Dodging Hurricane Ida While Listening to a Changing Gulf

When I started preparing for a three-week research cruise circumnavigating the Gulf of Mexico in August, surviving the heat was my main concern. I knew we were heading out to sea in the middle of hurricane season but it never crossed my mind that halfway through, we would travel to Key West, Florida to avoid a major hurricane that would later ravage coastal areas of the Gulf and Mid-Atlantic states.

I am a biological oceanographer and PhD student who participated in an expedition alongside other scientists from the Scripps Oceanography Marine Bioacoustics Research Collaborative (MBARC) in conjunction with the NOAA Southeast Fisheries Science Center and the U.S. Navy.

We set out on the Louisiana Universities Marine Consortium’s (LUMCON) R/V Pelican as part of a project called LISTEN, which stands for long-term investigations in soundscapes, trends, ecosystems, and noise. This ongoing project relies on a network of underwater listening devices, or hydrophones, throughout the heavily industrialized Gulf of Mexico. This project originated during the initial monitoring of the effects of the 2010 Deepwater Horizon oil spill using acoustics. What started as a handful of recording sites in 2010 has now evolved into decades’ worth of data from a large-scale passive acoustic monitoring project that is one of a kind.

Our objective for the 2021 Gulf LISTEN cruise was to visit 19 of these recording sites throughout the deep waters of the U.S. and Mexico and reset the instruments that were recording on the seafloor for the last year. Once the hydrophones were recovered, we deployed new instruments with fresh batteries and empty hard drives, ready to continue recording the soundscape of this region. Although most of our operations went well, we had a few challenges along the way, including an instrument that got mysteriously stuck on its way up to the surface and was not recovered.

With another year of acoustic data, this project hopes to continue learning about when and where marine mammals are found and monitor changes to their population over time. This is particularly important in the face of climate change and increasing human impacts on the Gulf of Mexico. Marine mammals are ecosystem sentinels, or indicators, of ecosystem change. By monitoring their populations with long-term acoustic recordings, we also learn about changes in their ecosystem and better understand the ocean’s currents and water masses.

When we weren’t working on the deck of the ship recovering or deploying hydrophones or in the lab getting the instrumentation ready, we were in the galley of R/V Pelican watching the Weather Channel. We watched so much Weather Channel that at first, I thought that was the only channel available. It’s not an outlandish idea given we were hundreds of miles away from land. What I eventually realized was how quickly the weather can change in the Gulf of Mexico this time of year.

As someone who grew up in Southern California, I’m as ignorant as they come about hurricanes. After hearing the Weather Channel reporters repeat the phrase ‘Invest 99L’ about 100 times, a quick Google search told me this phrase is used to describe a feature that is being monitored for potential development into a tropical depression or storm. The term “invest” is short for investigation, followed by a number 90 through 99, and ending with a letter that identifies the ocean basin of interest. We watched as Invest 99L became a tropical depression in the Atlantic Ocean, then Tropical Storm Ida later that day, and finally strengthened into a hurricane just as it traveled over Cuba. As it traveled through the Gulf, the Weather Channel focused on a giant warm water eddy directly ahead in the hurricane’s path. The same warm water patch we sampled a few hours ago to understand how sound would travel at one of our recording sites, was also the reason Hurricane Ida would rapidly intensify to a Category 4 hurricane as it made landfall in Louisiana. At this point, all of us were glued to the TV, especially the crew of the vessel who were concerned about their families and homes back on land.

Thanks to our chief scientists and the crew of R/V Pelican, we had a plan to move out of Hurricane Ida’s path by traveling to Key West, Florida. With a max transit speed of less than 10 mph, things got a little tense as we raced the storm to safety. After one day in Key West, we were safe to continue our journey south and back up along the eastern coast of Mexico. The hurricane passed as quickly as it formed and after a few calm days on the water, it was hard to imagine the 150 mph winds that swept through the Gulf just a few days ago.

Data from this expedition will build on existing acoustic time series that are used for several different projects to understand how increases in noisy human activities will affect the Gulf’s soundscapes and cetaceans. This research can inform the management and conservation of this region. The disruption by Hurricane Ida highlighted the challenges of designing protections for a system that is already damaged and constantly threatened.

Intense storms like Ida can result in small oil spills, destruction of wetlands, and critical or fatal effects on nearshore marine animals. As we got closer to Cocodrie, Louisiana where R/V Pelican docks, one of the crew members reminded us of the terrible damage we were about to see on land. On our drive to the airport in New Orleans, we didn’t see a single home, structure, or electrical line that was not impacted by Hurricane Ida. We saw thousands of people cleaning up debris on their properties and repairing their damaged homes, as we drove over one downed power line after another.

Hurricane Ida is now considered one of the most dangerous hurricanes to make landfall on the U.S. coastline. And although scientists are still uncertain whether climate change will increase the frequency of hurricanes, warmer ocean temperatures and warm water eddies like the one that allowed Hurricane Ida to intensify will lead to stronger hurricanes.

To learn more about the Gulf LISTEN project, meet the science crew, and learn about onsite operations, check out the Scripps Whale Acoustics Lab blog. Our heart goes out to all of those affected by Hurricane Ida, especially the crew of the R/V Pelican that continued to support our science operations.

Natalie Posdaljian is a fifth-year graduate student at Scripps Institution of Oceanography at UC San Diego, working in the Scripps Acoustic Ecology Lab. She’s interested in how human-caused changes to our climate are impacting our ocean. Natalie is answering this question by eavesdropping on marine mammals and learning about changes in their behavior or distribution over long periods of time.