32Wildlife Conservation Plan for Seabirds

32 Wildlife Conservation Plan for Seabirds

Turbidity is implicated in coastal and deepwater seagrass habitat loss (Westphalen et al. 2006; Tanner 2006). The implications of turbidity related impacts from other activities such as dredging on seabirds is unclear. Turbidity may impact upon seabird feeding, for species which may need clear water to view prey (i.e. terns). For example, increased turbidity from European Carp in Murray Mouth lakes appeared to interfere with Australian Fairy Tern feeding (Copley 1996).

Pesticides accumulate in seabirds and species which had been tested in South Australia have had elevated organochlorine levels (Silver Gulls, Little Penguins, Australian Pelican, White-bellied Sea-eagle) (Falkenberg et al. 1994). There have been concerns over organochlorine pesticide contamination and reproductive failure in Osprey (Pandion haliaetus) and White-bellied Sea Eagle (Falkenberg et al. 1994). Pesticide levels were also of concern for several prey species commonly found in the diet of White-bellied Sea Eagle, such as Feral Pigeon and Silver Gull. DDT was also found at high concentration in pelican eggs. Concentrations found were well above those known to cause

reproductive failure in falcons (Falco spp.). Dieldrin was present in most samples, but at low concentrations (Falkenberg et al. 1994).

Agricultural land runoff containing pesticides may inhibit zooplankton grazing which can then result in algal blooms (Hallegraeff 1995). Harmful algal blooms can affect seabirds that feed on filter-feeding fish and shellfish. Harmful algal blooms can affect a range of marine species including seabirds, including reduced feeding activity, inability to lay eggs, loss of motor coordination and death, and impacts to seabird population recruitment (Shumway et al 2003). Systematic monitoring of blooms and impacts on marine species is needed to determine long-term impacts.

Hormones and endocrine disruptors which may be present in pesticides, agricultural runoff, antifouling and municipal and industrial effluent are known to impact on some fish species and other wildlife (Environment Canada 1999, ORD & USEPA 1998, Colborn et al. 1993). More recently concerns have been raised over Endocrine Disrupting Chemicals (EDCs) contained in Pharmaceuticals and Personal Care Products (PPCPs) which may enter aquatic environments in sewerage or reclaimed water (Ying et al. 2004). At certain concentrations chemicals such as estradiol, nonylphenol, bisphenol A, polychlorinated biphenyls (PCBs) and some pesticides can cause disruption to endocrine systems and can affect hormonal control of development in aquatic wildlife. Whilst poorly documented in Australia, one impact is the feminisation of fish by wastewater effluent from sewage treatment (Ying et al. 2004).

Marine pollution is becoming increasingly apparent in the Southern Hemisphere and impacts on Australian seabirds are likely to increase in the future. Internationally, only a few studies of any seabird species have been undertaken to identify whether marine contaminants (e.g. organochlorines and dichloro-diphenyl-trichloroethane (DDT) affect seabird survival, in particular aspects of their breeding biology (Croxall 1998; Ludwig et al. 1998).

Wildlife Conservation Plan for Seabirds 33

Acute pollution

Bulk fuel and oil spills also have the potential to affect high numbers of seabirds. Birds coming into contact with oil can become physically smothered, or suffer

oiled plumage, which leads to reduced insulation and increased heat loss, loss of waterproofing, reduced ability to forage efficiently, usually resulting in emaciation and death. Birds may also ingest oil, leading to potential toxicity. Since seabirds spend much of their time on the sea surface, they are particularly vulnerable to the hazards of oil or fuel spills and are difficult to rehabilitate. Shipping discharge of oil and other pollutants is regulated by the International Convention for the Prevention of Pollution from Ships (1973) and its Protocol (1978) - MARPOL 73/78. The Australian Maritime Safety Authority (AMSA) administers MARPOL in Australian waters under the Commonwealth Protection of the Sea (Prevention of Pollution from Ships) Act 1983.

Response to marine oil spills is managed by AMSA, in conjunction with the states and the Northern Territory, through the Intergovernmental Agreement on the National Plan to Combat Pollution of the Sea by Oil and Other Noxious and Hazardous Substances. The Plan sets out the role and responsibilities for government and industry in the event of an oil spill. The Plan identifies the potential effects on wildlife and the operations and procedures that should be put into place in the event of an oil spill. However, if the incident occurs in remote areas, there may be little that can be done when large numbers of birds are affected.

For offshore petroleum activities in Commonwealth waters, the titleholder is responsible for managing oil spill response (being accountable under the OPGGS Act and Environment Regulations). For oil pollution response in State and Territory waters, whether the incident occurs in the State/Territory waters or oil pollution migrates into State/Territory waters, the State/Territory authorities manage the response and provide direction to the responsible party (titleholder) to respond, which includes response to oiled wildlife.

In Port Bonython, South Australia an oil spill occurred on 30 August 1992 from the fuel tanker Era during berthing operations in upper Spencer Gulf. An estimated 300 000 litres (296 tonnes) of heavy bunker oil was released in sensitive mangrove and seagrass communities of upper Spencer Gulf. An estimated 23 hectares of mangroves subsequently died or totally defoliated in heavily oiled areas. There was a significant loss of birdlife. About 500 birds were affected, of which 300 required treatment. Species affected were mostly: cormorants, pelicans, terns, grebes, herons and ducks.

Two other ship-based events in Australasia (MV Iron Baron, Tasmania in 1995 (Giese et al. 2000, Goldsworthy et al. 2000a, b), and MV Rena in New Zealand in 2011 (Sievwright 2014, Chilvers et al. 2015) impacted numerous seabirds. When the Montara well spill (August 2009) in the Timor Sea released crude oil and gas condensate, 16 individual seabirds (noddies, shearwater, frigatebird and booby) were collected (Watson et al. 2009; Gagnon and Rawson 2010).

Heavy metals

The bio-accumulation of heavy metals in seabirds in the Australian region is complex as natural levels of some metals may be relatively high particularly in some fish species (Denton and Breck 1981; Lyle 1984). A study of levels of lead, mercury and cadmium in tropical terns in Australia (Burger and Gochfeld 1991) showed that levels of lead and mercury were highest in Black Noddy and cadmium levels were highest for Common Noddy and Sooty Tern and lowest for Black Noddy. The data indicates that levels of these heavy metals in tropical terns in Australia are similar to, or higher than, those reported from birds in temperate areas subject to industrial pollution.