Predictive modelling to map subtidal communities is an alternative to “traditional” methods, such as direct sampling, remote
sensing and acoustic survey, which are neither time- nor cost-effective for vast expanses. The principle of this modelling
is the use of a combination of environmental key parameters to produce rules to understand species distribution and hence
generate predictive maps. This study focuses on subtidal kelp forests (KF) on the coast of Brittany, France. The most significant
key parameters to predict KF frequency are (1) the nature of the substrate, (2) depth, (3) water transparency, (4) water surface
temperature and (5) hydrodynamics associated with the flexibility of algae in a flow. All these parameters are integrated
in a spatial model, built using a Geographical Information System. This model results in a KF frequency map, where sites with
optimum key parameters show a deeper limit of disappearance. After validation, the model is used in the context of Climate
Change to estimate the effect of environmental variation on this depth limit of KF. Thus, the effects of both an increase
in water temperature and a decrease in its transparency could lead to the complete disappearance of KF. 相似文献
The food web of two intertidal seagrass (Zostera marina and Zostera noltii) beds that may be influenced by the seasonal variation in food source abundance was studied in winter and in summer with
δ13C and δ15N analysis. In spite of high relative variation of abundance of main primary producers at the two sites, the food web did
not vary between winter and summer. The δ13C range of primary producers was wide. Zostera leaves, the most 13C-enriched source, were not consumed directly by grazers. Deposit and filter feeders have a similar δ13C and could use a mix of suspended and sedimented organic particulate matter, largely composed of detritus from macroalgae
to seagrass. This trophic pathway allows the local incorporation of the high biomass produced by seagrasses. The wide δ15N range of predators was linked either to a large variety from omnivore to carnivore predators or to the also wide ranges
of δ15N of primary consumers. 相似文献
The fate of six human-use drugs was assessed and predicted in mesocosms designed to mimic shallow constructed wetlands during the onset of fall and senescence. Mesocosms were monitored for 28 days after the addition of carbamazepine, clofibric acid, fluoxetine and naproxen (nominal initial concentrations of 5 μg/L each), sulfamethoxazole, and sulfapyridine (nominal initial concentrations of 150 μg/L each), with and without phosphorous (P) addition at 1.6 mg/L. We hypothesized that addition of P would stimulate primary productivity and enhance removal of pharmaceuticals from the water column. Carbamazepine, clofibric acid, fluoxetine, and naproxen had half-lives of 8.7, 11, 1.5, and 2.5, and 8.6, 11.0, 1.4, and 2.5 days in treatments with and without P amendment, respectively. Sulfamethoxazole and sulfapyridine had half-lives of 17 and 4.9 days in mesocosms with P amendment and 17 and 4.7 days without amendment. A concurrent pulse of P with pharmaceuticals did not significantly enhance the removal of these compounds. Predicted half-lives from modeling efforts were consistent with observed values, with photolysis the greatest contributor to chemical attenuation.
Temperature is expected to have an effect on the behavioral patterns of all organisms, especially ectotherms. However, although several studies focused on the effect of temperature on acoustic displays in both insects and anurans, almost nothing is known about how environmental temperature may affect ectotherm visual courtship displays and sexual performance. The purpose of this study was to determine the effect of environmental temperature on the sexual behavior of Alpine newts (Triturus alpestris). We subjected T. alpestris to two different temperatures in controlled laboratory conditions. Temperature had a major effect on both male and female behaviors: at low temperature, the frequencies of several displays, including tail-raising during sperm deposition, are lowered. This variation is caused indirectly by temperature because it is due to female responsiveness, which is temperature-dependent. However, the fanning movement of the males tail during its main courtship display is independent of female behavior: at lower temperatures, the tail beats at a lower rate, but for a longer time. The similar reproductive success (i.e. sperm transfer) at the two temperature ranges indicates that breeding in cold water is not costly but instead allows males and females to mate early in the season. This is particularly adaptive because, in many habitats, the reproductive period is shortened by drying or freezing conditions, which may impair survival of branchiate offspring. This study also demonstrates the necessity of considering environmental parameters when modeling optimality and characteristics of ectotherm behaviors.Communicated by W. Cooper 相似文献
In many European countries, milk production per cow has more than doubled in the last 40 years. The increase in production has been accompanied by declining ability to reproduce, increasing incidence of health problems, and declining longevity in modern dairy cows. Genetic selection for increased milk yield increasingly is viewed as increasing profit at the expense of reducing animal welfare. The economic future of the dairy industry is related directly to public acceptance of its breeding and production practices. It is important to the dairy industry that welfare problems should be addressed before there is widespread condemnation of breeding and management practices. A new breeding goal aimed at improving fitness and tolerance of metabolic stress is necessary to prevent the decrease in the quality of life of dairy cows and instead, perhaps, enhance it. 相似文献
Summary. 22-Acetyl-20-hydroxyecdysone was identified
as a major component in the secretion of elytral and pronotal
glands of Chrysolina carnifex, at an estimated concentration
of 1.5 x 10-1 M. This unexpected high concentration
of an ecdysteroid in an exocrine secretion of an insect is
discussed in terms of its potential defensive function, and in
the light of steroid production in similar glands of closely
related leaf beetles. 相似文献
The detection and structural elucidation of micropollutants treatment by-products are major issues to estimate efficiencies of the processes employed for drinking water production versus endocrine disruptive compounds contamination. This issue was mainly investigated at the laboratory scale and in high concentration conditions. However, potential by-products generated after chlorination can be influenced by the dilution factor employed in real conditions. The present study proposes a new methodology borrowed to the metabolomic science, using liquid chromatography coupled to high-resolution mass spectrometry, in order to reveal potential chlorination by-products of ethinylestradiol in spiked real water samples at the part-per-billion level (5 μg L−1). Conventional targeted measurements first demonstrated that chlorination with sodium hypochlorite (0.8 mg L−1) led to removals of ethinylestradiol over 97%. Then, the developed differential global profiling approach permitted to reveal eight chlorination by-products of EE2, six of them being described for the first time. Among these eight halogenated compounds, five have been structurally identified, demonstrating the potential capabilities of this new methodology applied to environmental samples. 相似文献