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.

Movements of blue sharks (Prionace glauca) in depth and course

Abstract: Acoustic telemetry was used to follow 22 blue sharks,Prionace glauca (Linnaeus), over the continental shelf and slope in the region between George's Bank and Cape Hatteras between 1979 and 1986. The sharks frequently made vertical excursions between the surface and depths of several hundred meters. The oscillations, which were repeated every few hours, were largest in the daytime and were smaller in amplitude and confined to depths near the thermocline at night. This behavior was prominent in trials from August through March, but was not seen from June through July. Diving is discussed in terms of a hunting tactic and behavioral thermoregulation. Most of the sharks moved in a southeasterly direction from the release point and many maintained a constant course day and night for several days. The sharks may orient to the earth's magnetic field, or to the ocean's electric fields, allowing them to swim on a constant heading in the absence of celestial cues. These possibilities are discussed in the appendix.

Evolution of climatic adaptation in homeotherms

Abstract: Climatic adaptation in warm-blooded animals has been a subject of much concern to ecologists and evolutionists. With the formulation of the climatic rules of Bergmann and Allen it has become almost dogma that a reduction in the surface area relative to weight is a morphogenic factor of prime importance in the evolution of cold-hardy species or races. This idea is based on the simple reasoning that, other factors being equal, the less surface area an animal has the less heat it would lose. Natural selection would therefore favor an arctic fauna tending towards large globular woolly balls with the least possible ears, tail, snout and legs. Tropical animals would tend in the opposite direction, towards smaller skinny forms, with long legs, snout, ears and tail. Clines of this sort have been looked for and have been found in many mammals and birds, and are given in textbooks on evolution as classical examples of the workings of adaptation by selection. Lately anthropologists have seen in the climatic rules a powerful tool by which to explain many racial features in man. Adaptation, in the sense of "rendered fit for," implies an understanding of how and why the observed trend or response is useful, and is hence linked up with physiology. Sufficient information on the physiological adjustments of arctic and tropical animals is now available so that we may attempt an analysis of what phylogenetic pathways evolution has actually followed in the engineering of climatic adaptation of warm-blooded animals. CLIMATIC ADAPTATIONS FOUND IN ARCTIC AND TROPICAL MAMMALS AND BIRDS

Temporal and spatial patterns of biological community development at nascent deep-sea hydrothermal vents (9°50 N, East Pacific Rise)

Abstract: The April 1991 discovery of newly formed hydrothermal vents in areas of recent volcanic eruption between 9°45′N and 9°52′N on the East Pacific Rise provided a unique opportunity to follow temporal changes in biological community structure from the “birth” of numerous deep-sea hydrothermal vents. In March l992, DSV Alvin was used to deploy an on-bottom observatory, the Biologic–Geologic Transect, to monitor faunal succession along a 1.37 km segment of the axial summit caldera between 9°49.61′N and 9°50.36′N (depth ∼2520 m). Photo- and videographic documentation of megafaunal colonization and chemical analyses of diffuse hydrothermal fluids associated with many of these developing communities within the Transect were performed in March 1992, December 1993, October 1994, and November 1995. Photographic and chemical time-series analyses revealed the following sequence of events in low-temperature venting areas. (1) Immediately following the 1991 eruption, hydrogen sulfide and iron concentrations in diffuse fluids were extremely high (>1 mmol kg-1) and microbially derived material blanketed active areas of venting in the form of thick microbial mats. (2) Mobile vent fauna (e.g. amphipods, copepods, octopods, and galatheid and brachyuran crabs) and non-vent fauna (e.g. nematocarcinid shrimp) proliferated in response to this increased biological production. (3) Within 1 yr of the eruption, areal coverage of microbial mat was reduced by ∼60% and individuals of the vestimentiferan tube worm Tevnia jerichonana settled gregariously in areas where diffuse flow was most intense. (4) Two years after the eruption, maximum levels of H2S decreased by almost half (from 1.90 to 0.97 mmol kg-1) and dense thickets of the vestimentiferan Riftia pachyptila dominated vent openings previously inhabited by Tevnia jerichonana. (5) Three years after the eruption, maximum hydrogen sulfide levels declined further to 0.88 mmol kg-1 and mussels (Bathymodiolus thermophilus) were observed on basaltic substrates. (6) Four years after the eruption, galatheid crabs and serpulid polychaetes increased in abundance and were observed close to active vent openings as maximum hydrogen levels decreased to 0.72 mmol kg-1. Also by this time mussels had colonized on to tubes of Riftia pachyptila. (7) Between 3 and 5 yr after the eruption, there was a 2- to 3-fold increase in the number of species in the faunal assemblages. In the absence of additional volcanic/tectonic disturbance, we predict that mytilid and vesicomyid bivalves will gradually replace vestimentiferans as the dominant megafauna 5–10 yr following the eruption. We also anticipate that the abundance of suspension feeders will decline during this period while the abundance of carnivores will increase. We hypothesize that the above series of events (1–7) represents a general sequence of biological successional changes that will occur at newly formed low-temperature deep-sea hydrothermal vents along the northern East Pacific Rise and contiguous ridge axes. Megafaunal colonization at deep-sea hydrothermal vents is considered to be the consequence of an intimate interaction of the life-history strategies of individual species, physical oceanographic processes, and the dynamic hydrothermal environment. Our observations indicate that the successful sequential colonization of dominant megafaunal vent species, from Tevnia jerichonana to Riftia pachyptila to Bathymodiolus thermophilus, also may be strongly influenced by temporal changes in geochemical conditions. Additional evidence demonstrating the close link between diffuse vent flux, fluid geochemistry, and faunal succession included the rapid death of several newly formed biological assemblages coincident with abrupt changes in the geochemical composition of the venting fluid and the local refocusing or cessation of vent flow. These correlations suggest that future models of faunal succession at hydrothermal vents along intermediate to fast-spreading mid-ocean ridges should consider not only the interplay of species-specific life-history strategies, community productivity, and physical oceanographic processes, but also the influence of changing geochemical conditions on the sequential colonization of megafaunal species.

Variations in nitrogen isotopic composition between sinking and suspended particles: implications for nitrogen cycling and particle transformation in the open ocean

Abstract: Significant and consistent differences in nitrogen isotopic ratio (measured as δ15N relative to atmospheric N2) are observed between suspended and sinking particles in the Sargasso Sea. Suspended particles in the euphotic zone have an annual average of −0.2% while particles sinking out of the euphotic average 3.7%. This latter value is equivalent to the average of δ15N value for the sources of new nitrogen to the euphotic zone. The δ15N of NO3− below the euphotic zone is similar, confirming that this is the major source. The downward particle flux acts to preferentially export 15N out of the euphotic zone, with the result that suspended particles are depleted in 15N relative to new nitrogen sources. The observed difference in δ15N is evidence that the net transformation of suspended into sinking particles in this region is a result of active processes such as macrozooplankton feeding, as opposed to passive physical effects. Suspended particles below 200 m are 6% higher in δ15N relative to those within the euphotic zone. This observation reflects, in part, the origin of suspended particles below the euphotic zone from the larger, faster sinking particles which are enriched in δ15N. Since these suspended particles are also higher in δ15N relative to sinking particles by 3%, isotopic fractionation must occur during the disaggregation of sinking particles and/or the subsequent degradation of suspended particles.