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.

Prokaryotic Cells in the Hydrothermal Vent Tube Worm Riftia pachyptila Jones: Possible Chemoautotrophic Symbionts.

Abstract: The existence of a symbiotic association between vestimentiferan tube worms from deep-sea hydrothermal vents and chemoautotrophic sulfur-oxidizing prokaryotes, based on histological and enzymatic evidence, is suggested.

Carbon emissions from tropical deforestation and regrowth based on satellite observations for the 1980s and 1990s.

Abstract: The increase of carbon dioxide in the atmosphere relative to emissions from fossil-fuel burning and land-use change indicates that terrestrial and marine environments are absorbing approximately one-half to three-quarters of the emitted carbon dioxide. Several lines of evidence indicate uptake of carbon dioxide in the terrestrial extratropical Northern Hemisphere including land-inventory data, atmospheric CO2 and O2 data, isotopic analyses, and ecosystem models (1–5). Regrowth on abandoned agricultural land, fire prevention, longer growing seasons, and fertilization by increased concentrations of carbon dioxide and nitrogen have been proposed as possible mechanisms responsible for the Northern Hemisphere uptake (6–8). Future atmospheric carbon-dioxide concentrations and consequent climate change depend to a large extent on the future course of the terrestrial uptake (9). If the underlying mechanisms are no longer able to sequester carbon at some point in the future, as for example would be the case once regrowing forests mature, a larger proportion of emitted carbon dioxide would remain in the atmosphere, and carbon-dioxide concentrations would increase at a greater rate for the same level of emissions. Atmospheric inversion studies, which calculate net sources and sinks of carbon dioxide from the spatial distribution of atmospheric concentrations, indicate a net land sink of 0.6–2.3 petagrams (Pg)⋅yr−1 in the extra tropics (6). In the tropics, inverse models are poorly constrained but indicate that the region, overall, is neutral or a small source of carbon to the atmosphere (10). Although inversion studies locate and quantify the net terrestrial sources or sinks, the attribution to mechanisms and their possible future trajectories depend on quantifying the gross sources and sinks. For a net sink, the mechanisms responsible for uptake of carbon dioxide must be powerful enough to offset the sources from fossil fuel and deforestation. The carbon dioxide emitted from fossil-fuel combustion is well quantified (11), but the emission from tropical land-use change is highly uncertain. Without more precise estimates of this source term, deciphering possible mechanisms sequestering the missing carbon remains problematic. The flux of carbon to the atmosphere from tropical land-use change is one of the largest uncertainties in the contemporary carbon budget (6, 12) because of the difficulties in quantifying deforestation and regrowth rates, initial biomass, and fate of carbon in areas where vegetation has been cleared. Estimates of carbon fluxes from tropical deforestation as reported by the Intergovernmental Panel on Climate Change (IPCC; ref. 12) from refs. 5 and 13 range from 0.6 to 2.5 Pg⋅yr−1 for the 1980s, based primarily on calculations using cropland statistics from the United Nations Food and Agriculture Organization (FAO) and deforestation rates from the FAO Forest Resource Assessment (FRA). The FRA information is obtained through national reporting supplemented by limited satellite analysis in the assessment for the 1990s (14–16). Participation of individual countries through national reporting is a strength from some perspectives, but it generates problems from varying definitions of forest cover among countries and time intervals (17). These problems are particularly acute in developing countries, where most tropical deforestation occurs. Comparisons of national statistics from the FRA with other country-level analyses suggest that the FRA overestimated changes in forest cover in some African countries (18), Bolivia (19), and other developing countries (20, 21). For the 1990–2000 interval, the FRA also conducted a remote-sensing survey, analyzing 10% of all tropical land area (15, 21). Forest area and deforestation rates from the FRA remote-sensing survey are generally lower than the FRA (15, 22) country reports for the 1990–2000 interval for Latin America and tropical Asia, although the differences are not statistically significant. For tropical Africa, the difference is very large (3 million ha/yr), suggesting exaggerated deforestation rates in the country data (15). For the 1980–1990 interval, on which the IPCC estimates of carbon fluxes from tropical deforestation are based, the country reports are the sole source of information for the FRA analysis. Satellite data offer the possibility of spatially and temporally consistent estimates of forest cover to complement national reports. Data acquired by the Landsat platform, with a pixel resolution of ≈30 m for the thematic mapper sensor and 60 m for the multispectral scanner sensor before the early 1980s, have provided estimates of deforestation rates for individual regions such as the Amazon basin (23). However, because of cloud coverage and limited acquisitions over the past several decades, it has not been possible to obtain comprehensive coverage for the entire tropics. Global data from the early 1980s to present acquired by the National Oceanic and Atmospheric Administration's Advanced Very High Resolution Radiometer (AVHRR) provide daily coverage but at a coarse spatial resolution of 8 km (24). AVHRR data at the sensor resolution of ≈1 km are not available for the full time series with adequate spatial coverage. In this study we estimate changes in forest area by using an approach to estimate subpixel changes in tree cover within the coarse spatial resolution of the AVHRR data. This analysis thus provides a spatially explicit alternative to the FAO's nationally reported changes in forest area and an alternative estimate for carbon fluxes over the past two decades.

Recent Changes in Phytoplankton Communities Associated with Rapid Regional Climate Change Along the Western Antarctic Peninsula

Abstract: The climate of the western shelf of the Antarctic Peninsula (WAP) is undergoing a transition from a cold-dry polar-type climate to a warm-humid sub-Antarctic-type climate. Using three decades of satellite and field data, we document that ocean biological productivity, inferred from chlorophyll a concentration (Chl a), has significantly changed along the WAP shelf. Summertime surface Chl a (summer integrated Chl a approximately 63% of annually integrated Chl a) declined by 12% along the WAP over the past 30 years, with the largest decreases equatorward of 63 degrees S and with substantial increases in Chl a occurring farther south. The latitudinal variation in Chl a trends reflects shifting patterns of ice cover, cloud formation, and windiness affecting water-column mixing. Regional changes in phytoplankton coincide with observed changes in krill (Euphausia superba) and penguin populations.

Patterns and Processes in the Time-Space Scales of Plankton Distributions

Abstract: It is evident that organisms have aggregated, patchy distributions of abundance on a wide variety of space and time scales. This can easily be seen in the terrestrial and littoral environments. It has been more difficult to observe in the pelagic realm simply because we cannot see into the ocean. Thus we must depend upon sampling to gain an impression of the space-time scales of pattern in this habitat. Despite the difficulties, enough sampling of the right sort has now been done so that we can make some very general statements about the nature of pattern in the ocean, particularly with regard to pattern in the distribution and abundance of planktonic organisms. All the evidence indicates that plankton is patchy on a broad spectrum of scales. Because this aggregated spatial pattern is such a general phenomenon, there is little question of its ecological and evolutionary importance. Further, because we assume our samples represent a larger universe, patchiness strongly affects our efforts to obtain estimates of the abundance of organisms and our ability to detect significant spatial and temporal changes in abundance. It is therefore of great importance that we understand its nature, causes, and effects.