It’s A Waterbird Wasteland

Maybe sewage could offer salvation. Wetlands built to filter sewage and polluted runoff have become essential habitat for some of the world’s endangered waterbirds, but pose disease risks and other problems. Now, two recent studies offer some insight into the potential conservation promise – and peril – of artificial swamps.

One of the studies, published online on August 26 by Environmental Science & Technology, reviews the 50-year history of building wetlands to purify water. Humans have dumped waste into nearby mires, marshes and bogs for centuries, notes Jan Vymazal of the Czech University of Life Sciences in Prague. In 1901, an inventor even filed a U.S. patent on the idea using them as cleaners. It wasn’t until the 1950s, however, that a German scientist named Kathe Seidel began systematic experiments. By the 1960s, builders in Europe and North America were beginning to specifically engineer wet areas to handle waste. Since then, the technology has spread and evolved; various types of constructed wetlands are now used to treat everything from municipal sewage to effluents from tanneries, wineries and shrimp farms.

These artificial habitats have become increasingly important to waterbirds as natural wetlands have been drained and filled, Christopher G. Murray and Andrew J. Hamilton of the University of Melbourne, Australia, note in the October issue of the Journal of Applied Ecology. In dry regions, for instance, they may provide the best available nesting and feeding grounds. “But they are not without risks,” Murray and Hamilton write. “Waterbirds may adversely affect the water treatment process and may act as vectors of human disease, whilst wastewater treatment wetlands could potentially have detrimental impacts on waterbird health due to pathogens, heavy metals, chemical contaminants and human disturbance.” What’s needed, they say, is more systematic study of just how waste-treatment wetlands could be designed to optimize both public health and conservation uses. In particular, artificial wetlands could provide attractive “win-win” benefits in places like Asia and Africa, which have both big needs for water treatment, and a large number of at-risk waterbird species. – David Malakoff

Sources: Vymazal, J. (2010). Constructed Wetlands for Wastewater Treatment: Five Decades of Experience. Environmental Science & Technology DOI: 10.1021/es101403q

Murray, C., & Hamilton, A. (2010). REVIEW: Perspectives on wastewater treatment wetlands and waterbird conservation. Journal of Applied Ecology, 47 (5), 976-985 DOI: 10.1111/j.1365-2664.2010.01853.x

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