Ecological Discovery

First hydrothermal vent discovered on the Mid-Atlantic Ridge south of the Equator

On March 13, 2005, scientists from the Biogeography of Deep-Water Chemosynthetic Ecosystems (ChESS) project of the Census of Marine Life aboard the RSS Charles Darwin noted that the Autonomous Benthic Explorer (ABE) come home with a dirty nose. When the ABE surfaced from a dive, its housing was found with scorch marks and embedded sulfide particles, indicating that it had flown through the plume of a hydrothermal vent. Other indications were a temperature reading in excess of 50° C (122° F) and chemical readings showing significant manganese irregularities. This discovery signifies a benchmark in the study of hydrothermal vents for it is the first hydrothermal vent on the Mid-Atlantic Ridge found south of the Equator.

Up until this discovery, scientists have been puzzled by the differences between North Atlantic vent communities and their Indian Ocean and Pacific Ocean counterparts. A hypothesis to account for these differences suggests that the Romanche and Chain Fracture Zones near the equator in the Mid-Atlantic act as a type of "Subsea Berlin Wall" segregating the North Atlantic vent communities from those in other oceans. Now that a Mid-Atlantic Ridge vent has been found south of the equator and these fracture zones, comparisons can be made that may shed light on ecological differences in hydrothermal vent communities.

What: Discovery of first Mid-Atlantic Ridge hydrothermal vent site south of the Equator
Who: ChESS scientists aboard the RSS Charles Darwin
When: March 13, 2005
Where: South of the Equator along the Mid-Atlantic Ridge near Ascension Island in the South Atlantic
How: Using a combination of chemical sensing techniques, submersible ROV surveys, and geologic analyses
Reference: N/A

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