The history of our planet is best revealed by studying the global ocean seafloor. Understanding the geological, chemical and biological processes that form and alter the ocean crust, all of which influence the chemical composition of the ocean, are crucial goals of 21st century oceanographic science. The technological and scientific challenges involved in unraveling these processes and their linkages in space and time are significant. The Deep Ocean Exploration Institute (DOEI) at WHOI plays a key role in supporting scientists, engineers and students working on these topics, fostering innovative cross-disciplinary research and developing unique technologies to explore, map and sample in the deep ocean and beneath the seafloor in earth’s crust and mantle.
In 2010, DOEI continued to support WHOI staff and students through Institute themes and the Ocean Ridge Initiative (ORI), which encompasses a broad agenda of research focused on Earth's most continuous volcanic and tectonic lineament—the global mid-ocean ridge, the 50,000 mile-long undersea mountain chain where oceanic crust is generated.
Initially the ORI has funded research on microbial and dynamic geological/geochemical processes and the nature of deep-sea fauna at oceanic spreading centers. Technology and instrument development that facilitates such studies are an integral part of the ORI.
DOEI's research themes expand the breadth of the ORI by providing opportunities for high-risk/high-reward science that can lead to breakthroughs in our understanding of coupled dynamic processes in deep seafloor environments, from trenches to mid-ocean ridges to continental slopes. DOEI funding has focused on detailed geochemical studies pertaining to the role of the deep earth and ocean in global elemental cycles—especially the role of volatile elements in magmatic and volcanic systems, carbon sequestration in ocean floor strata and investigating what is perhaps the largest unknown ecosystem on this planet, the deep biosphere within the oceanic crust and the deep ocean.Nine proposals were funded in 2010 covering various DOEI themes and ORI topics:
Nobu Shimizu (Geology and Geophysics Department, G&G) will establish a comprehensive dataset for sulfur isotopic variations in rocks associated with subduction of altered oceanic crust and sediment by determining sulfur isotopic compositions in situ in sulfides, apatite minerals and high-pressure metamorphic rocks. The resulting data are essential to developing a quantitative understanding of fluid fluxes across subduction zones and will provide a major step forward in understanding the global sulfur cycle and processes of deep geochemical cycling of elements.
Virginia Edgcomb (G&G) will study the long-term consequences of contamination of the marine food web. Ginny's research will use protists—single-celled organisms—that play key roles in microbial food webs, and in global biogeochemical cycles involved in transporting hydrocarbons to higher food chain levels when the protists are consumed. This project aims to determine if the presence of protists enhances degradation of hydrocarbons in deep marine sediments under varying oxygen and nutrient (phosphorus and nitrogen) concentrations, what impact hydrocarbon contamination has on seafloor microbe communities, and whether protists' presence leads to species changes in the in situ microbial community.
John 'Chip' Breier (Applied Ocean Physics & Engineering Department, AOPE) will develop a new, multifaceted sampling tool for Autonomous Underwater Vehicles (AUVs). This is the next technical evolution of sampling technology Chip and his colleagues developed using DOEI seed money. Migrating the new sampler to WHOI's Sentry AUV will enable autonomous, sensor-triggered sample collection during multi-depth, vent field-scale surveys. This new tool will give us unique scientific capabilities for hydrothermal vent research and for multidisciplinary Ocean Observing Initiative (OOI) studies that WHOI is implementing.
Tim Shank (Biology Department, BIO), DOEI Fellow. In summer 2010 Tim participated as a “virtual” chief scientist, with an international team led by U.S. and Indonesian scientists, on cruises exploring deep Indonesian waters in the Coral Triangle—a region where more than 65 percent of the world's shallow-water reef-forming coral species live. Tim helped plan the expedition and collected high-definition video imagery during dives by the “Little Hercules” ROV from the NOAA ship Okeanos Explorer. Researchers discovered a diversity and abundance of deep corals that they believe is the highest in the world, in more than 25 habitats on varied terrains at depths from 250 meters to more than 3,600 meters in the Sulawesi Sea. Tim and his colleagues video-imaged 40 potentially new deep-sea species and found dramatically different assemblages of coral species on different seamounts and depths. This expedition provides baseline data to let us better understand these ecosystems and identify future changes, information important in Indonesian seas and around the world.James Kinsey (AOPE) is engineering the application of a new class of accelerometers to develop an innovative gravimeter for use on AUVs. Gravity measurements can provide valuable information about the density and porosity of the sub-seafloor structure. Gravity anomalies (differences between expected and measured values) are measured from ships and satellites—both too far above the seafloor to resolve small-scale density differences. James and AOPE colleagues will determine the sensitivity of a new class of accelerometer and test it alongside a standard ship gravimeter, allowing them to investigate the potential of AUV gravimetry for solving geophysical problems in the deep ocean and work towards integrating the sensor into WHOI's Sentry AUV. The new sensing capability will augment Sentry's geophysical instrumentation and motivate future research using this new class of accelerometers to develop low-cost, high-precision inertial navigation systems—technology with applications to ocean, land, and aerial robotics.
Ocean Ridge Initiative
Henry Dick and Frieder Klein (G&G) will conduct a systematic study of carbonate-altered serpentinite minerals—minerals that take up carbon dioxide—from several types of hydrothermal vent systems. They will analyze the composition and associations of secondary minerals in these rocks using classic and new methods to unravel reaction pathways during CO2 uptake. Their results will provide valuable new insights into the process of carbonate alteration in serpentinites and the consequences for CO2 exchange between the abyssal mantle and the ocean.
Susan Humphris (G&G) and MIT/WHOI Joint Program student Evelyn Mervine will determine the natural rate of carbonation of mantle rocks (or peridotite) in an ophiolite—a section of oceanic crust and mantle exposed to the atmosphere by tectonic uplifting. Considerable attention has focused on carbon capture and storage as a way to mitigate CO2 input to the atmosphere from human activities. One proposed option is to increase the conversion of CO2 gas to stable, solid carbonate minerals, which happens when mantle rock is exposed to the atmosphere. Susan and Evy will study the Samail Ophiolite in Oman—one of the world's largest and best-exposed ophiolites—and measure the volume, ages and weathering rates in ophiolite layers, which will let them quantify the residence time of carbon in three kinds of carbonate-altered rocks within the ophiolite, some of them 350,000 years old. Studying carbonate formation in an ophiolite will provide a case study for seafloor rocks' potential for carbon sequestration, a potentially important 'sink' in the global carbon cycle.
Lauren Mullineaux and Susan Mills (BIO) will study how submarine eruptions along a mid-ocean ridge, the East Pacific Rise (EPR) near 9o 50' N, affect the supply of larvae and the recolonization of fauna specific to hydrothermal vents. They had been monitoring larvae and colonization at the site before a volcanic eruption there in 2005-2006, and were able to mobilize quickly afterward to resume sampling. A striking change in the assortment of species colonizing the site after the eruption, driven in part by the supply of larvae, led Lauren and Susan to ask if these new pioneer species will persist and lead to a different stable community at the vent—or if the vent community will transition back to the pre-eruption assemblage of species? They will address this question by long-term monitoring of species at the eruption site. An invitation to participate in a French cruise to the EPR gave them an opportunity to start this effort in collaboration with a colleague who will provide associated measurements of biologically important environmental components, pH (acidity) and sulfide. Biological and chemical monitoring will let them evaluate the roles of larval supply and environmental change in the recovery of EPR vent communities post-eruption, and to pursue further funding and collaborations to study them.Jared Goldstone, Tim Shank, and John Stegeman (BIO) will identify genetic (DNA) sequences that can be used as markers of organic chemical (hydrocarbon) exposure in deep-sea mussels, Bathymodiolus thermophilus and related species. When exposed to such toxins, animals employ (express) specific genes to produce the enzymes that detoxify those compounds, but how animals in vent or seep environments accomplish this task is not known. It's hard to obtain samples for genetic analysis from the deep sea, so little information is available on the mussels' gene sequences or genes expressed. But they are closely related to a shallow-water species, the blue mussel, for which researchers do have gene sequences. By analyzing evolutionary relationships between mussel species, the team will identify Bathymodiolus gene sequences expressed when the mussels are exposed to organic chemicals, which in turn will help define the chemical environment that animals experience at deep-sea vents and hydrocarbon seeps.
2010 DOEI Fellows, Postdocs, Graduate students, and the Geodynamics Program