Researchers and scientists are tenaciously looking for effective ways to collect data to better understand the impacts of climate change on our oceans. As relayed by Carol Rasmussen of NASA’s Earth Science News Team, in the article, “Data with Flippers? Studying the Ocean from a Seal’s Point of View,” Scientist, Lisa Siegelman, has come up with an innovative way to do so by attaching a specialized sensor similar to a small hat, to a southern elephant seal. Although seals are rather sluggish on land, this is not the case under water. On average, seals spend most of their time in the ocean: about 9 – 10 months, and dive roughly 3,000 miles deep. Seals only come up for air about two hours at a time, so Siegelman’s method brings accurate results.
For over two decades, a French research program called SO-MEMO has been tagging seals to get a better look into the oceans’ top layers, particularly in Kerguelen Island, a French territory in the Antarctic. The seals are tagged under ethical standards whereby sensors with antennae are glued to their heads. When the seals return to land, scientists remove the antennae and collect the data. Seals molt, so if a tag is missed, the antennae come off when their dead skins shed.
Tagging seals collect valuable data from the top layer of the Southern Ocean. Some seals even travel under the Antarctic sea ice where typical ocean instruments cannot reach. The study of this area is useful because as global warming occurs, it changes the ocean currents which affect the Antarctic melting rate.
Siegelman observed one female seal on her three-month journey: typically seals from the Kerguelen Island travel east but this particular seal traveled west, making it to the Antarctic Circumpolar Current where, as Rasmussen states, “…there’s a standing meander – a place where the topography of the ocean floor creates a permanent bend in the path of the current.” The Antarctic Circumpolar Current flows around Antarctica connecting the Atlantic, Pacific, and Indian Oceans. It is one of the most important ocean currents in our climate system because it transfers heat. Siegelman’s seal zigzagged in this area for about a third of her journey gathering critical data in a region where there have been limited oceanographic measurements.
Heat transfer, in particular, from the top layer of the ocean to the bottom layers, is not fully understood. Thankfully, Siegelman’s seal was able to capture some valuable data that brings new insight into how heat moves between ocean layers in such a difficult area. This information provides a better understanding of how much heat the Antarctic Ocean can absorb from the sun.
The data collected from tagged seals help scientists discover the location of dramatic changes in water density called fronts. Similar to cold and warm fronts in the atmosphere, the oceans’ fronts have a width of 3-12 miles. Between the fronts, dense and light waters raise nutrients from the depths which cause the fertilization of plants called phytoplankton.
Using the data collected, scientists focus on vertical heat transfer with surprising results. Siegelman states, “These medium-sized eddies are known to drive the production of small-scale fronts — sudden changes in water density similar to cold and warm fronts in the atmosphere. We found that these fronts were evident some 500 meters [550 yards] into the ocean interior, not just in the surface layer like many studies suggest, and that they played an active role in vertical heat transport.”
To conclude, the analyses demonstrate that ocean fronts carry a lot of heat to the surface. Furthermore, as Siegelman explains, “most current modeling studies indicate that the heat would move from the surface to the ocean interior…, but with the new observational data provided by the seal, we found that that’s not the case.” Siegelman’s discovery opens up many questions about heat transfer in our oceans, so the research doesn’t end here. She hopes that more scientists would use seals to get a better understanding of what is going on in our oceans, especially since we’re experiencing climate changes.