Current wetlands restoration may backfire
28 Jul 2010
When Hurricane Katrina tore across the Mississippi delta in 2005, it tore up wetlands—but some fared better than others, a new study shows. Wetlands in areas with saltier water—generally nearer the coast—survived better, whereas in wetlands with fresher water, the plants were torn up by their roots and suffered widespread erosion.
As I wrote about in an article in Nature Reports Climate Change, “Working With Water”, there are efforts underway now to release more river water upstream, to flow through these wetlands with the aim of restoring them.
But, the study suggests, this may shift the wetlands toward the more vulnerable, fresh water form, setting them up for more destruction during future hurricanes. As the authors put it: “The dramatic difference in resiliency of fresh versus more saline marshes suggests that the introduction of freshwater to marshes as part of restoration efforts may therefore weaken existing wetlands rendering them vulnerable to hurricanes.”
If that’s so, then this factor has to be weighed up against all the others. Wetlands in many places are dying because they don’t get enough water and nutrients from upstream. So even with this new factor, then restoration with fresh water might still be better than not doing anything. But perhaps there are other ways—and which are still affordable—to rebuild resilient wetlands.
The study: “Hurricane-induced failure of low salinity wetlands”, Proceedings of the National Academy of Sciences, 26 July 2010. (The paper is open-access, available for free.)