This paper describes the effects that temperature changes in the Rhine river distributaries have on native and exotic fish diversity. Site-specific potentially affected fractions （PAFs） of the regional fish species ...This paper describes the effects that temperature changes in the Rhine river distributaries have on native and exotic fish diversity. Site-specific potentially affected fractions （PAFs） of the regional fish species pool were derived using species sensitivity distributions （SSDs） for water temperature. The number of fish species in the river distributaries has changed remarkably over the last century. The number of native rheophilous species declined up until 1980 due to anthropogenic disturbances such as commercial fishing, fiver regulation, migration barriers, habitat deterioration and water pollution. In spite of progress in river re- habilitation, the native rheophilous fish fauna has only partially recovered thus far. The total number of species has strongly in- creased due to the appearance of more exotic species. After the opening of the Rhine-Main-Danube waterway in 1992, many fish species originating from the Ponto-Caspian area colonized the Rhine basin. The yearly minimum and maximum river tempera- tures at Lobith have increased by circa 4 ~C over the period 1908-2010. Exotic species show lower PAFs than native species at both ends of the temperature range. The interspecific variation in the temperature tolerance of exotic fish species was found to be large. Using temporal trends in river temperature allowed past predictions of PAFs to demonstrate that the increase in maximum river temperature negatively affected a higher percentage of native fish species than exotic species. Our results support the hy- pothesis that alterations of the river Rhine＇s temperature regime caused by thermal pollution and global wanning limit the full recovery of native fish fauna and facilitate the establishment of exotic species which thereby increases competition between native and exotic species. Thermal refuges are important for the survival of native fish species under extreme summer or winter temperature conditions展开更多
Under stressful thermal environments, insects adjust their behavior and physi- ology to maintain key life-history activities and improve survival. For interacting species, mutual or antagonistic, thermal stress may af...Under stressful thermal environments, insects adjust their behavior and physi- ology to maintain key life-history activities and improve survival. For interacting species, mutual or antagonistic, thermal stress may affect the participants in differing ways, which may then affect the outcome of the ecological relationship. In agroecosystems, this may be the fate of relationships between insect pests and their antagonistic parasitoids un- der acute and chronic thermal variability. Against this background, we investigated the thermal tolerance of different developmental stages of Chilo partellus Swinhoe （Lepi- doptera： Crambidae） and its larval parasitoid, Cotesia sesamiae Cameron （Hymenoptera： Braconidae） using both dynamic and static protocols. When exposed for 2 h to a static temperature, lower lethal temperatures ranged from -9 to 6 ℃, -14 to -2 ℃, and -1 to 4 ℃ while upper lethal temperatures ranged from 37 to 48 ℃, 41 to 49 ℃, and 36 to 39 ℃ for C partellus eggs, larvae, and C. sesamiae adults, respectively. Faster heating rates improved critical thermal maxima （CTmax） in C partellus larvae and adult C partel- lus and C sesamiae. Lower cooling rates improved critical thermal minima （CTmin） in C partellus and C. sesamiae adults while compromising CTmin in C. partellus larvae. The mean supercooling points （SCPs） for C. partellus larvae, pupae, and adults were -11.82 ± 1.78, -10.43 ±1.73 and -15.75 ±2.47, respectively. Heat knock-down time （HKDT） and chill-coma recovery time （CCRT） varied significantly between C partellus larvae and adults. Larvae had higher HKDT than adults, while the latter recovered significantly faster following chill-coma. Current results suggest developmental stage differences in C partellus thermal tolerance （with respect to lethal temperatures and critical thermal limits） and a compromised temperature tolerance of parasitoid C. sesamiae relative to its host, suggesting potential asynchrony between host-parasitoid population phenology and con- sequently biocontrol efficacy under global change. These results have broad implications to biological pest management insect-natural enemy interactions under rapidly changing thermal environments.展开更多
文摘This paper describes the effects that temperature changes in the Rhine river distributaries have on native and exotic fish diversity. Site-specific potentially affected fractions （PAFs） of the regional fish species pool were derived using species sensitivity distributions （SSDs） for water temperature. The number of fish species in the river distributaries has changed remarkably over the last century. The number of native rheophilous species declined up until 1980 due to anthropogenic disturbances such as commercial fishing, fiver regulation, migration barriers, habitat deterioration and water pollution. In spite of progress in river re- habilitation, the native rheophilous fish fauna has only partially recovered thus far. The total number of species has strongly in- creased due to the appearance of more exotic species. After the opening of the Rhine-Main-Danube waterway in 1992, many fish species originating from the Ponto-Caspian area colonized the Rhine basin. The yearly minimum and maximum river tempera- tures at Lobith have increased by circa 4 ~C over the period 1908-2010. Exotic species show lower PAFs than native species at both ends of the temperature range. The interspecific variation in the temperature tolerance of exotic fish species was found to be large. Using temporal trends in river temperature allowed past predictions of PAFs to demonstrate that the increase in maximum river temperature negatively affected a higher percentage of native fish species than exotic species. Our results support the hy- pothesis that alterations of the river Rhine＇s temperature regime caused by thermal pollution and global wanning limit the full recovery of native fish fauna and facilitate the establishment of exotic species which thereby increases competition between native and exotic species. Thermal refuges are important for the survival of native fish species under extreme summer or winter temperature conditions
文摘Under stressful thermal environments, insects adjust their behavior and physi- ology to maintain key life-history activities and improve survival. For interacting species, mutual or antagonistic, thermal stress may affect the participants in differing ways, which may then affect the outcome of the ecological relationship. In agroecosystems, this may be the fate of relationships between insect pests and their antagonistic parasitoids un- der acute and chronic thermal variability. Against this background, we investigated the thermal tolerance of different developmental stages of Chilo partellus Swinhoe （Lepi- doptera： Crambidae） and its larval parasitoid, Cotesia sesamiae Cameron （Hymenoptera： Braconidae） using both dynamic and static protocols. When exposed for 2 h to a static temperature, lower lethal temperatures ranged from -9 to 6 ℃, -14 to -2 ℃, and -1 to 4 ℃ while upper lethal temperatures ranged from 37 to 48 ℃, 41 to 49 ℃, and 36 to 39 ℃ for C partellus eggs, larvae, and C. sesamiae adults, respectively. Faster heating rates improved critical thermal maxima （CTmax） in C partellus larvae and adult C partel- lus and C sesamiae. Lower cooling rates improved critical thermal minima （CTmin） in C partellus and C. sesamiae adults while compromising CTmin in C. partellus larvae. The mean supercooling points （SCPs） for C. partellus larvae, pupae, and adults were -11.82 ± 1.78, -10.43 ±1.73 and -15.75 ±2.47, respectively. Heat knock-down time （HKDT） and chill-coma recovery time （CCRT） varied significantly between C partellus larvae and adults. Larvae had higher HKDT than adults, while the latter recovered significantly faster following chill-coma. Current results suggest developmental stage differences in C partellus thermal tolerance （with respect to lethal temperatures and critical thermal limits） and a compromised temperature tolerance of parasitoid C. sesamiae relative to its host, suggesting potential asynchrony between host-parasitoid population phenology and con- sequently biocontrol efficacy under global change. These results have broad implications to biological pest management insect-natural enemy interactions under rapidly changing thermal environments.
