March 12, 2012

Whitecaps are never good news when you’re diving. Sure enough, the swell and breeze both grew overnight, though luckily not too big to take the Calcutta out. After a late start for some repairs, the dive boat brought the group to the first site of the day.  Under a merciless sun, everyone was happy to get in the water and set about their various tasks.

Brian Beck and CAPT Phil Renaud paired off to do transects: coral and photographic, respectively. Brian laid out a weighted 10-meter line on the bottom and proceeded to record every coral species for half a meter on either side, a slow, meticulous task that took the entire dive. Phil followed his own 10-meter line, taking high-resolution, digital photos of every square meter.

Back on the ship, these photos will be analyzed using an open-source program called Coral Point Count with Excel extension or CPCe. This gives you statistics on how much of the bottom each coral species (or whatever else you want to record) covers. It scatters any number of points on each photo, which you then have to tag as being a particular species of coral, healthy or not, or any other variable you want to record. It can take a long time — graduate school and internships involve a lot of this sort of work.

On his dive, Ken Marks spotted a species of coral that had just been described as new last November. Meandrina jacksoni is a hermatypic (stony) coral, meaning it helps build reefs with its calcium skeleton, as opposed to soft-bodies corals, which don’t. It looks a lot like Meandrina meandrites, the species it was originally lumped under, but its “brain” pattern has smaller ridges and whitish valleys. There are less than 100 hermatypic species in the Caribbean, so it’s a reef scientist’s dream to identify a new one.

Meandrina jacksoni (top) compared to Meandrina meandrites (bottom). See the difference?

Read the rest of Currents, Corals and a “Sleeping” Nurse Shark »