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451.
Inferring nocturnal surface fluxes from vertical profiles of scalars in an Amazon pasture 总被引:1,自引:0,他引:1
Otávio C. Acevedo Osvaldo L. L. Moraes† Rodrigo da Silva David R. Fitzjarrald† Ricardo K. Sakai† Ralf M. Staebler† Matthew J. Czikowsky† 《Global Change Biology》2004,10(5):886-894
Ecosystem carbon budgets depend on there being good representative surface flux observations for all land use types during the entire diurnal cycle. In calm conditions that often occur at night, especially in areas of small roughness (such as pastures), ecosystem respiration rate is poorly measured using the eddy covariance (EC) technique. Nocturnal vertical profiles of temperature, humidity and winds were observed using tethered balloon soundings in a pasture in the eastern Amazon during two campaigns in 2001. The site is characterized by very weak winds at night, so that there is insufficient turbulence for the EC technique to determine fluxes accurately. To compensate, the time evolution of the profiles is used to determine surface fluxes at early morning and these are compared with those observed by EC at a nearby micrometeorological tower. The nocturnal boundary layer thickness h is determined as the height to which the surface fluxes must converge so that energy budget closure is achieved. The estimated values range from 30 m, around 22:00 hours LST, to more than 100 m just before dawn. These are in good agreement with the observed thickness of a frequently observed fog layer during the middle of the night. During the early portion of the night, when the accumulation layer is shallow, there is appreciable decrease of dCO2/dt with height. On calm nights, CO2 accumulation rate is larger near the surface than at higher levels. On windier nights, this accumulation rate is vertically uniform. Hence, extrapolation of tower profiles for estimating fluxes must be done carefully. Although uncertainties remain large, an alternate approach to the EC method is described for measuring nighttime surface CO2 fluxes under stable atmospheric conditions. 相似文献
452.
Daniel Torres Jorge Acevedo Daniel E. Torres Romeo Vargas Anelio Aguayo-Lobo 《Polar Biology》2012,35(3):469-473
A vagrant adult male Subantarctic fur seal Arctocephalus tropicalis was observed among Antarctic fur seals A. gazella at Cape Shirreff, Livingston Island, Antarctica, which is located to ~4,190 and ~5,939 km from the nearest breeding colonies
of Subantarctic fur seals. Although the colony of origin of this animal and the reason for its movement outside its distribution
range are unknown, this sighting shows the high dispersal capacity of this species and provides an insight into possible changes
in its distribution. Although this vagrant was not observed with females Antarctic fur seal, news sightings in the future
could result in viable hybrid, and introgressive hybridization could represent a threat for Cape Shirreff population recovery,
if still the population way to go to recover to presailing levels. 相似文献
453.
Non-offspring maternal care should be common in phocids, but their occurrence would be uncommon among otariids due to the high costs of raising offspring, particularly lactation, and an efficient recognition system that allow for accurate recognition during the frequent mother–pup re-associations. However, non-offspring maternal care has been documented in some otariid species. While the phenomenon in general is not novel among the colonially breeding seals, the exclusive care to a single pup by two lactating females for an extended time is a behavior scarcely documented in natural population. In an extension of this allonursing care, we document the first case of the kidnapping of a pup with subsequent shared nursing in Antarctic fur seal including data on the effect of this interaction on the pup’s growth. While all other lactating females nursed exclusively their own pups, the shared nursing was advantageous for the pup because he grew noticeably larger (in weight and axillary girth) than other of his cohort, particularly after 50 days. This advantage would have been influenced by the asynchrony of the foraging cycle of the biological and foster mother, which resulted in a higher attendance on shore than any other male pups. Although several explanations have been hypothesized for allolactation in mammals, our observations suggest a misguided parental care, associated with recognition errors by the foster mother whose pup was stillborn. 相似文献
454.
455.
A. Machordom U. Ramírez-Escobar I. Acevedo R. García-Jiménez P. Cabezas M. Calvo C. Toledo P. Bloor 《Conservation Genetics》2010,11(3):1083-1086
The limpet Patella ferruginea is one of the most endangered marine invertebrates on western Mediterranean rocky shores. We have isolated and characterised
11 polymorphic microsatellites markers to provide new tools to investigate genetic structure and gather information necessary
for the proper management of this severely threatened species. The number of alleles per locus ranged from 2 to 16 (mean;
Na = 8.37) with an average observed heterozygosity of 0.64 (He = 0.66). The levels of polymorphism uncovered at these loci
suggest that they should be useful for population genetic studies, parentage analysis and assessment of connectivity among
protected areas. None of the pairwaise comparisons among loci showed significant linkage disequilibrium after sequential Bonferroni
correction. All but one locus (Pf-31IF1) conformed to HW equilibrium. Further investigation revealed that departures at Pf-31IF1
were not caused by null alleles. Results from cross-species amplifications suggest that some of these loci may also be useful
for Patella tenuis (two loci) P. ulyssiponensis (one locus) and P. piperata (three loci). 相似文献