The objectives of the present study were to evaluate the yolk-sac and oil globule absorption and point of no return （PNR） ofpikeperch （Sander lucioperca L.） larvae. Artificial propagation ofpikeperch was performed...The objectives of the present study were to evaluate the yolk-sac and oil globule absorption and point of no return （PNR） ofpikeperch （Sander lucioperca L.） larvae. Artificial propagation ofpikeperch was performed at （15±2）℃. Yolk-sac absorption, oil globule absorption, larval growth and the first initial feeding rate were observed to analyze the early growth and to determine the PNR of pikeperch larvae. The total length of newly hatched （0 day after hatching, DAH） pikeperch larvae was （4.25±0.22） mm and the volume of the yolk-sac and the oil globule was （0.30±0.12）mm^3 and （5.14±2.28） 10-2 mm^3 respectively. The yolk-sac and the oil globule were exhausted at 11 DAH and 14 DAH, respectively. Pikeperch larvae began feeding at 8 DAH with an initial feeding rate about 10.0%. From 9 to 14 DAH, the initial feeding rate increased rapidly, and reached its highest （about 82.7%） at 14 DAH. It declined thereafter, 48.9% at 15 DAH and 35.6% at 16 DAH, thus the pikeperch larvae reached PNR by 15-16 DAH. The appropriate first feeding time for the pikeperch larvae is 11-12 DAH, when the initial feeding rate is higher than half of the maximum initial feeding rate.展开更多
Interest in phenotypic flexibility has increased dramatically over the last decade, but flexibility during reproduction has received relatively little attention from avian scientists, despite its possible impact on fi...Interest in phenotypic flexibility has increased dramatically over the last decade, but flexibility during reproduction has received relatively little attention from avian scientists, despite its possible impact on fitness. Because most avian species maintain atrophied reproductive organs when not active, reproduction in birds requires major tissue remodeling in preparation for breeding. Females undergo rapid （days） recrudescence and regression of their reproductive organs at each breeding attempt, while males grow their organs ahead of time at a much slower rate （weeks） and may maintain them at maximal size throughout the breeding season. Reproduction is associated with significant metabolic costs. Egg production leads to a 22%-27% increase in resting metabolic rate （RMR） over non-reproductive values. This is partly due to the activity of the oviduct, an organ that may allow females to adjust reproductive investment by modulating egg size and quality. In males, gonadal recrudescence may lead to a 30% increase in RMR, but the data are inconsistent and general conclusions regarding energetic costs of reproduction in males will require more research. Recent studies on captive female zebra finches describe the impacts of these costs on daily energy budgets and highlight the strategies used by birds to maintain their investment in reproduction when energy is limited. Whenever possible, birds use behavioral flexibility as a first means of saving energy. Decreasing locomotor activity saves energy during challenges such as egg production or exposure to cold temperatures and is an efficient way to buffer variation in individual daily energy budgets. However, when behavioral flexibility is not possible, birds must rely on flexibility at the physiological level to meet energy demands. In zebra finches breeding in the cold, this results in a reduced pace of laying, likely due to down-regulation of both reproductive and non-reproductive function, allowing females to defend minimal egg size and maintain reproductive success. More research involving a range of species in captive and flee-living conditions is needed to determine how phenotypic flexibility during tissue remodeling and early reproductive investment translates to natural conditions and affects fitness [Current Zoology 56 （6）： 767-792, 2010].展开更多
El Nino, as characterized by above average sea surface temperatures in the equatorial tropical Pacific, is the largest source of natural climate variability from sea- sonal to interannual scales and can profoundly res...El Nino, as characterized by above average sea surface temperatures in the equatorial tropical Pacific, is the largest source of natural climate variability from sea- sonal to interannual scales and can profoundly reshape the global weather patterns. Currently, the tropical Pacific Ocean appears to be primed for a potentially significant El Nino event, and some similarities exist between the oce- anic and atmospheric states in early 2014 compared to the observations shortly before the onset of the 1997/1998 Super El Nino event. For example, as one of the most important early signs of El Nino, a splitting eastbound propagation of the subsurface warm water is evident over the equatorial Pacific since January 2014. In this study, the pulses of subsurface warm water are reflected by the Kel- vin waves over the equatorial Pacific estimated from the satellite altimetry data. Results show that the current （i.e., March 2014） Kelvin wave over the equatorial Pacific has achieved the largest amplitude compared to those in the corresponding period prior to the E1 Nifio events since the availability of satellite altimetry, and is even significantly larger than the one that preceded the 1997/1998 Super El Nifio event. As the Kelvin waves can help induce El Nino conditions within about 2--4 months, the current fastest/ strongest eastbound propagation of subsurface warm water indicates that the likelihood of an El Nino event will sig- nificantly increase during the next several months in 2014.展开更多
基金Supported by the Science Fund of Jiangsu Province(No.BY2015039-10)the Fund of Jiangsu Province Collaborative Center of Regional Modern Agriculture&Environmental Protection(No.HSXT219)the Science Fund of Changshu Science and Technology Bureau,China(No.CN201408)
文摘The objectives of the present study were to evaluate the yolk-sac and oil globule absorption and point of no return （PNR） ofpikeperch （Sander lucioperca L.） larvae. Artificial propagation ofpikeperch was performed at （15±2）℃. Yolk-sac absorption, oil globule absorption, larval growth and the first initial feeding rate were observed to analyze the early growth and to determine the PNR of pikeperch larvae. The total length of newly hatched （0 day after hatching, DAH） pikeperch larvae was （4.25±0.22） mm and the volume of the yolk-sac and the oil globule was （0.30±0.12）mm^3 and （5.14±2.28） 10-2 mm^3 respectively. The yolk-sac and the oil globule were exhausted at 11 DAH and 14 DAH, respectively. Pikeperch larvae began feeding at 8 DAH with an initial feeding rate about 10.0%. From 9 to 14 DAH, the initial feeding rate increased rapidly, and reached its highest （about 82.7%） at 14 DAH. It declined thereafter, 48.9% at 15 DAH and 35.6% at 16 DAH, thus the pikeperch larvae reached PNR by 15-16 DAH. The appropriate first feeding time for the pikeperch larvae is 11-12 DAH, when the initial feeding rate is higher than half of the maximum initial feeding rate.
基金funded by the National Science and Engineering Research Council of Canada (NSERC) through a discovery granta postdoctoral fellowship a Nouveaux chercheurs grant from the Fonds Québécois de Recherche sur la Nature et les Technologies (FQRNT)
文摘Interest in phenotypic flexibility has increased dramatically over the last decade, but flexibility during reproduction has received relatively little attention from avian scientists, despite its possible impact on fitness. Because most avian species maintain atrophied reproductive organs when not active, reproduction in birds requires major tissue remodeling in preparation for breeding. Females undergo rapid （days） recrudescence and regression of their reproductive organs at each breeding attempt, while males grow their organs ahead of time at a much slower rate （weeks） and may maintain them at maximal size throughout the breeding season. Reproduction is associated with significant metabolic costs. Egg production leads to a 22%-27% increase in resting metabolic rate （RMR） over non-reproductive values. This is partly due to the activity of the oviduct, an organ that may allow females to adjust reproductive investment by modulating egg size and quality. In males, gonadal recrudescence may lead to a 30% increase in RMR, but the data are inconsistent and general conclusions regarding energetic costs of reproduction in males will require more research. Recent studies on captive female zebra finches describe the impacts of these costs on daily energy budgets and highlight the strategies used by birds to maintain their investment in reproduction when energy is limited. Whenever possible, birds use behavioral flexibility as a first means of saving energy. Decreasing locomotor activity saves energy during challenges such as egg production or exposure to cold temperatures and is an efficient way to buffer variation in individual daily energy budgets. However, when behavioral flexibility is not possible, birds must rely on flexibility at the physiological level to meet energy demands. In zebra finches breeding in the cold, this results in a reduced pace of laying, likely due to down-regulation of both reproductive and non-reproductive function, allowing females to defend minimal egg size and maintain reproductive success. More research involving a range of species in captive and flee-living conditions is needed to determine how phenotypic flexibility during tissue remodeling and early reproductive investment translates to natural conditions and affects fitness [Current Zoology 56 （6）： 767-792, 2010].
基金supported by the National Program for Support of Top-notch Young Professionalsthe National Basic Research Program of China(2012CB417404)the ‘‘Western Pacific Ocean System:Structure,Dynamics and Consequences’’ Project of the Chinese Academy of Sciences(WPOS:XDA10010405)
文摘El Nino, as characterized by above average sea surface temperatures in the equatorial tropical Pacific, is the largest source of natural climate variability from sea- sonal to interannual scales and can profoundly reshape the global weather patterns. Currently, the tropical Pacific Ocean appears to be primed for a potentially significant El Nino event, and some similarities exist between the oce- anic and atmospheric states in early 2014 compared to the observations shortly before the onset of the 1997/1998 Super El Nino event. For example, as one of the most important early signs of El Nino, a splitting eastbound propagation of the subsurface warm water is evident over the equatorial Pacific since January 2014. In this study, the pulses of subsurface warm water are reflected by the Kel- vin waves over the equatorial Pacific estimated from the satellite altimetry data. Results show that the current （i.e., March 2014） Kelvin wave over the equatorial Pacific has achieved the largest amplitude compared to those in the corresponding period prior to the E1 Nifio events since the availability of satellite altimetry, and is even significantly larger than the one that preceded the 1997/1998 Super El Nifio event. As the Kelvin waves can help induce El Nino conditions within about 2--4 months, the current fastest/ strongest eastbound propagation of subsurface warm water indicates that the likelihood of an El Nino event will sig- nificantly increase during the next several months in 2014.
