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Search Results: 1 - 10 of 1758 matches for " mid-ocean ridges "
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Bringing Mid-Ocean Ridge Discoveries to Audiences Far and Wide: Emerging Trends for the Next Generation
Liz Goehring,Véronique Robigou,Katherine Ellins
Oceanography , 2012,
Abstract: The "Ridge" community has pioneered not only scientific exploration of and research on the global mid-ocean ridge system but also innovative and attractive ways of reaching out to the public with fascinating stories of scientific discovery and cutting-edge deep-sea technology. This article summarizes 30 years of education and public outreach (EPO) projects conducted by scientists and outreach professionals in the Ridge community to highlight the key principles of effective EPO, such as the importance of targeting specific audiences' needs and expectations. Other elements discussed include collaboration with professionals outside of the scientific community, increased participation of individuals from underrepresented groups in science, and rigorous evaluation to strengthen the impact of future programs. The article also explores how cyber technology and observatory science offer new opportunities for sharing discoveries as they occur and involving the public in the research endeavor. By reaching audiences on a more direct and personal level, these novel approaches may hold the most promise for increasing public appreciation for the marine environment. Scientists' perspectives on EPO programs, lessons, learned, and personal benefits address the question "Why should I do outreach?" Ridge EPO programs highlighted include (1) "Research and Education: Volcanoes, Exploration and Life" (REVEL)—a seagoing, research-focused professional development program for K–12 teachers; (2) "Why is Earth Habitable?"—an iconic American Museum of Natural History exhibit; (3) "Volcanoes of the Deep Sea" and "Aliens of the Deep," two popular IMAX films; (4) "Dive & Discover," an online resource and expedition archive; (5) Extreme 2000, Student Experiments at Sea (SEAS), and From Local to Extreme Environments (FLEXE), three innovative education projects for K–12 students; (6) the Ridge 2000 Distinguished Lecturer Series targeting institutions without marine science programs; and (7) "Beyond the Edge of the Sea," a traveling exhibit of vent-ecosystem illustrations.
The Prediction, Verification, and Significance of Flank Jets at Mid-Ocean Ridges
J. William Lavelle,Andreas M. Thurnherr,Lauren S. Mullineaux,Dennis J. McGillicuddy Jr.
Oceanography , 2012,
Abstract: One aspect of ocean flow over mid-ocean ridges that has escaped much attention is the capacity of a ridge to convert oscillatory flows into unidirectional flows. Those unidirectional flows take the form of relatively narrow jets hugging the ridge's flanks. In the Northern Hemisphere, the jets move heat and dissolved and particulate matter poleward on the west and equatorward on the east of north-south trending ridges. Recent measurements and a model of flow at the East Pacific Rise at 9–10°N show that these ridge-parallel flows can extend 10–15 km horizontally away from the ridge axis, reach from the seafloor to several hundreds of meters above ridge crest depth, and have maximum speeds in their cores up to 10 cm s–1. Because of their along-ridge orientation and speed, the jets can significantly affect the transport of hydrothermal vent-associated larvae between vent oases along the ridge crest and, possibly, contribute to the mesoscale stirring of the abyssal ocean. Because jet-formation mechanisms involve oscillatory currents, ocean stratification, and topography, the jets are examples of "stratified topographic flow rectification." Ridge jets have parallels in rectified flows at seamounts and submarine banks.
Estimating Zooplankton Biomass Distribution in the Water Column Near the Endeavour Segment of Juan de Fuca Ridge Using Acoustic Backscatter and Concurrently Towed Nets
Brenda J. Burd,Richard E. Thomson
Oceanography , 2012,
Abstract: Logistical challenges, time, and the cost of towed net surveys make it difficult to obtain estimates of secondary biomass and production in the open ocean outside the summer sampling season. Alternate approaches are sometimes needed. This study examines the relationship between biomass obtained from 197 mixed-species zooplankton net samples and proximate acoustic backscatter data collected over six summers, a depth range of 3,000 m, and a spatial scale of 200 km centered at a major hydrothermal region in the Northeast Pacific Ocean. Results show that the acoustic backscatter data from a single-frequency (150 kHz) acoustic Doppler current profiler mounted near the opening of the towed net system accounts for 84% of the variance in total net biomass, despite the remarkable mix of faunal types and depth range, and the broad spatial and temporal extent of the study. We discuss the potential reasons for the minor remaining variance in net biomass. The present findings demonstrate that profiling or moored acoustic backscatter instrumentation can provide a less-challenging methodology than net tows for obtaining bulk estimates of deep-sea zooplankton biomass in the open waters of the Northeast Pacific.
On the Potential for Bioenergy and Biofuels from Hydrothermal Vent Microbes
Peter R. Girguis,James F. Holden
Oceanography , 2012,
Abstract: The discovery of deep-sea hydrothermal vents caused scientists to reconsider their notions about life in the deep sea. In these seemingly inhospitable environments, free-living microbes, as well as microbial-animal symbioses, thrive in the warm waters around vents. The biomass per unit area in this environment is comparable to that of rainforests. Uniquely, these highly productive ecosystems are based on microbial chemoautotrophic metabolism, wherein microbes generate metabolic energy by drawing oxygen or nitrate from surrounding seawater to oxidize reduced chemicals (e.g., sulfide) found in the vent fluids (Sievert and Vetriani, 2012, in this issue). The rapid and voluminous fluid flux through hydrothermal vents replenishes these substrates at a rate sufficient to support this substantial community. The tremendous microbial productivity observed at vents raises the question as to whether these microorganisms are also well suited for bioenergy and biofuel production. Here, we discuss the utility and issues associated with two example approaches: in situ bioelectricity generation and microbially mediated large-scale biofuel production.
Larval Dispersal: Vent Life in the Water Column
Diane K. Adams,Shawn M. Arellano,Breea Govenar
Oceanography , 2012,
Abstract: Visually striking faunal communities of high abundance and biomass cluster around hydrothermal vents, but these animals don't spend all of their lives on the seafloor. Instead, they spend a portion of their lives as tiny larvae in the overlying water column. Dispersal of larvae among vent sites is critical for population maintenance, colonization of new vents, and recolonization of disturbed vents. Historically, studying larvae has been challenging, especially in the deep sea. Advances in the last decade in larval culturing technologies and more integrated, interdisciplinary time-series observations are providing new insights into how hydrothermal vent animals use the water column to maintain their populations across ephemeral and disjunct habitats. Larval physiology and development are often constrained by evolutionary history, resulting in larvae using a diverse set of dispersal strategies to interact with the surrounding currents at different depths. These complex biological and oceanographic interactions translate the reproductive output of adults in vent communities into a dynamic supply of settling larvae from sources near and far.
The Lau Basin Float Experiment (LAUB-FLEX)
Kevin Speer,Andreas M. Thurnherr
Oceanography , 2012,
Abstract: Before 2004, little was known about deep ocean circulation in the Lau Basin, a semi-enclosed basin in the South Pacific Ocean, about 1,500 km north of New Zealand. This basin hosts a number of back-arc spreading centers with active hydrothermal vents, including the Eastern Lau Spreading Center (ELSC), a Ridge 2000 Integrated Study Site where coordinated interdisciplinary experiments were carried out between 2004 and 2010 (Tivey et al., 2012, in this issue). Answering numerous important questions in hydrothermal research requires an understanding of oceanic circulation on a range of temporal and spatial scales. For example, we need to be able to make flux calculations of heat and hydrothermal chemicals and to know the pathways for larval dispersal, which determine colonization of new hydrothermal sites, gene flow, and ultimately the biogeography of vent species. Knowledge of turbulent dispersion (mean squared displacement averaged over groups of floats) enables quantification of spreading rates and direction in complex ocean circulation regimes, and Lagrangian measurement techniques are often used to observe dispersion. Near mid-ocean ridges, however, this approach is still relatively rare (Speer et al., 2003; Jackson et al., 2010).
Lava Geochemistry as a Probe into Crustal Formation at the East Pacific Rise
Michael R. Perfit,V. Dorsey Wanless,W. Ian Ridley,Emily M. Klein
Oceanography , 2012,
Abstract: Basalt lavas comprise the greatest volume of volcanic rocks on Earth, and most of them erupt along the world's mid-ocean ridges (MORs). These MOR basalts (MORBs) are generally thought to be relatively homogeneous in composition over large segments of the global ridge system (e.g., Klein, 2005). However, detailed sampling of two different regions on the northern East Pacific Rise (EPR) and extensive analysis of the samples show that fine-scale mapping and sampling of the ridge axis can reveal significant variations in lava chemistry on both small spatial and short temporal scales. The two most intensely sampled sites within the EPR Integrated Study Site (ISS) lie on and off axis between 9°17'N and 10°N, and from a wide region centered around 9°N where two segments of the EPR overlap (see Fornari et al., 2012, Figure 3, in this issue). The chemical composition of erupted lavas, similar to the genotype of an organism, can be used by igneous petrologists to trace the evolution of magmas from the mantle to the seafloor. The extensive and detailed geochemical studies at the EPR highlight how a thorough understanding of the variability in lava compositions on small spatial scales (i.e., between lava flows) and large spatial scales (i.e., from segment center to segment end and including discontinuities in the ridge crest) can be used in combination with seafloor photography, lava morphology, and bathymetry to provide insights into the magmatic system that drives volcanism and influences hydrothermal chemistry and biology at a fast-spreading MOR.
Introduction to the Special Issue: From RIDGE to Ridge 2000
Daniel J. Fornari,Stace E. Beaulieu,James F. Holden,Lauren S. Mullineaux
Oceanography , 2012,
Abstract: Articles in this special issue of Oceanography represent a compendium of research that spans the disciplinary and thematic breadth of the National Science Foundation's Ridge 2000 Program, as well as its geographic focal points. The mid-ocean ridge (MOR) crest is where much of Earth's volcanism is focused and where most submarine volcanic activity occurs. If we could look down from space at our planet with the ocean drained, the MOR's topography and shape, along with its intervening fracture zones, would resemble the seams on a baseball, with the ocean basins dominating our planetary panorama. The volcanic seafloor is hidden beneath the green-blue waters of the world's ocean, yet therein lie fundamental clues to how our planet works and has evolved over billions of years, something that was not clearly understood 65 years ago—witness the following quote from H.H. Hess (1962) in his essay on "geopoetry" and commentary on J.H.F. Umbgrove's (1947) comprehensive summary of Earth and ocean history: The birth of the oceans is a matter of conjecture, the subsequent history is obscure, and the present structure is just beginning to be understood. Fascinating speculation on these subjects has been plentiful, but not much of it predating the last decade [the 1950s] holds water.
Low-Temperature Hydrothermal Plumes in the Near-Bottom Boundary Layer at Endeavour Segment, Juan de Fuca Ridge
Susan Hautala,H. Paul Johnson,Matthew Pruis,Irene García-Berdeal
Oceanography , 2012,
Abstract: Low-temperature (typically 5–75°C) fluid, commonly referred to as "diffuse" hydrothermal flow, emanates from fractures over a significant portion of the Juan de Fuca Ridge seafloor in the Northeast Pacific Ocean (Kelley et al., 2012, in this issue). Although some fraction of the diffuse effluent becomes entrained relatively quickly into nearby plumes from high-temperature sources, a number of studies suggest that a significant portion flows laterally as discrete low-level plumes that remain detectable downstream for considerable distances (Trivett and Williams, 1994; Kinoshita et al., 1998, Veirs et al., 2006). The seafloor near diffuse hydrothermal vents supports densely populated, localized biological communities in a bottom boundary layer (BBL) environment that is highly variable in both space and time. Currents, temperature, and turbulence in the BBL, in addition to a complex array of biological, chemical, geological, and other physical factors, influence community structure near diffuse vents. Tides strongly affect the flow direction of both high-temperature (Veirs et al., 2006) and diffuse (Kinoshita et al., 1998) plumes within the water column, and have been observed to affect temperature in the immediate vicinity of diffuse vents (Little et al., 1988; Tivey et al., 2002; Sheirer at al., 2006). Here, we describe recent measurements that reveal in greater detail the important role that tidal advection plays in modulating the BBL environment near diffuse hydrothermal plumes.
Recent Advances in Multichannel Seismic Imaging for Academic Research in Deep Oceanic Environments
Juan Pablo Canales,Hélène Carton,John C. Mutter,Alistair Harding
Oceanography , 2012,
Abstract: Academic research using marine multichannel seismic (MCS) methods to investigate processes related to Earth's oceanic crust has made substantial advances in the last decade. These advances were made possible by access to state-of-the-art MCS acquisition systems, and by development of data processing and modeling techniques that specifically deal with the particularities of oceanic crustal structure and the challenges of subseafloor imaging in the deep ocean. Among these methods, we highlight multistreamer three-dimensional (3D) imaging, streamer refraction tomography, synthetic ocean bottom experiments (SOBE), and time-lapse (4D) studies.
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