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The Florida Keys marine environment likely will need decades to recover from Hurricane Irma, scientists told marine advisers.

Mangrove forests that lay in the Lower Keys path of Irma endured “extensive canopy damage from high winds,” typically losing more than half their canopy cover, Kara Radabaugh of the Florida Fish and Wildlife Conservation Commission said in a briefing to the Sanctuary Advisory Council, meeting in Marathon.

Mangroves that once had 85 to 100 percent canopy cover were left with about 40 percent cover, she said, noting that larger trees took the most severe hits.

Professor Jim Fourqurean, director of the Center for Coastal Oceans Research, told the council that the recovery rate for Florida Bay seagrass has been largely established at a quarter-century.

Following a seagrass die-off in the 1980s, Fourqurean said, monitoring showed “it takes about 25 years for seagrasses in Florida Bay just to get back to where they were before the die-off event. And that was the year we had another die-off event.”

Following Irma, water quality measurements revealed “really high, almost unbelievably high, chlorophyll concentrations” in the bay.

“After the hurricane we had a big algal bloom, but it’s calmed down and seems to be heading back to normal. Current trends show improvement. Water quality impacts have largely subsided,” Fourqurean said. “We know there are still algae blooms floating around the bayside.”

In the Lower Keys backcountry where Irma crossed, “significant decreases in seagrass biomass” were recorded, he said. Many of these areas were similarly affected by Hurricane Georges in 1998.

“Many sites that were devastated by Georges in 1998 also were impacted by Irma,” Fourqurean said. “Georges and Irma had almost the same track. … I’m sure all of you know a place where there was grass patch but isn’t there now.”

Staff with the Florida Keys National Marine Sanctuary reported the current timeline for release of the sanctuary management plan’s draft environmental impact statement, which will outline possible alternatives and the effects of each, points toward “late spring.”

Read the Keys News post for the full story.