2006 Submarine Ring of Fire Where Did They Come From? (adapted from the 2005 Galapagos: Where Ridge Meets Hotspot Expedition) FOCUS SEATING ARRANGEMENT Biogeography of hydrothermal vent communities Classroom style or groups of 3-4 students GRADE LEVEL MAXIMUM NUMBER OF STUDENTS 9-12 (Life Science) 30 FOCUS QUESTION KEY WORDS Why are different hydrothermal vent communities Hydrothermal vent inhabited by different species? Spreading center Biogeography LEARNING OBJECTIVES Biogeographic province Students will be able to define and describe bio- Mid-ocean ridge geographic provinces of hydrothermal vent com- Plate tectonics munities. Ring of Fire Mariana Arc Students will be able to identify and discuss processes that could contribute to isolation and BACKGROUND INFORMATION species exchange between hydrothermal vent The Submarine Ring of Fire is an arc of active vol- communities. canoes that partially encircles the Pacific Ocean Basin and results from the motion of large pieces Students will be able to discuss characteristics of the Earth’s crust known as tectonic plates. that may contribute to the survival of species that These plates are portions of the Earth’s outer crust inhabit hydrothermal vent communities. (the lithosphere) about 5 km thick, as well as the upper 60 - 75 km of the underlying mantle. The MATERIALS plates move on a hot flowing mantle layer called Copies of “Guidance Questions for Research on the asthenosphere, which is several hundred the Biogeography of Hydrothermal Vents,” one kilometers thick. Heat within the asthenosphere copy for each student or student group creates convection currents (similar to the currents that can be seen if food coloring is added to a AUDIO/VISUAL MATERIALS heated container of water) that cause the tectonic None plates to move several centimeters per year rela- tive to each other. TEACHING TIME One or two 45-minute class periods, plus time for If tectonic plates are moving apart their junction student research is called a divergent plate boundary; if they slide 1 2006 Submarine Ring of Fire – Grades 9-12 (Life Science) Focus: Biogeography of hydrothermal vent communities oceanexplorer.noaa.gov horizontally past each other they form a transform before. Since they were first discovered, sea-floor plate boundary; and if they collide more or less hot springs around spreading ridges have been head-on they form a convergent plate boundary. intensively studied. In contrast, the hydrothermal The Pacific Ocean Basin lies on top of the Pacific systems around convergent plate boundaries are Plate. To the east, new crust is formed by magma relatively unexplored. rising from deep within the Earth and erupt- ing at divergent plate boundaries between the Some of the key questions about hydrothermal Pacific Plate and the North American and South systems concerns biogeography: How do new American Plates. These eruptions form subma- vents become populated with organisms that are rine mountain ranges called oceanic spreading uniquely adapted to the extreme conditions that ridges. While the process is volcanic, volcanoes are characteristic of these habitats? Since vents and earthquakes along oceanic spreading ridges can appear (and disappear) relatively quickly, are not as violent as they are at convergent plate what reproductive strategies might be used by boundaries. vent organisms to ensure that their offspring have a chance of finding a suitable habitat? Previous To the west, the Pacific Plate converges against expeditions to the Submarine Ring of Fire, and the Philippine Plate. The Pacific Plate is forced to other active hydrothermal vent sites such as beneath the Philippine Plate, creating the the Galapagos Rift, have provided some clues to Marianas Trench (which includes the Challenger these questions. The 2006 Submarine Ring of Fire Deep, the deepest known area of the Earth’s Expedition is focussed on interdisciplinary investi- ocean). As the sinking plate moves deeper into gations of the hydrothermal and volcanic process- the mantle, fluids are released from the rock caus- es on the submarine volcanoes of the Mariana ing the overlying mantle to partially melt. The Arc, and will probably provide some additional new magma (molten rock) rises and may erupt clues; as well as some additional questions. This violently to form volcanoes, often forming arcs is the nature of exploration and scientific inquiry. of islands along the convergent boundary. The In this lesson, students will investigate some Mariana Islands are the result of this volcanic aspects of the biogeography of hydrothermal vent activity, which frequently causes earthquakes as systems. well. The movement of the Pacific Ocean tectonic plate has been likened to a huge conveyor belt LEARNING PROCEDURE on which new crust is formed at the oceanic 1. To prepare for this lesson, review spreading ridges off the western coasts of North • Introductory essays for the 2006 Submarine and South America, and older crust is recycled to Ring of Fire Expedition at http://oceanexplorer.noaa. the lower mantle at the convergent plate boundar- gov/explorations/06fire/welcome.html; ies of the western Pacific. • NOAA Learning Object on Hydrothermal Vent Life at http://www.learningdemo.com/noaa/; and Underwater volcanism produces hot springs in the • Articles on biogeography of hydrothermal middle of cold, deep ocean waters. These springs vents by Cindy Lee Van Dover and Timothy (known as hydrothermal vents) were first discov- Shank (http://www.divediscover.whoi.edu/hottopics/biogeo. ered in 1977 when scientists in the submersible html and http://www.whoi.edu/cms/files/dfino/2005/4/ Alvin visited an oceanic spreading ridge near the v42n2-shank_2276.pdf, respectively). Galapagos Islands, and made one of the most exciting discoveries in 20th century biology. Here You may also want to visit the Dive and they found warm springs surrounded by large Discover presentation on the 25th anniver- numbers of animals that had never been seen sary of the discovery of hydrothermal vents 2 2006 Submarine Ring of Fire – Grades 9-12 (Life Science) oceanexplorer.noaa.gov Focus: Biogeography of hydrothermal vent communities (http://www.divediscover.whoi.edu/ventcd/vent_discovery), islands and seamounts formed from hotspot and obtain the CD-ROM or download selected lava as a plate moves over a hotspot location. images to enhance group discussions in Step 4. • Hydrothermal vent biogeographic provinces 2. Briefly review the concepts of plate tectonics, include the Northeast Pacific (Gorda, Juan de being sure that students understand the process- Fuca, and Explorer Ridge systems); Eastern es that take place at convergent and divergent Pacific (East Pacific Rise and Galapagos boundaries, and why these boundaries are spreading center systems); Western Pacific often the site of volcanic activity. Introduce the (Mariana, Lau, Fiji, and Manus systems); Ring of Fire expeditions, and tell students that a Deep Atlantic (or Mid-Atlantic) (Trans-Atlantic primary focus of the 2006 Submarine Ring of Geotraverse (TAG), Snake Pit, and Broken Fire Expedition is interdisciplinary investigations Spur systems); Shallow Atlantic (or Azorean) of hydrothermal and volcanic processes on (Menez Gwen and Lucky Strike systems); and the portion of the Ring of Fire that includes the Central Indian (Kairei and Edmond systems). Mariana Arc. • Species that characterize the biogeographic 3. Tell students that their assignment is to research provinces of hydrothermal vent systems are: some basic questions and theories about the – tubeworms, clams, and limpets (eastern biogeography of hydrothermal vent systems, Pacific and northeast Pacific; different and prepare a report that includes answers species of each group in each province); to the ”Guidance Questions for Research on – shrimp and mussels (Deep Atlantic and the Biogeography of Hydrothermal Vents.” Shallow Atlantic; different species of each Information needed to answer questions on the group in each province); and worksheet can be found on the Web sites refer- – barnacles, mussels, and snails (western enced in Step 1, as well as many other sourc- Pacific; different species than those found es. You may want to provide these references in the eastern Pacific or Atlantic). to your students, or allow them to discover them The Indian Ocean province is dominated by (and others) on their own. shrimp similar to those found in the Atlantic, as well as snails and barnacles similar to 4. Lead a discussion of students’ reports. The fol- those in the western Pacific province. lowing points should be included: • Processes that can contribute to migrations • A spreading center (mid-ocean ridge) is between hydrothermal vent communities formed where tectonic plates move apart include: (divergent plate boundaries). This movement – whalefalls – decomposition of whale car- causes a rift to form that allows magma casses that fall to the seafloor creates (molten rock) to escape from deep within conditions that are somewhat similar to the Earth and become new crust material. those found at hydrothermal vent sites, Hotspots are thought to be formed by natu- so these carcasses may provide “step- ral pipelines to reservoirs of magma in the ping stones” for the migration of species upper portion of the Earth’s mantle, and are between vent sites; believed be relatively stationary compared – woodfalls – decomposing wrecks of wood- to tectonic plates. The combination of com- en ships may create conditions similar to paratively stationary hotspots and plates that those described