Drought poses greater long-term threat to wetlands than hurricanes

Higher salinity levels caused by drought may be a bigger long-term threat to Louisiana’s wetlands than salinity storm surges from hurricanes.

The findings are part of research by Nicholas Lonergan, a graduate research assistant in the College of the Coast & Environment (CCE), John White, CCE associate dean of research, and Christopher Potter, a senior research scientist at NASA Ames Research Center.

“The 2023 drought was as severe as the drought of 2000 that affected more than 100,000 hectares of marsh and severely damaged 43,000 hectares,” White said. “We combined salinity data from the 390 stations in the state’s Coastwide Reference Monitoring System (CRMS) with satellite imaging from NASA, which captured marsh browning due to the lack of rain. We determined drought-driven hypersalinity events could lead to faster wetlands loss and coastal erosion than salinity from hurricane storm surge."

The CRMS data showed the increase in salinity levels from the 2023 drought was twice or three times as high in salt and brackish marsh compared to Hurricane Isaac. In fresh marsh, the difference was even greater: 10 times that from the hurricane.

White said Louisiana's fresh marsh vegetation can't adapt to higher levels of salt in the water. In that, they are much like people.

“If people drink saltwater, we don’t do well. We get sick. It’s the same for these types of plants,” White said.

The researchers believe their findings can act as an early warning system, enabling state and federal agencies to take action to try to offset damage to the coast's most at-risk areas.

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