Exploring Ancient Coral Gardens
Davidson Expedition, January 26 - February 4, 2006

January 28, 2006
Davidson Seamount Expedition Log: Day 3

Objectives for the day: benthic transects, manipulator-held current measurements, Niskin water samples, coral samples from “Big Valley,” bamboo coral collections on “Bamboo Ridge,” ascend to peak for final transect.

Today was a very exciting day. We saw many “Coral Gardens” on the ridges, peaks, and valleys of Davidson Seamount. We dropped down to 1750 meters and took several current measurements and then began a 180 m transect on the rocky edge of the valley floor. We ended this transect by taking a push core of the gravel and mud in a sediment pool, sampling a white trumpet sponge and a rock for MBARI scientist David Clague. Surprisingly, we found many more corals than we had expected to on this transect. We saw what appeared to be several species in the family Primnoidae, many Corallium, and many small but beautiful bamboo corals called Acanella.

We also sampled a Primnoidae that appeared to be overgrown with a colony of zoanthids – we’ll see when the sample comes up! We sampled a gold gorgonian, Acanthogorgia, as well (see image to left). The geology on the last portion of the 2nd transect was not what we were expecting to see. We had expected mostly flat sediment, however, pillow lava and some angular talus covered the benthos. We began the ascent up to “Bamboo Ridge” from “Big Valley” where we finally saw the large bamboo corals Keratoisis, which Allen Andrews is using for age and growth studies. We sampled a community of Keratoisis, took some Niskin water samples, and current measurements in the vicinity of the Keratoisis community. We finally made the ascent to the ridge at 1500 meters and found several very large bubblegum corals, Paragorgia arborea, clinging to the edge of a vertical face, where current velocity appears to be highest. We took several more current measurements around the bubblegum corals and started our ascent. We were able to film a “Big Red” jelly, Tiburonia granrojo,  in HD before finally returning to the R/V Western Flyer for the evening.  What an exciting day! 

- Lonny Lundsten

Tiburonia granrojo - a new species described by researchers from MBARI and from the Japanese Marine Science and Technology Center (JAMSTEC). This amazing jelly gets up to 1 meter in diameter and is found throughout the Pacific Ocean.

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