Scientists Reconstruct Coral Decline and Recovery Timeline for Hawaiian Chain

Land-based human events had dramatic impact on health of coral reefs

Written by
John Virata

A study in the scientific journal PLoS One points to human changes to a coral reef ecosystem can often be attributed to what occurs on land. Scientists with the Institute for Ocean Conservation Science at Stony Brook University studied the interaction of Hawaiians and the coral reefs surrounding the main island chain as well as the Northwest Hawaiian Islands over the course of some 700 years.

The scientists used detailed datasets of the region’s ecological conditions, proximate anthropogenic stressor regimes (overexploitation, disease, invasive species, land-based pollution and the threats resulting from climate change), and social change, according to the study, to detail the health of Hawaii’s coral reefs. They then reconstructed a timeline of the Hawaiians and their relationships with coral reefs to look for changes in the seascapes. The reconstruction covers 700 years on the timeline, in which the scientists correlate coral reef decline and recovery with specific incidences occurring on land.

The study points to a high rate of coral reef exploitation after the settlement of Polynesians on the islands more that 700 years ago that was later curbed after the domestication of land animals, which became the Hawaiian’s main source of protein, around the year 1400. This, coupled with the Native Hawaiians employing their own conservation efforts, as well as deaths of large populations of Hawaiians due to the introduction of Western disease, in which Hawaiians had no immunity, helped coral reefs to periodically recover. Other economic and sociological changes that resulted in coral reef recovery included the re-direction of reef fishing labor to other pursuits such as whaling and trading.

The reefs then experienced a decline in the mid to late 1800s due again to overexploitation and land based pollution and other factors such as a change in Hawaii’s economic social systems, demographics, and new technologies. The Hawaiian reef system since the late 1800s is experiencing a continued decline, with the exception of the time during World War II, when the reefs and beaches were closed to most human contact.

Reefs in the main Hawaiian Islands have been declining for more than 150 years, and similar degradation that has occurred in other reef ecosystems indicates that we may be approaching a tipping point or threshold, beyond which recovery is doubtful, Dr. John N. Kittinger, lead author of the study told Green Magazine Hawaii. If we look at historical ecosystem recoveries, reversing this decline will require protection of a broad range of habitat types over large areas, such as marine no-take reserves. Additionally, appropriate institutions and policies will need to be in place to effectively engage the diverse community of ocean-users in Hawai’i in collaborative marine ecosystem stewardship, he said.

The full report can be read at the PLoS One website

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Fish · Saltwater Fish