Researchers have confirmed the presence of organic contaminants in the blood of southern giant petrels in several colonies in the Antarctic Peninsula. Studies of carcasses and other tissues had already detected signs of contamination. These have now been confirmed using blood samples, indicating the presence of several harmful substances, including DDT, a pesticide banned in the United States in 1972 when it was found to endanger the survival of several species of predatory and fish-eating birds.
The study was performed by Fernanda Imperatrice Colabuono, a biologist at the University of São Paulo’s Oceanographic Institute (IO-USP). Colabuono studied colonies of southern giant petrels on Elephant and Livingston Islands, part of the South Shetlands off the coast of Antarctica in the southern Atlantic Ocean. She was supported by FAPESP with a postdoc scholarship and a research internship scholarship abroad.
The research project was also supported by Vale do Rio dos Sinos University (UNISINOS) and the US National Institute of Standards & Technology (NIST). The Brazilian Antarctic Program provided logistical support.
The southern giant petrel (Macronectes giganteus) is a magnificent bird and an important apex predator in the South Atlantic and Southern Ocean. With a wingspan of about two meters, it is one of the planet’s largest flying birds, behind only the albatross and the condor. Another striking feature of the species is its longevity: southern giant petrels can live for more than 50 years.
They spend their relatively long lives in the sky over the Southern Ocean looking for food. During the mating season in the austral summer, they return to their birthplace. This is useful for biologists who study the species as ringed individuals can be tracked for many years.
Having collected blood samples from 113 of these birds during consecutive breeding seasons (November 2011, and November 2012 until February 2013), Colabuono detected the presence of several organic contaminants, such as polychlorinated biphenyls (PCBs), hexachlorobenzene (HCB), pentachlorobenzene (PeCB), dichlorodiphenyltrichloroethane and derivatives (DDTs), chlordane (another pesticide, banned in the US in 1998), and Mirex (used in the northern and southern hemispheres to combat ants and termites and as a flame retardant – banned in 1978 in the US and recently in Brazil).
According to Colabuono, all these organic pollutants are persistent in the environment, are carcinogenic, and cause hormone dysfunction and reproductive problems. The results of the study were published in an article in Environmental Pollution.
The levels of contamination detected in these birds of the Antarctic Peninsula are low compared with those detected in birds of the northern hemisphere, Colabuono said, but long-term monitoring is now the prime objective “to determine whether the levels of the contaminants are rising or falling in the environment that provides their habitat”.
DDT is transported by the air and by rain, polluting rivers and lakes and accumulates in the food chain. Fish eat contaminated insects and are eaten in turn by other predators. The levels of DDT in tissue increase with every step up the food chain.
The damage done by DDT is especially visible in apex predators at the top of the chain. The southern giant petrel is one of these types of predators. It feeds on fish, squid and carrion, including the carcasses of other birds. The levels of contaminants in its body build up constantly as it eats hundreds of pounds of contaminated fish throughout its long life.
The same situation arose for the peregrine falcon and California condor in the US, where populations of these birds began to decline dramatically in the 1960s. Only a few hundred condors were left at one point, taking the species to the brink of extinction.
Then, the role of DDT in this tragedy was discovered. The pesticide accumulated in adult females and their eggshells, which became thin and brittle, endangering the reproduction of the species. DDT manufacturing, marketing and use were all banned in 1972. The peregrine and condor populations have gradually recovered.
Brazil is currently the world’s largest consumer of agrochemicals. Its National Health Surveillance Agency (ANVISA) only banned the use of DDT in 2009, and DDT’s persistence in the environment means it is still detected in the tissue of animals like the southern giant petrel. Hence Colabuono’s determination to track these birds for as long a period as possible.
The article “Persistent organic pollutants in blood samples of Southern Giant Petrels (Macronectes giganteus) from the South Shetland Islands, Antarctica” by Fernanda I. Colabuono, Stacy S. Vander Pol, Kevin M. Huncik, Satie Taniguchi, Maria V. Petry, John R. Kucklick and Rosalinda C. Montone, published in Environmental Pollution, can be retrieved fromwww.sciencedirect.com/science/article/pii/S0269749116304298.