Coral reefs are expert record keepers. Corals build their calcium homes in layers that accumulate over decades or even millennia, and differences between these layers can reveal a lot about a reef’s history. Much like analyzing tree rings, these layers can tell stories about the corals’ health, and how environmental conditions changed over time.
By tapping into a coral reef’s storytelling ability, a team of researchers has unlocked a 56-year record of sewage discharge off Guam, an American territory in the northwest Pacific. The record reflects changing patterns of discharge as the island’s population grew, and echoes periods when the local waste treatment plant was inoperative.
Aside from the Guam-specific record, the study shows coral is a sensitive record keeper of changes in sewage runoff, and could even be used to study historical pollution levels.
Photo: Roderick Eime/Flickr (CC BY 2.0)
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