Author: Caitlin Kight
Source: Science 2.0 
December 2, 2012
"Although we know that humans have had a significant impact on the environment and the species that dwell within it, we don't always have detailed information on when our influence was first felt, or how the effects of our activities interact with those caused by other types of perturbation. As a result, it can be difficult to establish goals associated with conservation and management efforts. For instance, if we are trying to return an ecosystem to a pre-disturbance baseline, how do we know what that baseline actually is?
To help answer this question for corals in Australia's Great Barrier Reef, a group of researchers recently surveyed both living and dead coral assemblages at three sites around Pelorus Island, an inshore reef located near the outlets of both the Herbert and Burdekin Rivers. Since the late 19th century, when Queensland was colonized by Europeans (and their associated livestock and agricultural crops), the rivers have delivered altered levels of sediments, nutrients, and herbicides to the Australian shore--and the corals located along it. During the recent study, researchers collected paleoecological data in order to determine the impacts of these anthropogenic influences on coral growth.
Specifically, they sent scuba divers underwater to survey both living and dead coral assemblages. The divers noted the identity, percent cover, and growth morphology of the corals. They also gathered samples of dead corals that could later be examined with computed axial tomography (CAT) scans, which can provide information on the age of each coral colony. Finally, the researchers scoured the scientific literature for information on historical climate, weather, and hydrological patterns that might have been associated with fluctuations in coral communities and growth over time."
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