What can 80+ year-old shipwrecks teach us about underwater landslides?
October 07, 2024
What can 80+ year old shipwrecks teach us about underwater landslides?
Quite a lot, as it turns out.
In summer of 2024, an LSU-led team of researchers - working with scientists from the Bureau of Ocean Energy Management, SEARCH, U.S. Geological Survey, and Florida Institute of Oceanography - took multiple research cruises to sites off the Louisiana coast, including visits to two World War II era-shipwrecks. The team hopes to gain a better understanding of how these important historic sites – and the biological communities that have come to inhabit them - are impacted by the moving sediments of the Mississippi River Delta. The trips are part of a larger LSU-led investigation of underwater landslides in the Gulf of Mexico, called OASIS.
Better understanding of how and when sediment moves along the floor of the Gulf of Mexico can have big implications for the future of offshore infrastructure safety, development, navigation, communications, and other activities.
LSU graduate student researchers Rongqing Du, Abby Roche, Jacob Reinhardt and research associate D’Metrie King, all joined the cruises using multiple vessels. The team operated a remote operated vehicle (ROV), a high frequency side-scan sonar and a subbottom seismic profiler, and collected sediment cores and other samples.
We caught up with them to find out more about their experiences.
To see more pictures from their trip, please see our Instagram or Facebook.
Reinhardt (center) assisted DOCS' Kevin Xu in geophysical surveys of the project area.
Jacob Reinhardt
Masters Student, Department of Oceanography & Coastal Sciences
Jacob Reinhardt works with DOCS professor Kevin Xu in Xu's Sediment Dynamics Lab.
What was your role on the cruise?
I primarily assisted with geophysical surveying of the shipwrecks as well as core collection. We collected multicores and gravity cores surrounding the wrecks.
How does this relate to your personal research?
Conducting geophysical surveys will be part of my PhD dissertation research, so this allowed me further experience in conducting geophysical surveys. The project area is from South West Pass to Pass au Loutre from water depths of 5-m to 200-m. I am researching the effects of waves, winds, and cold fronts on sediment transport in a shallow water estuary that is also influenced by the Mississippi River.
What was the coolest thing you saw?
We collected very high-quality data of the shipwrecks where we were able to see features on the vessel (as seen in some of my images). Being able to collect this data and see the shipwrecks using Chirp was very cool, as well as watching some of the ROV dives and seeing the ecosystems that have been created on these wrecks.
Roche will be using this research as part her Masters thesis.
Abby Roche
Masters Student, Department of Oceanography & Coastal Sciences
Abby Roche works in Cassandra Glaspie’s Marine Community Ecology lab. Glaspie served
as a co-principal investigator on the cruise.
What were some of your daily tasks on the cruise?
I am specifically looking at the benthic biological community composition on and near shipwrecks. My daily tasks included being in the control room during the day when the ROV was in the water, making “bio calls” and asking the technicians to zoom in on encrusted communities and interesting organisms. Then, at the end of the ROV dive, push cores were taken ten meters from the shipwreck site. When it returned to the surface, my job was to process these push cores by recording physical observations, slicing them into three sections (0-2 cm, 2-5 cm, 5-10 cm) and placing them in jars with formalin for preservation. These benthic samples will be sieved and sorted in our lab here at LSU, and all species found will be identified to their lowest taxonomic classification.
How does this work relate to your own research?
The work conducted on the cruise directly relates to my personal research, because I plan to write my master’s thesis about these communities near shipwrecks! I also was on board a coring cruise earlier this summer looking at unstable sediments in the Mississippi River Delta, and this will tie into my research, too. Submarine landslides in the delta are not only causing large masses of mud to move, but also the shipwrecks that have been sitting atop of the mud. All of this ties together to understand how impacts of moving sediments and shipwrecks will affect not only offshore infrastructure, but also the living communities in the delta.
What was the most interesting thing you saw?
Definitely a giant reef manta ray on the ROV camera… I’m still not over it!! Everything was insanely cool, though. Getting the chance to be one of the first people to see some of these shipwrecks was incredibly special.
Rongqing Du
PhD Student, Department of Oceanography & Coastal Sciences
Rongqing Du works in Kevin Xu’s Sediment Dynamics Lab.
Tell us some of your duties on the cruise.
During the cruise, my primary responsibility for the coring operations was to document the coring locations and associated data. I also assisted in labeling, slicing, and organizing the collected core samples, ensuring that all information was meticulously recorded for future analysis.
How does this work relate to your personal research?
As part of the MissDelta project, my research focuses on modeling sediment transport in the Mississippi River delta front. The sediment cores and acoustic data collected during this cruise will be instrumental in calibrating and refining my model. Moreover, this experience allowed me, as a modeler, to engage with the practical side of fieldwork, familiarize myself with field equipment, and gain hands-on experience. This direct involvement will undoubtedly enrich my research and deepen my understanding of sediment dynamics in the region.
What were some of the highlights of the cruise for you?
One of the highlights was working with ROV (remotely operated vehicle) technology, which not all research vessels are equipped to deploy. Additionally, collaborating with archaeologists to detect shipwrecks and with biologists to explore marine life introduced me to fascinating areas I hadn’t worked in before.
What is the coolest thing you saw?
One of the most exciting moments was witnessing the detailed images of shipwrecks captured by the side-scan sonar and sub-bottom profilers. It was fascinating to apply familiar technologies to uncover hidden structures that had never been examined before. Additionally, seeing a diverse array of marine life through the ROV’s video feed, including species I had never encountered, was another highlight of the cruise.
King (far left) on board with fellow researchers.
D'Metrie King
Researcher, Department of Geology & Geophysics
What were some of the tasks you performed on the cruise?
My tasks included coring operations, subsampling material as we cored, and just extra hands wherever necessary. For coring operations, we took 3-meter Gravity cores, 10-meter piston cores, and >1-meter multi-cores. There were a lot of moving parts so I helped wherever it would be best.
How does your work on this cruise relate to your personal research?
I am researching gravity core 15 specifically, which was taken off the pass a loutre outlet. I was able to collect more cores from surrounding areas to compare and able to see and understand how they collected the core, along with the current conditions of the area.
What is the most interesting thing you saw?
The most interesting thing I saw, besides dolphins swimming along up parts of the river, was an old lighthouse from probably over 100 years ago. It was still standing at the mouth of the river with such little land left there.