Back in the 1950s, when our family visited Cape Cod, my father described the ocean as too big to get polluted. There were only 3 billion or so humans occupying the planet then, and he may have been right. The oceans offered a place of infinite dilution.
But today, the human population has more than doubled, and the oceans are showing signs of human impacts. We don’t have a vast stock of old seawater samples for comparison, but seabirds have done our sampling for us.
When museum specimens of seabirds and seabird eggs – some collected more than a century ago – are compared to their modern counterparts, they show dramatic increases in mercury, organic compounds, and other industrial byproducts. Some of these pollutants are only created by humans, so when they show up in seabirds, we know they came from us.
Seabirds forage over vast areas. Pollutants accumulate in their fatty tissues from the fishes that they consume. A recent analysis of feathers from black-footed albatross collected over a 120-year period to show significant increases in methylmercury in the Pacific Ocean.
Degradation products from DDT peaked in 1970, when the use of DDT was severely restricted. In contrast, polybrominated diphenyl ethers—newly developed flame retardants—started increasing in the 1990s, as seen in samples from auklets from an island in northwestern Canada.
Seabirds act as proxies for what is happening to the marine environment, which is certainly cause for concern. The effluents of modern society are beginning to show up in measurable quantities in the ocean.
No living creature can escape the fingerprint of people on planet Earth.
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Photo, taken on January 28, 2009, courtesy of Pete Markham via Flickr.
Earth Wise is a production of WAMC Northeast Public Radio. Support for Earth Wise comes from the Cary Institute of Ecosystem Studies in Millbrook, NY.