Ocean Change and Beach Health

— Written by Megan Guidry

Sand beach habitat across the street from the lab

I’ve escaped the Louisiana heat for a summer in sunny California. In a shocking turn of events, I, once a child who despised sand and all of its clingy properties, have ended up in a sandy beach ecology lab for the summer. My project focuses on how grain size effects the burrowing abilities of endemic beach invertebrates (sand/mole crabs, beach hoppers, clams, and even worms).  These highly mobile little creatures need to move constantly to adjust to ever shifting waves and tides and must burrow quickly in the sand to protect themselves from predators, waves, sun and desiccation.

Sand crab on top of the sand and furiously scurrying/swimming away- a rare sighting.

As beaches erode and sea level rises, humans are filling many beaches with imported sediment, which is, in most cases, a different size and type than the natural, local sand the animals are used to. The introduction of new non-native sediment can alter beach ecosystems and cause ecological change both at the original beach and downcoast where the new sand moves. A previous study suggested that the burrowing creatures of beaches have a hard time burrowing into the muddy sand added from salt marsh channel dredging which affected their ability to survive on a filled beach. My project will test the other end of the sediment size spectrum and compare burrowing times of these animals in natural sand and in coarse poorly graded sand.            

Burrowing success and resulting health of these spineless creatures at the base of the food web could be the key to maintaining healthy beach ecosystems as a whole. More knowledge about how filling in disappearing beaches can alter beach ecosystem diversity and productivity will help us inform decisions about adapting to shoreline change and conserving these dynamic coastal ecosystems.

Beach hopper “playing dead” before jumping across the sand

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