SEA Currents: Corwith Cramer
December 04, 2014
Finding Researcher’s Ridge
14°56.5’N x 49°39.0’W
Description of location
NEC Transition Zone, Mid-Atlantic Ridge Marine Debris Observed last 24hrs: None Sargassum Observed last 24hrs: windrows as far as the eye can see!
Ship Heading (degrees)
Ship Speed (knots)
Taffrail Log (nm)
Weather / Wind / Sail Plan
Starboard tack under a full stack, the mainstays’l, and the main. Winds from the SE at force 3, 3/8 cumulus cloud coverage.
We forwent our regularly scheduled science stations yesterday. Instead of dropping our Secchi disk, free CTD, phyto net, and Neuston net in the morning, we charged forward, making miles early so that we could spend an extra few hours with science gear overboard in the afternoon and evening.
We sailed towards the Mid-Atlantic Ridge’s western side from the heart of its rift valley, a tight and narrow topographic feature bounded by almost incomprehensively steep, deep cliffs that plunge over two thousand meters vertically in a mere hundred horizontal meters. We sailed west, and set our sights toward an elusive shallow spot called Researcher’s Ridge.
All afternoon we zigzagged back and forth around areas our chart told us were unusually shallow, but according to our modern instrumentation the seafloor remained 1000s of meters away. B watch was trained to use a piece of equipment called the Shipek Grab, a great metal scoop that brings up rich loads of whatever happens to be on the ocean floor at the point of deployment. But after all their training, B watch ended up turning over the Shipek to evening’s C watch unused. The peak of Researcher’s Ridge still a mystery.
Many excited B-watchers stayed up on deck waiting for the Cramer to find shallow water. People also crowded into the lab to watch our CHIRP’s depth readings shrink from four digits to three. The night was hot and the moon brilliantly bright. Now that the moon has waxed its way near to fullness, flashlights on deck are rendered mostly superfluous. The moon’s brightness even allows us to read our sextants and the horizon is so distinct that we can shoot stars throughout most of the night. Indeed, some B-watchers had propped themselves up against the rails to better find the stars when science let out a series of tremendous cries and came dashing back to the quarterdeck to say we had found it—we had found Researcher’s Ridge!
Researcher’s Ridge is a somewhat misleadingly named feature that researchers have, in fact, only encountered once. In 1975, the vessel RV Researcher recorded depths in the mid-500 meters. The Cramer has now recorded more bathymetric data on Researcher’s Ridge than any other scientific mission in history! The shallowest depth our cruise recorded at the ridge was 467 meters, which means the Cramer may get to contribute to future charts of the area. Most exciting, however, was what came up in the Shipek. Hove to in the moonlight, with Cramer’s gentle glassy wake glistening silver off the port beam, the crew waited with bated breath as scientists opened up the great metal jaws of the Shipek that only moments before had found the seafloor at 660m depth.
“Ooooooooh!” cried everyone who could see inside.
We had pulled up great hunks, not of dirt, which we’d expected, but of finely spun glass sponges, a strange, filter feeding organism that grows attached to a rocky seafloor like a honeycomb in tightly spiraling silica-based structures. These sponges had such delicate little hexagonal patterns that for a while we thought they might be bryozoans, a filigree-like organism that coats the Sargassum we’ve been harvesting for the past few days. But they were in fact sponges, colonized in some places by even more delicate brittle stars, benthic filter feeders that stick their little legs up in the water to catch whatever’s floating by. We even found a few small crustaceans, including an extremely confused crab.
This breathtaking array life on top of Researcher’s Ridge, was so surprising that even now, almost a full day later, the crew can’t stop returning to lab just to examine it some more. Our second Shipek Grab, deployed at the 467m depth, returned the sandy sediment we’d expected in the first, handfuls of wet, brown benthos.
Overjoyed and flush with success, Cramer turned once more towards Dominica after her second Shipek Grab and a Neuston tow. We spent today, an almost cloudless, hot tropical day alternately motoring and sailing northwest, with our usual morning stop for science. We managed to catch still more Sargassum in our new dip net, and this afternoon we sailed through patches of the sparkling bronze weed so large that one crew member favorably compared their size to Rhode Island.
At the time of writing, the Cramer is motor-sailing towards the Caribbean beneath another gigantic moon. The stars Sirius and Canopus are twinkling furiously from red to blue to green, and the light from above spangles the water all around us.
Shout outs to any Osborns, Amblers, Todds, Millers, and other wonderful people I know who might be following the Cramer during her transatlantic crossing! Best wishes and lots of love for the upcoming wave of birthdays!