34Wildlife Conservation Plan for Seabirds

34 Wildlife Conservation Plan for Seabirds

Heavy metal pollution has been an issue in the Adelaide metropolitan area and outside the upper Spencer Gulf (EPA 2004). Heavy metal contamination is known in marine mammals in South Australia’s gulfs, particularly cadmium which is assumed to be related to emissions from the Port Pirie smelter (Kemper et al. 1994). However, there is limited research on effects on seabirds in South Australia.

Wildlife exposure to metal contaminants may correlate with local anthropogenic emissions. Mott et al. (2017) investigated the feather mercury concentrations of adult and juvenile Lesser Frigatebirds (Fregata ariel) and Great Frigatebirds (F. minor) breeding in the eastern Indian Ocean. Low mercury concentration in juveniles relative to adults, higher mercury concentration in adult females than adult males, and a trend for Lesser Frigatebirds to have higher mercury concentration than Great Frigatebirds implicated non-breeding ground exposure as the major influence on mercury burden. The authors noted that aspects of the frigatebird foraging ecology were consistent with high exposure occurring in inshore waters of the non-breeding range, particularly in the South China Sea.

Seabirds (Fairy Prions, Pachyptila turtur) off Tasmania are known to have significantly higher cadmium levels in areas close to the source of cadmium pollution (Kemper, et al. 1994). Lavers and Bond (2013) detailed contaminant loads in Short-tailed Shearwaters, and recent studies in Tasmania and Western Australia in Little Penguins (Einoder et al. 2018; Dunlop et al unpublished data) showed high metal levels in penguin feathers from historical industrial discharges in estuarine environments.

In Western Australia, a study on Caspian Terns showed that most breeding adults had elevated levels of mercury in their tail feathers (mean 2.27 mg/kg) (Dunlop and McNeill 2017). Two of the sampled Caspian Terns had feather mercury levels above the threshold considered capable of producing deleterious effects (5 mg/kg, Burger & Gochfeld 2004); four individuals registered above 4 mg/kg (Dunlop and McNeill 2017). One bird with a feather mercury of 5.8 mg/kg was observed dying on the Peel Inlet three months after sampling, with symptoms consistent with nervous disintegration caused by mercury intoxication (Burger & Gochfeld 2004; Dunlop and McNeill 2017). These observations indicate that the Caspian Terns foraging in the southern metropolitan coastal waters of Perth may well be subject to an elevated level of mercury exposure (Dunlop and McNeill 2017). High mercury exposure would appear to be related to the increased eutrophication in these aquatic ecosystems.

The release of mercury from permafrost regions in the Arctic are likely to impact Arctic breeding seabirds that migrate to Australia. The extent to which the bio-accumulation of heavy metals reflects anthropogenic or geological sources and the role of the food chain requires further investigation in other species that breed in and migrate to Australia.

Aquaculture

The use of coastal land and nearshore waters for various types of aquaculture may have adverse consequences for a number of species. Few major problems have yet been experienced in Australia, but in South-East Asia, where aquaculture is a major industry, species such as cormorants become regarded as pest and integrated land-use planning is essential (White 1984).

In Australia, the largest aquaculture industries are present in Tasmania and South Australia. The tuna aquaculture venture using cages off Port Lincoln in South Australia has been attributed to increases in the number of Silver Gulls through the provision of food (Ross et al. 1996). Bacteriological discharges from aquaculture facilities may cause adverse problems if concentrations of pathogens are too high. Deaths of seabirds from sewage discharge have been documented in North America (Ankerberg 1984).

Wildlife Conservation Plan for Seabirds 35

The spread of the herpes virus in wild stocks of pilchards, causing mortality impacted

Little Penguins in southern Australia (Murray et al. 2003; Chiaradia et al. 2010).

The herpes virus is thought to have originated in feed used in aquaculture

(Gaughan et al. 2000).

Low levels of entanglement of seabirds and bird strikes (primarily gulls and cormorants)

occasionally resulting in low numbers of mortalities are known from Tasmania.

Current and proposed moves to offshore locations off southeast Tasmania may see

an increased level of interaction with Southern Ocean species such as albatrosses

and petrels.

The Australian Government has developed industry guidance for offshore aquaculture (DEH 2006), which provides specific guidance to the marine-based aquaculture industry to assist proponents to decide whether or not actions which they propose to take require assessment and approval under the EPBC Act.

Disease

Throughout their lifecycle, seabirds can contract a range of diseases such as

Newcastle disease (caused by avian paramyxovirus), avian influenza, avian cholera, and avian pox (Morgan et al. 1981; Weimerskirch 2004; Grimaldi et al. 2011;

Uhart et al. 2018). Infectious diseases have the potential to cause rapid decreases in seabird populations and pose a potentially major conservation problem for small or already declining populations.

Because seabirds spend large amounts of time at sea, the impact of diseases on seabirds is perhaps more difficult to detect than in terrestrial environments. Fortunately, in Australia no major disease outbreak causing mass mortality has been reported. Elsewhere, the global spread of avian cholera has been partly held responsible for the decline of Indian Yellow-nosed Albatross (Thalassarche carteri) and could be threatening other seabirds on Amsterdam Island in the Southern Ocean (Weimerskirch 2004).

Malaria-like blood parasites have been detected in some Little Penguin populations in Western Australia (Cannell 2013) and South Australia (Colombelli-Négrel, 2016), and noted worldwide in penguin populations (Grilo et al 2016). In Little Penguin colonies monitored across the Gulf St Vincent, South Australia, blood parasites (Haemoproteus and Plasmodium spp.) were identified in 86 per cent of the individuals sampled and individuals with multiple infections had longer bills than those with single infection or non-infected individuals. A South Australian penguin monitoring program recorded Little Penguin mortality from multiple organ failure directly related to blood parasites (Tomo and Kemper 2016). There is a need to identify parasite infections, viruses and vectors across colonies to better assess their impact on population trends.

In Australia, the National Avian Influenza Wild Bird (NAIWB) Steering Group was established in January 2006 to facilitate collaboration between State and Territory programs and non-government organisations undertaking surveillance for avian influenza. Primary Industry agencies agreed to strengthen national surveillance for avian influenza in both poultry and wild birds.

Activities under the NAIWB Surveillance Program are conducted Australia- wide. The Program has two main components: Targeted surveillance: pathogen-specific, risk-based surveillance via convenience sampling of apparently healthy, live and hunter-killed wild birds; and General (passive) surveillance: investigation of significant, unexplained morbidity / mortality events in wild birds, including captive and wild birds within zoo grounds. During 2017, targeted surveillance activities included testing of samples for avian paramyxoviruses (APMVs), predominantly targeting APMV-1.