Wednesday, August 10, 2011

MSI Deep Dive and Fish Surveys

(Click on the YouTube logo to watch the video in HD!)

This morning, after a bit of fish identification review, the interns assembled their gear on the R/V Henry Stommel (a BIOS vessel captained by the great Mr. Bomber) and ventured over to Natural Arches on the south shore of Bermuda. In a fit of diving amidst the limitless clarity of crystal blue waters and colonies of vibrantly colored corals, the interns completed both a deep dive and 30 meter fish surveys.

On their first dive, the interns went to seventy-two feet where they partook in a bit of diving physics and witnessed a disappearing act preformed by the color red. Because of the way that light reflects underwater, the wavelength that transmits the color red to human eyes is undetected at greater depths. As Dean Lea, a dive instructor with the BIOS Ocean Academy, took down a red bag to 72 feet, the interns observed its hue slip slowly to black.

Mr. Lea, being the trickster and master physicist that he is, also took down with him a few raw eggs. The interns were instructed to crack open the eggs at the deeper depth and observe the consistency of the liquids inside.

Eliza Gardener commented on the experiment, “When we went under the water and cracked the eggs instead of it spreading out, like it would at sea-level, it stayed together. It demonstrated that when you go down deeper underwater, the pressure increases, causing particles to become smaller and more pressurized and allowing eggs to keep their shape! The egg felt sort of like a jellyfish underwater. It was so cool!

This experiment can be observed in the following video:

(Click on the YouTube logo to watch the video in HD!)

On their second dive, the interns completed eight fish surveys along 30 meter transect lines in slightly shallower depths. They counted the number of different species of fish seen along those transect lines and analyzed the data collected to determine if there are any trends in species density of the 26 most abundant reef fish in Bermuda. The interns determined that the most amount of fish in a feeding guild per meter squared were the invertivores, with the greatest population of Bermuda Chub.

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