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Dauphin Island (feat. Sea Oats and Jellyfish)

On Friday, October 21st, the VFOB team headed to Dauphin Island to check out the beaches along the west end. As expected for an October morning, the beach was deserted. Despite (or perhaps by virtue of) the lack of people, we were able to observe:

 

  • A sand dune restoration project;
  • Litter, including a rusty spiral staircase; and
  • Dozens of dead jellyfish washed ashore.

 

The dune restoration and the jellyfish piqued our curiosity, so we set to work looking for answers once we returned to the office. Read on to learn some fascinating facts about sand dunes and jellyfish!

 

Dunes

Dauphin Island, like most barrier islands, is prone to erosion and storm damage. In order to address this, the Dauphin Island Beach Restoration Project began in 2005 to restore the dunes in the wake of Hurricane Katrina. The project was further progressed in 2007 when the Bryant Care Technical Center (Bryant CTC) joined the initiative. If you come across the signs they have posted, please abide by them! It is important both to the sustainability of their hard work as well as the sustainability of the dunes that you avoid walking across them.

At first glance, the value of the tall grasses adoring the tops of the dunes appears to be purely aesthetic. However, as we dug deeper (figuratively) we discovered that their importance is much more profound and fascinating.

 

The predominant vegetation throughout the dunes are grasses called “sea oats.” The simplicity of this plant is deceptive; they are actually responsible for creating the dunes. The blades of the sea oats catch grains of blowing sand and over time the sand builds up around the base of the plant, creating a dune. Sea oats, which are native to the Alabama coast, are equipped with a strong horizontal root system, which anchors the sand and sediment in place, effectively preventing erosion. This is the main reason it is essential to include native vegetation when undertaking a dune restoration. In the absence of erosion control, the dunes are quickly gone with the wind. Sea oats are a prime example of a species that is essential to the health and sustainability of an ecosystem. Additionally, we discovered that sea oats create a habitat for insects, the endangered Alabama beach mouse, and thousands of migratory birds.

#DidYouKnow that Dauphin Island is a key barrier island for migratory birds? For many birds returning from the Yucatan Peninsula, Dauphin Island is the first landfall they encounter for 600 miles—whew! Sand dunes also serve as valuable buffers during hurricanes and large storms. In fact, the root systems of sea oats have been found to withstand large hurricanes in the past.

 

Jellyfish

We wrapped up our day on the public beach, where we discovered scores of dead jellyfish trapped among the driftwood. The most common time of year for jellyfish to wash ashore is from June-August, which means that we should be seeing the number of beached jellyfish diminish in the coming weeks. 

 

Curious about the unseasonable “jellyfish bloom” we checked in with Dauphin Island Sea Lab and found that there are a variety of variables that may influence sudden explosions in jellyfish populations.

 

An article from Dauphin Island Sea Lab suggests that “Increasing influences, like climate change, over-harvesting of fish, fertilizer run-off, habitat modifications, and other factors could help to fuel jellyfish blooms. Indeed, we’ve see this already in many regions around the world.” To read the rest of this article, click here.

Besides being a nuisance to beach-goers, jellyfish blooms can also cause nutrient and food shortages for other sea creatures and thus stunt other aquatic populations. Jellyfish have also been found to clog intake pipes at power plants around the world.

Our research ultimately left us with even more questions than answers, as all good research does. Namely, we wondered what would cause so many jellyfish so late in the season.  Was it the absence of a key predator or a competing species? Was it the weather or something in the water? What happens to jellyfish once they wash up on the beach? And finally: what creatures actually eat jellyfish?

 

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Join us next time when we venture into Rattlesnake Bayou to investigate the curious die-off of dozens of cypress trees!

 

And, as always, when you are out and about, be our eyes and ears! Take a picture, make some notes, and let us know what you see. Go to saveourgulf.org to file a report, and give us a call at (251) 433-4229 (Mobile Baykeeper) or (251) 990-6002 (Alabama Coastal Foundation).