Complementary (secondary) metabolites in a soft coral: sex-specific variability, inter-clonal variability, and competition   总被引：2，自引：0，他引：2  

Beatriz Fleury  John Coll  & Paul Sammarco 《Marine Ecology》2006,27(3):204-218

Sex‐specific interactions involving competition for space between the dioecious alcyonacean soft coral Sarcophyton glaucum and the scleractinian coral Acropora robusta were assessed experimentally on Bald Rock, central region of the Great Barrier Reef. To examine this, plus inter‐clonal responses, one male colony of S. glaucum, known to produce sarcophytoxide as its predominant complementary (secondary) metabolite, was sectioned, producing 10 clones. The same was done for a female colony. These two sets of clones were then relocated to grids and placed in contact with Acropora clones. Relocated and non‐relocated controls were also monitored. High levels of tissue necrosis were observed in the hard coral under contact conditions with both the male and female clones after 20 days. The development of a protective polysaccharide layer in the alcyonacean was also observed. Differences observed in the concentrations of complementary metabolites within the two different S. glaucum colonies were related to sex. Both under competition and non‐competition conditions, females exhibited significantly higher concentrations of sarcophytoxide than males, and this increased with time. Fatty ester concentration was also higher in females than males, varying significantly through time, and falling dramatically just after spawning. Fatty ester concentrations decreased linearly through time in the male clones. When involved in competition for space, females possessed higher concentrations of fatty esters than males, both at the site of contact and in non‐contact sites, again, decreasing after spawning. No significant changes in sarcophytoxide levels were noted in the parental colonies, but such changes were observed in fatty esters, with the female producing higher concentrations until after spawning. The use of these two variates in the form of a ratio (sarcophytoxide concentration:fatty ester concentration) yielded a variable Rho (ρ) which was a more sensitive indicator of biochemical change than either of its components alone. These two sets of compounds appeared to have a negative association through time and varied highly significantly between sexes. The diterpene sarcophytoxide may be considered an allelopathic or stress metabolite, while the lipids act as energy storage metabolites.  相似文献   

Short-term effects of fishing on life history traits of fishes   总被引：4，自引：4，他引：4  

Rochet  Marie-Joelle 《ICES Journal of Marine Science》1998,55(3):371-391

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Lunar rhythms in the egg hatching of the subtidal crustacean: Callinectes arcuatus Ordway (Decapoda: Brachyura)     

M. C. DeVries  C. E. Epifanio  A. I. Dittel 《Estuarine, Coastal and Shelf Science》1983,17(6):717-724

The Gulf of Nicoya, an estuary on the Pacific coast of Central America, contains a large population of the portunid crab Callinectes arcuatus. Results of a 12 month survey indicated that spawning activity occurs throughout the year, but with a distinct peak during the five-month dry season (December-April). Mature females were most prevalent in the upper regions of the gulf during the rainy season and appeared to migrate to the lower gulf to spawn during the dry season. Patterns of spawning and apparent migration differed from those reported in an earlier study of C. arcuatus along the Pacific coast of Mexico.  相似文献   

Life-history strategies of calanoid congeners under two different climate regimes: a comparison   总被引：5，自引：0，他引：5  

Halsband-Lenk  Claudia; Carlotti  Francois; Greve  Wulf 《ICES Journal of Marine Science》2004,61(4):709-720

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Absence of seasonal changes in reproductive function of cultured Atlantic salmon migrating into a Canadian river     

Lacroix  G. L.; Galloway  B. J.; Knox  D.; MacLatchy  D. 《ICES Journal of Marine Science》1997,54(6):1086-1091

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Age, growth and reproduction of the sand smelt Atherina boyeri Risso, 1810 in the Gomishan wetland – southeast Caspian Sea     

Rahman Patimar  Morteza Yousefi  Seyyed Morteza Hosieni 《Estuarine, Coastal and Shelf Science》2009,81(4):457-462

A total of 2256 specimens of Atherina boyeri caught in Gomishan wetland (a marsh lagoon located at the southeast Caspian Sea) during spawning season from February to August 2007 were examined for life-history attributes. The population has a 4-year life cycle. Length–weight relationship was estimated as W = 0.0053TL^3.0181 for males and W = 0.0050TL^3.063 for females, being allometrically positive for both sexes. The von Bertalanffy growth function fitted to back-calculated size at age data was: Lt = 155.17[1 − exp − 0.28(t + 0.738)] and Lt = 162.77[1 − exp − 0.27(t + 0.727)] for males and females respectively. The sex ratio was 1:1.30 in favor of females. The reproductive season, evaluated from GSI, extended from March to July, with a peak in March. The average absolute and relative fecundities were 2976 eggs and 874 eggs g⁻¹ of body weight respectively. The diameter of oocytes ranged from 0.03 to 0.20 mm with a mean value of 0.68. The life-history patterns of A. boyeri in the population under study imply that the population of this species in the southeast Caspian Sea differs markedly from those of other localities of its range distribution. The differences were thought to be due to differences in geographical locations.  相似文献   

Probability field for the post-processing of stochastic simulations     

G. Bourgault 《Mathematical Geology》1996,28(6):723-734

A combination of factorial kriging and probability field simulation is proposed to correct realizations resulting from any simulation algorithm for either too high nugget effect (noise) or poor histogram reproduction. First, a factorial kriging is done to filter out the noise from the noisy realization. Second, the uniform scores of the filtered realization are used as probability field to sample the local probability distributions conditional to the same dataset used to generate the original realization. This second step allows to restore the data variance. The result is a corrected realization which reproduces better target variogram and histogram models, yet honoring the conditioning data.  相似文献   

Abundance,breeding and growth of the ocypodid crab Dotilla myctiroides (Milne-Edwards) on a West Malaysian beach     

A.J. Hails  S. Yaziz 《Estuarine, Coastal and Shelf Science》1982,15(2):229-239

The ocypodid crab, Dotilla myctiroides, was studied on the south-west coast of peninsular Malaysia. The mean numbers and biomass over a year along a transect from high to low water ranged from 37·5 to 579 crabs m^?2 and from 2·22 to 50·79 g m^?2 (wet weight) respectively. Berried females were found in all months of the year but two peaks of activity were apparent, from November to February and May to July. It is suggested that this may be related to changes in food abundance associated with the effects of monsoon winds on sea currents. Laboratory growth studies indicated that maximum life span was approximately 13 months (from first crab stage) for males and 10 months for females. Growth rate decreased with increasing size of crab. Egg number increased with size of female.  相似文献   

‘Selling Our Own Skin:’ Social dispossession through microcredit in rural Bangladesh     

《Geoforum》2016

In this paper, I articulate a notion of ‘social dispossession,’ an optic that extends current theorizing on agrarian dispossession into the realm of social reproduction, by examining the testimonies of microcredit borrowers in rural Bangladesh. In recent years, research on microcredit has highlighted new forms of subject-making employed by microcredit and other NGO entrepreneurship development programs. These developments have received insufficient attention in scholarship on agrarian change, both globally and in specific places. I correct this by arguing that microcredit drives social dispossession through three specific mechanisms: the confiscation of assets necessary to social reproduction (as well as to production); the construction of debt relations within a community which reshape what reproduction can look like; and the re-configuration of women’s social status and subjectivities in relation to their communities.  相似文献   

忠实于景物的层次复制函数的研究   总被引：3，自引：0，他引：3  

刘全香  朱元泓 《武汉大学学报(信息科学版)》2000,25(5):464-467

层次复制函数是彩色图像复制的重要基础和先决条件。本文以现代彩色复制理论为基础 ,在力求印刷品忠实景物的层次复制的基础上 ,根据感光材料的感光特性 ,通过研究建立了彩色复制各个环节之间图像层次传递的函数及分色层次再现曲线。  相似文献