Growing on the Dark Side

Yesterday I saw coral reefs. Not in the sweltering tropics, but in my very own backyard of Trondheim fjord.  They are cold corals that grow in the dark cold waters of the fjord.  In fact, I believe cold corals were first described here in Norway back in the 1700's by Gunnerus a Norwegian compatriot of the botanist  Linnaeus.  The ones growing in Trondheim fjord are the shallowest coral reefs in the world growing at 40 m depth.   The most common species Lophelia is mostly white, but then occasionally it has a bright orange hue.  No one really knows why or when they produce the orange pigment.  Growing amidst the corals are white sponges (lower right) that apparently have a special mechanism to clean themselves -- even when found near tar and oil.  No one know how either, but I'd like to patent it.  I could use a self-cleaning house.

We put in a remotely operated vehicle with lots of sensors, videos, and cameras and had the underwater "robots" pilot themselves dynamically along transects of the seafloor.  As part of my project, I am helping Geir and his students with techniques for optical image analysis.   We got to watch the underwater footage live on the screen in the main galley.

So, why do cold corals live here?  They thrive in the cold high flow seawater of the fjord. By the way, fjords  are created by glacier erosion and have steep sides protruding into the water and a shallow sil or threshold to the open sea.  While certainly not as delicious as the food I got onboard the ship today (salmon, apple crisp...mmmm thanks chef), corals are animals that actively feed on plankton and particles they catch with extended tentacles.   If you want to know more about cold corals, check out Sir David Attenborough and his website  http://www.lophelia.org/corals/video-introduction. 

I end with an image of my host Geir Johnsen, faculty NTNU, and myself on the deck of the ship.  Some of us are also exploring the dark side :)