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511.
Teresa Catry Jaime A. Ramos Inês Catry David Monticelli José P. Granadeiro 《Marine Biology》2013,160(5):1189-1201
We investigated inter-annual variability in the breeding performance of six tropical seabirds with different life histories. We further examined the extent to which presumed differences among years in food availability to seabirds were related to large-scale oceanic processes (El Niño Southern Oscillation and Indian Ocean Dipole) or local features around the colony (Sea Surface Temperature—SST, chlorophyll-a concentration, wind patterns, association with underwater predators). Two food shortages were recorded: (1) a short-term event operating at a local-scale, lacking any relationship with any measured oceanographic parameters and affecting only a few seabird species; (2) a generalized and protracted event, strikingly characterized by low SST, possibly induced by a La Niña and/or negative IOD event, and with detrimental impacts in the whole seabird community. Overall, species with inflexible feeding habits and fast chick growth rates were more affected by food shortage events than those with more plastic life-history traits. 相似文献
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Guiomar Rotllant Francisco Javier Moyano Mireia Andrés Alicia Estévez Manuel Díaz Enric Gisbert 《Marine Biology》2010,157(10):2215-2227
The effect of food deprivation on larval performance of the spider crab Maja brachydactyla was studied in terms of survival, moulting capacity, size, weight and enzymatic activities. Five feeding treatments that
differed in the initial age of first feeding larvae (fed from hatching, 2, 4 and 6 days post-hatching and unfed) were tested
for 20 days. Newly hatched larvae kept without food supply lasted for 10 days and did not moult; with 50% survival observed
at 6 days post-hatching. Larvae (zoea I stage) were only able to tolerate 2 days of food deprivation after the onset of exogenous
feeding without their performance being compromised. Multivariate analyses suggest that digestive enzyme activities may be
good indicators of the nutritional condition of larvae. 相似文献
513.
José A. Martínez-Casasnovas María Concepción Ramos Sílvia Espinal-Utgés 《Environmental monitoring and assessment》2010,163(1-4):379-396
The availability of heavy machinery and the vineyard restructuring and conversion plans of the European Union Common Agricultural Policy (Commission Regulation EC no. 1227/2000 of 31 May 2000) have encouraged the restructuring of many vineyards on hillslopes of Mediterranean Europe, through the creation of terraces to favor the mechanization of agricultural work. Terrace construction requires cutting and filling operations that create soil spatial variability, which affects soil properties and plant development. In the present paper, we study the effects of hillslope terracing on the spatial variability of the normalized difference vegetation index (NDVI) in fields of the Priorat region (NE Spain) during 2004, 2005, and 2006. This index was computed from high-resolution remote sensing data (Quickbird-2). Detailed digital terrain models before and after terrace construction were used to assess the earth movements. The results indicate that terracing by heavy machinery induced high variability on the NDVI values over the years, showing significant differences as effect of the cut and fill operations. 相似文献
514.
Environmental externalities and efficiency measurement 总被引:1,自引:0,他引:1
Production of desirable outputs often produces by-products that have harmful effects on the environment. This paper investigates technologies where the biggest good output producer is not the greatest polluter, i.e. technologies located on the downward-sloping segment of the frontier depicted in Färe et al. (1989). Directional distance functions and Data Envelopment Analysis techniques are used to define an algorithm that allows them to be identified empirically. Furthermore, we show that in such situations producers can contribute social goods, i.e. reducing polluting wastes, without limiting their capacity to maximise production of marketable output. Finally, we illustrate our methodology with an empirical application to a sample of Spanish ceramic tile producers. 相似文献
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Detailed knowledge of the mating system in specific social insect populations is essential for testing general evolutionary
hypotheses of multiple paternity in eusocial Hymenoptera. We have studied the mating frequency of queens in a polygynous population
of the red ant Myrmica sulcinodis. Genetic mother-offspring analysis showed that double mating occurred at a considerable frequency, but that the effective
number of queen-mates remained close to one. After quantifying the effects of multiple maternity (polygyny) and multiple paternity
(polyandry) on the genetic diversity of workers, we conclude that multiple paternity in M. sulcinodis did not evolve as an adaptation to increase genetic variation within colonies. Contrary to the predictions from `genetic
variability' hypotheses, we found a positive correlation between colony-specific queen number and the average number of mates
per queen. Such positive association of queen number and frequency of multiple mating was also found after analysing comparative
data across six species of Myrmica ants. These results suggest that resticted dispersal of young queens may be a common factor promoting both polygyny and polyandry
at the same time, and that moderate degrees of multiple mating may be an unselected consequence of (1) mating at low cost
when mating occurs close to the nest and (2) mating in swarms with a highly male biased operational sex ratio. Future comparative
tests of genetic-variability hypotheses should therefore not include species with such evolutionary derived mating system
characteristics.
Received: 30 April 1998 / Accepted after revision: 19 August 1998 相似文献
518.
Kamran Moradkhani Laurence Cuisset Pierre Boisseau Olivier Pichon Marine Lebrun Houda Hamdi-Rozé Marie-Laure Maurin Nicolas Gruchy Marie-Christine Manca-Pellissier Perrine Malzac Frédéric Bilan Marie-Pierre Audrezet Pascale Saugier-Veber Anne-Laure Fauret-Amsellem Chantal Missirian Paul Kuentz Gregory Egea Agnès Guichet Isabelle Creveaux Caroline Janel Ines Harzallah Renaud Touraine Carole Goumy Nicole Joyé Jacques Puechberty Emmanuelle Haquet Sandra Chantot-Bastaraud Sébastien Schmitt Philippe Gosset Bénédicte Duban-Bedu Bruno Delobel Philippe Vago François Vialard Denise Molina Gomes Jean-Pierre Siffroi Jean-Paul Bonnefont Jean-Michel Dupont Philippe Jonveaux Martine Doco-Fenzy Damien Sanlaville Cédric Le Caignec 《黑龙江环境通报》2019,39(11):986-992
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