Video: The dotted line is the surface of the sand in the bucket. The red movement illustrates earthworms in motion. Three worms are buried in the sand, while the fourth is left on the surface. see more
Image source: University of Southern Denmark
A large number of small animals live on the seabed, which are hidden in sandy sediments. Here, they play an important role in maintaining the health of the ocean. But the way these animals behave and how they interact with each other is unclear, because it is impossible to see them without disturbing the sediments.
Researchers like Dr. Matthieu Delefosse would like to wear a pair of X-ray glasses and study live animals in the sediment without disturbing them.
"We understand the bits and pieces of these animals through different measurements/experiments, but we don't have a comprehensive method that allows us to measure these bits and pieces at the same time in the natural environment," he explained.
This inspired him to use PET/CT scanners when studying benthic organisms. The results of this work are published in PLOS ONE magazine.
Matthieu Delefosse was working in the Department of Biology at the University of Southern Denmark when he was doing benthic research. Today, he works as an environmental consultant for Maersk Oil and Gas.
"Our research shows that it is possible to understand the natural life of benthic animals by scanning them in a relatively undisturbed environment. It may be interesting to use this technology to validate and develop further ecological models to scan real-life samples. Animals. Look at the content displayed by the scanner: Which animals live in the area? How do they behave and affect the surrounding environment?", he said.
To test his idea, Matthieu Delefosse filled a 10-liter bucket with sediment from Bregnør Bight in the Odense Fjord in Denmark. The buckets are left for 8-10 days, so their sediment content can be compacted and the sandworms (Arenicola marina) can reproduce themselves. After scanning five barrels, Delefosse observed the behavior of their different levels of sandworms.
There is a worm in a bucket. It burrows into the sand and pushes the water in front of itself, so the water eventually soaks the sand at the bottom of the bucket.
"The other bucket has more worms. We can see how three of them were buried, while the fourth remained on the water."
According to Matthieu Delefosse, it is important to understand the behavior and activities of benthic animals.
"Their activities have a major impact on the health of the ocean system. Take earthworms as an example-they are buried in sediments looking for microalgae to eat. Like other animals, they need oxygen and get oxygen from the surrounding water, and then pump it in. Cave. This will transport oxygen into the sediment," he explained.
Professor Poul Flemming Høilund-Carlsen from the Department of Nuclear Medicine at Odense University Hospital made PET/CT scanning possible.
"This kind of interdisciplinary cooperation is a good example of how researchers from different fields and specialties should meet and try to solve tasks that can only be solved through interdisciplinary cooperation. Here we have large hospital scanners, cyclotrons, and Radiochemistry laboratories are usually used to help patients. Even though they are working during the day, night and Saturday, there are still a lot of time without using the equipment, which can be used by researchers in other fields. During these times, the equipment is used for interdisciplinary Research can produce very interesting scientific results", says Poul Flemming Høilund-Carlsen.
Contact: Matthieu Delefosse, phone 45 60477950, email: matthieu.delefosse@gmail.com
Movie 002 and image: A bucket is filled with sand (grey), and a sandworm runs from the surface of the bucket to the bottom of the bucket (the cave is shown in green). There is a red volume at the bottom; the worm has pushed so much water in front of itself that the water has soaked the sand in the red area.
Film 005: The dotted line is the surface of the sand in the bucket. The red movement illustrates earthworms in motion. Three worms are buried in the sand, while the fourth is left on the surface.
Journal reference: Seeing the Unseen-Bioturbation in 4D: Using positron emission tomography and computed tomography to track biological irrigation in marine sediments. Matthieu Parts Fosse, Erik Kristensen, Diane Crunelle, Poul Erik sting, Johan Hygum Dam, Helge Thisgaard, Anders Thomassen, Poul Flemming Høilund-Carlsen.
http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0122201
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Copyright © 2021 American Association for the Advancement of Science (AAAS)
Copyright © 2021 American Association for the Advancement of Science (AAAS)