We collected many shrimp, bacteria and other organisms at our first research site, so why last night did we move to another potential hydrothermal vent area in the Indian Ocean?

One of our scientific objectives is to see how vent organisms in the Indian Ocean relate to and differ from organisms at Pacific and Atlantic Ocean vents. Another is to see how organisms differ between vent sites in the Indian Ocean.

We want to learn the distribution patterns of animals and what causes those patterns to exist, a branch of science called biogeography.

Studying only one vent site is not enough. It would be like visiting Michigan and concluding that every state in America is flat, covered in leafy trees and surrounded by fresh water lakes.

The same concept is true at hydrothermal vent sites. Just like trees and geographic features vary from place to place on land, “we know from studies in the Eastern Pacific Ocean that animal species can differ from vent site to vent site,” said Biologist Tim Shank.

Tim has studied vent shrimp and other animals along the East Pacific Rise, located offshore Mexico. At 13°N, he saw many mussels.

“But looking north nearly 500 miles, we saw a big difference in the distribution of animals,” said Tim. “We saw mostly clams and tube worms, but no sign of a mussel.”

Tonight we are at a second site on the Central Indian Ridge, located about 80 nautical miles north of the Kairei Vent Field. Will the fauna be the same at this deeper site? Maybe clams or tube worms live here, animals we did not find at Kairei. Or perhaps we will see now-familiar mussels, shrimp and crabs?

The Plume Team hit the ground running when we arrived at 24°S last night under a star-littered sky. Plume Team members Bob Collier, Marvin Lilley and Darryl Green worked until late afternoon today narrowing our search area on the eastern wall of the rift valley.

Tonight, we will send Jason down to explore. If we find a vent, it will be only the second hydrothermal vent site ever found and explored in the Indian Ocean.

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