Lungs of the Sea

As a diver and marine biologist for EPA, I spend a fair amount of time underwater. My area of expertise is in the study and conservation of seagrass. These underwater meadows can cover vast swaths of the seafloor and they serve as important nurseries for many fish and shellfish species.

Recently, I had the great fortune of taking a family trip to France and spending some time along the southern coast. It was my first visit to the Mediterranean Sea and I was looking forward to exploring the underwater realm. We stopped in the small town of Cassis, which reminded us of Gloucester, Mass. Cassis has its own fisherman’s statue. It does not have a greasy pole to climb like Gloucester, but it does have its own unique tradition. Local fishermen mount planks on the back of two dories. Boys of about 10 years old are lifted up onto the planks wearing pads on their chests and are given lances. The boats then drive directly at each other and the boys joust until one or both fall into the water.

Version 2 DSC_0728

The local culture was interesting, but Cassis is also known for “les calanques.” Calanques are inlets surrounded on three sides by steep cliffs; they also are known as mini-fjords. Within these inlets, seagrass flourishes in the clean, calm protected waters. The French refer to seagrass as “les poumons de la mer,” which translates to the lungs of the sea. Like all plants, seagrasses produce oxygen through photosynthesis. On sunny days, it is common to see bubbles of oxygen being released from the leaves of seagrass into the water.

In Cassis, protecting seagrass is taken very seriously with a variety of rules. Boaters are not allowed to anchor or place a mooring in seagrass meadows. Boaters are required to stay in the marked navigation channels and when in shallow water reduce their speed so no wakes are produced. In our three days in Cassis, we watched many boats come and go, and not one of them broke the rules.

I approached one of the local fishermen and with my limited French asked him about the local seagrass meadows. He spoke little English. I spied a shoot of seagrass floating near his boat. He scooped it up and held it close to his heart and said “les poumons de la mer.” Posidonia

We didn’t speak the same language, but our common love of the ocean easily transcended the language barrier.

More information on EPA Seagrass research:

Connect with EPA New England on Facebook:

Connect with EPA Divers on Facebook:

About the author: Phil Colarusso is a marine biologist in the Coastal and Ocean Protection Section of EPA’s New England office, and is an avid diver.

Editor's Note: The views expressed here are intended to explain EPA policy. They do not change anyone's rights or obligations. You may share this post. However, please do not change the title or the content, or remove EPA’s identity as the author. If you do make substantive changes, please do not attribute the edited title or content to EPA or the author.

EPA's official web site is Some links on this page may redirect users from the EPA website to specific content on a non-EPA, third-party site. In doing so, EPA is directing you only to the specific content referenced at the time of publication, not to any other content that may appear on the same webpage or elsewhere on the third-party site, or be added at a later date.

EPA is providing this link for informational purposes only. EPA cannot attest to the accuracy of non-EPA information provided by any third-party sites or any other linked site. EPA does not endorse any non-government websites, companies, internet applications or any policies or information expressed therein.