DLS Abstracts 2011
Anna-Louise Reysenbach
Science Community Lecture: From mantle to microbe: Geology shapes microbial communities of hydrothermal vent deposits
At mid-ocean ridges and back-arc basins, deep-sea hydrothermal vents are recognized as important biogeochemical environments that support unique ecosystems rich in microbial diversity. As the high temperature hydrothermal fluid mixes with the cold, oxygenated seawater, minerals precipitate to form vent deposits. These porous deposits are quickly colonized by a diversity of Archaea and Bacteria that harness the abundant geochemical energy available in the hydrothermal fluids. The composition of the hot fluid is dependant on such factors as the depth of fluid circulation, the depth of the heat source, and the composition of the rocks that the fluid reacts with as it circulates through the EarthÕs crust. Over the past decade or so, patterns of microbial diversity associated with these deposits are beginning to emerge, yet very few studies explore the role large-scale geological processes might influence the microbial diversity and colonization. Using a combination of thermocouple array deployments and multiplexed bar-coded pyrosequencing of the 16S rRNA genes from multiple vent deposits from the Mid-Atlantic Ridge, Eastern Lau Spreading Center, East Pacific Rise, and Guaymas Basin, it appears that the biogeographical patterns of hydrothermal vent microorganisms are shaped by large-scale geologic processes and local hydrothermal fluid mixing styles.
General Public Lecture: From there to here, from here to there, funny microbes are everywhere (at deep-sea vents)
We live on a microbial planet. Most of the biodiversity of life on Earth is microbial. These microscopic organisms occupy almost any conceivable habitat where there is available water, energy and carbon for growth, even in the minutest quantity. They live in some of the most salty, cold, hot, nutrient-starved, dry and acidic places on this planet, and they form critical partnerships with many other organisms, including us. At deep-sea vents, microorganisms form the base of the food web, fueling the chemosynthetic-based ecosystem. Here, a huge diversity of microbes are supported by geochemical fluxes from EarthÕs interior and the chemical disequilibria that result when chemically reduced fluids vent at the seafloor and mix with oxic seawater. Many of the unusual invertebrates, like tubeworms which lack a mouth and gut, have formed obligate partnerships with their microbial symbionts who in turn rely on the geochemistry of the fluids for energy and carbon. Using DNA fingerprinting techniques, we are starting to get a better picture of the extent of the microbial diversity at deep-sea vents. Yet, with only a very small percentage of our deep sea explored, we are just scratching the surface! Nonetheless, every new site explored, every new study initiated, provides new biological discoveries. Much of the research is detective work, knowing that a certain microorganism resides in a particular habitat, yet looking for signs for what that organism is doing through careful sleuthing. Understanding the extent of life on Earth, how that life survives and thrives, whether at deep-sea vents or in a very dry desert or a salt pan, provides scientists with a more informed approach for looking for signs of past and present life elsewhere in the Solar System.
Ken Rubin
Science Community Lecture: Ocean ridge and other submarine eruptions - the link between Earth's deep interior and the sea floor
Submarine volcanism transfers heat and chemicals from Earth's interior to the deep sea, playing an important role in ocean chemistry and benthic ecology. Lavas erupting onto the sea floor at many locations along and between the plate boundaries also provide a geographically widespread, first-order snapshot of the composition of Earth's mantle. A range of processes occur between melt generation at depth and eruption on the sea floor, producing regular chemical, isotopic, and radiometric signals in erupted lavas which reveal how these volcanoes operate and how they impact the marine environment. Samples and maps of recent eruption deposits provide the highest resolution and easiest to read record of the rates and length scales of magmatic processes at submarine volcanoes. For instance, the sizes, durations, and chemical characteristics of erupted lavas are systematically linked to the rate of magma and heat supplied to mid-ocean ridge volcanoes, providing a framework for estimating fluxes from the mantle to the oceans.
General Public Lecture: Caught in the act - first observations of a deep-sea lava flow and pyroclast eruption
Most volcanic eruptions on Earth occur beneath the sea surface, unseen and undetected. But dramatic new video footage, rock and water samples collected in May 2009, during a volcanic eruption at more than 3600-ft depth in the ocean at West Mata volcano, in the territorial waters of Tonga, now tell the story of deep-sea volcanism in unprecedented detail. Physical and geochemical analysis of red hot lava flows, glowing gas bubbles, sulfurous fumes, hurtling volcanic bombs and glassy ejecta reveal the conditions before and during the eruption. Together with observations made soon after eruptions at other deep-sea sites, Ridge 2000 scientists are piecing together the story of deep-sea volcanism and its ecological impacts. This presentation will include dramatic video and still images of this historic eruption.
Bruce Strickrott
Science Community Lecture: Engineering technologies for scientific study of the deep sea
Since 1964 the Woods Hole Oceanographic Institution has been operating the human-occupied submersible Alvin, taking thousands of scientific observers into the deep ocean. But how is this accomplished, and what technologies are used? This discussion will outline the basic technologies used on Alvin to take scientists to the deep ocean. The presentation will include the basics of manned deep submersible design, including a history of design evolution, current technologies in use and an outline of future plans for manned systems upgrades to Alvin over the next few years. Additionally, the presentation will discuss specific methods that are used to interact with the deep ocean environment and how complex scientific experiments can be accomplished in these harsh environments. The talk will include some of my personal experiences working with Alvin and our user community and thoughts on how new technologies can be implemented to improve the scientific study of the deep sea.
General Public Lecture: Human presence in the deep ocean, from fantasy to reality
In 1870, Jules Verne penned his famous novel, 20000 Leagues Under the Sea, putting on paper as fiction what many had dreamed about, the ability to visit and explore the unknown depths of the ocean. From that time moving forward, the dream of deep ocean exploration has become a reality and has uncovered profound discoveries about the planet and the ocean environment. This presentation will outline a history of human-occupied submersibles, starting from the early primitive designs and working toward how we operate Alvin today. The talk will include some of my personal experiences diving in Alvin. I will discuss the evolution and future of technologies associated with taking humans into the deep ocean, including the future of human-occupied vehicles at Woods Hole Oceanographic Institution, specific improvements and upgrades to Alvin, and the plan to take Alvin even deeper over the next few years.
Brandy Toner
Science Community Lecture: Integrated nested-scale biogeochemistry of hydrothermal plumes at a back-arc spreading center
Hydrothermal venting associated with mid-ocean ridge volcanism is globally widespread. Hydrothermal plumes created by this venting represent a dynamic biogeochemical interface between the sub-seafloor and deep ocean that is poorly understood in terms of process-level mechanisms and global ocean implications. Advancing understanding of the role of plume processes in global ocean biogeochemistry requires highly integrated, multi-disciplinary research that accesses physical, chemical, and biological properties within individual buoyant plumes. In addition, comparisons among plumes in a given vent field, and among vent fields representing a continuum of geophysical and geochemical conditions are essential. To address this research need, a large nested-scale research program focused on hydrothermal vent fields along the Eastern Lau Spreading Center has begun. During June-July 2009, rising plumes at Kilo Moana, ABE, Tahi Moana, Mariner, and Tui Malila vent fields were sampled at discrete elevations for geochemistry, metal speciation, mineralogy, and microbial ecology. The trajectory of oxidation-reduction sensitive elements as they move through a buoyant plume at ABE vent field will be highlighted. In terms of global ocean elemental fluxes, hydrothermal vent plumes represent a critical oceanic interface where biogeochemical processes leading to particle formation, surface reactivity, and dispersal are poorly constrained.
General Public Lecture: Can iron from deep-sea hot springs fertilize the oceans?
The global mid-ocean ridge system is a 60,000-km volcanic chain that crosses the floor of all major ocean basins on Earth. Dispersed along this baseball seam are deep-sea hydrothermal vents that release hot fluids rich in iron and other reduced chemicals. Every year, the iron released to the ocean by hydrothermal venting at the seafloor is approximately equal to all of the iron flushed from the continents by rivers - this is a lot of iron. With all of this iron entering the oceans, how do we explain the large regions of the global ocean where iron availability is so low that it limits life? The key to understanding iron mobility and bioavailability is the specific chemical form of the iron. In this lecture, I will discuss current scientific understanding of the chemistry and biology of hydrothermally derived iron. I will also highlight recent research discoveries that demonstrate the limits of current understanding and examine the rich complexities of iron biogeochemistry in the deep ocean.
