Sept. hurricane ravaged reefs in the Bahamas, researchers find

When Hurricane Dorian slammed into the Bahamas in September, it not only leveled entire communities and killed dozens of people, it also destroyed about 30 percent of the coral reefs around the islands, according to a report issued Friday by the Perry Institute for Marine Science.

“We saw on several reefs that a significant amount of corals were broken, rolled around on the bottom and killed, or just smashed up to the point that the actual structure of the reef itself was reduced to rubble,” said Craig Dahlgren, lead researcher at the Perry Institute, which has been examining effects of the hurricane since October.

Reef structures the size of small cars were dislodged or buried in debris, mud and sediment several feet deep, in some instances, Dahlgren said.

Reef diving and snorkeling are an important part of the country’s tourism industry, which accounts for some 50 percent of its gross domestic product.

Even before Dorian, the reefs were in jeopardy. In 2016, the Perry Institute, based in Waitsfield, Vt., found reefs in the Bahamas to be under stress and classified them as impaired, the category just above poor.

Healthy reefs are vital to marine ecosystems in the area, and the storm damage appears to have hit the country’s fisheries as well. Dahlgren’s team reported a significant decline in fish populations linked to habitat damage.

In addition to extremely turbulent waters, Dorian brought a surge of rainwater that changed sea salinity. The storm also caused water temperatures to fluctuate rapidly — both conditions that quite likely shocked the corals, according to researchers.

But the report’s news was not all bad. “We did see some areas that came out of it looking almost untouched, amazingly,” Dahlgren said. “The patterns of damage that we saw were not consistent. You could have reefs that were a few miles apart. One would be totally destroyed, and the other, you couldn’t even tell a hurricane was there.”

Some of the fragmented corals could be regrown in nurseries and then reattached to dead pieces to replenish them. But that would take time, as some species take many years to grow.