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Cruise report: Bear Seamount 2003

 Ramshorn squid
Picture of a ramshorn squid found on the cruise

Bear Seamount is a dormant undersea volcano, located off the east coast of the US near Georges Bank. It rises around 2000m above the sea floor, but its relatively flat top remains about 1000m below the ocean surface.

The May 2003 cruise was Vecchiones's third cruise to the area. Seamounts hold great promise for undiscovered biodiversity, says Mike Vecchione. We know so little about life in the sea below 1000m, and yet this realm makes up more that 90% of the earth's biosphere. Vecchione goes on to explain that an important aspect of studies of biodiversity is to gain greater understanding of the relationships between organisms. For example, he says preliminary analysis of the data collected on the two previous Bear Seamount cruises shows that a small percentage of the fauna collected involves what he describes as "natural invader" species. These are species that are more typically found in the eastern Atlantic and only rarely or never previously in the western Atlantic. Such results have given rise to the "stepping stone" hypothesis for seamounts, whereby seamounts act as stepping stones for populations across the deep seafloor.

One of the challenges of deep sea exploration is the risk of losing gear. Bear Seamount's rough, volcanic and steep slopes increase this risk. One of Vecchione's students recounts the technique for undoing snags: A snag could actually pull the ship backwards. To escape, the ship would have to stop, reverse course for a few hundred meters, the resume its forward motion.

One of the cruises exciting finds was a ram's horn squid. Vecchione explains that this is a very unusual kind of deep-sea cephalopod because it has an internal coiled shell, the ram's horn. The squid control their height in the water column by varying the amount of gas in the shell.

The main goal of the May cruise was to explore the biodiversity of the seamount by collecting fish and cephalopods in bottom and mid-water trawls. The deepest trawls went to more than 2000m. In conjunction with the Census of Marine Life's goal to develop and implement new marine science technologies, researchers on the cruise also tested a new computer-based measuring system.

See als an article about this cruise (pdf.)

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See the cruise report

See an article about the cruise (pdf)

 

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