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111.
112.
The bone-eating marine annelid Osedax consumes mainly whale bones on the deep-sea floor, but recent colonization experiments with cow bones and molecular age estimates
suggesting a possible Cretaceous origin of Osedax indicate that this worm might be able grow on a wider range of substrates. The suggested Cretaceous origin was thought to
imply that Osedax could colonize marine reptile or fish bones, but there is currently no evidence that Osedax consumes bones other than those of mammals. We provide the first evidence that Osedax was, and most likely still is, able to consume non-mammalian bones, namely bird bones. Borings resembling those produced
by living Osedax were found in bones of early Oligocene marine flightless diving birds (family Plotopteridae). The species that produced these
boreholes had a branching filiform root that grew to a length of at least 3 mm, and lived in densities of up to 40 individuals
per square centimeter. The inclusion of bird bones into the diet of Osedax has interesting implications for the recent suggestion of a Cretaceous origin of this worm because marine birds have existed
continuously since the Cretaceous. Bird bones could have enabled this worm to survive times in the Earth’s history when large
marine vertebrates other than fish were rare, specifically after the disappearance of large marine reptiles at the end-Cretaceous
mass extinction event and before the rise of whales in the Eocene. 相似文献
113.
Establishing A Earth Observation Product Service For The Terrestrial Carbon Community: The Globcarbon Initiative 总被引:3,自引:0,他引:3
Stephen Plummer Olivier Arino Muriel Simon Will Steffen 《Mitigation and Adaptation Strategies for Global Change》2006,11(1):97-111
'Greenhouse gases', especially carbon dioxide, are intimately connected to climate change. To understand the future evolution
of the climate system and find ways to manage the concentration of atmospheric carbon dioxide, the processes and feedbacks
that drive the carbon cycle must first be understood. However, our current knowledge of spatial and temporal patterns is uncertain,
particularly over land and in regions of potentially high sensitivity to change like the boreal zone. The European Space Agency
(ESA) GLOBCARBON project aims to generate fully calibrated estimates of at-land products quasi-independent of the original
Earth Observation source for use primarily in Dynamic Global Vegetation Models, but also as a contribution to the Global Carbon
Project, a cooperation between the International Geosphere Biosphere Programme, International Human Dimensions Programme and
the World Climate Research Programme to aid understanding of global carbon cycling. The service will feature estimation of
global burned area, the fraction of absorbed photosynthetically active radiation (fAPAR), leaf area index (LAI) and Vegetation Growth Cycle. The demonstrator will focus on ten complete years, from 1998 to 2007
when overlap exists between ESA Earth Observation sensors and others that are synergistic. However, the system will be flexible
so that it is not dependent on any single satellite sensor and therefore can be retrospectively applied to existing archives
and used with future satellite sensors. 相似文献
114.
The Southeastern United States is a global center of freshwater biotic diversity, but much of the regions aquatic biodiversity is at risk from stream degradation. Nonpoint pollution sources are responsible for 70% of that degradation, and controlling nonpoint pollution from agriculture, urbanization, and silviculture is considered critical to maintaining water quality and aquatic biodiversity in the Southeast. We used an ecological risk assessment framework to develop vulnerability models that can help policymakers and natural resource managers understand the impact of land cover changes on water quality in North Carolina. Additionally, we determined which landscape characteristics are most closely associated with macroinvertebrate community tolerance of stream degradation, and therefore with lower-quality water. The results will allow managers and policymakers to weigh the risks of management and policy decisions to a given watershed or set of watersheds, including whether streamside buffer protection zones are ecologically effective in achieving water quality standards. Regression analyses revealed that landscape variables explained up to 56.3% of the variability in benthic macroinvertebrate index scores. The resulting vulnerability models indicate that North Carolina watersheds with less forest cover are at most risk for degraded water quality and steam habitat conditions. The importance of forest cover, at both the watershed and riparian zone scale, in predicting macrobenthic invertebrate community assemblage varies by geographic region of the state. 相似文献