Climate change, coral bleaching and the future of the world's coral reefs

Sea temperatures in many tropical regions have increased by almost 1 degrees C over the past 100 years, and are currently increasing at similar to 1-2 degrees C per century. Coral bleaching occurs when the thermal tolerance of corals and their photosynthetic symbionts (zooxanthellae) is exceeded. Mass coral bleaching has occurred in association with episodes of elevated sea temperatures over the past 20 years and involves the loss of the zooxanthellae following chronic photoinhibition. Mass bleaching has resulted in significant losses of live coral in many parts of the world. This paper considers the biochemical, physiological and ecological perspectives of coral bleaching. It also uses the outputs of four runs from three models of global climate change which simulate changes in sea temperature and hence how the frequency and intensity of bleaching events will change over the next 100 years. The results suggest that the thermal tolerances of reef-building corals are likely to be exceeded every year within the next few decades. Events as severe as the 1998 event, the worst on record, are likely to become commonplace within 20 years. Most information suggests that the capacity for acclimation by corals has already been exceeded, and that adaptation will be too slow to avert a decline in the quality of the world's reefs. The rapidity of the changes that are predicted indicates a major problem for tropical marine ecosystems and suggests that unrestrained warming cannot occur without the loss and degradation of coral reefs on a global scale.

The pareto-stability concept is a natural solution concept for discrete matching markets with indifferences

In a decentralized setting the game-theoretical predictions are that only strong blockings are allowed to rupture the structure of a matching. This paper argues that, under indifferences, also weak blockings should be considered when these blockings come from the grand coalition. This solution concept requires stability plus Pareto optimality. A characterization of the set of Pareto-stable matchings for the roommate and the marriage models is provided in terms of individually rational matchings whose blocking pairs, if any, are formed with unmatched agents. These matchings always exist and give an economic intuition on how blocking can be done by non-trading agents, so that the transactions need not be undone as agents reach the set of stable matchings. Some properties of the Pareto-stable matchings shared by the Marriage and Roommate models are obtained.

Re-description and new combination of five New World species of Chrysotus Meigen, with comments on the Neotropical genus Lyroneurus Loew (Diptera: Dolichopodidae)

Five New World species of Chrysotus Meigen are redescribed, four of them herein transferred from Diaphorus Meigen: C. angustifrons (Robinson), comb.nov., C. maculatus (Parent), comb.nov. (= D. maculipennis Robinson), C. robustus(Robinson), comb. nov., C. spectabilis (Loew) and C. wirthi (Robinson), comb. nov. The female of C. maculatus is described for the first time. Terminalia of both males and females are illustrated. The previous suggestion that C. angustifrons, C. robustus, C. wirthi, and C. spectabilis and the Neotropical genus Lyroneurus Loew are closely related based on wing venation similarities is analyzed and rejected.