Wetlands Face Multiple Theats From People.

Humans Threaten Wetlands' Ability to Cope with Sea Level Rise

Wetlands can usually cope when it comes to sea level rise. They can move further inland over time, adapting to changing conditions. Despite this resiliency, though, it seems as if wetlands may be in danger. Scientists have revealed that humans may be sabotaging some of their best defenses against sea level rise...

"Tidal marsh plants are amazing ecosystem engineers that can raise themselves upward if they remain healthy, and especially if there is sediment in the water," said Patrick Megonigal, one of the researchers, in a news release. "They would either build vertically at faster rates or else move inland to slightly higher elevations. But now we have to decide whether we'll let them."

Tidal marshes build up their soils when water floods the marshes during high tide. This water brings sediment with it, which then is trapped by the plants and adds new soil to the ground. This means that when sea level rise accelerates and flooding occurs more often, more soil can be added more quickly. Yet everything has a threshold; if a wetland becomes so flooded that vegetation dies off, then the positive feedback loops are lost.

People do lots of things that can mess up the balance, dike and drain the wetlands which slows the return of sediment to the wetland, pull water, and sometimes even oil out of the ground under the marsh, and cause subsidence, burning the salt marsh grass as an "improvement", and even the "accidental" introduction of an invasive species like the Nutria, which simply eats up all the marsh grass responsible for the bulk of the marsh rebirth.

It's good to see an article with a realistic look at the problems facing salt marshes, and not the monotonic focus on climate change and sea level rise that we've seen over the course of the last several years.