University of Georgia

About: University of Georgia is a education organization based out in Athens, Georgia, United States. It is known for research contribution in the topics: Population & Gene. The organization has 41934 authors who have published 93622 publications receiving 3713212 citations. The organization is also known as: UGA & Franklin College.

Coral bleaching: interpretation of thermal tolerance limits and thermal thresholds in tropical corals

Abstract: 'It should be clear that the upper temperature limit for life cannot be accurately defined' (Schmidt-Nielsen 1996). The thermal physiology of zooxanthellate reef corals is reviewed in this paper in the context of organismal and biochemical responses occurring during coral bleaching, with emphasis on methods of detection and interpretation of animal and algal symbiont stress. Coral bleaching, as presently defined in the literature, is a highly subjective term used to describe a variety of conditions pertaining to low symbiont densities in the coral–algal complex, including response to thermal stress. Three general types of high-temperature bleaching are defined: physiological bleaching, which may or may not include higher-than-normal temperature responses; algal-stress bleaching, involving dysfunction of symbiotic algae at high light and/or high temperatures; and animal-stress bleaching, where coral cells containing symbiotic algae are shed from the gastrodermal layer of cells. Since none of these methods of bleaching is mutually exclusive, a combination of intrusive and non-intrusive techniques is necessary to determine which mechanisms of symbiont loss are occurring. While quantification of symbiont densities, algal pigments, and coral tissue biomass provide unambiguous evidence of bleaching severity, measurements of physiological and biochemical degradation offer additional correlative evidence of temperature stress. Pulse-amplitude-modulated (PAM) fluorometry has emerged as an easy and relatively inexpensive non-invasive technique for monitoring symbiotic algal function both in situ and in the laboratory, when proper assumptions and interpretations are made. The roles of global warming, water quality, acclimation/adaptation processes, and relation to coral disease and reef heterogeneity are also discussed. A thorough understanding of the organismal responses occurring during bleaching will help explain changes in coral populations and in the coral reef community, and perhaps assist in predicting the future of reef corals and coral reefs during the next century of global climate change.

Symbol Nomenclature for Graphical Representations of Glycans.

Abstract: Author(s): Varki, Ajit; Cummings, Richard D; Aebi, Markus; Packer, Nicole H; Seeberger, Peter H; Esko, Jeffrey D; Stanley, Pamela; Hart, Gerald; Darvill, Alan; Kinoshita, Taroh; Prestegard, James J; Schnaar, Ronald L; Freeze, Hudson H; Marth, Jamey D; Bertozzi, Carolyn R; Etzler, Marilynn E; Frank, Martin; Vliegenthart, Johannes Fg; Lutteke, Thomas; Perez, Serge; Bolton, Evan; Rudd, Pauline; Paulson, James; Kanehisa, Minoru; Toukach, Philip; Aoki-Kinoshita, Kiyoko F; Dell, Anne; Narimatsu, Hisashi; York, William; Taniguchi, Naoyuki; Kornfeld, Stuart

Habitat associations of trees and shrubs in a 50-ha neotropical forest plot

Abstract: Summary 1 Tests of habitat association among species of tropical trees and shrubs often assume that individual stems can be treated as independent sample units, even though limited dispersal conflicts with this assumption by causing new recruits to occur near maternal parents and siblings. 2 We developed methods for assessing patterns of association between mapped plants and mapped habitat types that explicitly incorporate spatial structure, thereby eliminating the need to assume independence among stems. 3 We used these methods to determine habitat-association patterns for 171 species of trees and shrubs within the permanent 50-ha Forest Dynamics Project plot on Barro Colorado Island, Panama. 4 Many fewer significant habitat associations result from the new methods than from traditional, but inappropriate, chi-square tests. The low-lying plateau, the most extensive habitat on the 50-ha plot, had nine species positively associated with it and 19 species negatively associated, leaving 143 species whose distributions were not biased with respect to this habitat. A small swamp in the plot was the most distinct habitat, with 32 species positively and 20 species negatively associated, leaving more than two-thirds of the species neither positively nor negatively associated. 5 To the extent that habitat association reflects habitat specialization, our results suggest that local habitat specialization plays a limited role in the maintenance of species diversity in this forest.