15 December 2013
Source: Science Codex
Long-lived deep-sea corals preserve evidence of a major shift in the open Pacific Ocean ecosystem since around 1850, according to a study by researchers at the University of California, Santa Cruz.
The findings, published December 15 in Nature, indicate that changes at the base of the marine food web observed in recent decades in the North Pacific Subtropical Gyre may have begun more than 150 years ago at the end of the Little Ice Age.
Deep-sea corals are colonial organisms that can live for thousands of years, feeding on organic matter that rains down from the upper levels of the ocean. The corals' branching, tree-like skeletons are composed of a hard protein material that incorporates chemical signatures from their food sources. As a result, changes in the composition of the growth layers in deep-sea corals reflect changes in the organisms that lived in the surface waters at the time each layer formed.
"They're like living sediment traps, recording long-term changes in the open ocean that we can't see any other way," said coauthor Matthew McCarthy, professor of ocean sciences at UC Santa Cruz.