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561.
A total of 22 magellanic penguins (Spheniscus magellanicus) from Isla Martillo in the Beagle Channel, Argentina, were successfully satellite tracked in 2004 (n = 7), 2005 (n = 7) and 2006 (n = 8) to monitor their winter migration after moult. Only one magellanic penguin migrated northwards into the Pacific Ocean,
whereas all others remained in the Atlantic Ocean. In general, these birds left the island in an easterly direction, rounded
Cabo San Diego, the southeasterly tip of South America, and continued northwards occupying inshore waters mostly less than
50 km from the coast, only occasionally venturing further offshore. By the end of the transmission period, birds were still
travelling northwards and the most northerly positions were obtained from birds located in the area of Peninsula Valdés, Argentina,
at a latitude of around 42°S, some 1,500 km from their breeding site on Isla Martillo. The mean maximum distance to the breeding
site was, however, only 624 ± 460 km. The mean minimum distance covered during the study period was 1,440 ± 685 km, which
corresponded to a mean distance of 23.2 ± 6.6 km covered per day. The northbound migration of the penguins could be separated
into periods of rapid movement, interspersed with periods during which the birds remained for some time in particular coastal
regions. Areas with a high density of daily penguin positions were observed in three distinct areas: at the northeastern coast
of Tierra del Fuego, at the southern entrance of Golfo San Jorge and to the northeast of the Peninsula Valdez. The observed
migration pattern is presumably driven by the formation and subsequent dispersal of areas of enhanced productivity as the
season progressed. Our findings also suggest that magellanic penguins are increasingly threatened by human activities in coastal
areas as penguins migrate northwards. 相似文献
562.
Silvia Nava Paolo Prati Franco Lucarelli Pier Andrea Mandò Alessandro Zucchiatti 《Water, Air, & Soil Pollution: Focus》2002,2(5-6):247-260
We describe the results of an aerosol sampling campaign performedin 1999 in the medium-size industrial town of La Spezia, in theNorthwest of Italy. We used two-stage continuous streakersamplers in three different sites and periods of the year. This kind of samplers allows the separation of the PM10 andPM2.2 fractions of the particulate matter. Moreover, the hourly resolution in the aerosol collection is particularly useful inan urban environment where, typically, many pollution sourceswith fast variations are present. Up to 1700 samples have beenanalysed by Particle Induced X-ray Emission (PIXE) at the INFNaccelerator facility in Florence, obtaining hourly concentrationfor about 20 elements from Na to Pb, with a sensitivity rangingfrom below 1 to about 10 ng m-3. The total hourly aerosolmass has been estimated with an optical analysis of the samesamples performed (before the PIXE analysis) by an equipment designed and mounted in Genoa. An extensive statistical analysisof the data included standard and Absolute Principal ComponentFactor Analysis (PCFA and APCFA) to deduce the compositionand the weight of the major aerosol sources in both fractions.Thorough different statistical approaches, we generally resolvedcontributions from vehicle emission, fossil fuel combustion,soil-road dust and sea salt aerosol. 相似文献
563.
564.
565.
Daniele Contini Franco Belosi Andrea Gambaro Daniela Cesari Angela Maria Stortini Maria Chiara Bove 《环境科学学报(英文版)》2012,24(11):1954-1965
The Venice Lagoon is exposed to atmospheric pollutants from industrial activities, thermoelectric power plants, petrochemical plants, incinerator, domestic heating, ship traffic, glass factories and vehicular emissions on the mainland. In 2005, construction began on the mobile dams (MOSE), one dam for each channel connecting the lagoon to the Adriatic Sea as a barrier against high tide. These construction works could represent an additional source of pollutants. PM10 samples were taken on random days between 2007 and 2010 at three different sites: Punta Sabbioni, Chioggia and Malamocco, located near the respective dam construction worksites. Chemical analyses of V, Cr, Fe, Co, Ni, Cu, Zn, As, Mo, Cd, Sb, Tl and Pb in PM10 samples were performed by Inductively coupled plasma-quadrupole mass spectrometry (ICP-QMS) and results were used to identify the main aerosol sources. The correlation of measured data with meteorology, and source apportionment, failed to highlight a contribution specifically associated to the emissions of the MOSE construction works. The comparison of the measurements at the three sites showed a substantial homogeneity of metal concentrations in the area. Source apportionment with principal component analysis (PCA) and positive matrix factorization (PMF) showed that a four principal factors model could describe the sources of metals in PM10. Three of them were assigned to specific sources in the area and one was characterised as a source of mixed origin (anthropogenic and crustal). A specific anthropogenic source of PM10 rich in Ni and Cr, active at the Chioggia site, was also identified. 相似文献
566.
The females of several internal fertilizers are able to store sperm for a long time, reducing the risk of sperm limitation. However, it also means that males can attempt to mate outside females’ receptive period, potentially increasing the level of sperm competition and exacerbating sexual conflict over mating. The guppy (Poecilia reticulata), an internally fertilizing fish, is a model system of such competition and conflict. Female guppies accept courtship and mate consensually only during receptive periods of the ovarian cycle but receive approximately one (mostly forced) mating attempt per minute both during and outside their sexually receptive phase. In addition, females can store viable sperm for months. We expected that guppy females would disfavour sperm received during their unreceptive period, possibly by modulating the quality and/or quantity of the components present in the ovarian fluid (OF) over the breeding cycle. Ovarian fluid has been shown to affect sperm velocity, a determinant of sperm competition success in this and other fishes. We found that in vitro sperm velocity is slower in OF collected from unreceptive females than in OF from receptive females. Visual stimulation with a potential partner prior to collection did not significantly affect in vitro sperm velocity. These results suggest that sperm received by unreceptive females may be disfavoured as sperm velocity likely affects the migration process and the number of sperm that reach storage sites. 相似文献
567.
We present reports of sightings of living and stranded specimens of Rhizostoma luteum on the Atlantic coast of Morocco and along the south shore of the Iberian Peninsula in June–July 2012 and in January–February 2013. During summer 2012 and following the dominant currents, the jellyfish first appeared in the Gulf of Cadiz west of the Strait of Gibraltar. Subsequently, seven additional sightings were reported east of the Strait, in the Alboran Sea. In winter 2013, another event of stranded individuals of this species occurred in the Gulf of Cadiz. A phylogenetic analysis performed on the mitochondrial cytochrome c oxidase I (COI) gene sequence in specimens from both stranding events confirmed the morphological classification, ratifying that R. luteum differs from Rhizostoma octopus and Rhizostoma pulmo. This study records the presence of this species for the first time in 60 years. 相似文献
568.
Andrea Ludwig Marty Matlock Brian Haggard Indrajeet Chaubey 《Journal of the American Water Resources Association》2012,48(5):896-908
Ludwig, Andrea, Marty Matlock, Brian Haggard, and Indrajeet Chaubey, 2012. Periphyton Nutrient Limitation and Maximum Potential Productivity in the Beaver Lake Basin, United States. Journal of the American Water Resources Association (JAWRA) 48(5): 896‐908. DOI: 10.1111/j.1752‐1688.2012.00657.x Abstract: The objectives of this study were to measure periphytic growth responses to enrichment with nitrogen (N), phosphorus (P), and simultaneous N and P using in situ bioassays in streams draining Beaver Reservoir Basin, Northwest Arkansas; compare periphytic growth responses measured with in situ bioassays with a range of land use and point sources; and test the lotic ecosystem trophic status index (LETSI) as a simplifying metric to compare effects of nonpoint‐source pollutant‐limiting variables of N, P, and sediment across the basin. P limitation was observed at sites across a transect of stream orders throughout the basin; however, at the two sites with highest ambient nitrogen concentrations, limitation was often coupled with nitrogen limitation. Nutrients were at nonlimiting levels at both of two sites below wastewater treatment plants in all seasonal deployments. A Michaelis‐Menten growth equation described LETSI as a function of ambient PO4‐P concentrations (p < 0.05); the midpoint (LETSI of 0.50) corresponded with a PO4‐P concentration of approximately 3 μg/l. Change‐point analysis indicated a threshold point at LETSI of 0.80 and 15 μg/l PO4‐P. These low values show that the periphytic community has a high affinity for available P, and that the watershed as a whole is sensitive to available nutrient inputs. 相似文献
569.
Andrea Zoia Christelle Latrille Alberto Beccantini Alain Cartadale 《Journal of contaminant hydrology》2009,109(1-4):14-26
We investigate the spatial and temporal features of variable-density contaminant plumes migration in porous materials. Our analysis is supported by novel experimental results concerning concentration profiles inside a vertical column setup that has been conceived at CEA to this aim. The experimental method relies on X-ray spectrometry, which allows determining solute profiles as a function of time at several positions along the column. The salient outcomes of the measurements are elucidated, with focus on miscible fluids in homogeneous saturated media. The role of the injected solution molarity is evidenced. As molarity increases, the solutes plume transport progressively deviates from the usual Fickian behavior, and pollutants distribution becomes skewed in the direction dictated by gravity. By resorting to a finite elements approach, we numerically solve the nonlinear equations that rule the pollutants migration: a good agreement is found between the simulated profiles and the experimental data. At high molarity, a strong dependence on initial conditions is found. Finally, we qualitatively explore the (unstable) interfacial dynamics between the dense contaminant plume and the lighter resident fluid that saturates the column, and detail its evolution for finite-duration contaminant injections. 相似文献
570.
Andrea Bonisoli-Alquati Diego Rubolini Manuela Caprioli Roberto Ambrosini Maria Romano Nicola Saino 《Behavioral ecology and sociobiology》2011,65(9):1779-1790
Transfer of maternal hormones to the eggs is a major source of offspring phenotypic variation. The developmental and organizational
effects of egg hormones can extend into adulthood and affect behavioral and morphological traits involved in sexual and reproductive
behavior, with important consequences for offspring fitness. In this study, we injected testosterone (T) in egg albumen of
captive ring-necked pheasant (Phasianus colchicus) eggs. We then assessed the consequences for chick growth, cell-mediated immunity, and multiple male secondary sexual traits
at maturity by comparison with a control group. We also compared the covariation between traits in the two experimental groups.
We found that control males had redder wattles than males from T-injected eggs, suggesting that attractiveness and reproductive
success of the offspring might vary depending on maternal transfer of T to the eggs. T treatment also modified the covariation
between cell-mediated immunity and wattle coloration and between the area of the wattle and the expression of another secondary
sexual trait, the ear tufts. These effects are likely to translate into fitness differences among the offspring if mate acquisition
depends on the simultaneous expression of several traits that are differentially affected by the same maternal contribution.
Maternal effects mediated by egg hormones might affect the fitness of the offspring not only by directional modification of
phenotypic traits, but also by facilitating or inhibiting their covariation. This suggests the possibility that female choice
based on the relative expression of multiple secondary sexual traits exerts a pressure on how maternal transfer of androgens
contributes to developmental programs. 相似文献