Human Influence Changes Open-Ocean Food Chain: Seabird Bones Study
The bones of generation seabirds have helped scientists figure out a dramatic change in the ocean's food web. Hawaiian petrels are known to spend most of their lives foraging the open waters of the Pacific Ocean, from the equator to Alaska's Aleutian Islands. But, they find shelter in caves and burrows, and if they die there their bones are preserved.
Scientists from Michigan State University and the Smithsonian Institution studied a collection of more than 17,000 petrel remains. The study was intended to measure the ratio of nitrogen isotopes and unique molecules so as to find what and where on the food chain the birds were eating.
The study is published in The Proceedings of the National Academy of Sciences. Co- author Peggy Ostrom said that petrels fed on large prey such as squid and crustaceans between 100 and 4,000 years ago. However, as fishing operations began to move beyond the continental shelf in the mid-20th century, the birds began to rely on smaller fish and other prey.
The Hawaiian petrel is an endangered species and researchers concluded that open-ocean food webs have experienced a change on a large scale due to human influence.
Ostrom said, "The team's study is one of the first to explore whether fishing has gone beyond an influence on targeted species to affect non-target species and potentially, entire food webs in the open ocean".
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