Chronic oil pollution harms Magellanic penguins in the Southwest Atlantic
Introduction
Petroleum is one of the most common toxic substances released into the marine environment with chronic petroleum pollution (small but frequent oil discharges) accounting for most petroleum pollution in the ocean (USNRC, 2003). However, because accidental discharges of oil receive considerable media attention, the public perceives those oil spills as extremely damaging to natural systems (Hunt, 1987, Boersma et al., 1995, Parrish and Boersma, 1995), but remains largely unaware of chronic petroleum pollution.
Seabirds are one of the most vulnerable groups of marine animals affected by oil pollution (Clark, 1984, Dunnet, 1987, Piatt et al., 1990). Penguins are particularly vulnerable to oil spills because they swim low in the water, do not fly, and likely are less able to detect and avoid petroleum than other seabirds. When the Apollo Sea sank in 1994 off Cape Town, South Africa, spilling about 2,000 tons of petroleum, 10,000 African penguins (Spheniscus demersus) were oiled (IBRRC, 2005). Similarly when the Treasure sank in 2000 near Cape Town, South Africa, spilling 1300 tons of bunker oil, 20,000 African penguins were affected, and another 19,500 were prevented from becoming oiled because they were moved 800 km from the spill site (Nel and Whittington, 2003, IBRRC, 2005). Impacts of oil spills on seabirds often are better documented than exposures to chronic discharge (from ships, at terminals, or from oily ballast water). However, in the case of Argentina there are long-term records documenting chronic oil pollution and its effects on penguins along the Chubut coast (Gandini et al., 1994).
Oiling of penguins is likely a common problem wherever tankers and penguins mix. Residues and oily sludge from ship’s bunker tanks killed or harmed about 350 Little penguins (Eudyptula minor) yearly at Phillip Island, Australia (Revill and Healy, 1999). One of the best documentations of how vulnerable penguins are to petroleum discharge is the chronic pollution problem along the coast of Argentina. For decades chronic oil pollution killed Magellanic penguins in Argentina (Jehl, 1974, Jehl, 1975, Korschenewski, 1975, Jenkins, 1978, Perkins, 1983, Boersma, 1987, Knaus, 1990, Gandini et al., 1994) and more recently has been documented as a problem in Brazil (Petry and Fonseca, 2002, Petry et al., 2004). Gandini et al. (1994) estimated over 40,000 Magellanic penguins (Spheniscus magellanicus) were killed each year by chronic oil pollution along the coast of Chubut Province, Argentina, from 1982 to 1991. In 1994 tanker lanes were moved 100 km farther offshore and few penguins are now found dead with petroleum along the Chubut coast (Boersma, unpublished data).
Magellanic penguins migrate between Argentina and Brazil in the Atlantic Ocean on routes that can overlap with heavy maritime traffic and petroleum development (Stokes et al., 1998, Pütz et al., 2000). Our goal was to assess the location, nature and magnitude of the chronic oil pollution problem for Magellanic penguins along the Southwest Atlantic coast in their wintering range, where little information is available. If chronic oil pollution is a serious problem, we expected there would be a number of rehabilitation groups dedicated to washing seabirds. Further, we predicted that more groups would be located in areas where the problem was chronic. Here, we document the location and number of rehabilitation groups for seabirds along the Southwest Atlantic coastline from northern Brazil to central Argentina to use them as an index of the extent and nature of chronic oil pollution. We report the number of penguins collected alive by four rehabilitation groups along the coast of northern Argentina to Southern Brazil.
Section snippets
Methods
We searched for organizations that counted oiled seabirds and/or rehabilitated them from Fortaleza, Brazil (3°46′S, 38°33′W) to San Antonio Oeste (40°47′S, 64°47′W), Argentina, covering approximately 8200 km of coastline (Fig. 1). We contacted nongovernmental organizations (NGOs), governmental agencies, research institutions, museums, rehabilitation centers, aquariums and zoos, and compiled a directory of these organizations. We concentrated on penguins instead of all seabirds because penguins
Results
Twenty five groups from Salvador, Brazil (12°58′S, 38°29′W) to San Antonio Oeste, Argentina (40°43′S, 64°55′W) survey or rehabilitate sick or oiled seabirds along 6800 km of coastline (Table 1, Fig. 1). Nineteen solely rehabilitate birds, three only survey beaches and four groups do both (Table 1). The oldest group started in Mar del Plata, Argentina, in 1980. All groups reported finding penguins with petroleum and said penguins were most common on the coast in winter (June to September). By far
Discussion
Penguins are brought to rehabilitation centers along the Southwest Atlantic coast every year during their non-breeding season and the majority of them are oiled. Petroleum pollution along this coast is not a new problem as rehabilitation groups have existed for more than 20 years. Clearly, chronic pollution is not new and is a long-term problem from northern Argentina to Southern Brazil. Existing laws and enforcement have failed to solve the pollution problem in the Southwest Atlantic. The
Acknowledgements
We thank all our contacts at the organizations involved in Argentina, Uruguay and Brazil who provided information. Support was provided by the Wildlife Conservation Society, the Wadsworth Endowment for Conservation Science, Friends of the Penguins, Centro Nacional Patagónico (CONICET), and the University of Washington. We are indebted to the Prefectura Naval Argentina for helping us gather the data for the Argentina exploration trends, and to Patricia dell’Arciprete and María Rosa Marín for
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