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137 results on '"McClanahan, Timothy"'

103. Decadal changes in common reef coral populations and their associations with algal symbionts (Symbiodinium spp.).

Author

McClanahan, Timothy R., Starger, Craig J., and Baker, Andrew C.

Subjects
*CORALS, *ANTHOZOA, *SYMBIODINIUM, *DINOFLAGELLATES, *ENDOSYMBIOSIS
Abstract

Decadal populations changes in four coral taxa and their patterns of association with algal symbionts (Symbiodinium spp. - 10 years of sampling) were examined on Kenyan back reefs over a period of climatic disturbances (1991-2009). Some of the better surviving taxa, Pavona and Pocillopora, were associated with variable temperature regimes and >50% of sampled colonies in these taxa had some of the more thermally tolerant Symbiodinium in clade D. In contrast, only around 35% of Acropora and no branching forms of Porites contained detectable levels of clade D, and both taxa experienced high levels of thermally-induced mortality and poor recovery. Overall, however the relationship between Symbiodinium clade and population-level success of coral hosts was not strong, and differential success inside and outside fisheries closures suggests that other factors, such as predation on corals, were also influential. Consequently, while Symbiodinium in clade D may contribute to the success of coral hosts across thermal disturbances, multiple ecological factors and additional biological traits also influence their long-term survival. [ABSTRACT FROM AUTHOR]

Published
2015
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109. Development of the probing in-situ with Neutron and Gamma rays (PING) instrument for planetary science applications

Author

Ann, Parsons, primary, Bodnarik, Julia, additional, Burger, Dan, additional, Evans, Larry, additional, Floyd, Samuel, additional, Lim, Lucy, additional, McClanahan, Timothy, additional, Namkung, Min, additional, Nowicki, Suzanne, additional, Schweitzer, Jeffrey, additional, Starr, Richard, additional, and Trombka, Jacob, additional

Published
2011
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111. Time - resolved Gamma Ray spectral analysis of planetary neutron and Gamma Ray instrumentation

Author

Bodnarik, Julia G., primary, Burger, Keivan G., additional, Burger, Arnold, additional, Evans, Larry G., additional, Floyd, Samuel L., additional, Lim, Lucy F., additional, Mcclanahan, Timothy P., additional, Namkung, Min, additional, Nowicki, Suzanne F., additional, Parsons, Ann M., additional, Schweitzer, Jeffrey S., additional, Starr, Richard D., additional, Stassun, Keivan G., additional, and Trombka, Jacob I., additional

Published
2010
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129. Observations of a new source of coral mortality along the Kenyan coast.

Author

Martens, K., Fautin, Daphne G., Westfall, Jane A., Cartwrigh, Paulyn, Daly, Marymegan, Wyttenbach, C. R., McClanahan, Timothy R., McLaughlin, Shawn M., Davy, Joanne E., Wilson, William H., Peters, Esther C., Price, Kathy L., and Maina, Joseph

Abstract

In early 2002 coral mortality occurred along 600 km of coastline from Tanzania to Kenya. Astreopora, Echinopora, and Montipora species were severely affected, with Montipora being nearly eliminated from Kenyan reefs. Acropora, Platygyra, Goniopora, and massive Porites were also affected; however, Porites and Goniopora rarely died and often recovered, whereas death for most other species occurred within 2 weeks. In Echinopora and Montipora, a dull ashy tissue color and brittle skeletons characterized the early stages of this event with a mucus layer on the tissue surface in intermediate stages. Mucus and embedded debris then disappeared and surfaces were left covered in a white calcareous dust that sometimes capped a black layer. Astreopora tissues became dull and pale, and seldom produced mucus; eventually the skeleton became bare and white. Either a colorless translucent or brownish thin margin of tissue was visible between living tissue and bare skeleton, depending on species. Scanning electron micrographs of affected corals revealed the presence of fungi. Histology and staining showed that the fungi were mostly in the three genera that died from the syndrome and it may be that fungi invaded and killed corals weakened by another unidentified pathogen. Key words: Astreopora, Echinopora, coral disease, coral histology, marine fungi, Montipora [ABSTRACT FROM AUTHOR]

Published
2004
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130. X‐ray fluorescence measurements of the surface elemental composition of asteroid 433 Eros

Author

Nittler, Larry R., primary, Starr, Richard D., additional, Lim, Lucy, additional, Mccoy, Timothy J., additional, Burbine, Thomas H., additional, Reedy, Robert C., additional, Trombka, Jacob I., additional, Gorenstein, Paul, additional, Squyres, Steven W., additional, Boynton, William V., additional, Mcclanahan, Timothy P., additional, Bhangoo, Jesse S., additional, Clark, Pamela E., additional, Murphy, Mary Ellen, additional, and Killen, Rosemary, additional

Published
2001
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131. A Ground Systems Template for Remote Sensing Systems.

Author

McClanahan, Timothy P., Trombka, Jacob I., Floyd, Samuel R., Truskowski, Walter, Starr, Richard D., Clark, Pamela E., and Evans, Larry G.

Subjects
*REMOTE sensing, *GAMMA ray spectrometer, *X-ray spectroscopy
Abstract

Spaceborne remote sensing using gamma and X-ray spectrometers requires particular attention to the design and development of reliable systems. These systems must ensure the scientific requirements of the mission within the challenging technical constraints of operating instrumentation in space. The Near Earth Asteroid Rendezvous (NEAR) spacecraft included X-ray and gamma-ray spectrometers (XGRS), whose mission was to map the elemental chemistry of the 433 Eros asteroid. A remote sensing system template, similar to a blackboard systems approach used in artificial intelligence, was identified in which the spacecraft, instrument, and ground system was designed and developed to monitor and adapt to evolving mission requirements in a complicated operational setting. Systems were developed for ground tracking of instrument calibration, instrument health, data quality, orbital geometry, solar flux as well as models of the asteroid's surface characteristics, requiring an intensive human effort. In the future, missions such as the Autonomous Nano-Technology Swarm (ANTS) program will have to rely heavily on automation to collectively encounter and sample asteroids in the outer asteroid belt. Using similar instrumentation, ANTS will require information similar to data collected by the NEAR X-ray/Gamma-Ray Spectrometer (XGRS) ground system for science and operations management. The NEAR XGRS systems will be studied to identify the equivalent subsystems that may be automated for ANTS. The effort will also investigate the possibility of applying blackboard style approaches to automated decision making required for ANTS. [ABSTRACT FROM AUTHOR]

Published
2002

132. Infrastructure Needs to Support Unattended and Remote Detector Systems.

Author

Trombka, Jacob, McClanahan, Timothy, and Floyd, Samuel

Subjects
*DETECTORS, *TELEMEDICINE, *NATIONAL security, *NUCLEAR nonproliferation
Abstract

The use of unattended and remote detection systems for use in telemedicine, teleforensics and applications to operations in homeland security and nuclear non proliferation programs will require the development of portable detector systems and public information network systems. With the availability of such networks, the deployment of relatively inexpensive sensor systems can be achieved. [ABSTRACT FROM AUTHOR]

Published
2002

133. Data processing system for the Near-Earth Asteroid Rendezvous (NEAR) x-ray and gamma-ray spectrometer (XGRS) ground system

Author

McClanahan, Timothy P., primary, Mikheeva, Irina, additional, Trombka, Jacob I., additional, Floyd, Samuel R., additional, Boynton, William V., additional, Bailey, H., additional, Bhangoo, Jasbir, additional, Starr, Richard D., additional, Clark, Pamela E., additional, Evans, Larry G., additional, Squyres, Steven W., additional, McCartney, Elaina, additional, Noe, E., additional, McNutt, Jr., Ralph L., additional, and Brueckner, Johannes, additional

Published
1999
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136. To Fish or ot to Fish: Factors at Multiple Scales Affecting Artisanal Fishers' Readiness to Exit a Declining Fishery.

Author

Daw, Tim M., Cinner, Joshua E., McClanahan, Timothy R., Brown, Katrina, Stead, Selina M., Graham, Nicholas A. J., and Maina, Joseph

Subjects
FISHING, FISHERIES, CLIMATE change, SOCIAL factors, FISHERS, TECHNOLOGY
Abstract

Globally, fisheries are challenged by the combined impacts of overfishing, degradation of ecosystems and impacts of climate change, while fisheries livelihoods are further pressured by conservation policy imperatives. Fishers' adaptive responses to these pressures, such as exiting from a fishery to pursue alternative livelihoods, determine their own vulnerability, as well as the potential for reducing fishing effort and sustaining fisheries. The willingness and ability to make particular adaptations in response to change, such as exiting from a declining fishery, is influenced by economic, cultural and institutional factors operating at scales from individual fishers to national economies. Previous studies of exit from fisheries at single or few sites, offer limited insight into the relative importance of individual and larger-scale social and economic factors. We asked 599 fishers how they would respond to hypothetical scenarios of catch declines in 28 sites in five western Indian Ocean countries. We investigated how socioeconomic variables at the individual-, household- and sitescale affected whether they would exit fisheries. Site-level factors had the greatest influence on readiness to exit, but these relationships were contrary to common predictions. Specifically, higher levels of infrastructure development and economic vitality - expected to promote exit from fisheries - were associated with less readiness to exit. This may be due to site level histories of exit from fisheries, greater specialisation of fishing households, or higher rewards from fishing in more economically developed sites due to technology, market access, catch value and government subsidies. At the individual and household scale, fishers from households with more livelihood activities, and fishers with lower catch value were more willing to exit. These results demonstrate empirically how adaptive responses to change are influenced by factors at multiple scales, and highlight the importance of understanding natural resource-based livelihoods in the context of the wider economy and society. [ABSTRACT FROM AUTHOR]

Published
2012
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