The Importance of Barrier Islands

Figure reposted from Sherwood et al. (2014). Link to original source at the end of the post.

This week--well really this weekend--featured barrier islands in full force, so I thought I would dedicate this week's blog to these geographic wonders. Barrier islands, as you may have guessed from their names, are coastal sediment landforms parallel to a coast that act as barriers for shorelines and the communities therein, making them similar to coral reefs. These islands change over time due to wave action and storm surges, which often erode these landforms and change the surrounding ecological communities. Reductions in barrier island structure and stability can lead to increased shoreline erosion, reduce submerged aquatic vegetation biomass, and limits suitable habitat for small fishes and invertebrates that rely on the protection from the islands and the seagrass meadows. I had the pleasure of listening to some researchers speak about what they hope to learn by studying local barrier islands in Mississippi and Louisiana at this past weekend's graduate student symposium. In Mississippi, our shores are protected by a band of four barrier islands--Cat Island, Horn Island, Petit Bois Island, and Ship Island (that really is a few islands)--which support the beachfront real estate, tourism, and fishing aspects of our local economy. We also have the Chandeleur Islands in Louisiana just south of us, which are a set of beautiful barrier islands that form a big protective arc reducing storm surges that may hit the coastal wetlands of Louisiana. However, the Chandeleur Islands are facing a lot of change due to recent major storm events that have altered the stability and morphology of the islands. The figure here from Sherwood et al. (2014) shows changes in the islands modeled after Hurricane Isaac, a category 1 hurricane that made landfall in 2012. As we expect the frequency of severe storms and overall storm intensity to increase, following climate change trends, we need to understand how threatening continued storm activity is for our vulnerable systems. Through attending talks at recent conferences in the area, I learned that there are dredging plans in place to redistribute sediment to some of these barrier islands. However, since dredging is an intensive and not always precise process, since you can't land the sediment exactly where you want it to end up, local monitoring efforts will likely serve as valuable indicators to where management and conservation efforts are most necessary and where the efforts may provide the best outcomes.

I hope this brief overview helps explain the importance of these geographic features, especially if you've never had the chance to get to the Gulf to see these islands. If you want to see a snapshot of more barrier islands and the communities they protect, you can find them on Google Maps if you zoom in on coastal areas you can get some satellite images of these wonders of nature.

References:
Sherwood, C. R., J. W. Long, P. J. Dickhudt, P. S. Dalyander, D. M. Thompson, and N. G. Plant (2014), Inundation of a barrier island (Chandeleur Islands, Louisiana, USA) during a hurricane: Observed water-level gradients and modeled seaward sand transport, J. Geophys. Res. Earth Surf., 119, 1498–1515, doi.org/10.1002/2013JF003069.​

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