Dr. Larry Mayer UNH

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October 10, 2016

History of Bathymetry: Early Methods

With Google Maps readily available at our fingertips, it’s pretty safe to say that the world has been mapped out. Has it though? Our oceans make up 71 percent of the Earth, but their depths are not accurately mapped out entirely. This series will explain the techniques used in the past and present to record this information, and new methods we hope to put into practice in the future.

Bathymetry is the study of the depths of water in oceans, lakes, and seas from the surface to the bottom. The depths of the ocean vary greatly, so seafarers and scientists have had to rely on methods to calculate this information.

Bathymetry has been around longer than you might think. The first technique of bathymetry started in ancient times and was used up until the 1870s. This method was to lower a weighted, heavy rope into the water from the side of a ship. The depth of the sea was determined by measuring the length of rope needed to reach the sea floor. This rudimentary method was useful in knowing how deep the water was at one specific point so that the ships wouldn’t run aground on an unsuspecting sandbar. There were many downsides to this method because it didn’t take into account currents in the water that could drag the rope or the movement of the ship. Even in the best conditions, the rope could only determine the depth of one specific point on the sea floor.Measuringoceandepthswithrope

The 19th century was when people started investigating and recording the depths of the ocean for scientific discovery and commercial interests. In 1840, British scientist,  Sir James Clark Ross, used the method of lowering a weighted hemp rope and created the first bathymetric map of the Gulf of Mexico. While not very accurate, this map showed features of the Gulf of Mexico that were unknown prior to this time.

In the 1870s, Sir William Thomson attempted to counter the problems posed with the heavy rope method by inventing the Kelvin Sounding Machine. The Kelvin Sounding Machine was much more sophisticated and used piano wire weighted with a lead sinker, instead of rope and could quickly be dropped to the bottom of the ocean floor, saving a lot of time and effort. As long as a determination of the ship’s forward motion was made, this movement would not skew the results as they did before. One of the downsides to this machine was that it still only measured one singular point in the ocean floor, which was still not an accurate representation of the varying depths of the seabed.

These early methods helped grow the study of bathymetry and inspired future scientists to improve the methods. Check out my blog next month as we explore how technological advances changed bathymetry during the 20th century.

July 21, 2016

Custom Microscope for Ocean Exploration

Ocean PictureResearchers of oceanography have, for a while, been crafting new and innovative technology to explore more of the ocean floor. While engineers have churned out everything from humanoid robots to submersibles, there is something to be said for getting up close. This is why a research team at Scripps Institution of Oceanography has created an underwater microscope. This new exploration technology is meant to be operated by divers and studies naturally occurring processes on the seafloor at a millimeter scale. Biological processes on the ocean floor have, in the past, been observed by taking samples from different areas to labs. This microscope gives researchers the unique opportunity to study biological processes as they happen, undisturbed.

It is called the Benthic Underwater Microscope, and it is the first device able to take data from the ocean floor at such a small scale. It has a diver interface that is attached to a microscopic imaging unit. The unit itself is magnified, has LED lights for fast exposure times, and has the ability to change focus, much like the human eye does to best view what it is studying. According to the researchers, this microscope even has the ability to see single cells.

This new device was first tested in the Red Sea. The researchers wanted to see how much of the interaction between two corals it could pick up. The microscope showed that these corals, who were rivals, were actually emitting filaments to secrete enzymes in attempts to break down the tissue of the other. It was a purely chemical battle for more space on the ocean floor. The researchers made sure of this by moving two coral of the same species close to each other and observing that the same chemical warfare did not take place. This has determined that coral are smart enough to recognize if they are surrounded by others of their kind or by different species, and they react accordingly.

The next target of the researchers was just off of Maui, where a large coral bleaching event had taken place. The microscope showed that initial signs of algae colonization were happening on the bleached coral, in between coral polyps. This discovery is huge in the study of the abilities of algae. It shows that algae is able to completely take over coral when bleaching is occurring.

The above are just initial findings of this new microscope, but they show the vast implications of its creation. Instead of having to bring samples of life on the ocean floor back to a lab, this device allows the ocean floor to become a lab. With it, researchers are able to see microscopic processes happening at a natural rate. I am excited to see what else we will find.  

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