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951.
Singlet molecular oxygen—mediated photooxidation of monochloro and mononitrophenols. A kinetic study
A kinetic and mechanistic study on the aerobic dye sensitized photooxidation of the mono—nitro and chlorophenols was carried out. A singlet molecular oxygen mechanism operates in the photooxidation. Solvent and substituent effects, suggest the intermediacy of a complex with partial charge transfer character, as has been postulated for other phenols. Chemical (reactive) and physical interactions of the substrates with singlet molecular oxygen were discriminated. Quantum yields for photooxidation (higher for the chlorophenols) range from 3 × 10‐2 to 2 × 10‐3, as measured by substrate or oxygen consumption. These values indicate the viability of a singlet molecular oxygen photooxidation as a way for the degradation of nitro and chlorophenol environmental contaminants. 相似文献
952.
Alejandro Ariel Ríos-Chelén Esmeralda Quirós-Guerrero Diego Gil Constantino Macías Garcia 《Behavioral ecology and sociobiology》2013,67(1):145-152
In noisy conditions, several avian species modulate their songs in amplitude and in the temporal or frequency domains, presumably to improve communication. Most studies on how passerine birds perform such adjustments have been carried out in oscines, a group well known for the importance of learning in the development of their songs. On the other hand, suboscines, in which learning appears to have little influence on the development of their songs, have been largely neglected. We evaluated song adjustment to noise in the vermilion flycatcher (Pyrocephalus rubinus), a suboscine bird. We conducted song recordings and noise measurements at several territories within Mexico City during the length of the dawn chorus. Males living in noisier places sang long songs, while those males inhabiting quieter places sang both short and long songs. We also found evidence of individual song plasticity, as males sang less versatile songs (i.e., songs with more introductory elements) later in the morning when noise levels were higher. This individual shift in song seems to be more associated to time of the day rather than to the observed rise in noise. However, we cannot discard an effect of noise, which should be evaluated with an experiment. We discuss our results in the context of other studies with oscine passerines and other taxa and consider implications for signaling in intra- and intersexual contexts. 相似文献
953.
954.
Carmen B. de los Santos Fernando G. Brun Juan J. Vergara José Lucas Pérez-Lloréns 《Marine Biology》2013,160(5):1083-1093
Seagrasses may acclimate to environmental heterogeneity through phenotypic plasticity. In contrast to leaf morphology, which has been a central point in seagrass acclimation studies, plasticity in leaf biomechanics and fibre content is poorly understood, despite being crucial in plant ecological performance, especially regarding physical forces. We hypothesised that mechanical traits (e.g. breaking force, strength, toughness, and stiffness) and fibre content of seagrass leaves vary as morphology does under differential environments. Cymodocea nodosa was seasonally monitored at three locations around Cádiz Bay (southern Spain) with hydrodynamic regime as the most noticeable difference between them. Leaves showed plasticity in both morphology and mechanical traits, with wave-exposed individuals presenting short but extensible and tough leaves. Leaf fibre content was invariant along the year and with little spatial variability. Cross-sectional area rather than material properties or fibre content differentiates leaf mechanical resistance. Seagrass capacity to thrive under a range of mechanical forces may be dictated by their plasticity in morpho-biomechanical traits, a key element for the hydrodynamical performance and, hence, for species colonisation and distribution. 相似文献
955.
Maryline Le Vaillant Céline Le Bohec Onésime Prud’Homme Barbara Wienecke Yvon Le Maho Akiko Kato Yan Ropert-Coudert 《Marine Biology》2013,160(5):1147-1156
As predicted by life history theory, once recruited into the breeding population and with increasing age, long-lived animals should be able to manage more efficiently the conflict between self-maintenance and reproduction. Consequently, breeding performances should improve with age before stabilizing at a certain level. Using temperature–depth recorders and isotopic analysis, we tested how age affects the foraging behaviour of king penguin Aptenodytes patagonicus during one trip in the chick-rearing phase. Depending on sex and age, king penguins expressed two different foraging strategies. Older birds gained more daily mass per unit body mass than younger ones. Older females conducted shorter trips, dived deeper and performed more prey pursuits. They also had higher blood levels of δ15N than younger individuals and males indicating sex- and age-specific dietary regimes. However, we found no differences in carbon isotopic signature, suggesting that individuals exploited the same foraging areas independently of sex and age. Our results suggest that king penguins are able to increase the quantity of energy extracted with increasing age and that such a strategy is sex-related. Our study is the first to reveal of an interaction between age and sex in determining foraging efficiency in king penguins. 相似文献
956.
The photoacclimation capacity of the seagrass Cymodocea nodosa was evaluated considering temporal (i.e. seasonal) and spatial (i.e. depth and within-leaf position) factors of variation. Changes along the leaf were measured in a population growing along a depth gradient (from intertidal to subtidal) in Cadiz Bay (Southern Spain) from 2004 to 2005. Photoacclimation was evaluated by photosynthesis (P–E curves), pigment content and leaf morphology. Plants of Cymodocea nodosa showed large physiological and morphological plasticity (mean %CV = 35.8 ± 3.4) according to the three factors considered. Seasonal patterns appeared for photosynthesis, respiration, pigment content and morphology. Nevertheless, seasonal patterns were not consistent with depth or leaf portions. The resulting data set offered different information depending on the analysis conducted; when only one factor (season, depth or leaf portion) was considered, some tendencies observed in the 3-way full design were masked. Accordingly, considering spatio–temporal variability is crucial when describing photoacclimation and estimating productivity in seagrass meadows. 相似文献
957.
Anne-Leila Meistertzheim Sophie Arnaud-Haond Pierre Boudry Marie-Thérèse Thébault 《Marine Biology》2013,160(2):453-463
As a result of aquaculture activities, Pacific oysters Crassostrea gigas (Thunberg, 1793) have invaded European coasts. Using seven microsatellites, we found virtually no genetic differentiation between natural populations throughout the European range (from the south of the Wadden Sea (the Netherlands) to the south of France) and French cultivated oysters. The genetic homogeneity of Pacific oyster samples appears to be the result of repeated transfers from same seed stocks made for aquaculture and, to a lesser extent, widespread dispersal due to specific biological traits of this species. The only genetic differentiation of Sylt population in the north of the Wadden Sea (Germany) suggests a stronger, persistent impact of ongoing supply of new genetic material from hatchery production, corresponding to seeds selection made by breeders. All of our genetic data highlighted the importance of aquaculture practices on the genetic structure of the keystone invader C. gigas in Europe. 相似文献
958.
Paula Méndez-Fernandez Graham J. Pierce Paco Bustamante Tiphaine Chouvelon Marisa Ferreira Angel F. González Alfredo López Fiona L. Read M. Begoña Santos Jérôme Spitz José V. Vingada Florence Caurant 《Marine Biology》2013,160(11):2825-2840
This study aims to assess niche segregation among the five main toothed whales that frequent the NW Iberian Peninsula waters: the common dolphin, the harbour porpoise, the bottlenose dolphin, the striped dolphin and the long-finned pilot whale. We used cadmium (Cd) and stable isotope ratios (δ13C and δ15N) as ecological tracers to assess degree of segregation in diet/trophic level and in foraging habitat, over various time-scales. δ13C values highlighted different habitats, while Cd concentrations highlighted feeding differences between oceanic and neritic species. Moreover, δ15N values suggest different trophic levels of prey targeted within oceanic and neritic species. Hence, results revealed long-term ecological segregation among five toothed whales that coexist in the NWIP and demonstrated the ability of ecological tracers to discriminate ecological niches among closely related species. 相似文献
959.
The fate of microzooplankton production, whether it is channeled to mesozooplankton or recycled within the microbial food web, has major implications for the oceanic carbon cycle. The aim of this study was to estimate internal predation within naturally occurring microzooplankton communities. A dilution series based on the Landry and Hasset technique was created by mixing 200-μm-screened water (used as whole water) with 5-μm-screened seawater due to the dominance of pico- and small nanoplankton at our study site. This modification of the original technique allows for gradual reduction in microzooplankton abundance and thus internal predation while maintaining sufficient phytoplankton prey levels for microzooplankton growth in diluted treatments. Microzooplankton growth and mortality rates were calculated based on the changes in abundance during 24-h incubation. In the diluted treatments, microzooplankton growth rates were significantly higher (1.21 ± 0.20 day?1 for ciliates and 0.88 ± 0.05 day?1 for heterotrophic dinoflagellates) compared to those in whole seawater where microzooplankton abundance remained unchanged or even declined over time. Approximately 79 % of microzooplankton production was consumed within the microzooplankton, with aloricate ciliates being the most vulnerable to predation. These findings support the assumption that trophic interactions between microzooplankton can be an important factor controlling their production and, thus, energy transfer in picoplankton-dominated pelagic ecosystems. 相似文献
960.
F. C. Félix-Hackradt C. W. Hackradt J. Treviño-Otón A. Pérez-Ruzafa J. A. García-Charton 《Marine Biology》2013,160(9):2337-2352
Post-settlement events can significantly alter the density distribution of settlers and subsequently the adult population structure. The temporal and inter-annual variability of settlement and the effects of mortality on recruitment were investigated across 2 years in the vicinities of Cabo de Palos–Islas Hormigas Marine Reserve by visual census and light trap sampling. Settlement was seasonal with greater species richness and abundance in summer. Although temporal synchronization was observed between larval supply and settlement, densities of settlers could not be predicted from post-larval abundances. Timing of settlement was consistent between years but with high inter-annual variation in abundance. High mortality (~80 %) and general decoupling between post-larval and settlement stages suggest that early mortality is driving such patterns. Nevertheless, indications of habitat-mediated mortality were found for benthic species such as Symphodus and Diplodus, highlighting the importance of habitat in shaping population demography. 相似文献