Woods Hole Oceanographic Institution

About: Woods Hole Oceanographic Institution is a nonprofit organization based out in Falmouth, Massachusetts, United States. It is known for research contribution in the topics: Population & Mantle (geology). The organization has 5685 authors who have published 18396 publications receiving 1202050 citations. The organization is also known as: WHOI.

Seasonal and depth-related changes in the source of sinking particles in the North Atlantic

Abstract: LARGE, fast-sinking particles are important in the downward transport and redistribution of biogeochemical species in the deep ocean. Using nitrogen isotope ratio, 15N/14N, as an in situ tracer, we investigate the source and transformation of these particles in the North Atlantic ocean. We observe seasonal variations in δ15N associated with seasonal changes in near-surface nitrate concentration and particle flux; the nitrogen isotope variations are consistent with, but much larger than, previously observed variability1,2. Our results show that the signal from these near-surface changes propagates rapidly into the deep ocean, but is modified depending on the phase of the seasonal production cycle. Surprisingly, we find that δ15N values for sinking particles decrease with depth during low-flux periods—behaviour that may occur generally in the open ocean. The sinking particles must therefore be either gaining light nitrogen or losing heavy nitrogen, an effect that we believe requires there to be another source of sinking particles, apart from recent surface production.

Large benthic microbial communities in sulphide biota under Peru-Chile Subsurface Countercurrent

Abstract: BENTHIC observations off the coast of Chile have consistently disclosed the presence of large coherent microbial communities living at depths of about 50–280 m in the H2S-containing sediments of the shelf in contact with the deoxygenated waters of the Peru–Chile Subsurface Countercurrent (SCC). Similar observations were also made off Peru in 1969 by Gilbert T. Rowe, and in 1976 by G. T. Rowe and John Waterbury of Woods Hole Oceanographic Institution. The microflora, which has only been reported once before in the literature1, has been known for years by the local fishermen who call them estopa (Spanish for uncleansed wool or fiax) due to the filamentous appearance of its main components. In this report I describe this massive microbial community which includes organisms typical for sulphide biota, and may have unsuspected importance in the ecology and economy of the sea off western South America.

Discovery of a magma chamber and faults beneath a Mid-Atlantic Ridge hydrothermal field

Abstract: Crust at slow-spreading ridges is formed by a combination of magmatic and tectonic processes, with magmatic accretion possibly involving short-lived crustal magma chambers The reflections of seismic waves from crustal magma chambers have been observed beneath intermediate and fast-spreading centres, but it has been difficult to image such magma chambers beneath slow-spreading centres, owing to rough seafloor topography and associated seafloor scattering In the absence of any images of magma chambers or of subsurface near-axis faults, it has been difficult to characterize the interplay of magmatic and tectonic processes in crustal accretion and hydrothermal circulation at slow-spreading ridges Here we report the presence of a crustal magma chamber beneath the slow-spreading Lucky Strike segment of the Mid-Atlantic Ridge The reflection from the top of the magma chamber, centred beneath the Lucky Strike volcano and hydrothermal field, is approximately 3 km beneath the sea floor, 3-4 km wide and extends up to 7 km along-axis We suggest that this magma chamber provides the heat for the active hydrothermal vent field above it We also observe axial valley bounding faults that seem to penetrate down to the magma chamber depth as well as a set of inward-dipping faults cutting through the volcanic edifice, suggesting continuous interactions between tectonic and magmatic processes

West Antarctic Peninsula: An Ice-Dependent Coastal Marine Ecosystem in Transition

Abstract: The extent, duration, and seasonality of sea ice and glacial discharge strongly influence Antarctic marine ecosystems. Most organisms' life cycles in this region are attuned to ice seasonality. The annual retreat and melting of sea ice in the austral spring stratifies the upper ocean, triggering large phytoplankton blooms. The magnitude of the blooms is proportional to the winter extent of ice cover, which can act as a barrier to wind mixing. Antarctic krill, one of the most abundant metazoan populations on Earth, consume phytoplankton blooms dominated by large diatoms. Krill, in turn, support a large biomass of predators, including penguins, seals, and whales. Human activity has altered even these remote ecosystems. The western Antarctic Peninsula region has warmed by 7°C over the past 50 years, and sea ice duration has declined by almost 100 days since 1978, causing a decrease in phytoplankton productivity in the northern peninsula region. Besides climate change, Antarctic marine systems have been greatly altered by harvesting of the great whales and now krill. It is unclear to what extent the ecosystems we observe today differ from the pristine state.