), URS 2004b) o Carbon tetrachloride (CTC) in Penrhyn Estuary (max 10 µgL-1) and Floodvale and Springvale Drains (max 1000 µgL-1) o Trichloroethene (TCE) in Floodvale and Springvale Drains ( max 2000 µgL-1) o Tetrachloroethene (PCE) in Floodvale and Springvale Drains (max 200 µgL-1) The source of volatile chlorinated hydrocarbons is the discharge of shallow groundwater to Springvale and Floodvale Drains, and, to a lesser extent, discharge of deeper groundwater from the Southern Plume to Penrhyn Estuary. These chemicals volatise rapidly (i.e. on the order of hours to days) in surface waters and have low potential to accumulate in organisms (URS 2003). Penrhyn Estuary also receives runoff from urban and industrial areas and is subject to a range of gross contaminants and nutrient input (Lawson and Treloar 2002) Sediment quality in Penrhyn has also been the focus of studies investigations through time (AGC Woodward Clyde 1990, Kinhill 1990, Kinhill 1991, Kinhill 1993, Woodward-Clyde 1996, URS 2004). Concentrations of mercury in Penrhyn Estuary sediments exceeded ANZECC Interim Sediment Quality Guidelines ISQG – High (2000) in samples collected in The Ecology Lab Pty Ltd – Marine and Freshwater Studies Page 3 Botany Groundwater Clean-up – Aquatic Ecology Component Final, November 2004
December 2003 at most sites within Penrhyn Estuary, with concentrations up to 183 mg kg-1 . Mercury was not detected in sediments collected in the outer estuary near the derelict groyne and jetty (URS 2004). The maximum chromium concentration was 130 mg kg-1 , exceeding the ANZECC (2000) ISQG-L guideline value, but the mean concentration of chromium was 17.3 mg kg-1. Hexachlorobenzene (HCB) has been recorded in concentrations up to 2.2 mg kg-1); ANZECC (2000) has no guideline for this compound (URS 2004). The semivolatile CHC hexachlorobutadiene (HCBD) is likely to be present in sediments, but there are no data on current sediment concentrations in Penrhyn Estuary. These semivolatile CHCs adhere to sediment particles and have the potential to accumulate in sediment ingesting benthic invertebrates, fish and other aquatic animals.
2.3 Groundwater Behaviour and Contaminant Plumes The Botany Aquifer flows in a general south-westerly direction from the BIP towards Botany Bay and discharges into Botany Bay in the vicinity of Penrhyn Estuary. Groundwater currently discharges from the upper layer into Springvale and Floodvale Drains and the position of the water table near Penrhyn Estuary is controlled by recharge volumes in the drains. Based on a groundwater model (Merrick 1994), an estimated 6 percent of rainfall infiltrates groundwater on estuarine sediments and an estimated 37 percent on sand. There are several deep groundwater plumes up gradient of Penrhyn Estuary and Botany Bay characterised by high concentrations of EDC. The Southern Plume is currently discharging approximately 350m3 day-1 of contaminants, mainly EDC and TCE into the intertidal areas between Springvale and Floodvale drain channels with representative surface concentrations of EDC in the range of 1.1 to 0.019 mgL-1 and concentrations at 2 m depth ranging from 0.112 to 19.2 mgL-1. The maximum concentration of EDC occurs at low tide, when there is no dilution by seawater, and is at a minimum at high tide. Similar trends occur for other contaminants. It is estimated that approximately 0.2 kg day-1 of volatile chlorinated hydrocarbons (CHCs) enters Penrhyn Estuary from the Southern Plume (URS 2004a). Modelling has demonstrated that reduction of ethene compounds in the intertidal zone is due largely to dilution with seawater within a zone of groundwater diffusion rather than degradation of the compounds in situ. The Northern Plumes extend in a southwest direction from Botany Industrial Park and have core concentrations of EDC in the range of 100 to 200 mgL-1. Its front, with EDC concentrations of 10 mgL-1 is about 300 m wide at present. The Central Plume is predicted to discharge in the intertidal zone between Floodvale and Springvale drains by February 2006 and is the focus of Orica’s groundwater interception activities. It has higher core concentrations of volatile halogenated compounds (VHCs) compared to the southern plume (greater than 5000 mgL-1) and therefore potential to result in higher concentrations being discharged to the estuary. Interception and treatment of the central plume is the focus of the current cleanup activities and of this report.
2.4 Biota The groundwater interception proposal has potential to affect biota living in and near Penrhyn Estuary and Foreshore Beach. Those considered here include plants and invertebrates in saltmarsh and mangrove habitats, invertebrates (meiofauna and macrofauna) living in intertidal and subtidal habitats and plants (seagrass and algae) living in intertidal and subtidal aquatic habitats. Fish and shorebirds are important components of
The Ecology Lab Pty Ltd – Marine and Freshwater Studies Page 4 Botany Groundwater Clean-up – Aquatic Ecology Component Final, November 2004 the ecosystem that may be affected by the proposal and are discussed mainly in terms of indirect effects of the proposal on their supply of food and availability of shelter.
2.4.1 Invertebrate Fauna - Meiofauna Invertebrate fauna have been studied in terms of their general size classes. Meiofauna are invertebrates small enough to pass through a 0.5 mm mesh sieve and are present in saltmarsh, mangrove, intertidal and subtidal habitats. Macrofauna are animals that are retained on a 0.5 mm mesh sieve, although many researchers commonly use the 1 mm mesh size as definitive of this faunal component. Comparatively little is known about meiofauna compared to macrofauna. This is because they are small, often occur in great abundance and require specialised (and often rare) taxonomic expertise to identify. Ecological studies of meiofauna often incorporate the use of broad classes of invertebrates rather than species level identifications for these reasons. There are no studies are known on the meiofauna of mangrove or saltmarsh habitats near Penrhyn Estuary. There are, however, two studies on meiofauna in subtidal habitats in Penrhyn Estuary. Silveira (1993) used a replicated, hierarchical design to sample meiofauna from “very polluted” (in front of Springvale Drain), “moderately polluted” (Floodvale Drain) and control locations (either side of the mouth of the estuary). Metals were also sampled in sediments and were related to patterns in spatial distribution of meiofauna to HCB, HCBD, Hg and Cr sediment concentrations sampled earlier by SPCC (ACG – Woodward Clyde, 1990). The fraction of the sediment sampled retained in 1 mm, 0.5 mm and 0.35 mm sieves were identified to major taxonomic groups and counted. Sixteen taxa were recorded: nematodes accounted for 95% of all individuals in “very polluted” samples and approximately 70% in “moderately polluted” and one of the two control locations. The second control location was dominated by copepods. Together, nematodes and copepods accounted for 99.8% of all meiofauna abundance. Similarities between assemblages at contaminated sites were apparent, but large variations in the numbers of taxa and individuals masked significant differences between contaminated and control locations. Sediment concentrations of metals sampled showed higher total concentrations in the “moderately polluted” locations (Floodvale Drain) compared to the “very polluted” location (Springvale Drain), particularly with respect to concentrations of Zn and Pb, but both were higher than total sediment metal concentrations at control locations. Sediment concentrations for Hg and Cr were within the range recorded by SPCC (AGC Woodward- Clyde 1990). The levels of organic pollution and concentrations of hydrogen sulphide in sediments were not analysed, but thought to be related to differences in meiofauna distribution between “very polluted” and other locations. In November 1996 by Physalia Ltd sampled meiofauna in a grid pattern across the inner portion of the inner estuary, up into Floodvale and Springvale Drains, at the channel between the inner and outer estuary, near the new boat ramp and near the derelict groyne and jetty. Simultaneous samples were collected for analysis of sediment grain size distribution and concentrations of Hg and HCB. Meiofauna were dominated by nematodes (mean density 6,950 L-1) and copepods (mean density 1,509 L -1). Smaller densities of nematodes were found in Springvale Drain and at sites near the outflow of Springvale Drain lower in the estuary. These assemblages were species-poor and comprised tolerant, resistant animals (Physalia 1997). Communities at the mouth of the estuary were the most species rich and included several stress-tolerant species. Correlations between sediment concentrations of Hg and HCB failed to demonstrate a relationship between these and the distribution of
The Ecology Lab Pty Ltd – Marine and Freshwater Studies Page 5 Botany Groundwater Clean-up – Aquatic Ecology Component Final, November 2004 modified meiofaunal communities. The authors presented evidence that the distribution of modified communities was not related to freshwater input, but suggested that unusual sediment characteristics observed in Springvale Drain and along its outflow path could be investigated further to elucidate the cause of the observed stress.
2.4.2 Invertebrate Fauna - Macrofauna
2.4.2.1 Intertidal Fauna Kinhill (1991) sampled beach fauna at Foreshore Beach (denoted as Botany Beach in that study) and at two reference beaches, Towra Point and Runway Beach (on the eastern side of the original north-south runway, but now removed). At each beach three sites were sampled at two heights on the shore, 0.3 to 0.5 m and 0.5 to 0.7 m LAT. Five replicates were taken at each site/height, but the samples were combined to obtain a bulk sample for each site. This procedure limits the way in which these data can be evaluated. Samples were collected by coring and sieved through a 1 mm mesh sieve. Foreshore Beach was dominated by the nereid polychaete Australonereis ehlersi, which was also abundant at Runway Beach (Kinhill 1991). The fauna was quite distinctive compared to Towra Point, being numerically dominated by the amphipod Urohaustorius metungi and the polychaete Scolopsis simplex. Kinhill surveyed benthos along Foreshore Beach prior to construction of the Third Runway. They concluded that there was a distinctive gradient in abundance of benthos along the beach. The northern part was relatively sheltered, with a mean abundance of benthic invertebrates of 4,835 (SE = 419) individuals per m2; the central area supported an average of 1,190 (SE = 109) individuals per m2, while the southern, most exposed site sampled had an average of 854 (SE = 53) individuals per m2. These differences were attributed to a change in the abundance of A. ehlersi. Much of the section of Foreshore Beach surveyed by Kinhill (1991) was lost as a result of the construction of the Parallel Runway. The middle site sampled was close to the present mouth of the mill Stream, whilst the southernmost site was northwest of Penrhyn Estuary. The most recent data on intertidal macrofauna was collected in October 2002 by The Ecology Lab (2002) as part of investigation for the proposed port expansion. Samples that were collected near the south-eastern end of the beach may be affected by the proposal to extract groundwater, including sites S7 to S9, located within 500 m of the eastern end of Foreshore beach, sites S10 to S12, located along the sandy beach in the outer section of Penrhyn Estuary and sites S13 to S15 located in intertidal habitats in the inner section of Penrhyn Estuary (Figure 1). Six replicates samples were collected at each site using a 10 cm diameter PVC tube pushed into the sediment to a depth of 20 cm. Additional samples were collected for the analysis of sediment particle size distribution but no chemical analyses were undertaken. Sand flats along Foreshore Beach were dominated by medium to fine clean sandy sediments, while those within Penrhyn were muddier, with mangrove seedlings emerging occasionally from the sediment. In total 2,645 invertebrates were collected from the three locations (54 samples), comprising 30 taxa. Crustaceans were the most abundant group (46.5% of all individuals), dominated by amphipods from the family Exoedicerotidae (E. fossor and E. maculosus), which were particularly abundant at Site 11, near the derelict groyne and jetty. Polychaete worms were the next most abundant (34% of total individuals), dominated by the family Nereididae
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(Australonereis ehlersi and Ceratonereis aequisetis). Nereids were abundant at Site 13, near the outflow from Floodvale drain. The polychaete family Spionidae comprised 3% of individuals and was dominated by an unidentified genus (probably Spio or Microspio) that may have been found previously in small numbers along foreshore Beach (A. Murray, Australian Museum, pers. comm., Kinhill 1991). Burrowing worms from the family Orbiniidae have been reported previously from Foreshore beach (Kinhill 1991) and comprised 2% of individuals at the three locations sampled. Molluscs made up 2% of all individuals, comprised mainly of bivalves in the families Leptonidae and Psammobiidae. Other invertebrate phyla comprised 17% of individuals, dominated by oligochaete worms which were abundant but varied among replicates at Site 7.
2.4.2.1 Subtidal Fauna The available information on the community structure, abundance and distribution of subtidal benthic fauna in Botany Bay in general are summarised in The Ecology Lab (2003) in relation to the proposed expansion of Port Botany. Earlier sampling on behalf of ICI (now Orica) (SPCC 1990) did not sample benthic infauna. Only two studies have focussed on Penrhyn Estuary, one of those is recent enough to be indicative of benthic species currently present in the estuary. Silveira (1993) also sampled macrofauna in Penrhyn Estuary in relation to pollution. Using the same overall design as described for meiofauna (above), she collected six replicates sediment samples at locations representing two treatments and two controls. Samples were collected using a 55 mm diameter hand-held corer, then sieved through a 1 mm mesh sieve and identified to a more coarse level of taxonomy than used for the more recent study (The Ecology Lab 2003). A total of 2,376 individuals were collected in 48 samples, represented by 23 taxa. Seventy-five per cent of individuals and 17 taxa collected were from the inner estuary sites, while the remaining individuals and 21 taxa present were collected from the outer estuary sites. The greatest number of individuals per sample occurred at the “moderately polluted” locations, near the outflow of Floodvale Drain, and these samples were dominated by polychaetes. Capitellidae (probably Capitella capitata) made up 48% of individuals collected, with 92% of these collected at inner estuary sites. Nereididae and Spionidae also occurred and showed variations between replicates at Floodvale Drain and outer estuary sites. The most recent information available on subtidal benthic communities and the seagrasses in Penrhyn Estuary were collected by The Ecology Lab in 2002 for the proposed expansion of Port Botany. This information is too broad-scale to describe spatial distribution of subtidal benthos, or provide a baseline to test hypotheses regarding changes in groundwater input to the estuary or Botany Bay. Samples were collected on 24 October 2002 from three site in the inner estuary (Sites 1 to 3) and three sites in the Outer estuary (Sites 4 to 6) (Figure 1). Control locations (Quibray Bay and Towra Bay) were also sampled to provide a spatial comparison. Six replicate samples were collected around high tide using a Van Veen grab deployed from a small boat. Only five replicates were processed due to time constraints. Samples were sieved through a 1 mm mesh sieve, preserved, identified (mainly to family level) and counted. Additional samples were collected for analysis of sediment grain size, but no chemical analyses were done. A total of 26,114 individuals were collected in the 30 samples from Penrhyn Estuary, comprising 70 taxa. The inner and outer estuaries differed broadly in terms of the following:
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• The inner estuary was represented by 30 taxa, but 70 were present in the outer estuary. • The total number of individuals in the inner estuary was 22,071, while that for the outer estuary was 4,043. • Polychaetes comprised 65.5% of individuals in the inner estuary and 61% in outer estuary samples. • Ten polychaete families were present in the inner estuary compared to 22 in the outer estuary. • The numerically dominant polychaete family in the inner estuary were the Capitellidae (59% of polychaetes), represented by Capitella capitata, a species that has been associated with organically enriched and contaminated sediments (Pearson and Rosenberg 1978). Capitellidae in outer estuary samples comprised 43 % of polychaetes. • The two other families common in urbanised estuaries were Spionidae (20% of polychaetes in inner estuary, 18% in outer estuary) and Nereididae (14% inner, 7% outer). • The Sabellidae were represented by Desdemona ornata, a tiny filter feeding worm known to tolerant a wide variety of physical conditions (Kanandjembo et al. 2001). It has previously been found in great abundance in modified estuaries in the Sydney Region (The Ecology Lab 2001). A total of 602 individuals were present in the inner estuary and 79 individuals in the outer estuary. This species was not recorded in previous benthic surveys (Silveira 1993) and may represent a relatively recent introduction to Penrhyn Estuary. • In the inner estuary the next most abundant group was the nematodes, comprising 21% of individuals. In the outer estuary crustaceans comprised the next most abundant group, comprising 25% of individuals, dominated by amphipods and isopods. • In the inner estuary larval fish comprised 7% of individuals, due to their abundance in a single sample (1,760 individuals from one replicate sample at Site 1). No larval fish were recorded from the outer estuary. Larval fish are not usually considered members of the benthic community, but this result shows that fish larvae do occur in the inner estuary and when they do occur, their distribution can be patchy. • Bivalves made up 3% of individuals in the inner estuary (dominated by Tellinidae and Leptonidae) and 7 % in the outer estuary (dominated by Leptonidae).
2.4.3 Saltmarsh and Mangroves Saltmarsh and mangrove communities were mapped as part of the aquatic ecology study undertaken as part of the EIS studies for the proposed Port Botany Expansion (The Ecology Lab 2003) Field ground truthing was done in May 2002. Saltmarsh communities form a fringing habitat along the shoreline of the inner estuary only. On the north-western bank where Floodvale Drain flows, the community is dominated by Suaeda australis, a small patch of Sarcocornia quinqueflora and is backed by kikuyu grass, bitou bush and acacias. A stand of mixed saltmarsh species is present along the triangular land that separates the inflow from the two drains. The north-western bank of Springvale Drain is dominated by a stand of mangroves along the water’s edge and is backed by mixed saltmarsh species including Suaeda australis and Juncus krausii. The south-eastern bank of Springvale Drain and the south-eastern margin of the inner estuary are dominated by mixed saltmarsh and rush grass
The Ecology Lab Pty Ltd – Marine and Freshwater Studies Page 8 Botany Groundwater Clean-up – Aquatic Ecology Component Final, November 2004 along Springvale Drain and fringing mangroves that extend to near the new boat ramp. A small patch of Sarcocornia quinqueflora grows further south from the new boat ramp and is backed by beach spinifex, bitou bush and acacias (The Ecology Lab 2003).
2.4.4 Seagrasses and Algae Ten small seagrass beds comprised of Zostera capricorni grow on the fringes of the outer estuary. Four beds occur in the vicinity of the new boat ramp off Penrhyn Road ranging in size from 48 to 300 m2, with a total area of approximately 559 m2. They are comprised of sparse to moderately dense Zostera mixed with Halophila and in some places the algae Caulerpa filiformis. Six beds were mapped off the north-western shore of the outer estuary between the derelict groyne and jetty and the channel between the inner and outer estuary. The largest of these Zostera beds is located 70 to 90 m off shore, with smaller patches present closer to the shore in water depths of approximately 0.51 m LAT. Their total area is approximately 1,046 m2 (The Ecology Lab 2003). During recent studies in Penrhyn Estuary, The Ecology Lab has recorded the presence of a bed of Zostera growing intertidally on the eastern side of the inner estuary, to the north of the old boat ramp. This bed occurs amongst mangrove seedlings and pneumatophores and is relatively sparse.
2.4.5 Fish and Mobile Invertebrate Communities in Shallow Subtidal Habitats NSW Fisheries surveyed fish occurring off sandy beaches along Lady Robinsons Beach and at Towra Spit. The only samples taken off Foreshore Beach were from beds of Zostera capricorni (SPCC 1981a, b). As part of the studies for the Parallel Runway EIS, The Ecology Lab sampled fish along Runway Beach (Kinhill 1990). Apart from these studies, no other work on fishes using shallow, unvegetated sediments in Botany Bay were found, although there has been work in similar habitats in Jervis Bay, Port Hacking and Batemans Bay (CSIRO 1994). SPCC (1981a, b) recorded 68 species of fish from two shallow sandy sites in Botany Bay, 32 of which are economically important. Most of the commercial species were regarded as being transient in this habitat, with the exception of sand whiting (Sillago ciliata). Transient species of commercial value included tailor (Pomatomus saltatrix), southern herring (Herklotsichthys castelnaui), sand mullet (Myxus elongatus), flat-tail mullet (Liza argentea) and sea mullet (Mugil cephalus). All these species are common in other habitats. Species of limited economic value occurring as residents in the shallow sandy habitat included gobies and flounder (e.g. Ammotretis rostratus), while there were also several types of schooling bait fishes, including hardyheads (Atherinosoma ogilbyi), perchlets (Ambassis jacksoniensis), sandy sprats (Hyperlophus vittatus) and several species of toad fishes (Tetraodontidae) occurred in small schools in this habitat. The Ecology Lab sampled fish at three sites along the Runway Beach on three occasions from November to December 1989 (Kinhill 1990). Two seine hauls were done at each site and time. Forty-eight species of fish and mobile invertebrates were collected, totalling approximately 34,000 individuals. The species composition was similar to that reported for other sandy beaches in Botany Bay by SPCC (1981a, b), with sandy sprats and perchlets dominating the catch numerically. Other common species included three species of gobies, sand whiting, sand mullet and tarwhine.
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CSIRO (1994) sampled fish and mobile invertebrates at six beaches around Jervis Bay and at two sites each in Batemans Bay and Port Hacking. A seine net similar to the one used by The Ecology Lab was used. Ninety-seven species were collected, 41 of which are economically significant. As in Botany Bay, the catches were numerically dominated by schooling baitfish and there were no clear seasonal patterns (cf. SPCC 1981b). Moreover, changes in tidal height appeared to have little effect on abundance of fish and invertebrates off the sandy beaches in Jervis Bay. Several studies have reported presence of species of fish of commercial and recreational importance in seagrasses adjacent to Foreshore Beach (e.g. Bell et al., 1987; Worthington et al., 1991). Bell and Westoby (1986a, 1986b) manipulated shoot density within these beds and found that macro-fauna tended to inhabit dense seagrass over sparse, and that predation was not the proximate cause of the pattern. An alternative model, preference of individuals for dense seagrass, was proposed to explain the patterns of species abundance (Bell and Westoby, 1986b). At the larger scale, between seagrass beds, structure of the seagrass canopy (e.g. density of shoots) did not explain variation in faunal assemblages in natural (Bell and Westoby, 1986c; Worthington et al., 1992a) or artificial beds (Bell et al., 1987; Worthington et al., 1991). Other environmental factors (e.g. sediment size, area of seagrass and distance from the ocean) did not explain abundances of dominant small fish and macro- invertebrates (Bell and Westoby, 1986c). Instead, a model of stochastic settlement of fish and invertebrates to seagrass beds, followed by post-settlement movement within seagrass beds to favourable micro-habitats, was proposed to explain faunal abundances at the larger scale (Bell and Westoby, 1986c: Worthington et al., 1991, 1992). The model was later modified to include post-settlement movement of some species between seagrass beds (Sogard, 1989; Jenkins et al., 1998). Other studies have examined effects of hydrological processes on fish distribution and abundance. Kingsford and Suthers (1994, 1996) found larvae of several species of fish species (e.g. sparids, girellids, monacanthids), in waters adjacent to tidal fronts near the entrance to the bay. They proposed that larvae were transported along topographically stable fronts on flood tides to areas favouring retention of larvae (recruitment ‘hot spots’). Whilst there are no direct studies on the supply of larvae to seagrasses adjacent to Foreshore Beach, Steffe and Pease (1988) found a greater proportion of larvae derived from pelagic eggs (spawned in the ocean) adjacent to the entrance compared to other sites in the estuary. In a separate study, Steffe (1991) reported a greater abundance of larvae of commercially valuable species at a site near the entrance, adjacent to the port, relative to one other site in the main tidal stream, near Towra Point. It was proposed that reduced water flow at the Port site, caused by eddies, enhanced survival of larvae and resulted in greater numbers of juveniles settling in habitats adjacent to Foreshore Beach (Steffe, 1991). Recent work by Upston (unpub. thesis, 2001) investigating the patterns of abundance of variation of fish and macroinvertebrate assemblages throughout Botany Bay found trends consistent with studies discussed previously. Overall, there was a greater abundance of tarwhine, blue groper and the eastern king prawn (Penaeus plebejus) and fewer palaemonid prawns (Macrobrachium intermedium) associated with seagrasses adjacent to Foreshore Beach compared to other locations. The total number of taxa varied among locations, but the patterns of variation were not consistent among times of sampling (i.e. years). Given the greater abundances of species of fish of commercial and recreational importance in seagrasses adjacent to Foreshore Beach, Upston (2001) concluded that efforts should be made to protect these habitats from future disturbances.
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2.4.6 Bioaccumulation in Fish and Oysters The Ecology Lab (2004) has recently reviewed previous studies of bioaccumulation in fish and invertebrates from Penrhyn Estuary. The following text provides a summary of this previous work. As far as is known, there have been five surveys of the concentrations of contaminants in biota collected in and around Penrhyn Estuary. AG Environmental (1990) sampled a variety of invertebrate species collected opportunistically around Penrhyn Estuary in October and December 1989. Five sites were sampled – two each in and at the entrance to Penrhyn Estuary and one along Foreshore Beach to the west of the estuary. At each site a composite sample of at least 10 individuals was obtained. In addition, prawns were obtained from a commercial trawler operating outside the estuary, but in the northern part of Botany Bay. Due to a limited amount of tissue obtained for each taxon collected, it was not possible to do analyses for all contaminants in all specimens, although HCB was generally given priority. HCB was detected in all species except the gastropod Nerita sp., although it was not necessarily detected at all locations and on both times of sampling (AG Environmental 1990). The greatest concentrations of HCB were detected in a sample of soldier crabs (Mictyris longicarpus) collected near the entrance to the estuary in December 1989 (HCB = 0.71 mg kg-¹ wet weight basis, ww). Sydney rock oysters (Crassostrea commercialis – now designated Saccostrea glomerata) were collected only from the derelict wharf to the west of the estuary (site BS2 in AG Environmental 1990) and at a control location to the west of the estuary. At BS2, HCB was detected in only one sample (December 1989), with a concentration of 0.013 mg kg-¹ ww. AG Environmental (1990) did not obtain sufficient tissue for analysis of mercury in most samples. The highest concentrations were detected in the gastropods Bembicium auratum (0.2 mg kg-¹ ww, December 1989) and Pyrazus ebeninus (common name, mud whelk: 1.2. mg kg-¹ ww in December 1989). B. auratum were collected from the reference location and P. ebeninus came from within Penrhyn Estuary. Concentrations in oysters were much lower (0.2 – 0.3 mg kg-¹ ww), being collected from the derelict wharf (BS2) and the reference location. No oysters were collected for analysis from within the inner section of Penrhyn Estuary, and hence closest to the outlets of the drains. The Ecology Lab (1995) studied bioaccumulation in species of biota, including invertebrates and fish, that may be consumed by humans.. This study comprised two stages: a pilot study, which involved sampling fish in October 1993 and January 1994; and a broader collection of fish and invertebrates within Penrhyn Estuary and reference locations in Botany Bay, during March 1994. In October 1993, muscle and liver tissue were analysed in sea mullet (Mugil cephalus), sand mullet (Myxus elongatus), silver biddy (Gerres subfasciatus) and silver trevally (Pseudocaranx dentex). In January, muscle tissue from sea mullet, sand mullet, silver biddy, flat-tail mullet (Liza argentea), yellowfin bream (Acanthopagrus australis) and luderick (Girella tricuspidata) was analysed. Analytes included HCB, hexachloro-1-3- butadine (HCBD), hexachloroethane (HCE), mercury, chromium (Cr) and lipid (fat) content. Liver samples collected from fish in October 1993 were analysed for chlorinated hydrocarbons only, with the following results. HCE was not detected in any samples. HCBD was evident in all sea mullet (0.21-0.44 mg kg-¹ ww) and sand mullet (0.03-0.13 mg kg¹ ww). HCB was detected in all sea mullet (0.83-1.8 mg kg-¹ ww) and sand mullet samples (0.28-0.88 mg kg-¹ ww) and one trevally (0.04 mg kg-¹ ww). Overall, the levels of HCB and HCBD were significantly higher in sea mullet than any other species.
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HCE was not detected in muscle samples from both October 1993 and January 1994. HCBD was identified in sea mullet at both times (0.0-0.14 mg kg-¹ ww) and was also in two sand mullet collected in October 1993. HCB was found in all species (although not all individuals), with concentrations being greatest in sea mullet, regardless of sampling time. Chromium was not detected at any sampling time. Mercury was not detected in any species of mullet, but was present in silver biddy (0.0-0.1 mg kg-¹ ww), trevally (0.0-0.2 mg kg-¹ ww), bream (0.1-0.2 mg kg-¹ ww) and luderick (0.0-0.1 mg kg-¹ ww). Results from the pilot study were used to form the design of the main study done in March 1994 (The Ecology Lab 1995). The following species were analysed: sea mullet (muscle and liver samples), dusky flathead (Platycephalus fuscus) (muscle only), yellowfin bream (muscle only), silver biddy (whole fish), blue-swimmer crab (Portunus pelagicus), mud whelk (Pyrazus ebeninus), soldier crabs (Mictyrus longicarpus) and Sydney rock oyster (Saccostrea glomerata). The oysters were collected from the same site (BS2) as used by AG Environmental (1990). At the time, no oysters were observed growing in the inner estuary (The Ecology Lab pers. obs.). HCE was not detected in any biota (The Ecology Lab 1995). HCBD was detected in the muscle of some fish (0.01-0.02 mg kg-¹ ww). It also occurred in the liver of all sea mullet (0.02-0.05 mg kg-¹ ww). HCBD was also detected in one of the samples of mud whelk. All but two fish samples contained HCB. HCB was detected in all the invertebrates, except oysters, with the largest concentrations in the mud whelks. As noted above, AG Environmental (1990) did not detect HCB in oysters in October 1989, but it was detected in oysters in December 1989. None of the results for chromium indicated Penrhyn Estuary represented a significant, bioavailable source of this contaminant. Mercury was detected in many fish samples, particularly in yellowfin bream. It was also was detected in all invertebrates except oysters, with the highest concentrations found in mud whelks. Results suggested that Penrhyn Estuary might be a significant source of bioavailable mercury for a range of aquatic species. The Ecology Lab (1998) reported on further surveys of contamination in fish collected in 1996 and 1998). HCB and mercury were measured in muscle tissue of sea mullet, flat-tail mullet, sand mullet, dusky flathead and yellowfin bream, and in whole silver biddy. HCB was detected in every species of fish, in a total of 88% of individuals, with sea mullet having the largest concentrations (maximum: 0.479 mg kg-¹ ww), followed by silver biddy (0.340 - 0.343 mg kg-¹ ww). Mercury was detected in the muscle tissue of sea mullet, silver biddy, dusky flathead and bream. This study confirmed the continued presence of HCB and mercury in the tissue of fish occurring in Penrhyn Estuary. The NSW EPA (correspondence to ORICA, 27/11/03) sampled six Sydney rock oysters for HCB and a range of organochlorines, four oysters for mercury and three oysters for a range of metals, including chromium. Samples were collected in Penrhyn Estuary in August 2003, but the actual sampling positions within the estuary were not specified. HCB was detected in five of the six samples, with a mean concentration of 0.097 mg kg-¹ ww (SE = 0.023, n = 6; results below detection limit treated here as zero). Mercury was detected in all samples (mean = 0.093 mg kg-¹ ww, SE = 0.010, n = 4). These concentrations were considered to be higher than would be expected compared against the background for the state, whilst concentrations of lead and zinc were also higher than expected (EPA 2003). It was further suggested that oysters would be a simple and cost-effective way of monitoring changes in environmental concentrations in Penrhyn Estuary.
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This brief review of existing information indicates that there have been several studies of accumulation of contaminants in estuarine biota in and around Penrhyn Estuary over the past 15 years. Detectable concentrations of HCB and mercury have been found in fish and invertebrates consistently over that period, with sea mullet showing the greatest concentrations of HCB. This species is migratory and therefore is not likely to occur in the estuary year round. Notwithstanding this behaviour, some individuals appear to be present long enough to accumulate HCB. The use of oysters has shown a less consistent pattern. This may be due to the fact that in the earlier studies no oysters were collected from within the estuary itself – the closest site being the old wharf to the west of the estuary entrance. Indeed, it is likely that the presence of oysters within the estuary is a relatively recent occurrence and may not be permanent – this would limit their use as an indicator for ongoing studies. Oysters, however, were present during 2003 (EPA 2003, The Ecology Lab, personal observations) and hence provided an opportunity to sample a bioindicator that has been used in many studies elsewhere (e.g. Scanes and Roach 1999, Lincoln-Smith and Cooper 2004). The Ecology Lab (2004) sampled fish and oysters in Penrhyn Estuary in the most recent bioaccumulation studies undertaken on for URS on behalf of Orica. The results of the study confirmed those of previous studies, showing that HCB and mercury were present in fish and mercury present in oysters in the estuary. The results suggest that concentrations of HCB have decreased or stayed relatively similar over time. Concentrations of mercury may have increased in some biota over time, but the results are not conclusive due to differences in detection limits in the past, and periods when oysters were not present in the estuary to sample. Fish sampled in the most recent study included sea mullet (Mugil cephalus), flat tail mullet (Liza argentea), sliver biddy (Gerres subfasciatus), tarwhine (Rhabdosargus sarba), luderick (Girella tricuspidate), sand whiting (Sillago ciliata), yellowfin bream (Acanthopagrus australis) and trevally (Pseudocaranx dentex).
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3.0 BRIEF DESCRIPTION OF THE PROPOSAL The description of the proposal presented here focuses on issues relevant to aquatic ecology and is based on a more comprehensive description provided by URS (2004: Section 4 of the EIS). Orica has devised a Groundwater Cleanup Plan (GCP) as required by DEC which consists of pumping and treating contaminated plumes in three areas on and downgradient of its premises at Botany, NSW. Hydraulic containment of the existing contaminant plumes and their source areas would occur by excavating groundwater interception bores along strategically placed containment lines. Groundwater would be pumped to reduce discharge to Botany Bay by 15% and is expected to continue for a period of 30 years. During this period, extraction rates would be adjusted to cater for the changing concentrations of contaminants in the groundwater. The groundwater interception would also prevent shallow groundwater entering the nearby Springvale and Floodvale drains. This would result in no surface or groundwater flow to Penrhyn Estuary except in the case of local rainfall or flood event. The extraction of contaminated groundwater is designed to: • stop the movement of contaminant plumes, and • remove the contaminated groundwater for treatment. Extensive hydrogeological modelling has been undertaken to identify the number of extraction wells required, their location, depth, and extraction rates, to ensure containment of the plumes would be achieved with minimal impact. The proposed well locations are within the hydraulic containment lines specified in the NCUA, as follows: • Primary Containment Line: Core, Line A and Line 1, located along the southern boundary of Southlands Blocks 1 and 2; • Secondary Containment Line: Line 2 and Line 3, located in the median strip of Foreshore Road; and • DNAPL Containment Line: Lines 5 and 6, located along the western boundary of the BIP. Contamination of both the shallow and deep aquifers requires two layers of extraction wells to ensure that flow is fully intercepted and the contamination contained. The two layers for the proposed extraction wells are: • Layer 1 – Shallow wells, with total drilled depth typically up to 9 m; and • Layer 2 – Intermediate and deep wells, with total drilled depth typically between 10 m and 40 m. The wells that will intercept groundwater flow to Penrhyn Estuary and the south-eastern end of Foreshore Beach are Line 2 and Line 3, located in the median strip of Foreshore Road (Figure 1). The groundwater pumped out from extraction wells would be transferred via dedicated transfer pipelines, at a total rate of up to 15 ML/day. The location of the transfer lines and the methodology for groundwater treatment are detailed in the main EIS and, as they will have no effect on aquatic ecology, are not discussed further here.
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Re-use and Discharge of Treated groundwater Orica has investigated potential options to maximise reuse of the treated groundwater. The treatment process would produce the following discharges: • treated groundwater, to be reused by existing process users on the BIP; • excess treated groundwater, available for reuse by other potential users in the project area, currently proposed to be discharged into Botany Bay via Brotherson Dock; and • waste water from the reverse osmosis treatment step, to be discharged into Botany Bay at Brotherson Dock via Bunnerong Canal. All groundwater would be treated to water to a specified quality standard based on Australian Drinking Water standards and the ANZECC guideline (2000) for the protection of slightly to moderately disturbed marine ecosystems and Australian Drinking Water Standards. Impacts of the discharge into Brotherson Dock have been assessed directly by URS as part of the EIS; hence the assessment of impacts in this report focuses on Penrhyn Estuary and the south-eastern end of Foreshore Beach (Section 4). The reused groundwater would also be treated to a quality to achieve the process water standards of users on the BIP, and provision has been made in the design of the Groundwater Treatment Plant (GTP) to allow this final water treatment stage to be expanded to handle the full GTP flow of 15 ML/day as and when the future demand for treated groundwater increases.
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4.0 ASSESSMENT OF IMPACTS This assessment, which focuses on Penrhyn Estuary and the south-eastern end of Foreshore Beach, is based on extremely limited information both on the organisms occurring in the path of the contaminated groundwater plumes and on the toxicity of the plumes to biota. Overall assumptions used in the assessment include: • Intertidal and subtidal biota are characterised by estuarine species adapted to a range of salinities and include taxa present in a wide range of estuaries within Australia. • The presence of assemblages of invertebrates in Penrhyn Estuary and along Foreshore Beach (as sampled in October 2002 The Ecology Lab 2003) are probably already strongly affected by existing anthropogenic influences. This is evidenced by: o reduced species richness, o community structure dominated by a few taxa, o a paucity of small crustaceans such as amphipods, o dominance of a few families of polychaete worms, and dominance by species with small body size, and o short life spans that retain (by various means) offspring in the immediate vicinity of parents or within the parental habitat. • Based on the results of one snapshot survey (The Ecology Lab 2003), spatial distribution of communities within Penrhyn Estuary is assumed to be variable and there is insufficient information available to establish presence of spatial gradients of communities with respect to known concentrations of pollutants. Correlations between community structure and particle grain size distribution are confounded by tendency for sediment pollutants to adhere to silt and clay sized particles. The inner estuary has a higher proportion of fine sediments compared to the outer estuary and hence would be expected to retain more contaminants. • The current intertidal and subtidal communities have developed in the presence of, or in parallel to elevated contamination in Penrhyn Estuary. Contaminants present in the sediments include Hg, Cr and HCB which can have toxic effects and accumulate in fish, invertebrates and birds feeding on intertidal and subtidal fauna. There are no data available on responses to currents levels of these persistent metals and compounds in benthic fauna, however they have, along with other factors, probably caused responses in assemblages (e.g. tolerance by some biota, adaptation or mortality by others) resulting in the altered community structure as noted above. • Volatiles are likely to have toxic effects but are unlikely to bioaccumulate due to their volatility. Semivolatile CHCs, such as EDC and HCBD, are more likely to be found attached to sediment particles, than in the water column and can bioaccumulate. The extent to which CHCs may interact (either synergistically or antagonistically) with existing contaminants (e.g. mercury or HCB) is not known. • Currently concentrations of EDC, PCE, TCE, cis-1,2-DCE, trans- 1,2 –DCE, VC, CTC, and other CHCs are generally higher at low tide, reflecting their transport via shallow groundwater to Springvale and Floodvale Drains, and to a lesser extent,
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discharge of deeper groundwater from the Southern Plume, entering the estuary along its south-eastern margin. • There are elevated levels of nutrients such as nitrogen (as Ammonia and TKN) and phosphorus in surface water believed to be reaching the estuary via groundwater plumes. • Predicted changes in abundance and distribution of intertidal and subtidal biota are made against background conditions in which abundance and species richness in intertidal habitats are less than those in subtidal habitats. • groundwater interception could continue, albeit at varying levels, for 30 years. Changes due to reduction of groundwater to Penrhyn Estuary and the south-eastern end of Foreshore Beach are therefore considered to be long term (also referred to as “press” impacts). • There are no known studies in the scientific literature that are sufficiently similar to the proposed activity and set in similar physical and ecological settings that would inform predictions of the impacts of the proposed groundwater interception. The absence of detailed data on spatial distribution of intertidal and subtidal communities, the inability to decouple factors such as particle grain size and pollutant concentrations and lack of toxicity studies (particularly with respect to EDC) on any intertidal or subtidal species (including saltmarsh, seagrass, fish and shorebirds) hampers accurate predictions of the effects of this proposal on estuarine biota. As a result, the assessment of impacts of the proposal, including alternatives (e.g. the “Do Nothing” alternative) is largely qualitative. This requires the use of adaptive management to ensure that impacts on aquatic biota and habitats are carefully measured and mitigated where possible. The following assessment examines two alternatives: • “Do Nothing” (no groundwater interception) • The Proposal: Complete groundwater interception, with virtually no groundwater entering Penrhyn estuary or the south-western end of Foreshore Beach. Predicted effects of each scenario are presented for ecosystem components as a series of tables in the following sections. The final section considers the effects of the proposed groundwater remediation in relation to cumulative effects, specifically the proposed Port Botany expansion, which is currently the subject of a Commission of Inquiry.
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4.1 The “Do Nothing” Alternative In the “Do Nothing” alternative scenario, groundwater is not intercepted. The central, northern and southern plume would arrive via groundwater at Penrhyn Estuary and Foreshore Beach, with maximum concentrations of contaminants arriving after February 2006. Assumptions made in assessing this alternative include: 1. Surface water concentrations of EDC, PCE, TCE, cis-1,2-DCE, trans- 1,2 –DCE, VC, CTC, and other volatile CHCs would increase significantly, with greater concentrations at low tide. Semivolatile CHCs including HCB and HBCD present in the plumes would be absorbed onto estuary sediments, increasing their present concentrations in Penrhyn Estuary. 2. Present sediment concentrations of Hg, Cr would be unchanged. 3. There would be no change in levels of nutrients such as Nitrogen and Phosphorus reaching the estuary via the groundwater plumes.
Ecosystem Component Response Timeframe Benthic habitats Moisture levels in sediments remain Highest effect would same as at present, but coincide with influx of concentrations of volatile and highest concentrations of semivolatile CHCs in sediments and volatile CHCs in plume. water column would increase. Intertidal Biota Potential mortality of population Highest effect would due to acute toxicity of volatile and coincide with influx of semi volatile CHCs in plume (level highest concentrations of of acute toxicity unknown). volatile CHCs in plume. Intertidal benthos could fail to Longer term, at least until recolonise. concentrations of CHCs return to their current levels, >30 years. Subtidal Biota Potential mortality of population Highest potential would due to acute toxicity of volatile and coincide with influx of semi volatile CHCs in plume (level highest concentrations of of acute toxicity unknown). volatile CHCs in plume. Subtidal benthos could fail to Longer term, at least until recolonise due to high levels of concentrations of CHCs volatile and semivolatile CHCs in return to their current levels, plume, or recolonise slowly. > 30 years. Seagrass Could dieback or disappear due to Highest potential would acute toxicity of volatile and semi coincide with influx of volatile CHCs in plume (level of highest concentrations of acute toxicity to Zostera unknown). volatile CHCs in plume. Seagrass could recolonise. Longer term, at least until after concentrations of CHCs return to their current levels, > 30 years. Saltmarsh Habitat Saltmarsh plants could die due to Highest potential would acute toxicity of volatile and coincide with influx of semivolatile CHCs in plume (level of highest concentrations of The Ecology Lab Pty Ltd – Marine and Freshwater Studies Page 18 Botany Groundwater Clean-up – Aquatic Ecology Component Final, November 2004
acute toxicity unknown). volatile CHCs in plume. Invertebrate communities could die Highest potential would due to acute toxicity of volatile and coincide with influx of semivolatile CHCs in plume (level of highest concentrations of acute toxicity unknown). volatile CHCs in plume. Mangroves Mangrove plants and invertebrates Highest potential would fauna could die due to acute toxicity coincide with influx of of volatile and semivolatile CHCs in highest concentrations of plume (level of acute toxicity volatile CHCs in plume. unknown). Death of mangroves would reduce Long term, > 30 years. input of particulate organic matter to the estuary. Fish Fish kills could occur due to acute Highest potential for fish toxicity of volatile and semi volatile kills would occur when fish CHCs in plume (level of acute recruitment or migration into toxicity unknown). the estuary coincide with maximum influx of volatile CHCs in plume. Penrhyn Estuary could be lost as Longer term, at least until shelter or feeding habitat for fish concentrations of CHCs due to loss/ significant decrease in return to their current levels, abundance of benthic fauna. > 30 years. Loss of seagrass could slightly Longer term, at least until reduce available habitat for fish in concentrations of CHCs northern section of Botany Bay return to their current levels resulting in local decreases in fish and seagrass abundance. However, seagrasses in recolonises/recovers, > 30 outer Penrhyn Estuary have years. relatively low habitat value (short bladed, low density) compared to other seagrass habitats in Botany Bay and alternative sheltered habitats occur elsewhere (e.g. Quibray Bay. Shorebirds Potential direct effect: Birds roosting Highest potential would in Penrhyn Estuary could die due to coincide with influx of respiratory effects of volatile CHCs. highest concentrations of volatile CHCs in plume. Potential indirect effect: If large Timing would correspond to numbers of intertidal and subtidal influx of CHC level benthos die, shorebirds and seabirds exceeding the acute level (especially opportunistic silver gulls) (acute levels unknown). could increase rate of feeding on dying invertebrates. This could increase the birds’ dietary exposure to Hg, Cr and HCB present in sediment and benthic fauna compared to the current situation.
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Penrhyn Estuary could be lost as Longer term, at least until roosting and feeding habitat due to concentrations of CHCs loss/ significant reduction in return to their current levels saltmarsh habitat (for roosting) and and benthic communities abundance of benthic fauna (food recolonise. items).
Summary of outcome: The arrival of large concentrations of CHCs in groundwater would likely cause significant degradation of the estuarine ecosystem in Penrhyn Estuary, with greater effects seen in the inner estuary. The CHCs could cause mortality in invertebrates, fish and shorebirds, but acute levels of toxicity are unknown. The predicted decrease in invertebrate food items would have follow-on effects for mobile species such as fish and shorebirds, which may be able to use alternative habitats in Botany Bay. Saltmarshes, mangroves and intertidal seagrasses may die, with their recovery time linked to passage of contaminant plume and the duration of residual effects in sediments.
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4.2 Groundwater Interception Alternative In the proposal scenario, bores would be drilled along Foreshore Road and other locations and pumping and groundwater treatment would ramp quickly (< 6 months) to 15 ML/day. This would result in an overall reduction of groundwater input to Botany Bay overall by 15%, but virtually no groundwater would enter Penrhyn Estuary. The assumptions made in assessing this alternative include: 1. Groundwater interception could continue for up to 30 years. 2. No discharge from Springvale and Floodvale Drains except after major, local (seaward of Foreshore Road) rain events. 3. Surface water concentrations of EDC, PCE, TCE, cis-1,2-DCE, trans- 1,2 –DCE, VC, CTC, and other volatile and semi volatile CHCs in Penrhyn Estuary decrease significantly due to interception of plume and lack of surface run off from Floodvale and Springdale Drains. 4. The current sediment concentrations of semivolatile CHCs (HCB and HCBD) remain at their present levels. 5. Concentrations of nutrients (N, P) in surface water decrease due to interception of plume. 6. Intertidal habitats become drier and more saline during low tide, because no groundwater rises to the surface to dilute seawater. Upper layers of sediment (containing benthic fauna) could dry out during low tide, particularly during warmer months and during midday low tides. 7. Subtidal pore water and sediments may become more saline during low tide due to lack of dilution by groundwater, and the range of salinities experienced in pore water could shift in favour of higher average salinities during low tide. 8. The current cycling of pH levels in surface water (pH < 5 during low tide, pH >7 during high tide) would become dampened in amplitude in the absence of groundwater influx, with lowest pH values increasing slightly. No impacts on biota due to this dampening are predicted. A slight increase in lowest pH values could decrease bioavailability of metals (Hg, Cr) because they could become less soluble. Concentrations of HCB are not likely to change with changing water quality variables (ANZECC 2000). There is no information on potential interactions of metals and other contaminants with concentrations of volatile and semivolatile CHCs currently present in the estuary. 9. During low tide, sediment and pore water concentrations of Hg, Cr and HCB may increase due to evaporation of water and lack of dilution from groundwater. While overall concentrations of these metals and contaminants may remain unchanged, they may effectively become more concentrated on the small scale and therefore may be ingested and bioaccumulated by infauna at higher rates than at present. The following table presents the “High Level” range of responses to the withdrawal of groundwater, with the “Low Level” range presented in the following table.
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4.2.1 “High Level” Range of Responses to Groundwater Interception Ecosystem Component High Level Range of Responses Timeframe Benthic Habitats Moisture levels in sediments are Drying effect would be reduced during low tide. Overall, greater during spring tides, pore water salinity range shifts when low tide occurs at towards being more saline. midday and in warm weather. Intertidal Biota Significant, detectable reductions in Soon after maximum abundance and species richness of pumping extraction is intertidal fauna in response to achieved. Depends on reduced water content in intertidal weather conditions: more sand and increased salinity during rapid response expected low tide. when low tides occur in warm weather and at midday. Note: infauna inhabit the upper 10 cm of sediment where maximum effect of lack of groundwater would be seen during low tide. Intertidal benthos recolonises Longer term, for the duration slowly, with altered community of groundwater interception, shifted towards the subtidal zone. but potentially dependant on conditions when propagules settle out of water column. Subtidal Biota Reduction in abundance and species < 1 year after beginning of richness in response to increases in groundwater interception. average salinity, concentrations of CHCs, Hg, Cr and HCB during low tide in sediments and decrease in surface water nutrients. Subtidal benthos recolonise slowly Longer term, until biota due to increased physical stress, adapt to new physical and potentially with altered community chemical regime. structure. Seagrass No response, or may fail to grow or Responses of seagrasses to expand size of beds due to reduced decrease in groundwater not fresh groundwater input. known sufficiently to predict response or rate of response. Saltmarsh Habitat Some saltmarsh plants could die or Response time of saltmarsh fail to grow as a response to more plants to changes in saline groundwater conditions. groundwater unknown. Abundance of species preferred as roosting habitat by shorebirds may increase because they are more tolerant of fully saline conditions (Sarcocornia quinqueflora). Invertebrates in saltmarsh could Response times of saltmarsh reduce in abundance due to drier invertebrate communities The Ecology Lab Pty Ltd – Marine and Freshwater Studies Page 22 Botany Groundwater Clean-up – Aquatic Ecology Component Final, November 2004
conditions. unknown. Mangroves Plants could die or fail to grow as a Response time of mangroves response to more saline to changes in groundwater groundwater conditions. unknown. Fish Fish continue to bioaccumulate < 1 year after beginning of either at similar rates as at present or groundwater interception. at lower levels due to reduced populations of benthos. Penrhyn Estuary could be reduced Longer term, until biota in value feeding habitat due to adapt to new physical and reduction in abundance of benthic chemical regime. fauna. Seagrass provides habitat for fish in northern section of bay, but flow-on effect on fish unlikely because local beds provide relatively low habitat quality compared to elsewhere in Botany Bay and response of seagrass to reduced groundwater unknown. Shorebirds Potential direct effect: Initially Depends on timing of slightly increased short-term potential effects on potential for bioaccumulation of Hg, invertebrates. Cr, HCB and HCBD as shorebirds and seabirds (especially silver gulls, which feed opportunistically) increase feeding rate on dying invertebrates. Potential indirect effect: Penrhyn Longer term, until biota Estuary reduced in value as feeding adapt to new physical and habitat due reduction in abundance chemical regime and of benthic fauna. However, abundance recovers to levels decreases in groundwater also similar to present. decreases potential for bioaccumulation of Hg, Cr, HCB and HCBD from sediments in Penrhyn Estuary as shorebirds use alternative food sources in preference to Penrhyn Estuary. Potential indirect effect: Potential Response time of saltmarsh increase in saltmarsh plants suitable plants to changes in for roosting habitats. groundwater unknown. Potential reduction in saltmarsh Response time of saltmarsh invertebrate abundance unlikely to invertebrate community to impact on shorebirds: relatively changes in groundwater minor component of diet compared unknown. to inter- and subtidal invertebrates. Catchment input from Organic input to the estuary from Unknown, but probably long Drains drains would decrease significantly term effect. Time required due lack of flow in Springvale and for benthos to process
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Floodvale Drains, with particulate organic material currently in organic input dependant on rain the estuary is unknown. events in the immediate vicinity Long-term reduction of food (seaward of Foreshore Road). can be considered additive Benthic fauna could reduce in effect to short-term reduction abundance due to reduction in in benthos due to physical organic input. stresses. Vegetation lining the banks of Unknown and sections Floodvale and Springvale unpredictable, but possible Drains upstream of the estuary given possibly 30 years of could dry out and die due to groundwater interception. groundwater interception over long Research on burial of benthic term. If a major rain event occurred fauna suggests that most after vegetation died, species could not burrow unconsolidated sediments could upwards through more than mobilise, with the result of 10 to 50 cm of sediment, with deposition of sediments containing a the lower end of that range variety of substances (oil, grease, more applicable to the small metals, gross pollutants) in the sized fauna present in estuary. Should sufficient sediment Penrhyn Estuary. be mobilised and deposited in the estuary, the effect could be to smother benthic fauna.
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4.2.2 “Low Level” Range of Responses to Groundwater Interception The table below presents response to groundwater interception at the low end of the response spectrum. The assumptions made in assessing the potential responses are the same as those listed in section 4.2.1.
Ecosystem Response Low Level Range of Response Timeframe Benthic Habitats Moisture levels in sediments are Drying effect would be reduced during low tide. Overall greater during spring tides, pore water salinity range shifts when low tide occurs at towards being more saline. midday and in warm weather Intertidal Biota Response to reduced water content Soon after maximum in intertidal sand could be limited to pumping extraction is slight reduction in abundance and achieved. Depends on spatial shift toward lower intertidal average weather conditions: and shallow subtidal locations in greater response expected response to reduced moisture when low tides occur in content. warm weather and at midday. Intertidal benthos recolonise, but Longer term, for the duration community structure altered in of groundwater interception. favour of assemblages that have adapted to the increase in physical stress. Community structure may alter to reflect increased abundance of species more tolerant of higher salinities. Community may be dominated by smaller bodied invertebrates (meiofauna, invertebrates small enough to pass through a 0.5 mm mesh sieve), which are too small to be food items for shorebirds. Subtidal Biota Slight changes in community < 1 year after beginning of structure in response to physical groundwater interception. changes in habitat, with shift towards dominance by more salt- tolerant species. Subtidal benthos recolonise slowly Longer term, for the duration with altered community structure of groundwater interception. that favours assemblages adapted to new physical and chemical regime. Seagrass No detectable difference in seagrass Short and long term. morphology. Saltmarsh Habitat No detectable change in salt marsh Short and long term. plant community. No change in availability of Short and long term.
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saltmarsh plants as roosting habitats. No change in abundance of Short and long term. saltmarsh invertebrate community in response to lack of groundwater. Mangroves No detectable change in mangrove Short and long term. condition. Fish Fish continue to bioaccumulate at Short and long term. similar levels as prior to groundwater interception. Seagrass provides habitat for fish in Short and long term. northern section of bay of similar quality as before groundwater interception. Shorebirds No detectable difference in rate of Short and long term. bioaccumulation of Hg, Cr and HCB compared to before groundwater interception. Penrhyn Estuary provides similar Short and long term. quality feeding habitat as before groundwater interception because reduction in abundance of benthic fauna is slight. No change in availability or quality of roosting habitat for shorebirds. Catchment input from Organic input to the estuary from Unknown, but probably long Drains drains would decrease significantly term effect. Time required due lack of flow in Springvale and for benthos to process Floodvale Drains, with particulate organic material currently in organic input dependant on rain the estuary is unknown. events in the immediate vicinity Long-term reduction of food (seaward of Foreshore Road). can be considered additive Benthic fauna could reduce in effect to short-term reduction abundance due to reduction in in benthos due to physical organic input. stresses. Vegetation lining the banks of Unknown and Floodvale and Springvale Drains unpredictable, but possible upstream of the estuary could dry given possibly 30 years of out and die due to groundwater groundwater interception. interception over long term. If a Research on burial of benthic major rain event occurred after fauna suggests that most vegetation died, unconsolidated species could not burrow sediments could mobilise, with the upwards through more than result of deposition of sediments 10 to 50 cm of sediment, with containing a variety of substances the lower end of that range (oil, grease, metals, gross pollutants) more applicable to the small in the estuary. Should sufficient sized fauna present in sediment be mobilised and Penrhyn Estuary. deposited in the estuary, the effect could be to smother benthic fauna.
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4.3 Conclusions The arrival of large concentrations of CHCs in groundwater would likely cause significant degradation of the estuarine ecosystem in Penrhyn Estuary, with greater effects seen in the inner estuary. The CHCs could cause mortality in invertebrates, fish and shorebirds, but acute levels of toxicity are unknown. The predicted decrease in invertebrate food items would have follow-on effects for mobile species such as fish and shorebirds, which may be able to use alternative habitats in Botany Bay. Saltmarshes, mangroves and intertidal seagrasses may die, with their recovery time linked to passage of contaminant plume and the duration of residual effects in sediments. If groundwater removal and remediation is successful, it would remove significant risks to the ecosystem posed by large concentrations of CHCs arriving at Penrhyn Estuary and Botany Bay. However, there would be some consequential effects due to the removal of groundwater flow to Penrhyn Estuary. The most extreme response by invertebrates could range from some mortality in the intertidal tidal zone and shifts in community structure in subtidal communities, to changed community structure and spatial displacement of intertidal animals toward the subtidal zone. Potential follow-on effects on fish and shorebirds may range from a short-term chance of increased bioaccumulation to no detectable effects, as there are alternative habitats for these animals elsewhere in Botany Bay. Longer term effects on fish and shorebirds would be linked to the level of response of saltmarsh and mangrove habitats to withdrawal of groundwater, which may alter the quality of these habitats as sources of food and shelter. In the context of the effects on Botany Bay, Penrhyn Estuary represents a relatively small area. The loss of some benthos, seagrasses and mangroves are not likely to have a major effect on the productivity or diversity of the large bay ecosystem. Impacts on shorebirds that feed and roost in the estuary may of greater significance due to the protected status of some of species and due to the dwindling habitat in the Sydney region. Similarly, impacts on saltmarshes would be significant because this habitat is decreasing in Botany Bay and the Sydney region generally. However, as elsewhere in the region, the increase in the extent of mangroves in Penrhyn Estuary threatens saltmarshes there. Removal of groundwater may actually create conditions more favourable to the expansion of saltmarsh over mangrove habitat.
4.4 Cumulative Impacts URS has reviewed the risks of the current levels of contamination in Penrhyn Estuary with respect to the proposed expansion of Port Botany, which is currently the subject of a Commission of Inquiry. They concluded that the dredging and filling activities proposed in the port expansion, which would remove mangroves from Penrhyn estuary and alter estuarine habitats, would result in no changes to existing water or sediment contaminated concentrations in Botany Bay outside Penrhyn Estuary (URS 2003). As the current proposal would result in a decrease in water-borne contaminants in Penrhyn Estuary and Botany Bay, and no change in existing levels of sediment contamination, the cumulative effects of the proposal with respect to levels of contamination is considered to decrease future levels of contamination in Penrhyn Estuary and Botany Bay. The groundwater modelling for proposed port expansion (Merrick 2004) concluded that the changes in levels of groundwater due to the port expansion would fall within the range of normal variations in groundwater levels. The present proposal represents a change in groundwater levels well outside the normal range. With respect to changes to in The Ecology Lab Pty Ltd – Marine and Freshwater Studies Page 27 Botany Groundwater Clean-up – Aquatic Ecology Component Final, November 2004 groundwater levels, the current groundwater proposal represents greater potential change to the ecosystem than those associated with the port expansion, and hence the cumulative effects of the port expansion proposal on changes to groundwater levels are considered negligible in comparison. Predictions of environmental changes due to the Greenhouse effect include a rise in mean sea level of 0.34 m (estimated mean value) over the next 50 years, increase in water temperature, increased frequency of storms and variability in rainfall (Lawson and Treloar 2003). Seagrasses may establish on the flats of the inner estuary, but saltmarsh habitats may recede in response to greater water depth. Increases in water temperature are not predicted to affect the establishment or expansion of seagrasses, but assemblages of biota may include a larger proportion of subtropical species (The Ecology Lab 2003). The cumulative impact of the interception of groundwater and the predicted increase in water depth would have the effect of making Penrhyn Estuary a more saline environment, becoming more similar to those that occur in Botany Bay. The increased frequency of storms and variability in rainfall would not counteract this shift because during groundwater interception all but local rainfall would be intercepted by wells extracting the upper layer of groundwater.
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5.0 MITIGATION MEASURES The objective of the proposal is to intercept and treat contaminated groundwater for up to 30 years. Because the proposal would operate over a decade time horizon, it is important to ensure that impacts to the aquatic habitats and biota in Botany Bay are understood and distinguished from other anthropogenic and natural causes of change. There are three possible areas where mitigation should be considered: 4. If independent studies (e.g. toxicology) indicate that CHCs have limited toxicity on aquatic biota (including shorebirds), the interception of groundwater could be terminated or scaled down. 5. If concentrations of CHCs in groundwater plumes as they enter the bay are found to be highly variable, there may be periods when partial interception of groundwater might be feasible (and cost effective). 6. Reintroduction of treated groundwater to the estuary should be considered. If groundwater was only partially reintroduced, or applied locally as surface water, this may serve to mitigate the impacts of the proposal. Impacts on the estuarine ecosystem may vary greatly in magnitude and could affect several ecosystem components. Because the magnitude of effects on fish and birds are likely to flow on from the magnitude of impacts on benthic invertebrates, it is essential that the abundance and spatial distribution of the benthos be monitored before, during and after groundwater interception. It is recommended that a program of monitoring be developed in negotiation with the relevant government agencies and initiated as soon as possible to enable the effects of groundwater interception to be measured. Components of monitoring that should be considered include habitat mapping and surveys of benthos, shorebirds and fish using, wherever appropriate, control locations to provide a measure of natural variability. In addition, it is suggested that toxicological studies of CHCs be initiated using a range of indicator species (individually and as assemblages), preferably using Direct Toxicity Assessment.
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6.0 ACKNOWLEDGEMENTS This report was written by Dr Peggy O’Donnell and Dr Marcus Lincoln Smith. Dr Peggy O’Donnell prepared Figure 1.
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7.0 REFERENCES AG Environmental (1990). State Pollution Control Commission. ICI Botany Environmental Survey Stage 1 Preliminary Investigations, May 1990. Prepared by AG Environmental Engineers in association with Woodward Clyde Consultants Inc (USA).
ANZECC and ARMCANZ (2000). Water quality and monitoring guidelines. National water quality management strategy, CD. Prepared for: Australian & New Zealand Governments. ANZECC//ARMCANZ, Australia.
Bell J.D. & Westoby M. (1986a) Importance of local changes in leaf height and density to fish and decapods associated with seagrasses. J. Exp. Mar. Biol. Ecol. 104, 249-274. Bell J.D. & Westoby M. (1986b) Abundance of macro-fauna in dense seagrass is due to habitat preference, not predation. Oecologia 68, 205-209. Bell J.D. & Westoby M. (1986c) Variation in seagrass height and density over a wide spatial scale: effects on fish and decapods. J. Exp. Mar. Biol. Ecol. 104, 275-295. Bell J.D & Westoby M. (1987) Effects of an epiphytic alga on abundances of fish and decapods associated with the seagrass Zostera capricorni. Aust. J. Ecol. 12, 333-337. Bell J.D., Westoby M. & Steffe A.S. (1987) Fish larvae settling in seagrass: do they discriminate between beds of different leaf density? J. Exp. Mar. Biol. Ecol. 111, 133-144. Bell J.D.& Worthington D.G. (1993) Links between estuaries and coastal rocky reefs in the lives of fishes from south-eastern Australia. In: Proceedings of the second international temperate reef symposium. (eds. C.N. Battershill, D.R. Schiel, G.P. Jones, R.G. Creese & A.B. MacDiarmid) NIWA, Wellington, New Zealand, pp. 85-91. CSIRO Division of Fisheries (1994). Jervis Bay Baseline Studies - Final Report. Prepared for: Department of Defence. CSIRO, Perth, WA, Australia. Jenkins G.P., Keough M.J. & Hamer P.A. (1998) The contributions of habitat structure and larval supply to broad-scale recruitment variability in a temperate zone, seagrass- associated fish. J. Exp. Mar. Biol. Ecol. 226, 259-278. Kanandjembo, A.N, Platell, M.E. and Potter, I.C. (2001). The benthic macroinvertebrate community of the upper reaches of an Australian estuary that undergoes marked seasonal changes in hydrology. Hydrological Processes 15, 2481-2501. Kinhill Engineers Pty Ltd (1990). Proposed third runway, Sydney (Kingsford Smith) Airport. Draft Environmental Impact Statement. Prepared for: Federal Airports Corporation. Kinhill Engineers Pty Ltd, Sydney, NSW. Kinhill Engineers Pty Ltd (1991). Proposed third runway, Sydney (Kingsford Smith) Airport. Supplement to the Draft Environmental Impact Statement, Volume Two. Prepared for Federal Airports Corporation. Kinhill Engineers Pty Ltd and Federal Airports Corporation, Ultimo, NSW.
Kingsford M.J, Suthers I.M. (1994) Dynamic estuarine plumes and fronts: importance to small fish and plankton in coastal waters of NSW, Australia. Continental Shelf Research 14(6), 655-672.
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Kingsford M.J, Suthers I.M. (1996) The influence of tidal phase on patterns of ichthyoplankton abundance in the vicinity of an estuarine front, Botany Bay, Australia. Estuarine, Coastal and Shelf Science 43, 33-54. Lawson and Treloar (2003). Proposed Expansion of Container Port Facilities in Botany Bay, NSW: Coastal Process and Water Resources Issues. Report to Sydney Ports Corporation, Report Number J2076/R1999, 3 Volumes. Lawson and Treloar Pty Ltd, Gordon, NSW. Lincoln-Smith, M. P. and Cooper, T. F. (2004). Combining the use of gradients and reference areas to study bioaccumulation in wild oysters in the Hunter River estuary, New South Wales, Australia. Marine Pollution Bulletin, 48: 873 – 883.
Merrick, N.P. (2004). Optimal groundwater abstraction rates for hydraulic containment of contaminant plumes and source areas, Botany NSW. Prepared for Orica Australia Pty Ltd 16-20 Beauchamp Road Matraville NSW 2036. Project Number C04/44/001 Date: 13 September 2004. Pearson, T.H. and Rosenberg, R. (1978). Macrobenthic succession in relation to organic enrichment and pollution of the marine environment. Oceanography and Marine Biology Annual Review, 16: 229-311. Physalia (1997). Meiofaunal assemblages of Penrhyn Estuary, Botany Bay: a baseline survey of sediment communities. A confidential report prepared for ICI Botany Bay by Physalia Ltd, Harpenden, U.K. Scanes, P. R. and Roach, A. C. (1999). Determining the natural “background” concentrations of trace metals in oysters from New South Wales, Australia. Environmental Pollution, 105: 437 – 446.
Silveira, R. 1993. Patterns in macrobenthic and meiobenthic community composition, related to pollution. Submitted as partial fulfilment for BIOS 40333 Biological Science Honours, University of New South Wales 1993. Sogard S.M. (1989) Colonization of artificial seagrass by fishes and decapod crustaceans: importance of proximity to natural eelgrass. J. Exp. Mar. Biol. Ecol. 13, 15-37. State Pollution Control Commission (1981a). Environmental Control Study of Botany Bay :The ecology of fish in Botany Bay - Community structure., BBS 23A. SPCC, Sydney, Australia. State Pollution Control Commission (1981b). Environmental Control Study of Botany Bay: The ecology of fish in Botany Bay - Biology of Commercially and Recreationally Valuable Species: BBS 23B. Prepared for: NSW Government. SPCC, Sydney, Australia. Steffe A.S. & Pease B.C. (1988) Diurnal survey of ichthyoplankton abundance distribution and seasonality in Botany Bay, New South Wales. Proc. Linn. Soc. N.S.W. 110 (1), 1-10. Steffe A.S. (1991) Larval fish distributions within Botany Bay: implications for estuarine recruitment and management. PhD thesis, Macquarie University, Sydney, 334 pp. SPCC (1990). State Pollution Control Commission ICI Botany Environmental Survey Stage 1 Preliminary Investigations. Prepared by AG Environmental Engineers in association with Woodward-Clyde Consultants (USA). May 1990. The Ecology Lab Pty Ltd (April, 1995). Environmental survey on and in the vicinity of the premises of ICI Australia Pty Ltd Botany: Report on investigations for Stage 2. Prepared for: AGC Woodward-Clyde. The Ecology Lab Pty Ltd, Sydney, Australia. The Ecology Lab Pty Ltd – Marine and Freshwater Studies Page 32 Botany Groundwater Clean-up – Aquatic Ecology Component Final, November 2004
The Ecology Lab Pty Ltd (November, 1998). Environmental survey of fish in the vicinity of the premises of Orica Australia Pty Ltd Botany: Stage 3 investigations. Prepared for: AGC Woodward Clyde. The Ecology Lab Pty Ltd, Sydney, NSW.
The Ecology Lab Pty Ltd (2003). Port Botany Expansion – Aquatic Ecology, Conservation and Fisheries. Volume 1: Main Report, Appendix 1: Supplementary Study on Benthic Communities. Report to Sydney Ports Corporation. Report Number 41/0102 C. Final, May 2003. The Ecology Lab Pty Ltd (2004). Penrhyn Estuary Fish and Oyster Bioaccumulation Study. Report prepared for URS Australia Pty Ltd Level 3 116 Miller Street North Sydney, NSW 2060. Report Number 23/0304 B. Final, 8 October 2004. URS (2002) Draft Report. Review of contamination issues associated with the Prot Botany Expansion. Prepared for Sydney Ports Corporation 16 December 2002. S:43027/012/DRAFT Report URS (2004a). Final report. HCB and Mercury in sediment and biota, Penrhyn Estuary, NSW. August 2004. Prepared for Orica Australia Pty Ltd, 1 Nicholson Street, Melbourne, VIC 3000. 46160/0005/2801. URS (2004b). Final Report. Orica Botany Environmental Survey Stage 4 – Remediation. Groundwater Cleanup Plan (GCP) Quarterly Groundwater and Surface Water Monitoring Report – June 2004. Prepared for Orica Australia Pty Ltd. 1 Nicholson Street Melbourne Vic 3000. 19 August 2004. 43346038.4301/R018_A. Woodward-Clyde (1996). ICI Botany Groundwater Stage 2. Contract S2/C6 Overview Report. Prepared for ICI Australia Engineering Pty Ltd. August 1996, Project No 3393, Document 3393R1-E. Worthington D.G., Westoby M. & Bell J.D. (1991) Fish larvae settling in seagrass: effects of leaf density and an epiphytic alga. Aust. J. Ecol. 16, 289-293. Worthington D.G., Ferrell D.J., McNeill S.E. & Bell J.D. (1992a) Effects of the shoot density of seagrass on fish and decapods: are correlations evident over larger spatial scales? Mar. Biol. 112, 139-146. Worthington D.G., Ferrell D.J., McNeill S.E. & Bell J.D. (1992b) Growth of four species of juvenile fish associated with seagrass Zostera capricorni in Botany Bay, New South Wales. Aust. J. Mar. Freshwater Res. 34, 1189-1198. Worthington D.G., McNeill S.E., Ferrell, D.J. & Bell J.D. (1995) Large scale variation in abundance of five common species of decapod sampled from seagrass in New South Wales. Aust. J. Ecol. 20, 515-525.
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FIGURE Figure 1: Aerial photograph of Penrhyn Estuary (April 2001) showing locations of extraction bores (Line 2 an d Line 3) along Foreshore Road, locations of intertidal sampling sites (oranges dots), subtidal sampling sites (red dots) and seagrass beds (The Ecology Lab 2003).
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Fo re I8 sh or I7 e Ro ad I9 Fo res ho re Be ac h
Derelict Groyne Floodvale Drain and Jetty I11
I12 I13 Bores Intertidal Sampling Sites Springvale Subtidal Sampling Sites I10 I14 Drain Seagrass Beds Inner Estuary S1 S3 S5 Outer Estuary S2 0 100 200 I15 Old Boat Ramp S4 metres S6
New Boat Ramp
Figure 1: Aerial photograph of Penrhyn Estuary (April 2001) showing locations of extraction bores (Line 2 and Line 3) along Foreshore Road, locations of intertidal sampling sites (orange dots), subtidal sampling sites (red dots) and seagrass beds (The Ecology Lab 2003). The Ecology Lab Pty Ltd - Marine and Freshwater Studies BOTANY GROUNDWATER CLEANUP PROJECT
Significant Flora and Fauna Species
To identify flora and fauna species which could potentially occur within the vicinity of the study area a review of relevant information databases and previous relevant studies was carried out. The study area was limited to those areas that could be impacted upon as a result of the BGC Project. The following databases and studies were reviewed:
• Department of Environment and Heritage National List of Threatened Fauna;
• Department of Environment and Heritage National List of Threatened Flora;
• NSW Scientific Committee Threatened Species Conservation Act Schedules 1, 2 and 3 (updated to 24th September, 2004);
• the Proposed Third Runway Sydney (Kingsford Smith) Airport Draft EIS (Kinhill 1990);
• the Botany Bay City Council State of the Environment Report (2000)
• Patrick Port Botany Container Terminal Upgrade EIS (PPK 2002)
• the Port Botany Expansion EIS (URS, 2003).
Table 1 lists all the flora species identified and discusses the likelihood of them occurring within the vicinity of the study area.
Table 1Significant Flora Species Recorded in the Vicinity of the Study Area
Species Conservation Habitat Requirements Likelihood Of Occurrence Status* And Comments
Acacia bynoeana E1 V2 Heath and woodland on sandy soils Low Bynoe’s wattle Habitat not present within study area. No recent records of the species in the vicinity of the study area. Acacia gordonii E1, 2 Dry heath in eucalypt woodland, usually Low in shallow sandy soil amongst Habitat not present within study sandstone outcrops area. No recent records of the species in the vicinity of the study area. Acacia terminalis subsp. E1, 2 Scrub and dry sclerophyll woodland on Low Terminalis sandy soil Species was not recorded within the study area during the present study and is unlikely to recruit within the study area from local seed sources. Species Conservation Habitat Requirements Likelihood Of Occurrence Status* And Comments
Acacia pubescens V1, 2 Open forest on clay soils Low downy wattle Habitat not present within study area. Eucalyptus pulverulenta V 1, 2 Mallee Low silver-leaved mountain Low likelihood of occurrence. gum Habitat not present within study area. Caladenia tessellata V 1, 2 Low open forest with a heathy or Low thick-lipped spider sometimes grassy understorey, in Habitat not present within study orchid, daddy long legs sheltered moist places in forest and area. No recent records of the scrub particularly on stony laterites on species in the vicinity of the study coastal tops area. Tetratheca juncea V 1 Ridgetops on southeast to southwest Low aspects on Munmorah Conglomerate Species not recorded within study geology and Awaba Soil Landscape area during present study. This Unit and is found growing in dense species is considered regionally undisturbed understorey vegetation extinct in Sydney. beneath an open forest dominated by E. capitellata, A. costata- C. gummifera (Payne 1998) Cryptostylis hunteriana V1, 2 Sandstone soils Low leafless tongue-orchid Species occurs from the Ku-ring-gai area and recently from near Campbelltown. Prostanthera densa V1, 2 Heath and sea coasts on sandstone Low. villous mintbush Occurs from Cronulla south to the Royal National Park. Pterostylis sp E1, 2 Coastal scrub Low Botany Bay bearded No recent records of the species in greenhood the vicinity of the study area. Thesium australe V1, 2 Grasslands, grassy woodlands or sub- Low austral toadflax alpine grassy heathlands Habitat not present within study area. No recent records of the species in the vicinity of the study area. * Conservation Status is as follows: E = Endangered V = Vulnerable
where 1 = listing under TSC Act 1995 2 = listing EPBC Act 1999.
Table 2 lists all the fauna species identified and discusses the likelihood of them occurring within the vicinity of the study area.
2 Table 2Significant Fauna Species Recorded in the Vicinity of the Study Area
SPECIES HABITAT REQUIREMENTS LIKELIHOOD OF OCCURRENCE AND COMMENTS STATUS * CONSERVATION
Threatened Fauna
Frogs
Crinia tinnula V1 Confined to acid, paperbark swamps Low wallum froglet of the ‘wallum’ country Suitable habitat not present in study area. Heleioporus V1, 2 Burrows in banks of small creeks Low australiacus Suitable habitat not present in study area. giant burrowing frog Litoria aurea E1 V2 Aquatic, found among vegetation Low green and golden bell within or at the edges of permanent Suitable habitat not present in study area. frog water – streams, swamps, lagoons, Although there is one record of L.aurea near farm dams and ornamental ponds. ponds on Southlands, the GTP and pipeline Often found under debris on low, oft – sites do not provide suitable habitat. flooded river flats Litoria littlejohni V1, 2 Undisturbed woodland and heath Low Littlejohn’s tree frog, communities at mid to high altitude. Suitable habitat not present in study area. heath frog Shelters and feeds along permanent mountain streams with low water velocity. Also occurs near semi- permanent dams with some emergent vegetation. Shelters under rocks on high, exposed ridges during summer. It is not known from coastal habitats.
Birds Actitis hypoleucos M, J, C Steep-sided muddy or rocky margins Moderate common sandpiper of various waterbodies, whether Occurs most years in very low numbers in saline, fresh or brackish. In coastal Botany Bay and presently roosts on a wooden sites it is typically found on the jetty at Shell Point. The last sighting of the margins of salt or brackish species at Penrhyn Estuary was a single watercourses, tending to occur in the sighting recorded by the NSW Wader Study upper rather than the lower parts of Group in 1994. estuaries Anseranas V1, M Rush and sedge-dominated swamps, Low semipalmata floodplains Suitable habitat not present in study area. No magpie goose recent records in the area. Arenaria interpres M, J, C Occur mainly on rocky coasts, Moderate Ruddy Turnstone sometimes on ocean beaches, seldom Presently feeds and roosts on rock platforms at on estuarine mudflats. In northern Boat Harbour and also roosts on wooden Australia, prefer coasts with wide barges at Shell Point. This species is seldom intertidal mudflats seen on estuarine mudflats although may occasionally forage at Penrhyn Estuary. More often on rocky platforms and ocean beaches. Botaurus poiciloptilus V1 Dense reedbeds and swamps feeding Low australasian bittern on small fish and other aquatic life, Suitable habitat not present in study area. No sometimes in rice fields recent records in the area. Burhinus grallarius E1 Lightly timbered, open forest or Low bush stone-curlew woodlands associated with Suitable habitat not present in study area. casuarinas, eucalypts and acacias or epolycarpa. Dry, open grassland or cropland with cover nearby
3 SPECIES HABITAT REQUIREMENTS LIKELIHOOD OF OCCURRENCE AND COMMENTS STATUS * CONSERVATION
Cacatua leadbeateri V1 Mallee, mulga, Murray Pine and Low Major Mitchell's casuarina associations Suitable habitat not present in study area. cockatoo Calamanthus V1 Saltmarsh where there are sedges Low fuliginosus and reeds present No recent records in the area. striated fieldwren Calidris acuminata M, J, C Saltmarsh and intertidal mudflats but High sharp-tailed sandpiper seem to prefer non-tidal wetlands, Typically feeds and roosts in saltmarsh at the especially freshly exposed mudflats Barton Park (Eve Street) wetland and may around drying lakes and swamps. May occasionally forage and roost in the upper be found over a wide range of reaches of Penrhyn Estuary in mudflats and salinities, from freshwater wetlands saltmarsh. Has been recorded at Penrhyn through to hypersaline inland lakes. Estuary in 1995, 1996 (68 individuals) and Generally roost and often feed 1997 (32 individuals). amongst low vegetation. Occasionally visit mangroves, beaches and rocky shores Calidris alba V1,M, J, Sandy ocean beaches, where they High sanderling C feed in the wave washed zone at low Occasionally seen in Botany Bay. Typically tide. At high tide roost on beaches or feeds in the wave zone of ocean beaches at on nearby rocky reefs. Favour Boat Harbour and will generally flee to the beaches near estuaries rather than northern shores of the bay (Penrhyn long stretches of uninterrupted beach. Estuary).during rough weather for shelter and Sometimes roost or shelter in feeding. estuaries but seldom feed there Calidris canutus M, J, C Forage on intertidal sand and mudflats High red knot in estuaries. Usually roost at high tide Presently feeds on intertidal sand and mudflats on beaches and other open sites at Penrhyn Estuary and at Rocky Point and roosts at Penrhyn Estuary (typically in association with Godwits). Six individuals of the species have been recorded feeding at Woolooware Shorebird Lagoon on the southern shores of the Bay on bivalve molluscs (pers. com., Phil Straw). Up to about 200 individuals of the species may be present in the Bay in present times. Calidris ferruginea M, J, C Forage on intertidal sand and mudflats High curlew sandpiper in estuaries. At high tide roost on Presently feeds and roosts at Penrhyn Estuary beaches or rock platforms, or continue on intertidal mudflats (feeding) and sandflats at to feed in saltmarshes and the mouth of the estuary and on the north side backwaters. Frequent muddy margins of the channel (roosts). of shallow inland wetlands Calidris ruficollis M, J, C Most numerous on intertidal sand and High red-necked stint mudflats in estuaries. Frequent Presently feeds and roosts at Penrhyn Estuary saltmarsh, ocean beaches and rocky and occasionally at Boat Harbour and Spit shores. Inland, they are most Island. The species also roosts on barges at numerous on the muddy margins of Shell Point which demonstrates the general saline lakes, although they often occur lack of adequate high tide roosts for shorebirds at freshwater wetlands as well utilising the Bay. Straw (1996) notes that the birds roosting at Boat Harbour are likely a result of the displacement of these birds from Penrhyn Estuary due to disturbance in the area.
4 SPECIES HABITAT REQUIREMENTS LIKELIHOOD OF OCCURRENCE AND COMMENTS STATUS * CONSERVATION
Calidris tenuirostris V1, M, Forage on intertidal sand and mudflats High great knot J, C in estuaries. Usually roost at high tide Occasionally recorded feeding on mudflats at on beaches and other open sites Penrhyn Estuary, particularly since it was displaced from its preferred habitat at the former Pilots Embayment which was lost due to the Parallel Runway construction. Calyptorhynchus V1 Eucalypt forest and woodland. Feeds Low lathami almost exclusively on casuarina fruit Suitable habitat not present in study area. No glossy black-cockatoo recent records in the area. Charadrius bicinctus M Mainly found on intertidal sand and High double-banded plover mudflats in estuaries, often preferring Presently feeds on intertidal sand flats at sites near saltmarsh or other low, Penrhyn Estuary. The species also roosts at moist vegetation, where the birds roost Penrhyn Estuary, Boat Harbour and reportedly, and feed at high tide. Also feed and at present, Molineux Point and on the end of roost on ocean beaches and rocky the parallel runway. This species is thus quite shores. Inland, they inhabit the vulnerable to disturbance due to fishermen, margins of both saline and freshwater dogs and beach walkers given its key habitat wetlands at Penrhyn Estuary and Boat Harbour. This species used to feed at the former stockpile site and northern sections of Foreshore Beach which were both lost due to the parallel runway construction and have thus experienced a critical decline in their Bay habitat. Based on counts since the 1970s, Botany Bay is one of the three most important estuaries for the species in NSW (along with the Hunter and Shoalhaven Rivers). Charadrius V1, M, Forages on intertidal sand and High leschenaultii J, C mudflats in estuaries, and roosting Occasional visitor to Penrhyn Estuary and Boat greater sand plover during high tide on sand beaches or Harbour (often in association with the Lesser rocky shores Sand Plover) where it feeds on intertidal sand flats. Only one or two individuals are recorded in the Bay on an occasional basis (this is significant given the NSW estimated population for this species is only 80 birds with the majority occurring in the Clarence and Richmond estuaries). Charadrius mongolus V1, M J, Feed on intertidal sand and mudflats High lesser sand plover C in estuaries, roosting on sandy Roosts every year on intertidal sand flats at beaches or rocky shores at high tide, Boat Harbour (up to about 10 individuals) and and sometimes feeding at these sites feeds at Penrhyn Estuary and possibly elsewhere in the Bay. Dasyornis brachypterus E1, 2 Dense coastal and mountain heaths, Low eastern bristlebird taller swamps and stream thickets Suitable habitat not present in study area. No recent records in the area. Diomedea E2, M, Oceanic and coastal seas Low amsterdamensis Suitable habitat not present in study area. Amsterdam albatross Diomedea antipodensis V2, M, Oceanic and coastal seas Low Antipodean Albatross Suitable habitat not present in study area. Diomedea dabbena E2, M Oceanic and coastal seas Low Tristan Albatross Suitable habitat not present in study area. Diomedea exulans E1, 2, M Oceanic and coastal seas Low wandering albatross Suitable habitat not present in study area. No recent records in the area.
5 SPECIES HABITAT REQUIREMENTS LIKELIHOOD OF OCCURRENCE AND COMMENTS STATUS * CONSERVATION
Diomedea gibsoni V1, 2, M Oceanic and coastal seas Low Gibson’s albatross Suitable habitat not present in study area. Gallinago hardwickii M, J, C Wet grasslands; open, wooded Low Latham’s snipe swamps Suitable habitat not present in study area. Gygis alba V1 Oceanic and breeds on islands Low white tern Suitable habitat not present in study area. No recent records in the area. Haematopus V1 Rocky coasts within 50 m of the Low fuliginosus shoreline. Breeds on islands Suitable habitat not present in study area. Sooty Oystercatcher Haematopus V1 Favours ocean beaches and estuarine High longirostris sand and mudflats Presently occurs in relatively large numbers pied oystercatcher (up to 60 individuals) at Sandringham Bay where it feeds and roosts and at Penrhyn Estuary where it feeds on intertidal sandflats. Presently five or six pairs nest at Woolooware Shorebird Lagoon, Towra Spit Island and at the airport. The volume of pedestrian traffic and shoreline steepness of Foreshore Beach would be expected to preclude the use of this area by the species for its life cycle requirements, particularly nesting activity. Haliaeetus leucogaster M, C Large rivers, fresh and saline lakes, Low white-bellied sea-eagle reservoirs, estuaries, coastal seas, Suitable habitat not present in study area. and islands Hirundapus caudacutus M, C Aerial, mainly in E. Australia; often Low white-throated associated with coastal and mountain Suitable habitat not present in study area. needletail regions Lathamus discolor E1, 2 Dry open forests, woodlands and Low swift parrot gardens Suitable habitat not present in study area. No recent records in the area. Limicola falcinellus V1, M, Favour intertidal sand and mudflats in Moderate broad-billed sandpiper J, C estuaries Up to 17 individuals of this species were recorded on the northern shores of Botany Bay in 1953 (Straw 1996) and mostly single individuals have been recorded in the Bay on an occasional basis since the mid-1970’s (northern shoreline). This species may occasionally feed and roost at Penrhyn Estuary. Limosa lapponica M, J, C Intertidal sand and mudflats in High bar-tailed godwit estuaries. Also forage at times in Presently feeds on intertidal sandflats at saltmarsh, mangroves and ocean Penrhyn Estuary and at Rocky Point in the Bay beaches. Usually roost at high tide on and roosts on beaches at Penrhyn Estuary and beaches and other open sites Sandringham Bay. Limosa limosa M, J, C Forages on intertidal sand and Moderate black-tailed godwit mudflats in estuaries, roosting at high Feeds on intertidal mudflats and on muddy tide in a variety of open sites. Also margins of wetlands. Occurs in very small occurs on the muddy margins of inland numbers (one or two individuals) in the wetlands Parramatta River Estuary at Homebush Bay and may occasionally forage and roost at Penrhyn Estuary although no recent sightings of this species have been recorded at Botany in recent years.
6 SPECIES HABITAT REQUIREMENTS LIKELIHOOD OF OCCURRENCE AND COMMENTS STATUS * CONSERVATION
Macronectes giganteus E1, 2, M Oceans and bays Low southern giant-petrel Suitable habitat not present in study area. No recent records in the area. Macronectes halli V2, M, Oceans and bays Low northern giant-petrel P Suitable habitat not present in study area. Monarcha melanopsis M Forests Low black-faced monarch Suitable habitat not present in study area. Myiagra cyanoleuca M Tall and medium open forests Low satin flycatcher Suitable habitat not present in study area. Neochmia ruficauda E1, 2 Tall grass beside swamps and rivers Low star finch Suitable habitat not present in study area. No recent records in the area. Ninox strenua V1 Tall open forests Low powerful owl Suitable habitat not present in study area. Numenius M, J, C Intertidal sand and mudflats in Moderate madagascariensis estuaries, particularly where there are Presently feeds over much of the intertidal eastern curlew extensive seagrass beds and stands mudflats of the southern parts of the Bay, of mangroves. Usually roosts at high including Woolooware, Quibray, Weeney and tide on beaches or in saltmarshes Stinkpot Bays and Towra Point. Preferred roost sites on the southern shores of the Bay include sand spits and shoals and wooden poles of oyster leases. The species does not normally use the northern shoreline of the Bay to feed or roost, but may do so on occasion. Numenius phaepus M, J, C Typically forages on intertidal mudflats Moderate whimbrel near mangroves or along the banks of Presently feeds on exposed mudflats near and tidal creeks and rivers. They also often under mangrove trees at Towra Point Aquatic forage on intertidal rock shelves. Reserve and roosts in mangrove trees at Roost in mangroves or other shoreline Woolooware, Weeney and Stinkpot Bays. This trees, or on beaches or rocky shores species may occasionally feed at Penrhyn Estuary. Oxyura australis V1, M Permanent freshwater swamps, lakes, Low blue billed duck dams and larger rivers, usually with a Suitable habitat not present in study area. cover of dense vegetation Pandion haliaetus V1, M Fishes in fresh, brackish or salt water. Low osprey Sometimes seen inland although Suitable habitat not present in study area. No breeding usually confined to the coast recent records in the area. or islands Phipidura rufifrons M Wet forests, occasionally more open Low rufous fantail forests Suitable habitat not present in study area.
7 SPECIES HABITAT REQUIREMENTS LIKELIHOOD OF OCCURRENCE AND COMMENTS STATUS * CONSERVATION
Pluvialis fulva M, J, C Occurs mainly on estuarine sand and High Pacific golden plover mudflats and nearby saltmarsh and Regularly feeds on intertidal mudflats at short, moist pasture. Typically roost at Penrhyn Estuary and roosts in saltmarsh at high tide in saltmarsh and pasture, Penrhyn and on wooden barges at Shell Point and often feed in these areas as well. (up to six birds use the barges on the southern At some sites they feed on rocky side). Straw (1996) notes that a small number intertidal areas, roosting at high tide of birds also feed and roost at Boat Harbour on sandy beaches or rocks. which may be the result of disturbance to the Occasionally they visit coastal birds at Penrhyn Estuary. Key feeding habitat freshwater wetlands of the species at the mouth of the Mill Stream and Runway Beach have been lost due to the Parallel Runway construction and may explain, in part, the marked decline in numbers of this species in the Bay since the mid-1980’s. The erosion of intertidal sands off Towra Beach and increased 4WD usage of the Boat Harbour area may similarly explain the marked decline in usage of the southern part of the Bay by the species.
Pluvialis squatarola M, J, C Forages on intertidal sand and High grey plover mudflats, and roosting at high tide Occasionally recorded feeding on intertidal usually on beaches sand and mudflats at Penrhyn Estuary, Quibray Bay and west of Taren Point. One known roost of the species in the Bay is on the sandy points on either side of the channel at Penrhyn Estuary. The species was historically recorded from the original mouth of the Cooks River.
Polytelis swainsonii V1, 2 Riverine and floodplain open forest Low superb parrot and woodlands, particularly River Red Suitable habitat not present in study area. Gum Procelsterna cerulea V1 Oceanic and breeds on islands Low grey ternlet Suitable habitat not present in study area. No recent records in the area. Pterodroma leucoptera E1, 2, M Oceanic Low leucoptera Suitable habitat not present in study area. Gould’s petrel Pterodroma neglecta V1, 2 Oceanic Low neglecta Suitable habitat not present in study area. No Kermadec petrel recent records in the area. (western) Pterodroma nigripennis V1 Oceanic Low black-winged petrel Suitable habitat not present in study area. No recent records in the area. Pterodroma solandri V1 Oceanic Low providence petrel Suitable habitat not present in study area. No recent records in the area. Ptilinopus superbus V1 Rainforest, but will feed in adjacent Low superb fruit-dove mangroves or eucalypt forest Suitable habitat not present in study area. Puffinus assimilis V1 Oceanic and breeds on islands Low little shearwater Suitable habitat not present in study area. No recent records in the area.
8 SPECIES HABITAT REQUIREMENTS LIKELIHOOD OF OCCURRENCE AND COMMENTS STATUS * CONSERVATION
Puffinus carneipes V1, M, J Oceanic and breeds on islands Low flesh-footed shearwater Suitable habitat not present in study area. No recent records in the area. Rostratula M, C Marsh with moderate cover Low benghalensis Suitable habitat not present in study area. painted snipe Stagonopleura guttata V1 Woodland and forest with shrubby Low Diamond Firetail understorey for breeding Suitable habitat not present in study area. No recent records in the area. Sterna albifrons E1, M, Nest only on or near the coast of Moderate little tern J, C NSW, although in other parts of the Forages at the mouth of Penrhyn Estuary for world they may be found nesting small fish and also roosts at the Estuary. This beside rivers and lakes far from the species has successfully nested in recent sea. Some breeding sites in NSW are years on Towra Spit Island but was within estuaries or harbours. Other unsuccessful in the 2001/02 season due to the nesting sites are in dunes behind presence of foxes (pers. comm., Geoff Ross). ocean beaches, but most are on sand The species aborted nesting on Towra Spit in spits or sand islands where rivers, 2001/02 and fled to Molineux Point to nest. creeks or lakes enter the sea NPWS note that upwards of 60 pairs of the bird nested on Spit island during the past 10 years (pers. comm., Geoff Ross). The species returned to Towra Spit in 2002/03 for nesting and had a successful breeding season. Sterna fuscata V1 Oceanic and breeds on islands Low sooty tern Suitable habitat not present in study area. No recent records in the area. Thalassarche bulleri V2, M, Oceanic and coastal seas Low Buller’s albatross P Suitable habitat not present in study area. Thalassarche cauta V1, 2, M Oceanic and coastal seas Low shy albatross Suitable habitat not present in study area. No recent records in the area. Thalassarche impavida V2, M Oceanic and coastal seas Low campbell albatross Suitable habitat not present in study area. Thalassarche V1 M Oceanic and coastal seas Low melanophris Suitable habitat not present in study area. No black-browned lbatross recent records in the area. Thalassarche salvini V2, M Oceanic and coastal seas Low Salvin’s albatross Suitable habitat not present in study area. Thalassarche steadi V2, M Oceanic and coastal seas Low white-capped albatross Suitable habitat not present in study area. Tringa brevipes M, J, C Typically found in estuaries with Moderate grey-tailed tattler extensive mangroves and intertidal Presently feeds on exposed mudflats on the mudflats, although it also inhabits southern part of the Bay and has been rocky shores along the coast. Often recorded resting at a number of locations roosts in mangroves at high tide, or on including the groynes at Kurnell, the old rocky rocks in preference to beaches wharf at the mouth of Quibray Bay, in mature spreading mangroves and on platforms in mangroves at Quibray Bay. May occasionally feed in small numbers at Penrhyn Estuary.
9 SPECIES HABITAT REQUIREMENTS LIKELIHOOD OF OCCURRENCE AND COMMENTS STATUS * CONSERVATION
Tringa nebularia M, J, C Occur in all types of wetlands. Usually Moderate common greenshank found beside shallow waters generally Recorded on the mangrove lined shores of either saline, brackish or fresh, Woolooware Bay and used to favour the pond including intertidal sand and mudflats, at the Woolooware Shorebird lagoon site (H1 saltmarsh, mangroves and freshwater site). May be an occasional visitor to Penrhyn wetlands Estuary. Tringa stagnatilis M, J, C Saline or freshwater wetlands, both Moderate marsh sandpiper coastal and inland. Common on Presently feeds and roosts in the Hawkesbury intertidal mudflats in northern Swamps and at the waterbird refuge at Australia. Typical of pools in Homebush and Newington Wetlands in the saltmarshes. Often occurs at artificial Parramatta River Estuary in relatively low wetlands such as sewage treatment numbers (up to 17 birds have been recorded in works and saltworks the Hawkesbury Swamps). No recent records exist for this species in the Bay. One historical record for this species in the Bay was identified (in 1983 at the old mouth of the Cooks River). This species may feed on estuarine mudflats at Penrhyn on an occasional basis. Tyto novaehollandiae V1, 2 Forests, woodlands and caves Low masked owl Suitable habitat not present in study area. No recent records in the area. Xanthomyza phrygia E1, 2, M Woodland and open forest. Low regent honeyeater Uncommon, nomadic Suitable habitat not present in study area. Xenus cinereus V1, M, Forages on intertidal sand mudflats, Moderate terek sandpiper J, C often near mangroves or in tidal Presently feeds on intertidal mudflats between creeks. Occasionally forages on sandy Taren Point and Woolooware Bay on the ocean beach or rocky shores. southern shores of the Bay and roosts on a Typically roosts on or among disused jetty at Shell Point. This species may mangroves, but also on open beaches occasionally forage at Penrhyn Estuary (although no recent records exist of this species on the northern shores of the Bay). Mammals Chalinolobus dwyeri V1, 2 Dry sclerophyll forests and woodlands, Low large-eared pied bat sub-alpine woodland, rainforest and Suitable habitat not present in study area. moist eucalypt forests. Roosts in caves, mine tunnels and the abandoned mud nests of Fairy Martins Dasyurus maculatus V1, 2 Rainforest, open forest, woodland, Low spotted-tail quoll coastal heathland and inland riparian Suitable habitat not present in study area. forest Dasyurus viverrinus V1 Dry sclerophyll forest, scrub, Low eastern quoll heathland and cultivated lands Suitable habitat not present in study area. No recent records in the area. Miniopterus schreibersii V 1 Forages in tall open eucalypt forests, Low common bentwing-bat dry sclerophyll forest, woodland, wet May forage in Botany Bay whilst in transit sclerophyll forest, rainforest, between foraging and roosting sites. Melaleuca swamps and over grasslands and roost in caves and mines Myotis adversus V 1 Forages for insects over streams and Low large-footed myotis pools in mangroves, paperbark May forage in Botany Bay whilst in transit swamps, rainforest, wet and dry between foraging and roosting sites. sclerophyll forest and open woodland. Known to roost in caves, tree hollows, under bridges, in mines, tunnels and stormwater drains
10 SPECIES HABITAT REQUIREMENTS LIKELIHOOD OF OCCURRENCE AND COMMENTS STATUS * CONSERVATION
Petrogale penicillata V1, 2 Rocky areas in rainforest gullies, wet Low brush-tailed rock- and dry sclerophyll forest, open Suitable habitat not present in study area. wallaby woodland and rocky outcrops in semi- arid country. Sites with ledges, caves and crevices are favoured Potorous tridactylus V1, 2 Coastal heath and dry and wet Low long-nosed potoroo sclerophyll forests in areas with Suitable habitat not present in study area. relatively thick groundcover and an annual rainfall greater than 760 mm Pteropus poliocephalus V 1, 2 Canopy feeding frugivore, blossom Low grey headed flying fox eater and nectarivore of rainforests, May forage in Botany Bay whilst in transit open forests, woodland, Melaleuca between foraging and roosting sites. swamps and Banksia woodlands. Roosts in rainforest patches, Melaleuca stands, mangroves and riparian woodland or modified vegetation in urban areas Saccolaimus V 1 Forages for insects above the canopy Low flaviventris in a wide range of habitats including May forage in Botany Bay whilst in transit yellow-bellied rainforests, sclerophyll forests and between foraging and roosting sites. sheathtail-bat woodlands. Roosts in tree hollows, abandoned nests of sugar gliders or in buildings. Known to travel from roost trees to favoured foraging areas Reptiles Hoplocephalus E1 V2 Forest growing on shale adjacent to Low bungaroides conglomerate slopes and bluffs Suitable habitat not present in study area. broad-headed snake
Regionally Rare Species Perameles nasuta P A variety of habitats from rainforest to Low long-nosed bandicoot wet and dry woodlands to heathland The species is relatively common and widespread throughout NSW, however, the species is considered locally rare due to urban encroachment of their habitat. A population in Sydney Harbour National Park at Manly (North Head) has been listed as endangered under the TSC Act. Parsons Brinckerhoff (2002) reported the presence of “bandicoot footprints” in planted trees and shrubs along Penrhyn Road as part of an environmental assessment for the proposed expansion of the Patrick Stevedores terminal to the east of the study area. No direct (sightings, road kills) or indirect (conical hole diggings, tracks) evidence of bandicoots within the study area was recorded by URS during the present study. The likelihood of occurrence of a species or viable population of bandicoot (presumably a Long nosed Bandicoot) within the study area is considered to be low given the small size, isolation and disturbance of the planted shrubland as well as the regular presence of predators such as cats, dogs and to a lesser extent, foxes. Heavy vehicular traffic along Penrhyn Road would also limit the chances of survival of any individuals should
11 SPECIES HABITAT REQUIREMENTS LIKELIHOOD OF OCCURRENCE AND COMMENTS STATUS * CONSERVATION
the species be present. * Conservation Status is as follows: E = Endangered V = Vulnerable where 1 = listing under TSC Act 1995 2 = listing EPBC Act 1999 Act. M = Listed as Migratory under EPBC Act P = Protected under NSW National Parks and Wildlife Act 1974 J = Listed under JAMBA agreement C = Listed under CAMBA agreement.
12 Section 5A Assessment (8 Part Test)
Litoria aurea (Green and Golden Bell Frog)
Prepared by: Dr Gillian J. Eckert BSc(HonsI) U Qld, PhD (Zoology) U Syd.
(a) in the case of a threatened species, whether the life cycle of the species is likely to be disrupted such that a viable local population of the species is likely to be placed at risk of extinction. The green and golden bell frog was once widespread and abundant along the NSW coast and inland to Bathurst and the ACT (White and Pyke, 1996; NPWS, 1999). It was known to have a large population centre in the suburbs of Botany, Eastlakes, Mascot and La Perouse (White and Pyke, 1996). The species was widespread throughout Botany Swamps, including Veteran’s Swamp, which was drained and filled and is now known as Southlands (part of the project area). Since the mid-1800s, Southlands has been variously used for tanneries, peat cutting and dumping boiler ash and paper pulp. The site, which contains several man-made ponds, is now fenced off and is dominated by exotic weeds. Since the 1960’s, the distribution of the species has declined and it now occurs only in isolated pockets within its former range (Pyke and White, 1996). Remnants of the Botany Swamps population have been located, since 1990, at Eastlakes Golf Course and Roseberry (White and Pyke, 1996). There has been one unconfirmed record, in 1992, of the species in Springvale Drain which runs through Southlands (R.Evans, Orica, pers.comm). A survey on Southlands in autumn 1997 located 5 juvenile green and golden bell frogs in an ephemeral puddle on Block 2 (White, 1997). However, further intensive surveys carried out on the same site during warmer weather failed to locate any individuals of the species. White (1997) concluded that ‘ it can be confidently concluded that there are no permanent colonies of these frogs on Southlands.” There is therefore no evidence of a viable local population on Southlands. The ponds on Southlands are filled with a mix of rainwater and contaminated groundwater and also contain the exotic mosquito fish, Gambusia holbrooki, a known predator of frog eggs and tadpoles; particularly of tree frogs. White (1997) considers that the presence of the mosquito fish is a key reason for the Green and Golden bell frog not residing permanently on Southlands. The project involves building a Groundwater Treatment Plant (GTP), extraction wells and pipelines. The GTP will be built on Orica land on the BIP, adjacent to Southlands. This land is paved with asphalt and does not provide appropriate habitat for the species. Pipelines on Southlands will be installed above ground and none of the existing ponds will be affected. Groundwater extraction will have the effect of stopping bases flows of groundwater in drains during dry weather. On Southlands, the water level in existing ponds may fall and the land will become less boggy due to removal of groundwater. Since there is no permanent population of green and golden bell frogs on Southlands, this will have only a minor impact. Pipelines and extraction wells outside Southlands are underground within road reserves, railways and industrial land. These areas are not considered to provide habitat for green and golden bell frogs. It is considered that the proposal does not place a viable local population at risk of extinction. (b) in the case of an endangered population, whether the life cycle of the species that constitutes the endangered population is likely to be disrupted such that the viability of the population is likely to be significantly compromised. Not Applicable (c) in relation to the regional distribution of the habitat of a threatened species, population or ecological community, whether a significant area of known habitat is to be modified or removed. The proposal will result in a minor modification of potential feeding habitat and migration route on Southlands through installation of underground wells pipelines on concrete racks. This disturbance will be temporary (during construction) and the installed infrastructure will not impede movement of frogs. (d) whether an area of known habitat is likely to become isolated from currently interconnecting or proximate areas of habitat for a threatened species, population or ecological community The pipeline will be installed above ground on piperacks and will not impede movement of frogs. The extraction wells will be covered and level with the ground surface. Therefore the proposal will not cause any area of habitat to become isolated. (e) whether critical habitat will be affected. The study area is not listed as critical habitat under Part 3 Division 1 of the Threatened Species Conservation Act 1995. (f) whether a threatened species, population or ecological community, or their habitats, are adequately represented in conservation reserves (or other similar protected areas) in the region. The green and golden bell frog is not adequately represented in the Sydney Region. It has been recorded in Towra Point Nature Reserve and Botany Bay National Park on the southern side of Botany Bay. (g) whether the development or activity proposed is of a class of development or activity that is recognised as a threatening process. Not Applicable (h) whether any threatened species, populations or ecological community is at the limit of its known distribution Although its range has been reduced since the 1960s, the species has been recorded since 1990 at locations from as far north as Byron Bay and south to Gippsland with several populations between Newcastle and Nowra. It is thus not considered to be at its limit of distribution at Botany.
Section 5A Assessment Conclusion The proposed development of the Botany Groundwater Cleanup Project is not considered likely to significantly affect the threatened green and golden bell frog (Litoria aurea).
References
Threatened Species Information : Green and Golden Bell Frog (Litoria aurea) (Lesson, 1829). NPWS, Sept. 1999.
Pyke, G and White, A. 1996. Habitat Requirements for the Green and Golden Bell Frog Litoria aurea (Anura:Hylidae). 1996 Australian Zoologist 30(2): 224- 232.
White,A. 1997 Vertebrate Fauna of ICI Southlands, Botany, New South Wales 1996-1997. Report by Biosphere Environmental Consultants Pty Ltd for ICI Australia Engineering Pty Ltd October 1997.
White,A and Pyke,G 1996 Distribution and conservation status of the Green and Golden Bell Frog Litorea aurea in New South Wales. 1996 Australian Zoologist 30(2):177-189.
Section 5A Assessments
Section 5A Assessments
The table shown below, lists the eight species of resident and migratory shorebirds and seabirds listed under the TSC Act that are known to occur or have been previously recorded at Penrhyn Estuary and thus have been assessed under Section 5A of the NSW Environmental Planning and Assessment Act 1979 in relation to the Groundwater Interception. Shorebird and Seabird Species Known to Occur and Previously Recorded at Penrhyn Estuary requiring TSC (Section 5A Assessment) Consideration
TSC Act Migratory/non JAMBA CAMBA Bonn (E=Endangered migratory V=Vulnerable) Species listed under EPBC Act Species Scolopacidae Sanderling V XX X X Calidris alba Great Knot V X X XX Calidris tenuirostris Black-tailed Godwit VXXXX Limosa limosa Broad-billed Sandpiper V X X XX Limicola falcinellus Terek Sandpiper V X X XX Xenus cinereus Pied Oystercatcher V---- Haematopus longirostris Charadriidae Greater Sand Plover V X X XX Charadrius leschenaultii Lesser Sand Plover V X X XX Charadrius mongolus Laridae Little Tern E X X XX Sterna albifrons * non migratory species ** trans Tasman migrant
1 Section 5A Assessments
Section 5A Assessments (8 Part Tests)
Calidris alba (Sanderling) (a) in the case of a threatened species, whether the life cycle of the species is likely to be disrupted such that a viable local population of the species is likely to be placed at risk of extinction. Single birds of this species are occasionally seen in Botany Bay estuary. This species typically feeds in the wave zone of ocean beaches at Boat Harbour and will generally flee to the northern shores of the Bay during rough weather for shelter and feeding (Penrhyn Estuary). Straw (1996) notes that in the 1940s and 1950s the species was regularly present in summer at Boat Harbour, in numbers of up to 15 or more, with counts post 1970 revealing no more than one or two individuals. Remaining areas of Botany Beach and the southern shores of the Bay (with the exception of Spit Island) have not become significant feeding areas for the species given the level of human disturbance (recreational fishers, dog walking) on the beach and the erosion and associated increasing steepness of the shoreline in this area which is unsuitable habitat. Potential key impacts from the proposal on this species comprise a short-term slight increased potential for bioaccumulation of toxic chemicals in a ‘worse case response’ to groundwater interception, as a result of eating dead invertebrates that may die at the contaminated site, and a potential reduction in abundance of benthic fauna until invertebrate species reached a new balance. This may result in shorebirds having to look elsewhere for feeding habitat until Penrhyn Estuary invertebrates stabilise. In a ‘low-level response’ to groundwater interception there would be little change in the pre-existing condition of shorebirds and their habitat except a long-term improvement of contamination levels in feeding habitat. Whereas a ‘do nothing’ worse scenario may result in loss of prey, degradation of habitat and potential deaths of shorebirds, Predicted key impacts from the proposal on this species comprise disturbance to feeding from changes to their food source. Sanderlings typically feed in the ebb and flow of waves on flat beaches where the water is not too turbulent. This species typically feeds in the wave zone of ocean beaches at Boat Harbour and will generally flee to the northern shores of the Bay during rough weather for shelter and feeding (Penrhyn Estuary). Shorebirds preferably forage in areas where prey density, prey availability and intake rates are relatively high and where energy expenditure is low. Shorebird densities, therefore, tend to reach a maximum in the most preferred feeding areas (Boat Harbour and Penrhyn Estuary for this species) and where disturbances force birds to shift to alternative feeding areas, questions arise as to whether such areas are adequate, whether they can accommodate displaced individuals and what effect increased bird density has on intake rates and the fitness of those birds that move. A key potential impact to consider is the effect of any hydrological changes to the Estuary which may result in changes to shorebird feeding and roosting habitat. An assessment of impacts as a result of groundwater interception have been carried out which indicate that the proposed action is unlikely to impact on shorebirds.
2 Section 5A Assessments
(b) in the case of an endangered population, whether the life cycle of the species that constitutes the endangered population is likely to be disrupted such that the viability of the population is likely to be significantly compromised. Not Applicable (c) in relation to the regional distribution of the habitat of a threatened species, population or ecological community, whether a significant area of known habitat is to be modified or removed. The proposal may result in a modification to shorebird feeding at Penrhyn Estuary, considered to be an important shorebird habitat for the species on a local and regional basis. (d) whether an area of known habitat is likely to become isolated from currently interconnecting or proximate areas of habitat for a threatened species, population or ecological community The proposal would not result in isolation of shorebird feeding and roosting habitat at Penrhyn Estuary. (e) whether critical habitat will be affected. The study area is not listed as critical habitat under Part 3 Division 1 of the Threatened Species Conservation Act 1995. (f) whether a threatened species, population or ecological community, or their habitats, are adequately represented in conservation reserves (or other similar protected areas) in the region. No resident or migratory shorebirds in NSW are considered to be adequately conserved due to the unique location of their intertidal habitat. Smith (1991) notes that reservation of shorebird habitat on intertidal lands has posed a particular problem for NPWS as few coastal reserves include any areas below the high water mark which are generally Crown land. There has been some success, however, in establishing aquatic reserves in NSW such as the Towra Point Aquatic Reserve adjacent to Towra Point Nature Reserve in the Botany Bay estuary which supports important habitat for many shorebirds such as the Eastern Curlew and Whimbrel. (g) whether the development or activity proposed is of a class of development or activity that is recognised as a threatening process. Not Applicable (h) whether any threatened species, populations or ecological community is at the limit of its known distribution This species is regularly recorded in many estuaries on the north and south NSW coasts and is thus not considered to be at its limit of distribution in the Botany Bay estuary.
3 Section 5A Assessments
Section 5A Assessment Conclusion Given that the proposal represents long term protection of shorebirds and their habitat from contaminated groundwater and the long term reduction of existing contamination levels of shorebird habitat. And given that the saltmarsh and tidal flats used by shorebirds will be monitored and managed throughout the period of the proposal. No significant impact on shorebirds at Penrhyn Estuary is likely.
4 Section 5A Assessments
Calidris tenuirostris (Great Knot) (a) in the case of a threatened species, whether the life cycle of the species is likely to be disrupted such that a viable local population of the species is likely to be placed at risk of extinction. This species is a mudflat feeder and is occasionally recorded roosting and feeding at Penrhyn Estuary, particularly since it was displaced from its preferred habitat at the former Pilots Embayment which was lost due the Parallel Runway construction. The species is now restricted to Penrhyn Estuary in the Botany Bay estuary. The numbers of this species using the Bay are low (probably less than 4 or 5) although they are significant given the small size of the population on the east coast. Potential key impacts from the proposal on this species comprise a short-term slight increased potential for bioaccumulation of toxic chemicals in a ‘worse case response’ to groundwater interception, as a result of eating dead invertebrates that may die at the contaminated site and a potential reduction in abundance of benthic fauna until invertebrate species reached a new balance. This may result in shorebirds having to look elsewhere for feeding habitat until Penrhyn Estuary invertebrates stabilise. In a ‘low-level response’ to groundwater interception there would be little change in the pre-existing condition of shorebirds and their habitat except a long-term improvement of contamination levels in feeding habitat. Whereas a ‘do nothing’ worse scenario may result in loss of prey, degradation of habitat and potential deaths of shorebirds, Predicted key impacts from the proposal on this species comprise disturbance to feeding from changes to their food source. Great Knots typically feed by repeatedly jabbing their bills into soft, wet mud near the water’s edge or in shallow water. Minute gastropod molluscs have been found in the stomach of two West Australian specimens. Shorebirds preferably forage in areas where prey density, prey availability and intake rates are relatively high and where energy expenditure is low. Shorebird densities, therefore, tend to reach a maximum in the most preferred feeding areas (Penrhyn Estuary for this species) and where disturbances force birds to shift to alternative feeding areas, questions arise as to whether such areas are adequate, whether they can accommodate displaced individuals and what effect increased bird density has on intake rates and the fitness of those birds that move. This may be particularly significant to migratory shorebirds during the pre-migratory period of fat accumulation (and post migratory period of recuperation and moulting) where an increase in food requirements during this period results in shorebirds trying to maximise their net rate of resource acquisition and thus invest more time in foraging at the expense of vigilance and anti-predator behaviour. This is particularly significant for shorebirds whose feeding times are regulated by tidal flow (and even more significant for small billed shorebirds such as plovers and stints where foraging areas are further limited by amount of intertidal area not covered with water at low tide). Reductions in feeding may then affect the capacity of shorebirds to fatten at an adequate rate and therefore prolong the pre-migratory feeding period and departure delay. Such delays in migration departure from wintering grounds can seriously affect breeding success of migratory
5 Section 5A Assessments birds, where individuals arriving late at the summer breeding grounds may be at a disadvantage in the competition for mates and territories. A key potential impact to consider is the effect of any hydrological changes to the Estuary which may result in changes to shorebird feeding and roosting habitat. An assessment of impacts as a result of groundwater interception have been carried out which indicate that the proposed action is unlikely to impact on shorebirds. (b) in the case of an endangered population, whether the life cycle of the species that constitutes the endangered population is likely to be disrupted such that the viability of the population is likely to be significantly compromised. Not Applicable (c) in relation to the regional distribution of the habitat of a threatened species, population or ecological community, whether a significant area of known habitat is to be modified or removed. The proposal may result in a modification to shorebird feeding at Penrhyn Estuary, considered to be an important shorebird habitat for the species on a local and regional basis. (d) whether an area of known habitat is likely to become isolated from currently interconnecting or proximate areas of habitat for a threatened species, population or ecological community The proposal will not result in isolation of shorebird feeding and roosting habitat at Penrhyn Estuary from other known roost sites on the southern shores of the Bay and from general Bay wide bird movements which are undertaken over water. (e) whether critical habitat will be affected. The study area is not listed as critical habitat under Part 3 Division 1 of the Threatened Species Conservation Act 1995. (f) whether a threatened species, population or ecological community, or their habitats, are adequately represented in conservation reserves (or other similar protected areas) in the region. No resident or migratory shorebirds in NSW are considered to be adequately conserved due to the unique location of their intertidal habitat. Smith (1991) notes that reservation of shorebird habitat on intertidal lands has posed a particular problem for NPWS as few coastal reserves include any areas below the high water mark which are generally Crown land. There has been some success, however, in establishing aquatic reserves in NSW such as the Towra Point Aquatic Reserve adjacent to Towra Point Nature Reserve in the Botany Bay estuary which supports important habitat for many shorebirds such as the Eastern Curlew and Whimbrel.
6 Section 5A Assessments
Kooragang Nature Reserve in the Hunter estuary is one of the few present examples within an extensive representation of intertidal shorebird feeding grounds. This species is regularly recorded in relatively high numbers in the Hunter estuary. (g) whether the development or activity proposed is of a class of development or activity that is recognised as a threatening process. Not Applicable (h) whether any threatened species, populations or ecological community is at the limit of its known distribution This species is regularly recorded in some estuaries on the north and south NSW coasts (particularly the Richmond and Clarence estuaries) and is thus not considered to be at its limit of distribution in the Botany Bay estuary.
Section 5A Assessment Conclusion Given that the proposal represents long term protection of shorebirds and their habitat from contaminated groundwater and the long term reduction of existing contamination levels of shorebird habitat. And given that the saltmarsh and tidal flats used by shorebirds will be monitored and managed throughout the period of the proposal. No significant impact on shorebirds at Penrhyn Estuary is likely.
7 Section 5A Assessments
Limosa limosa (Black-tailed Godwit) (a) in the case of a threatened species, whether the life cycle of the species is likely to be disrupted such that a viable local population of the species is likely to be placed at risk of extinction. This species feeds on intertidal mudflats and on muddy margins of wetlands. The species occurs in very small numbers (1 or 2 individuals) in the Parramatta River estuary at Homebush Bay and may occasionally forage and roost at Penrhyn Estuary although no sightings of this species have been recorded in Botany Bay in recent years. The species is regularly recorded in the hundreds in the Hunter River and north coast estuaries (e.g. Clarence River)... Potential key impacts from the proposal on this species comprise a short-term slight increased potential for bioaccumulation of toxic chemicals in a ‘worse case response’ to groundwater interception, as a result of eating dead invertebrates that may die at the contaminated site and a potential reduction in abundance of benthic fauna until invertebrate species reached a new balance. This may result in shorebirds having to look elsewhere for feeding habitat until Penrhyn Estuary invertebrates stabilise. In a ‘low-level response’ to groundwater interception there would be little change in the pre-existing condition of shorebirds and their habitat except a long-term improvement of contamination levels in feeding habitat. Whereas a ‘do nothing’ worse scenario may result in loss of prey, degradation of habitat and potential deaths of shorebirds, Shorebirds preferably forage in areas where prey density, prey availability and intake rates are relatively high and where energy expenditure is low. Shorebird densities, therefore, tend to reach a maximum in the most preferred feeding areas (Penrhyn Estuary for this species) and where disturbances force birds to shift to alternative feeding areas, questions arise as to whether such areas are adequate, whether they can accommodate displaced individuals and what effect increased bird density has on intake rates and the fitness of those birds that move. Reductions in feeding may then affect the capacity of shorebirds to fatten at an adequate rate and therefore prolong the pre-migratory feeding period and departure delay. Such delays in migration departure from wintering grounds can seriously affect breeding success of migratory birds, where individuals arriving late at the summer breeding grounds may be at a disadvantage in the competition for mates and territories. A key potential impact to consider is the effect of any hydrological changes to the Estuary which may result in changes to shorebird feeding and roosting habitat. An assessment of impacts as a result of groundwater interception have been carried out which indicate that the proposed action is unlikely to impact on shorebirds. (b) in the case of an endangered population, whether the life cycle of the species that constitutes the endangered population is likely to be disrupted such that the viability of the population is likely to be significantly compromised. Not Applicable
8 Section 5A Assessments
(c) in relation to the regional distribution of the habitat of a threatened species, population or ecological community, whether a significant area of known habitat is to be modified or removed. The proposal may result in a modification to shorebird feeding at Penrhyn Estuary, considered to be an important shorebird habitat for the species on a local and regional basis. (d) whether an area of known habitat is likely to become isolated from currently interconnecting or proximate areas of habitat for a threatened species, population or ecological community The proposal will not result in isolation of shorebird feeding and roosting habitat at Penrhyn Estuary. (e) whether critical habitat will be affected. The study area is not listed as critical habitat under Part 3 Division 1 of the Threatened Species Conservation Act 1995. (f) whether a threatened species, population or ecological community, or their habitats, are adequately represented in conservation reserves (or other similar protected areas) in the region. No resident or migratory shorebirds in NSW are considered to be adequately conserved due to the unique location of their intertidal habitat. Smith (1991) notes that reservation of shorebird habitat on intertidal lands has posed a particular problem for NPWS as few coastal reserves include any areas below the high water mark which are generally Crown land. There has been some success, however, in establishing aquatic reserves in NSW such as the Towra Point Aquatic Reserve adjacent to Towra Point Nature Reserve in the Botany Bay estuary which supports important habitat for many shorebirds such as the Eastern Curlew and Whimbrel. Kooragang Nature Reserve in the Hunter estuary is one of the few present examples within an extensive representation of intertidal shorebird feeding grounds. This species is occasionally recorded in small numbers in the Hunter estuary. (g) whether the development or activity proposed is of a class of development or activity that is recognised as a threatening process. Not Applicable (h) whether any threatened species, populations or ecological community is at the limit of its known distribution This species is regularly recorded in some estuaries on the north and south NSW coasts (including the Hunter and Shoalhaven) and is thus not considered to be at its limit of distribution in the Botany Bay estuary.
9 Section 5A Assessments
Section 5A Assessment Conclusion Given that the proposal represents long term protection of shorebirds and their habitat from contaminated groundwater and the long term reduction of existing contamination levels of shorebird habitat. And given that the saltmarsh and tidal flats used by shorebirds will be monitored and managed throughout the period of the proposal. No significant impact on shorebirds at Penrhyn Estuary is likely.
10 Section 5A Assessments
Limicola falcinellus (Broad-billed Sandpiper) (a) in the case of a threatened species, whether the life cycle of the species is likely to be disrupted such that a viable local population of the species is likely to be placed at risk of extinction. Mostly single individuals of this species have been recorded in the Bay on an occasional basis since the mid 1970s (northern shoreline) and up to 17 birds were recorded on the northern shores of the Bay in 1953 (Straw 1996). No recent records of the species in the Bay exist; nevertheless the species may occasionally feed and roost at Penrhyn Estuary. Predicted key impacts from the proposal on this species comprise disturbance to feeding from changes to their food source. The Broad billed Sandpiper typically feed by rapidly and repeatedly jabbing their bills into soft wet mud. They also feed while wading, often so deep that they have to submerge their heads and necks when probing into the underlying mud. In Europe they feed on crustaceans, worms, molluscs and seeds. Potential key impacts from the proposal on this species comprise a short-term slight increased potential for bioaccumulation of toxic chemicals in a ‘worse case response’ to groundwater interception, as a result of eating dead invertebrates that may die at the contaminated site and a potential reduction in abundance of benthic fauna until invertebrate species reached a new balance. This may result in shorebirds having to look elsewhere for feeding habitat until Penrhyn Estuary invertebrates stabilise. In a ‘low-level response’ to groundwater interception there would be little change in the pre-existing condition of shorebirds and their habitat except a long-term improvement of contamination levels in feeding habitat. Whereas a ‘do nothing’ worse scenario may result in loss of prey, degradation of habitat and potential deaths of shorebirds, Shorebirds preferably forage in areas where prey density, prey availability and intake rates are relatively high and where energy expenditure is low. Shorebird densities, therefore, tend to reach a maximum in the most preferred feeding areas (Penrhyn Estuary for this species) and where disturbances force birds to shift to alternative feeding areas, questions arise as to whether such areas are adequate, whether they can accommodate displaced individuals and what effect increased bird density has on intake rates and the fitness of those birds that move. Reductions in feeding may then affect the capacity of shorebirds to fatten at an adequate rate and therefore prolong the pre-migratory feeding period and departure delay. Such delays in migration departure from wintering grounds can seriously affect breeding success of migratory birds, where individuals arriving late at the summer breeding grounds may be at a disadvantage in the competition for mates and territories. A key potential impact to consider is the effect of any hydrological changes to the Estuary which may result in changes to shorebird feeding and roosting habitat. An assessment of impacts as a result of groundwater interception have been carried out which indicate that the proposed action is unlikely to impact on shorebirds.
11 Section 5A Assessments
(b) in the case of an endangered population, whether the life cycle of the species that constitutes the endangered population is likely to be disrupted such that the viability of the population is likely to be significantly compromised. Not Applicable (c) in relation to the regional distribution of the habitat of a threatened species, population or ecological community, whether a significant area of known habitat is to be modified or removed. The proposal may result in a modification to shorebird feeding at Penrhyn Estuary, considered to be an important shorebird habitat for the species on a local and regional basis. (d) whether an area of known habitat is likely to become isolated from currently interconnecting or proximate areas of habitat for a threatened species, population or ecological community The proposal will not result in isolation of shorebird feeding and roosting habitat at Penrhyn Estuary. (e) whether critical habitat will be affected. The study area is not listed as critical habitat under Part 3 Division 1 of the Threatened Species Conservation Act 1995. (f) whether a threatened species, population or ecological community, or their habitats, are adequately represented in conservation reserves (or other similar protected areas) in the region. No resident or migratory shorebirds in NSW are considered to be adequately conserved due to the unique location of their intertidal habitat. Smith (1991) notes that reservation of shorebird habitat on intertidal lands has posed a particular problem for NPWS as few coastal reserves include any areas below the high water mark which are generally Crown land. There has been some success, however, in establishing aquatic reserves in NSW such as the Towra Point Aquatic Reserve adjacent to Towra Point Nature Reserve in the Botany Bay estuary which supports important habitat for many shorebirds such as the Eastern Curlew and Whimbrel. Kooragang Nature Reserve in the Hunter estuary is one of the few present examples within an extensive representation of intertidal shorebird feeding grounds. This species is occasionally recorded in small numbers in the Hunter estuary. (g) whether the development or activity proposed is of a class of development or activity that is recognised as a threatening process. Not Applicable (h) whether any threatened species, populations or ecological community is at the limit of its known distribution
12 Section 5A Assessments
This species is occasionally recorded in some estuaries on the north and south NSW coasts (including the Hunter and Shoalhaven) and is thus not considered to be at its limit of distribution in the Botany Bay estuary.
Section 5A Assessment Conclusion Given that the proposal represents long term protection of shorebirds and their habitat from contaminated groundwater and the long term reduction of existing contamination levels of shorebird habitat. And given that the saltmarsh and tidal flats used by shorebirds will be monitored and managed throughout the period of the proposal. No significant impact on shorebirds at Penrhyn Estuary is likely.
13 Section 5A Assessments
Xenus cinereus (Terek Sandpiper) (a) in the case of a threatened species, whether the life cycle of the species is likely to be disrupted such that a viable local population of the species is likely to be placed at risk of extinction. This species (2 individuals in the Bay based on recent counts) presently feeds on intertidal mudflats between Taren Point and Woolooware Bay on the southern shores of the Bay and roosts on a disused jetty at Shell Point. This species may occasionally forage at Penrhyn Estuary (although no recent records exist of this species on the northern shores of the Bay). Predicted key impacts from the proposal on this species comprise disturbance to feeding from changes to their food source. The species typically feeds by moving rapidly and erratically over soft, wet mud, pecking or probing the surface, sometime chasing prey. It has been recorded feeding in Victoria on amphipods, dipterans and some beetles. Potential key impacts from the proposal on this species comprise a short-term slight increased potential for bioaccumulation of toxic chemicals in a ‘worse case response’ to groundwater interception, as a result of eating dead invertebrates that may die at the contaminated site and a potential reduction in abundance of benthic fauna until invertebrate species reached a new balance. This may result in shorebirds having to look elsewhere for feeding habitat until Penrhyn Estuary invertebrates stabilise. In a ‘low-level response’ to groundwater interception there would be little change in the pre-existing condition of shorebirds and their habitat except a long-term improvement of contamination levels in feeding habitat. Whereas a ‘do nothing’ worse scenario may result in loss of prey, degradation of habitat and potential deaths of shorebirds, Shorebirds preferably forage in areas where prey density, prey availability and intake rates are relatively high and where energy expenditure is low. Shorebird densities, therefore, tend to reach a maximum in the most preferred feeding areas (Woolooware Bay for this species) and where disturbances force birds to shift to alternative feeding areas, questions arise as to whether such areas are adequate, whether they can accommodate displaced individuals and what effect increased bird density has on intake rates and the fitness of those birds that move. A key potential impact to consider is the effect of any hydrological changes to the Estuary which may result in changes to shorebird feeding and roosting habitat. An assessment of impacts as a result of groundwater interception have been carried out which indicate that the proposed action is unlikely to impact on shorebirds. (b) in the case of an endangered population, whether the life cycle of the species that constitutes the endangered population is likely to be disrupted such that the viability of the population is likely to be significantly compromised. Not Applicable
14 Section 5A Assessments
(c) in relation to the regional distribution of the habitat of a threatened species, population or ecological community, whether a significant area of known habitat is to be modified or removed. The proposal may result in a modification to shorebird feeding at Penrhyn Estuary, considered to be an important shorebird habitat for the species on a local and regional basis. (d) whether an area of known habitat is likely to become isolated from currently interconnecting or proximate areas of habitat for a threatened species, population or ecological community The proposal would not result in isolation of shorebird feeding and roosting habitat at Penrhyn Estuary. (e) whether critical habitat will be affected. The study area is not listed as critical habitat under Part 3 Division 1 of the Threatened Species Conservation Act 1995. (f) whether a threatened species, population or ecological community, or their habitats, are adequately represented in conservation reserves (or other similar protected areas) in the region. No resident or migratory shorebirds in NSW are considered to be adequately conserved due to the unique location of their intertidal habitat. Smith (1991) notes that reservation of shorebird habitat on intertidal lands has posed a particular problem for NPWS as few coastal reserves include any areas below the high water mark which are generally Crown land. There has been some success, however, in establishing aquatic reserves in NSW such as the Towra Point Aquatic Reserve adjacent to Towra Point Nature Reserve in the Botany Bay estuary which supports important habitat for many shorebirds such as the Eastern Curlew and Whimbrel. Kooragang Nature Reserve in the Hunter estuary is one of the few present examples within an extensive representation of intertidal shorebird feeding grounds. This species is regularly recorded in relatively high numbers in the Hunter estuary. (g) whether the development or activity proposed is of a class of development or activity that is recognised as a threatening process. Not Applicable (h) whether any threatened species, populations or ecological community is at the limit of its known distribution This species is regularly recorded in some estuaries on the north and south NSW coasts and is thus not considered to be at its limit of distribution at in the Botany Bay estuary.
15 Section 5A Assessments
Section 5A Assessment Conclusion Given that the proposal represents long term protection of shorebirds and their habitat from contaminated groundwater and the long term reduction of existing contamination levels of shorebird habitat. And given that the saltmarsh and tidal flats used by shorebirds will be monitored and managed throughout the period of the proposal. No significant impact on shorebirds at Penrhyn Estuary is likely.
16 Section 5A Assessments
Haematopus longirostris (Pied Oystercatcher) (a) in the case of a threatened species, whether the life cycle of the species is likely to be disrupted such that a viable local population of the species is likely to be placed at risk of extinction. This Australian resident shorebird presently occurs in relatively large numbers (up to 60 individuals) at several locations in southern parts of Botany Bay where it feeds and roosts and at Penrhyn Estuary where it occasionally feeds on intertidal sandflats. Presently 5 or 6 pairs nest at H1 lands at Woolooware Bay, Towra Spit Island and at the airport. The volume of pedestrian traffic on Foreshore Beach would be expected to preclude this from being used by the species for its life cycle requirements, particularly nesting activity. Predicted key impacts from the proposal on this species comprise disturbance to feeding from changes to their food source. There have been no detailed feeding studies in Australia, but chief prey appears to be molluscs (bivalves and gastropods). The birds also take marine worms and small fish. Potential key impacts from the proposal on this species comprise a short-term slight increased potential for bioaccumulation of toxic chemicals in a ‘worse case response’ to groundwater interception, as a result of eating dead invertebrates that may die at the contaminated site and a potential reduction in abundance of benthic fauna until invertebrate species reached a new balance. This may result in shorebirds having to look elsewhere for feeding habitat until Penrhyn Estuary invertebrates stabilise. In a ‘low-level response’ to groundwater interception there would be little change in the pre-existing condition of shorebirds and their habitat except a long-term improvement of contamination levels in feeding habitat. Whereas a ‘do nothing’ worse scenario may result in loss of prey, degradation of habitat and potential deaths of shorebirds. Shorebirds preferably forage in areas where prey density, prey availability and intake rates are relatively high and where energy expenditure is low. Shorebird densities, therefore, tend to reach a maximum in the most preferred feeding areas (Penrhyn Estuary for this species) and where disturbances force birds to shift to alternative feeding areas, questions arise as to whether such areas are adequate, whether they can accommodate displaced individuals and what effect increased bird density has on intake rates and the fitness of those birds that move. As bird density increases, average intake rates decline in many species as a result of increased competition, increased prey depletion and a greater proportion of the population feeding in sub-optimal areas. Where populations are limited, or are close to limitation by the quality and availability of habitat (such as for this species in Penrhyn Estuary and in the Botany Bay estuary in total), disturbance can have a negative impact on shorebird populations by affecting fitness and increased mortality. A key potential impact to consider is the effect of any hydrological changes to the Estuary which may result in changes to shorebird feeding and roosting habitat. An assessment of impacts as a result of groundwater interception have been carried out which indicate that the proposed action is unlikely to impact on shorebirds.
17 Section 5A Assessments
(b) in the case of an endangered population, whether the life cycle of the species that constitutes the endangered population is likely to be disrupted such that the viability of the population is likely to be significantly compromised. Not Applicable (c) in relation to the regional distribution of the habitat of a threatened species, population or ecological community, whether a significant area of known habitat is to be modified or removed. The proposal may result in a modification to shorebird feeding at Penrhyn Estuary, considered to be an important shorebird habitat for the species on a local and regional basis. (d) whether an area of known habitat is likely to become isolated from currently interconnecting or proximate areas of habitat for a threatened species, population or ecological community The proposal would not result in isolation of shorebird feeding and roosting habitat at Penrhyn Estuary. (e) whether critical habitat will be affected. The study area is not listed as critical habitat under Part 3 Division 1 of the Threatened Species Conservation Act 1995. (f) whether a threatened species, population or ecological community, or their habitats, are adequately represented in conservation reserves (or other similar protected areas) in the region. No resident or migratory shorebirds in NSW are considered to be adequately conserved due to the unique location of their intertidal habitat. Smith (1991) notes that reservation of shorebird habitat on intertidal lands has posed a particular problem for NPWS as few coastal reserves include any areas below the high water mark which are generally Crown land. There has been some success, however, in establishing aquatic reserves in NSW such as the Towra Point Aquatic Reserve adjacent to Towra Point Nature Reserve in the Botany Bay estuary which supports important habitat for many shorebirds such as the Eastern Curlew and Whimbrel. (g) whether the development or activity proposed is of a class of development or activity that is recognised as a threatening process. Not Applicable (h) whether any threatened species, populations or ecological community is at the limit of its known distribution This species is regularly recorded in many estuaries on the north and south NSW coasts and is thus not considered to be at its limit of distribution in the Botany Bay estuary.
18 Section 5A Assessments
Section 5A Assessment Conclusion Given that the proposal represents long term protection of shorebirds and their habitat from contaminated groundwater and the long term reduction of existing contamination levels of shorebird habitat. And given that the saltmarsh and tidal flats used by shorebirds will be monitored and managed throughout the period of the proposal. No significant impact on shorebirds at Penrhyn Estuary is likely.
19 Section 5A Assessments
Charadrius leschenaultii (Greater Sand Plover) (a) in the case of a threatened species, whether the life cycle of the species is likely to be disrupted such that a viable local population of the species is likely to be placed at risk of extinction. This species is an occasional visitor to Penrhyn Estuary and Boat Harbour (often in association with the Lesser Sand Plover) where it feeds on intertidal sand flats. Only 1 or 2 individuals are recorded in the Bay on an occasional basis (this is significant given the NSW estimate population for this species is only 80 birds with the majority occurring in the Clarence and Richmond estuaries). Predicted key impacts from the proposal on this species comprise disturbance to feeding from changes to their food source. The birds feed at low tide on wet ground, usually on away from the water’s edge. They detect prey visually, running short distances, stopping to look, then running to peck at the surface. The diet includes insects, crustaceans and molluscs. Potential key impacts from the proposal on this species comprise a short-term slight increased potential for bioaccumulation of toxic chemicals in a ‘worse case response’ to groundwater interception, as a result of eating dead invertebrates that may die at the contaminated site and a potential reduction in abundance of benthic fauna until invertebrate species reached a new balance. This may result in shorebirds having to look elsewhere for feeding habitat until Penrhyn Estuary invertebrates stabilise. In a ‘low-level response’ to groundwater interception there would be little change in the pre-existing condition of shorebirds and their habitat except a long-term improvement of contamination levels in feeding habitat. Whereas a ‘do nothing’ worse scenario may result in loss of prey, degradation of habitat and potential deaths of shorebirds, Shorebirds preferably forage in areas where prey density, prey availability and intake rates are relatively high and where energy expenditure is low. Shorebird densities, therefore, tend to reach a maximum in the most preferred feeding areas (Penrhyn Estuary for this species) and where disturbances force birds to shift to alternative feeding areas, questions arise as to whether such areas are adequate, whether they can accommodate displaced individuals and what effect increased bird density has on intake rates and the fitness of those birds that move. A key potential impact to consider is the effect of any hydrological changes to the Estuary which may result in changes to shorebird feeding and roosting habitat. An assessment of impacts as a result of groundwater interception have been carried out which indicate that the proposed action is unlikely to impact on shorebirds. (b) in the case of an endangered population, whether the life cycle of the species that constitutes the endangered population is likely to be disrupted such that the viability of the population is likely to be significantly compromised. Not Applicable
20 Section 5A Assessments
(c) in relation to the regional distribution of the habitat of a threatened species, population or ecological community, whether a significant area of known habitat is to be modified or removed. The proposal may result in a modification to shorebird feeding at Penrhyn Estuary, considered to be an important shorebird habitat for the species on a local and regional basis. (d) whether an area of known habitat is likely to become isolated from currently interconnecting or proximate areas of habitat for a threatened species, population or ecological community The proposal would not result in isolation of shorebird feeding and roosting habitat at Penrhyn Estuary. (e) whether critical habitat will be affected. The study area is not listed as critical habitat under Part 3 Division 1 of the Threatened Species Conservation Act 1995. (f) whether a threatened species, population or ecological community, or their habitats, are adequately represented in conservation reserves (or other similar protected areas) in the region. No resident or migratory shorebirds in NSW are considered to be adequately conserved due to the unique location of their intertidal habitat. Smith (1991) notes that reservation of shorebird habitat on intertidal lands has posed a particular problem for NPWS as few coastal reserves include any areas below the high water mark which are generally Crown land. There has been some success, however, in establishing aquatic reserves in NSW such as the Towra Point Aquatic Reserve adjacent to Towra Point Nature Reserve in the Botany Bay estuary which supports important habitat for many shorebirds such as the Eastern Curlew and Whimbrel. (g) whether the development or activity proposed is of a class of development or activity that is recognised as a threatening process. Not Applicable (h) whether any threatened species, populations or ecological community is at the limit of its known distribution This species is regularly recorded in many estuaries on the north and south NSW coasts (majority in the Clarence and Richmond estuaries on the north coast) and is thus not considered to be at its limit of distribution in the Botany Bay estuary.
Section 5A Assessment Conclusion Given that the proposal represents long term protection of shorebirds and their habitat from contaminated groundwater and the long term reduction of existing contamination levels of shorebird habitat. And given that the saltmarsh and tidal flats used by shorebirds
21 Section 5A Assessments will be monitored and managed throughout the period of the proposal. No significant impact on shorebirds at Penrhyn Estuary is likely.
22 Section 5A Assessments
Charadrius mongolus (Lesser Sand Plover) (a) in the case of a threatened species, whether the life cycle of the species is likely to be disrupted such that a viable local population of the species is likely to be placed at risk of extinction. This species roosts every year on intertidal sand flats at Boat Harbour (up to about 10 individuals) and feeds occasionally at Penrhyn Estuary and possibly elsewhere in the Bay. Predicted key impacts from the proposal on this species comprise disturbance to feeding from changes to their food source. The birds typically forage in loose flocks on wet intertidal flats, usually away from the water’s edge. Prey is detected visually, the birds making short, quick runs, with abrupt stops to lunge at the ground or to look for prey. The diet includes molluscs and crustaceans. Potential key impacts from the proposal on this species comprise a short-term slight increased potential for bioaccumulation of toxic chemicals in a ‘worse case response’ to groundwater interception, as a result of eating dead invertebrates that may die at the contaminated site and a potential reduction in abundance of benthic fauna until invertebrate species reached a new balance. This may result in shorebirds having to look elsewhere for feeding habitat until Penrhyn Estuary invertebrates stabilise. In a ‘low-level response’ to groundwater interception there would be little change in the pre-existing condition of shorebirds and their habitat except a long-term improvement of contamination levels in feeding habitat. Whereas a ‘do nothing’ worse scenario may result in loss of prey, degradation of habitat and potential deaths of shorebirds, Shorebirds preferably forage in areas where prey density, prey availability and intake rates are relatively high and where energy expenditure is low. Shorebird densities, therefore, tend to reach a maximum in the most preferred feeding areas (Penrhyn Estuary and Boat Harbour for this species) and where disturbances force birds to shift to alternative feeding areas, questions arise as to whether such areas are adequate, whether they can accommodate displaced individuals and what effect increased bird density has on intake rates and the fitness of those birds that move. A key potential impact to consider is the effect of any hydrological changes to the Estuary which may result in changes to shorebird feeding and roosting habitat. An assessment of impacts as a result of groundwater interception have been carried out which indicate that the proposed action is unlikely to impact on shorebirds. (b) in the case of an endangered population, whether the life cycle of the species that constitutes the endangered population is likely to be disrupted such that the viability of the population is likely to be significantly compromised. Not Applicable (c) in relation to the regional distribution of the habitat of a threatened species, population or ecological community, whether a significant area of known habitat is to be modified or removed.
23 Section 5A Assessments
The proposal may result in a modification to shorebird feeding at Penrhyn Estuary, considered to be an important shorebird habitat for the species on a local and regional basis. (d) whether an area of known habitat is likely to become isolated from currently interconnecting or proximate areas of habitat for a threatened species, population or ecological community The proposal would not result in isolation of shorebird feeding and roosting habitat at Penrhyn Estuary. (e) whether critical habitat will be affected. The study area is not listed as critical habitat under Part 3 Division 1 of the Threatened Species Conservation Act 1995. (f) whether a threatened species, population or ecological community, or their habitats, are adequately represented in conservation reserves (or other similar protected areas) in the region. No resident or migratory shorebirds in NSW are considered to be adequately conserved due to the unique location of their intertidal habitat. Smith (1991) notes that reservation of shorebird habitat on intertidal lands has posed a particular problem for NPWS as few coastal reserves include any areas below the high water mark which are generally Crown land. There has been some success, however, in establishing aquatic reserves in NSW such as the Towra Point Aquatic Reserve adjacent to Towra Point Nature Reserve in the Botany Bay estuary which supports important habitat for many shorebirds such as the Eastern Curlew and Whimbrel. (g) whether the development or activity proposed is of a class of development or activity that is recognised as a threatening process. Not Applicable (h) whether any threatened species, populations or ecological community is at the limit of its known distribution This species is regularly recorded in many estuaries on the north and south NSW coasts as well as inland and is thus not considered to be at its limit of distribution at Botany Bay estuary.
Section 5A Assessment Conclusion Given that the proposal represents long term protection of shorebirds and their habitat from contaminated groundwater and the long term reduction of existing contamination levels of shorebird habitat. And given that the saltmarsh and tidal flats used by shorebirds will be monitored and managed throughout the period of the proposal. No significant impact on shorebirds at Penrhyn Estuary is likely.
24 Section 5A Assessments
Sterna albifrons (Little Tern) (a) in the case of a threatened species, whether the life cycle of the species is likely to be disrupted such that a viable local population of the species is likely to be placed at risk of extinction. This assessment refers to the south-eastern Australian population of the Little Tern subspecies sinensis which migrates down the east coast of Australia during spring and summer to nest as solitary pairs or in small colonies (Smith 1991). This species forages at the mouth of Penrhyn Estuary for small fish and also roosts at the Estuary. This species has successfully nested in recent years on Towra Spit Island. NPWS note that upwards of 60 pairs of the bird nested on Towra Spit Island during the past 10 years (pers. comm., Geoff Ross). Only limited information is available on the feeding ecology of Little Terns in Australia. Gut contents of five breeding specimens from Mallacoota disclosed only fish remains, including two whole Hardyheads. More comprehensive data on European birds suggests that invertebrates are also important in their diet, especially crustaceans and insects. The birds generally work back and forth over the water with quick wing-beats and their head directed downward. They often hover before making a rapid vertical dive into or under the water, or drop or dip more slowly to the surface. A key potential impact to consider is the effect of any hydrological changes to the Estuary which may result in changes to Little Tern feeding and roosting habitat. An assessment of impacts as a result of groundwater interception have been carried out which indicate that the proposed action is unlikely to impact on Little Terns. (b) in the case of an endangered population, whether the life cycle of the species that constitutes the endangered population is likely to be disrupted such that the viability of the population is likely to be significantly compromised. Not Applicable (c) in relation to the regional distribution of the habitat of a threatened species, population or ecological community, whether a significant area of known habitat is to be modified or removed. The proposal is unlikely to result in modification to Little Tern feeding at Penrhyn Estuary, considered to be an important shorebird habitat for the species on a local and regional basis. (d) whether an area of known habitat is likely to become isolated from currently interconnecting or proximate areas of habitat for a threatened species, population or ecological community The proposal would not result in isolation of shorebird feeding and roosting habitat at Penrhyn Estuary. (e) whether critical habitat will be affected.
25 Section 5A Assessments
The study area is not listed as critical habitat under Part 3 Division 1 of the Threatened Species Conservation Act 1995. (f) whether a threatened species, population or ecological community, or their habitats, are adequately represented in conservation reserves (or other similar protected areas) in the region. Whilst the species main nesting site at Towra Spit Island does fall under the NPWS estate and is reserved, the constant threat to nesting sites from natural and human disturbance which cause the bird to seek alternative sites in the Bay on unreserved land needs to be considered when assessing the conservation status of the species in the locality and region. (g) whether the development or activity proposed is of a class of development or activity that is recognised as a threatening process. Not Applicable (h) whether any threatened species, populations or ecological community is at the limit of its known distribution This species is regularly recorded in many estuaries on the north and south NSW coasts and is thus not considered to be at its limit of distribution at Botany Bay estuary.
Section 5A Assessment Conclusion Given that the proposal represents long term protection of Little Terns and their habitat from contaminated groundwater and the long term reduction of existing contamination levels of shorebird habitat. And given that the habitat used by Little Terns will be monitored and managed throughout the period of the proposal. No significant impact on shorebirds at Penrhyn Estuary is likely.
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