Marine life, seafood, environment: Report details impacts of Bonnet Carre Spillway on the Mississippi Sound

A task force appointed by the governor released an updated report Tuesday detailing its efforts to monitor conditions in the Mississippi Sound.
Updated: Jun. 26, 2019 at 6:47 AM CDT
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SOUTH MISSISSIPPI (WLOX) - A task force appointed by Mississippi’s governor released an updated report Tuesday detailing its efforts to monitor conditions in the Mississippi Sound.

With the Bonnet Carre Spillway having been open for a record 50 days and dangerous algae blooms forming along part of the coast, experts from various agencies are working to report data to Gov. Phil Bryant.

The task force is made up of various environmental agencies, including Department of Marine Resources, Department of Environmental Quality, researchers from University of Southern Mississippi, and marine life experts from Institute of Marine Mammal Studies and Mississippi State University.

One of the goals of the task force is to make their data public to inform the public about the current conditions and their effects.

“That level of transparency is really critical, that’s one thing we learned in the oil spill was making sure that the public was at least engaged in the process,” said Dr. Monty Graham, the director of USM School of Ocean Science and Engineering.

Marine Life

According to the Institute for Marine Mammal Studies and Mississippi State University, the frequency of dolphin and turtle strandings has decreased considerably in June. For the week of June 16, no dead dolphins and only one dead sea turtle were reported. A total of 130 dolphins and 156 sea turtles have been found dead along the Mississippi coastline this year.


Shrimp season was opened last week by the state's Commission on Marine Resources, who voted to open the season despite the legal benchmark of 68 shrimp per pound not having been met. On June 20 when the season first opened, 133 shrimp boats fished in Mississippi waters and shrimpers indicated the overall catch was low. Brown shrimp in state monitoring trawls is down more than 82 percent over the past four weeks compared to the prior 5-year average.

Oyster aquaculture experiment suffers damage from spillway fresh water
Oyster aquaculture experiment suffers damage from spillway fresh water(Photo Source: WLOX)

Based on MDMR sampling for the week of June 10, oyster mortality on Mississippi harvest reefs was higher than 90 percent for all reefs except for Pass Marianne. Oyster mortality on the reefs have continued to increase as the spillway remains open.

While commercial landings of blue crab were down February through April compared to the prior five-year average, landings in May increased and were similar to the prior five years.

“MDMR continues to monitor Mississippi waters and the effects from the Bonnet Carré Spillway,” said MDMR Executive Director Joe Spraggins. “The Mississippi Department of Environmental Quality recently issued beach closures in Hancock and Harrison Counties due to an algal bloom on the surface of the water. MDEQ advises people, and their pets, to avoid contact, including swimming, with the blue-green algae because exposure can be harmful. MDMR also advises the public to not eat fish or any other seafood taken from any affected waters or in proximity to the beach closures. The public’s safety is very important to our state and our agency will continue working closely with MDEQ to monitor our waters and our seafood.”


Scientists at the USM School of Ocean Science and Engineering have been using models to monitor salinity levels.

While salinity levels started to increase mid-June, USM researchers found that salinity levels in the Mississippi Sound continued to decrease again as winds pushed surface waters to the north entrapping flow from the spillway.

“This week the winds have come back around from the south as we expected the salinities have dropped back down that’s because those fresh waters are being pushed up against the coast," said Dr. Graham.

USM researchers also conducted an expedited seagrass survey at Cat Island on June 17. Although the seagrass did not appear to be stressed, researchers observed the introduction of a low salinity species known as widgeon grass since monitoring began at these stations in 2011.

“USM is providing a very capable skillset that joins satellite oceanography, modeling of currents and ocean chemistry with our expertise fisheries monitoring,” said Dr. Graham. “Our scientists are using sophisticated approaches to understand and predict how wind and freshwater interact in the Mississippi Sound. While this is a complex system, it is not beyond our capacity to unravel ongoing and future impacts to our coastal waters and resources.”

What is blue-green algae and what are the impacts?

What’s Next

The next series of updates will feature chemistry data. According to the researchers, it’s being quality checked and will give them a pretty good insight about the water that is mixing in the sound.

“This is an important update,” said Gov. Bryant. “Real time information is critical as we work to examine the adverse effects of Bonnet Carré. "I appreciate the continued effort undertaken by the Department of Marine Resources and our partners in academia as we work to protect and preserve our marine resources.”

For questions, concerns or to report activity, USM urges the public to use their new Bonnet Carré Spillway Hotline at 228-818-8099. USM has also developed a website to post updates and photos on the latest with the Bonnet Carré Spillway research projects. You can reach it by clicking HERE.

Governor Bryant's Task Force is continuing to track the impact of the Bonnet Carré Spillway opening on the Mississippi Sound.

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