Scirpus mariqueter Tang et Zhang is a typical pioneer plant colonizing the bare beaches of the Yangtse River estuary. To explore the life history strategy of the species with reference to environmental physical stre...Scirpus mariqueter Tang et Zhang is a typical pioneer plant colonizing the bare beaches of the Yangtse River estuary. To explore the life history strategy of the species with reference to environmental physical stress, the biomass allocations to different plant components and some related morphological parameters were examined along an elevational gradient within a salt marsh. Authors found that S. mariqueter performed best at medium elevation within the marsh, with relatively high density of shoot and individual ramet dry mass. Biomass allocation to corm was the highest at low elevations, and the least at high elevations, suggesting that a conservative strategy was adopted by the species to cope with the harsh physical conditions at the low elevation. The investment in rhizome decreased from low to high elevations, while the proportion of inflorescence mass increased, indicating that during the life history, the species shifts from predominant asexual reproduction to predominant sexual reproduction. This may be favourable for the species to colonize larger area, and to spread and persist at a meta_population level. Correlation analyses showed that sexual reproduction was inversely related to growth and asexual reproduction. However, it is difficult to determine the relationship between asexual reproduction and growth possibly because of the varied function of the corms of the species in different life history stages.展开更多
Investigation of the ecology of introduced species in new habitats can allow determinations of the degree, direction, and rate of evolutionary change. The introduction of Gambusia holbrooki in the southern Caspian Sea...Investigation of the ecology of introduced species in new habitats can allow determinations of the degree, direction, and rate of evolutionary change. The introduction of Gambusia holbrooki in the southern Caspian Sea presents such a situation. We evaluated the life history traits of mosquitofish in the Tajan River basin. A total of 744 G. holbrooki specimens were collected between January and December 2008. The maximum observed ages are 0+ years for males and 1+ years for females. Both sexes grew allometrically (negative for males: b=2.442 and positive for females: b=3.232). The overall sex ratio is unbalanced and dominated by females. GSI values suggest that this population of G. holbrooki matures between February–July. The highest mean GSI value is 1.80 for males and 15.97 for females in May. Egg diameter ranges from 1.00 to 3.00 mm with a mean value of 2.098 mm. Absolute fecundity varied from 7 to 57 eggs. Both ova diameter and absolute fecundity were positively correlated to fish size (length and weight). Fecundity relative to total weight fluctuated from 34.44 to 582.64 eggs/g, and to total length from 2.33 to 12.95 eggs/cm. Both were negatively correlated with female size. The characteristics of this population are important with respect to life history of the species.展开更多
In order to reconstruct the paleoproductivity evolution history of the West Philippine Sea during the last 700 ka, the vertical gradient of Δδ13C in dissolved inorganic carbon Δδ13C between those of foraminifera P...In order to reconstruct the paleoproductivity evolution history of the West Philippine Sea during the last 700 ka, the vertical gradient of Δδ13C in dissolved inorganic carbon Δδ13C between those of foraminifera Pulleniatina obliquiloculata and Cibicidoides wuellerstorfi） and planktonic foraminiferal assemblages were analysed in piston Core MD06-3047 retrieved from the Benham Rise （east of the Luzon Island）. Paleoproductivity evolution in the West Philippine Sea during the last 700 ka is closely related to glacial-interglacial cycles and precession-controlled insolation. Controlling factors ofpaleoproductivity could have been both thermocline fluctuations related with ENSO-Iike processes and eolian input associated with East Asian winter monsoon, and the former could have been the primary factor. A higher productivity and a shallower thermocline coeval with the occurrence of low CO2 concentrations in the EPICA Dome C ice core might indicate that biological export production in the low-latitude could act as a significant sink in the global carbon cycle, and modify atmospheric CO2 concentrations. Spectral analysis further reveals that the paleoproductivity is mainly controlled by thermocline fluctuations subjected to ENSO processes responding to processional variability of insolation. High coherences in eccentricity, obliquity and precession periods fiuther revealing the close link between thermocline fluctuations, paleoproductivity and atmospheric CO2 levels.展开更多
For the first time, the present study reports the life-history traits, comprising length-frequency distribution （LFD）, sex ratio （SR）, length-weight relationships （LWRs）, condition factors （CFs）, and relative ...For the first time, the present study reports the life-history traits, comprising length-frequency distribution （LFD）, sex ratio （SR）, length-weight relationships （LWRs）, condition factors （CFs）, and relative growth （WR）, of Clupisoma garua in the coastal waters of Bangladesh. A total of 150 specimens ranging from 8.60 to 25.20 cm total length （TL） and 4.26 to 128.80 g body weight （BW） were collected using traditional fishing gear from August 2013 to July 2014. The overall sex ratio of males to females in the study did not differ significantly from the expected value of 1：1 （χ2=0.96, P〈0.05） but there were significant sex differences （P〈0.05） in the intercepts and slopes of graphs characterizing traits in C. garua. The calculated b values for the LWRs were 2.955, 2.893 and 2.927 for males, females and combined sexes, respectively, and there was negative allometric growth in all cases （b〈3）. The condition factors （KA, KF, KrR） and relative growth （WR） also did not differ significantly （P〈0.05） between the sexes. This study provides a useful tool for fishery specialists to evaluate the relative condition of fish and to initiate early management strategies and regulations for the sustainable management of the remaining stocks of this species in the entire coastal region of southern Bangladesh.展开更多
Aims Cistus albidus reproductive traits have been studied on typical Mediterranean shrublands along a water availability gradient in Northeastern Iberian Peninsula.Germination of this species is known to be highly fav...Aims Cistus albidus reproductive traits have been studied on typical Mediterranean shrublands along a water availability gradient in Northeastern Iberian Peninsula.Germination of this species is known to be highly favoured by fire.Moreover,Mediterranean species are particularly dependent on water availability.Therefore,we establish the hypothesis that in addition to fire disturbance,seedling recruitment in this Mediterranean seeder will be improved in drought-induced episodes resulting in generalized canopy die-off.Methods Individuals of several populations of C.albidus were collected and the size,weight and number of fruits and seeds were measured.Germination tests were also carried out on five pre-germination treatments:seeds’exposure to heat shock,imbibition,two cycles of imbibition/desiccation and the combination of heat shock and imbibition and imbibition/desiccation cycles.Moreover,the number of seedlings after a drought event was surveyed in the field and correlated with canopy die-off.Important findings Our study shows the variability of the C.albidus reproductive traits,such as germination rate or fruit production,along the water availability gradient.This variability resulted in a decrease in fruit production but an increase in successful germination under drier conditions.Cistus albidus seeds increased germination with heat,demonstrating their ability to successfully establish after fire.However,recruitment was not exclusively fire dependent since seedling establishment was higher under C.albidus canopies that had collapsed after the extreme drought.Finally,adult density increased C.albidus die-off and mortality,as well as seedling establishment.These results suggest that this species exhibits a trade-off between different reproductive outcomes(i.e.seed production vs.viability),which in turn is determined by climate.This study also provides evidence of how intra-specific competition,climate,particularly drought events and fire disturbance,can determine the success of key early stages of the life history of a common,representative Mediterranean fire-prone seeder shrub.展开更多
文摘Scirpus mariqueter Tang et Zhang is a typical pioneer plant colonizing the bare beaches of the Yangtse River estuary. To explore the life history strategy of the species with reference to environmental physical stress, the biomass allocations to different plant components and some related morphological parameters were examined along an elevational gradient within a salt marsh. Authors found that S. mariqueter performed best at medium elevation within the marsh, with relatively high density of shoot and individual ramet dry mass. Biomass allocation to corm was the highest at low elevations, and the least at high elevations, suggesting that a conservative strategy was adopted by the species to cope with the harsh physical conditions at the low elevation. The investment in rhizome decreased from low to high elevations, while the proportion of inflorescence mass increased, indicating that during the life history, the species shifts from predominant asexual reproduction to predominant sexual reproduction. This may be favourable for the species to colonize larger area, and to spread and persist at a meta_population level. Correlation analyses showed that sexual reproduction was inversely related to growth and asexual reproduction. However, it is difficult to determine the relationship between asexual reproduction and growth possibly because of the varied function of the corms of the species in different life history stages.
文摘Investigation of the ecology of introduced species in new habitats can allow determinations of the degree, direction, and rate of evolutionary change. The introduction of Gambusia holbrooki in the southern Caspian Sea presents such a situation. We evaluated the life history traits of mosquitofish in the Tajan River basin. A total of 744 G. holbrooki specimens were collected between January and December 2008. The maximum observed ages are 0+ years for males and 1+ years for females. Both sexes grew allometrically (negative for males: b=2.442 and positive for females: b=3.232). The overall sex ratio is unbalanced and dominated by females. GSI values suggest that this population of G. holbrooki matures between February–July. The highest mean GSI value is 1.80 for males and 15.97 for females in May. Egg diameter ranges from 1.00 to 3.00 mm with a mean value of 2.098 mm. Absolute fecundity varied from 7 to 57 eggs. Both ova diameter and absolute fecundity were positively correlated to fish size (length and weight). Fecundity relative to total weight fluctuated from 34.44 to 582.64 eggs/g, and to total length from 2.33 to 12.95 eggs/cm. Both were negatively correlated with female size. The characteristics of this population are important with respect to life history of the species.
基金Supported by the National Natural Science Foundation of China(Nos.41230959,41076030,40906038,41106042,41006032)the Pilot Project of the Knowledge Innovation Program of Chinese Academy of Sciences(No.KZCX2-YW-221)the Foundation of Key Laboratory of Marine Geology and Environment of Chinese Academy of Sciences(No.MGE2011KG01)
文摘In order to reconstruct the paleoproductivity evolution history of the West Philippine Sea during the last 700 ka, the vertical gradient of Δδ13C in dissolved inorganic carbon Δδ13C between those of foraminifera Pulleniatina obliquiloculata and Cibicidoides wuellerstorfi） and planktonic foraminiferal assemblages were analysed in piston Core MD06-3047 retrieved from the Benham Rise （east of the Luzon Island）. Paleoproductivity evolution in the West Philippine Sea during the last 700 ka is closely related to glacial-interglacial cycles and precession-controlled insolation. Controlling factors ofpaleoproductivity could have been both thermocline fluctuations related with ENSO-Iike processes and eolian input associated with East Asian winter monsoon, and the former could have been the primary factor. A higher productivity and a shallower thermocline coeval with the occurrence of low CO2 concentrations in the EPICA Dome C ice core might indicate that biological export production in the low-latitude could act as a significant sink in the global carbon cycle, and modify atmospheric CO2 concentrations. Spectral analysis further reveals that the paleoproductivity is mainly controlled by thermocline fluctuations subjected to ENSO processes responding to processional variability of insolation. High coherences in eccentricity, obliquity and precession periods fiuther revealing the close link between thermocline fluctuations, paleoproductivity and atmospheric CO2 levels.
基金Supported by the fellowship of National Science and Technology(NST),Bangladesh
文摘For the first time, the present study reports the life-history traits, comprising length-frequency distribution （LFD）, sex ratio （SR）, length-weight relationships （LWRs）, condition factors （CFs）, and relative growth （WR）, of Clupisoma garua in the coastal waters of Bangladesh. A total of 150 specimens ranging from 8.60 to 25.20 cm total length （TL） and 4.26 to 128.80 g body weight （BW） were collected using traditional fishing gear from August 2013 to July 2014. The overall sex ratio of males to females in the study did not differ significantly from the expected value of 1：1 （χ2=0.96, P〈0.05） but there were significant sex differences （P〈0.05） in the intercepts and slopes of graphs characterizing traits in C. garua. The calculated b values for the LWRs were 2.955, 2.893 and 2.927 for males, females and combined sexes, respectively, and there was negative allometric growth in all cases （b〈3）. The condition factors （KA, KF, KrR） and relative growth （WR） also did not differ significantly （P〈0.05） between the sexes. This study provides a useful tool for fishery specialists to evaluate the relative condition of fish and to initiate early management strategies and regulations for the sustainable management of the remaining stocks of this species in the entire coastal region of southern Bangladesh.
基金funders Agència de Gestiód’Ajuts Universitaris i de Recerca(AGAUR)(2014-SGR-00453 and 2017-SGR-001001 ID grants)Ministerio de Economía,Industria y Competitividad,Gobierno de España(CGL2015-67419-R ID grant).
文摘Aims Cistus albidus reproductive traits have been studied on typical Mediterranean shrublands along a water availability gradient in Northeastern Iberian Peninsula.Germination of this species is known to be highly favoured by fire.Moreover,Mediterranean species are particularly dependent on water availability.Therefore,we establish the hypothesis that in addition to fire disturbance,seedling recruitment in this Mediterranean seeder will be improved in drought-induced episodes resulting in generalized canopy die-off.Methods Individuals of several populations of C.albidus were collected and the size,weight and number of fruits and seeds were measured.Germination tests were also carried out on five pre-germination treatments:seeds’exposure to heat shock,imbibition,two cycles of imbibition/desiccation and the combination of heat shock and imbibition and imbibition/desiccation cycles.Moreover,the number of seedlings after a drought event was surveyed in the field and correlated with canopy die-off.Important findings Our study shows the variability of the C.albidus reproductive traits,such as germination rate or fruit production,along the water availability gradient.This variability resulted in a decrease in fruit production but an increase in successful germination under drier conditions.Cistus albidus seeds increased germination with heat,demonstrating their ability to successfully establish after fire.However,recruitment was not exclusively fire dependent since seedling establishment was higher under C.albidus canopies that had collapsed after the extreme drought.Finally,adult density increased C.albidus die-off and mortality,as well as seedling establishment.These results suggest that this species exhibits a trade-off between different reproductive outcomes(i.e.seed production vs.viability),which in turn is determined by climate.This study also provides evidence of how intra-specific competition,climate,particularly drought events and fire disturbance,can determine the success of key early stages of the life history of a common,representative Mediterranean fire-prone seeder shrub.
