Thanks to a $76,000 grant from the National Oceanic and Atmospheric Administration, a study by a researcher from the University of San Diego on how sedimentation impacts coral reefs will continue on St. John.
San Diego marine sciences professor Sarah Gray started looking at sedimentation in the waters around St. John in 2007. While that work will continue with this grant, she said it also covers work by Carlos Ramos-Scharron of the University of Texas at Austin, who Gray said studies the runoff that enters each watershed impacting Coral Harbor.
“For the first time there is integration between marine sedimentation and watershed runoff,” she said.
Using Stimulus Funds grants, Gray and her team of students were able to determine that, at some sites in the Coral Harbor waters, sedimentation decreased after the Coral Bay Community Council installed sedimentation ponds, repaired roads and did other work to cut down on the amount of sediment that runs into Coral Harbor from the steep hillsides that surround it. The restoration work was done between 2009 and 2011.
Since then, there hasn’t been a large amount of rain, a fact that keeps visitors happy but doesn’t help the project.
“There is a lot of variability year to year,” Gray said, adding the $76,000 grant will allow sedimentation monitoring to continue until the end of December so she’s hopeful Coral Harbor will get some heavy rains by then.
“We need one more year so we can compare,” she said.
Gray said the watershed monitoring by Ramos-Scharron will continue until September 2014.
Gray said she was aware the NOAA funding was on its way so San Diego allowed her to start work over the summer. She said things needed to be in place by the start of the fall rainy season and before any possible hurricanes hit.
According to Gray, for the first time scientists will be able correlate what goes down a gut to the sedimentation that ends up in the water. She said Ramos-Scharron installed monitors in guts that drain into Coral Harbor with this goal in mind.
“He’s looking in detail where land is eroding and where the storm water is going in the watershed,” Gray said.
Gray’s work started with evaluating what fell into “cups” placed in the water to collect sediment every 26 days. The $76,000 grant allowed her to install instruments that can give readings every 10 minutes. She said that if there is a storm, it will allow her to study how much turbidity is in the water during the storm.
Gray’s sedimentation work started with a study to compare sedimentation in areas that are developed and not developed. The first sites were at the undeveloped Lameshur Bay area and the developed Fish Bay.
After meeting Coral Bay Community Council President Sharon Coldren, the focus switched to the Coral Harbor area, including some work in Hurricane Hole.
The Community Council continues to provide volunteers and boats to work on the project.
Gray sees that the St. John study provides information that can be applied elsewhere. She said, as far as she knows, sedimentation studies have only been done on the Great Barrier Reef in Australia and in Hawaii.
“There are very few places in the world doing this work,” she said.
Leslie Craig, NOAA’s restoration center supervisor for the southeast region, said land-based sources of pollution are a top priority for the agency.
“Land-based sources of pollution are one of the main impacts to coral reefs,” Craig said, adding that one goal of the funding is to put in place best management practices to help deal with the issue.