By Bill Chadwick - Oregon State University and NOAA Pacific Marine Environmental Laboratory
Seamounts are underwater mountains, and sometimes they are also active volcanoes. The Mariana Arc is a chain of many seamounts (60) and a few islands (9), which are all active volcanoes. The islands are just the few volcanoes that have grown tall enough to reach above sea level. The seamounts in the Mariana Arc lie hidden below the ocean’s surface, and we are exploring them to find which have active hydrothermal systems and unique biological communities. Many of these seamounts are now part of the Mariana Trench Marine National Monument.
The more we explore in this region, the more amazing animals and environments we discover.
The "Ring of Fire" is a circular zone of active volcanoes that surrounds the Pacific Ocean basin, mostly along plate boundaries and above subduction zones. Much is known about volcanoes on land within the Ring of Fire (for example, in the Aleutians, the Cascades, the Andes, etc.), but comparatively little is known about the submarine volcanoes, simply because they are more difficult to observe.
Where submarine volcanoes bring magma near the seafloor or erupt lava at the surface, seafloor hot springs called hydrothermal vents are common. Seawater that circulates deep within a submarine volcano gets heated up before it returns to the seafloor. Hydrothermal vent fluid is rich in chemicals dissolved from the rocks they pass through, and these vents support unique ecosystems of microorganisms and animals that rely entirely on chemical energy for survival. In this way, submarine volcanoes actually support many of Earth’s most unusual ecosystems.
Our work on this expedition is focused on trying to understand how these ecosystems function and the interactions between volcanic activity, the chemistry of hydrothermal vents, and the ecology of their biological communities.