5 environmental setting 5 Environmental setting This chapter provides a broad overview of the natural and man-made environments in the area surrounding the Project. It sets the context for the detailed assessment of the key environmental issues (chapter 7) and other, less significant environmental issues (chapter 8) associated with the Project. 5.1 Traffic On the land sections of the cable routes, the cables would mostly be buried in road reserves. Accordingly, traffic disruption would temporarily be an issue during the cable laying process. Construction activities at the STSs, particularly Kurnell STS, would also have traffic impacts. The main features of the existing traffic network are as follows: • Traffic volumes along the affected roads on the northern side of the Project are greatest along Military Road, west of Bunnerong Road, which carries about 440 vehicles in the weekday afternoon peak hour. • The highest traffic volumes are experienced along Anzac Parade on weekends, where daily traffic volumes can approach 7,400 per average weekend day. This reflects the popularity of the La Perouse precinct and surrounds for active and passive recreation. • There are about 170 weekday bus movements in and out of La Perouse via Anzac Parade, south of Bunnerong Road. • Traffic volumes along the affected roads on the southern side of the Project are greatest along Captain Cook Drive, west of Silver Beach Road, which carries about 300 vehicles in the weekday afternoon peak hour. • There are about 24 weekday bus movements in and out of Kurnell via Captain Cook Drive, Prince Charles Parade and other roads. • There are no signalised intersections within the Project areas on both sides of the Bay. 5.2 Noise The northern section of the Project area consists of the predominately residential areas of La Perouse, Phillip Bay and Chifley that are to the east of Bunnerong Road. In addition, an industrial, bulky goods storage area is located around Bunnerong STS. Whilst this area is industrial in nature, it does not exhibit the noise generating characteristics of nearby heavy industry and port operations at Port Botany. Major contributors to noise levels in the northern section include traffic on Bunnerong Road, wave and water noise and flights to and from Sydney Airport. The results of ambient noise monitoring indicated background noise levels along the northern section of the Project area were 43 to 47dBA. The southern section of the Project area at Kurnell is relatively flat in nature and residential areas are located adjacent to the heavy industry associated with the Caltex Oil Refinery. As such, noise in this area results from industrial noise and traffic on Captain Cook Drive. The results of ambient noise monitoring revealed that background noise levels along the southern section of the Project area were 48 to 52dBA. 56 EnergyAustralia 5.3 Botany Bay aquatic environment 5.3.1 Aquatic plants The aquatic plants in Botany Bay include algae, seagrass beds and mangroves. Salt marsh plants which grow in intertidal waters are found in extensive stands around Towra Point and in Quibray Bay and occupy an area of 157 hectares (Watford and Williams 1998). Algae Phytoplankton are the plant component of plankton comprising microscopic plants ranging in size from about 2 to 300 µm, with a few reaching one millimetre length. Larkum (1981) estimated that the phytoplankton in Botany Bay contribute about 1.5 tonnes per hectare of biomass per year, or about 35 % of the total primary production of the Bay. The algae pest species (Caulerpa taxifolia) is reported to be widespread throughout the Bay. Seagrass and mangroves Botany Bay supports extensive seagrass beds and intertidal mangrove stands, with the most recent mapping estimate (from 1995) being 624 hectares of seagrass and 423 hectares of mangroves (Watford & Williams 1998). Both seagrass beds and mangrove stands are recognised as playing important roles in estuarine community structure and function (NSW State Pollution Control Commission, 1978c, SPCC 1981c and Ecology Lab 2003a,b). These marine plants contribute a significant proportion of the primary production in estuaries, with detrital material produced by marine plants forming the base of a significant detrital food chain via benthic organisms and the fish that prey on them. Larkum (1981) estimated that the seagrass beds in Botany Bay alone produced about 25 % of the total primary production for the Bay. Seagrass beds and mangrove mud flats, root systems plus drainage creeks provide important nursery habitat for fish and prawns, including a large number of the commercially and recreationally important fish (NSW State Pollution Control Commission 1981c,d,e, Middleton et. al. 1984). The seagrass beds comprise a number of different species with the three main taxa being strap weed (Posidonia australis), eel grass Zostera or Heterozostera species - mainly (Zostera capricorni) and paddle weed species (Halophila spp.). All the Posidonia beds and about 90% of the Zostera meadows are located on the southern side of Botany Bay, with most of the meadows located in the Towra Point Aquatic Reserve and off Silver Beach, Kurnell. There is another large Zostera meadow in the northern embayment off Botany beach (URS 2003) and there are smaller, mainly Zostera, beds along the western side of the Bay, plus small, predominantly Halophila, beds in Frenchmans and Yarra Bays. 5.3.2 Fish and benthic fauna The zooplankton component of the plankton comprises microscopic and small invertebrate and vertebrate (mainly larval fish) fauna. The zooplankton, including larval fish form a significant proportion of the grazers which feed on phytoplankton and they, in turn, become an important food source for older fish. Whilst there have been no published studies found on the ecology of the invertebrate zooplankton of Botany Bay, there are numerous studies of the ichthyoplankton of Botany Bay. This is probably due to the assumed important relationship between the distribution and fate of the ichthyoplankton and the eventual distribution and abundance of fish of commercial and recreational importance: Fish and sharks There have been a number of studies of the fish and mobile invertebrate fauna of soft sediment sea beds in Botany Bay. The NSW State Pollution Control Commission, 1981c,d,e described eight main habitat types for Botany Bay and found that these habitat types supported 229 fish species. The Botany Bay Cable Project Environmental Assessment 57 5 environmental setting diversity of the Bay's fish fauna was attributed to the complexity and variety of these habitats. The Bay was considered important primarily as a fish nursery area, with juveniles accounting for two-thirds of the commercially and recreationally valuable fish sampled (NSW State Pollution Control Commission, 1981e). Zostera seagrass beds, particularly those on the south side of the Bay which were closely linked with Posidonia seagrass beds and mangrove forests, provided an exceptionally important nursery habitat. Benthic fauna There have been few studies of the shallow intertidal benthic communities of Botany Bay. Those that have been done related to the sandy shallows adjacent to dredging operations and the northern embayment seagrass beds; Penrhyn Estuary; Foreshore Beach and Towra Beach. A number of studies have been conducted of the deeper muddy and sandy habitats of the Bay. NSW State Pollution Control Commission, assessed the macro-benthic fauna of dredged and un-dredged sea beds in 1976 (NSW State Pollution Control Commission 1979f, Jones 1981, Jones and Candy 1981). Some of the conclusions of the studies relevant to this Project were as follows: • The dredged areas generally had lower species numbers. • The abundance of benthos in dredged areas was either equal to or higher than the corresponding un-dredged area. • The dredged sites in the entrance channel, closest to the proposed cable route, supported a more diverse and abundant fauna than adjacent undredged sites and the difference was attributed to the greater depth of the dredged area compared to the surrounding un-dredged area, and which was consequently less subject to disturbance from wave activity (Jones and Candy 1981). 5.3.3 Marine mammals and reptiles There are a number of whales and dolphins which occur in shallow coastal waters off Botany Bay (Baker 1983). Whilst a large number of cetacean species is known from strandings (National Parks and Wildlife Service Southern Region records) only a few species are commonly sighted in the locality (Marine Pollution Research 1998, The Ecology Lab 2003a,b): 5.3.4 Sea, shore and wading birds Within the Project area, seasonally visiting sea birds such as the Australian gannet and the little tern feed on small fish prey over the shallow waters of the Bay. Waders and other shorebirds forage for invertebrates on intertidal sand spits and mudflats from time to time, and at high tide roost on low-lying, sparsely vegetated sandy areas above the high water mark in Quibray Bay and around Towra Point (Pegler 1997, Straw 1992. SMEC 2003), Little penguins are known from the waters of Botany Bay. With regard to shore and wading bird usage of the Bay, Pegler (1997), in her retrospective survey of 50 years of wader bird research, noted that within Botany Bay, Eastern Curlews roost in salt marsh and on structures associated with oyster leases, Whimbrels commonly roost in mangroves and Bar-tailed Godwits range freely around the Bay. Straw (1992) noted that generally, few small waders utilise the southern shores of Botany Bay. Whilst the Towra Point Spit Island is the main roost in Botany Bay for the Bar-tailed Godwit up to 500 have been recorded roosting on the Bay northern shoreline, which is also a major feeding area for this species. Further, the main roost in Botany Bay for the Pied Oystercatcher over time has been the Towra Point Spit Island. Over recent years, the National Parks and Wildlife Service have conducted wader and shorebird surveys around Botany Bay (see review in SMEC 2003).