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941.
Menghong Hu Youji Wang Sau Ting Tsang Siu Gin Cheung Paul K. S. Shin 《Marine Biology》2011,158(7):1591-1600
Energy budget is one of the most studied parameters in aquatic animals under environmental challenge. To examine how prolonged
starvation would affect their energy budget, respiration rate (RR), ammonia excretion rate (ER), oxygen consumption to ammonia–nitrogen
excretion (O:N) ratio and scope for growth (SfG) representing the balance between energy intake and metabolic output, two
Asian horseshoe crab species, Tachypleus tridentatus and Carcinoscorpius rotundicauda, were investigated in two feeding regimes (fed and starved) over a period of 7 weeks. No significant effects of species and
time course, as well as their interaction, on absorption efficiency were observed in the fed treatments. For both species,
RR and ER of the starved treatments significantly decreased, while their O:N ratio significantly increased during the experiment.
However, such values for the fed treatments remained relatively stable over the study period. A rapid reduction in SfG was
only apparent in the first week of the starved treatments for both species; thereafter, their SfG remained relatively constant.
In the fed treatments, SfG of T. tridentatus was significantly lower than that of C. rotundicauda throughout the experiment. In general, C. rotundicauda showed a greater decrease in SfG under starvation than T. tridentatus, suggesting that they may have a more competitive life-history strategy for adjusting to poor nutritional conditions. 相似文献
942.
Bo Terning Hansen Lars Erik Johannessen Tore Slagsvold 《Behavioral ecology and sociobiology》2007,61(8):1203-1209
Imprinting plays a key role in the development of species recognition, with young imprinting upon the morphological characters
of their parents. However, the potential role that cultural transmission might play in species recognition remains largely
uninvestigated. Great tits (Parus major) and blue tits (Cyanistes caeruleus) do not normally perceive each other as sexual competitors or potential partners. However, after reciprocal interspecific
cross-fostering, both species may perceive individuals of the foster species as potential rivals or mates. Although the experience
of being raised by heterospecifics clearly has affected the species recognition of cross-fostered birds, some of them breed
naturally with conspecifics. The offspring of such cross-fostered birds (OCF) are hence raised by parents that look like ordinary
conspecifics but display deviant species recognition as compared to controls in terms of aggressive response towards rivals.
Comparing the aggressive behavior of OCF, cross-fostered birds and controls towards territorial intruders may thus help tease
apart the influence of morphological vs behavioral cues of parents in the development of offspring species recognition. To
this end, we compared birds from all three treatments with respect to their aggressive response to territorial intruders of
both species during the breeding season. OCF and controls did not differ in their pattern of response towards heterospecific
and conspecific stimuli. Compared to cross-fostered birds, OCF and controls showed less aggression towards heterospecific
intruders, while the response towards conspecific intruders did not differ between treatments. These results demonstrate that
both tit species imprint on the morphological characters of their parents, but that parental behavior is not important for
the development of species recognition in terms of aggressive response towards territorial intruders. 相似文献
943.
In the summer of 2004, a video survey was carried out in the northern part of the central mud bank (Grande Vasière) of the
Bay of Biscay to study the small scale relationship between the dominant crustacean megafauna Nephrops norvegicus, Munida rugosa and Goneplax rhomboides and juvenile hake (Merluccius merluccius). Using a towed body, high-resolution videos were recorded in six sampling sites. Statistical modelling using generalised
additive models (GAM) revealed variations in activity patterns for two species. More N. norvegicus were observed outside their burrows at dawn and somewhat at dusk (no observations during night) while G. rhomboides was less observed in the morning. In addition, reduced spatial overlap between G. rhomboides and N. norvegicus suggested reduced competition for food but also space as both are burrowing species. The observed temporal and spatial activity
patterns may contribute to regulating assemblage structure as competing species may be actively foraging at different times
and locations thus reducing direct competition. 相似文献
944.
945.
Manuela Baumgarten Rainer Matyssek Christian Huber Hans-Peter Dietrich 《Environmental Sciences Europe》2010,22(5):579-595
Background, aim, and scope Increasing background concentrations of ground-level tropospheric ozone and more frequent and prolonged summer drought incidences due to climate change are supposed to increase the stress on Bavarian forests. For such scenarios growth reduction and yield losses are predicted. Sustainable forest management in Bavaria aims to significantly increase the proportion of beech (Fagus sylvatica L.) because of its broad ecological amplitude. In our regional study different approaches for calculating ozone impact were used to estimate the risks for Bavarian forests in the average climatic, rather moist year 2002 and the extremely dry year 2003.Materials and methods Measurements were conducted for eleven forest ecosystem sites and two forest research sites representing typical Bavarian forest stands under different climatic conditions and situated in different altitudes. For risk assessment currently used approaches were applied either based on the calculation of the cumulative ozone exposure (external dose; MPOC maximal permitted ozone concentration; critical level AOT40phen? accumulated ozone exposure over a threshold of 40 nl [O3] l–1, for the effective phenolgy of beech) or based on the calculation of the phytomedically relevant ozone flux into the stomata (internal dose, critical level AFst>1,6, accumulated stomatal flux above a flux threshold of 1.6 nmol O3?m–2 PLA; PLA = projected leaf area). For calculations continuously recorded ozone concentrations and meteorological and phenological data from nearby rural open field background measuring stations from the national air pollution control and from forested sites were used. Additionally ozone induced leaf symptoms were assessed.Results The exposure-based indices AOT40phen and MPOC as well as the flux-based index AFst>1.6suggest that Bavarian forests are at risk from O3 during a rather moist average year concerning climate conditions (2002) as well as in an extreme dry year (2003). Thus, growth reductions of 5?% are predicted when thresholds are exceeded. Threshold exceedance occurred in both years at all plots, mostly already at the beginning of the growing season and often even many times over. Ozone induced leaf symptoms could be detected only on a few plots in a very slight occurrence.Discussion The results for the applied critical level indices differed depending on climatic conditions during the growing seasons: Regarding exposure-based indices, the highest degree of threshold exceedance occurred in the dry year of 2003 at all plots; the flux-based approach indicated the highest stomatal ozone uptake and thus an increased risk at moist sites or during humid years, whereas the risk was decreasing at dry sites with prolonged water limitation. Hence, soil and accordingly plant water availability was the decisive factor for the flux-modelled internal ozone uptake via stomata. Drought and increased ozone impact can generate synergistic, but also antagonistic effects for forest trees. At water limited rather dry forest sites restricted transpiration and thus production, but concurrently lower ozone uptake and reduced risk for damage can be expected.Conclusions, recommendations, and perspectives For realistic site-specific risk assessment in forest stands the determination of the internal ozone dose via modeling flux based internal stomatal ozone uptake is more appropriate than the calculation of the external ozone dose. The predicted 5?% growth reductions are in discrepancy with the frequently observed increment increase during the last decades in forest stands. Comprehensive and significant statistical verification for ozone induced forest growth reduction as well as the systematic validation of thresholds for ozone in the field is still lacking. However, a multiplicity of different specific new and retrospective growth analysis data should allow closing the gap. Moreover, the determination of canopy transpiration with sap flow measurements is a novel approach to provide cause-effect related, site specific results for the effective internal ozone dose as well as for canopy water supply and consecutively for regional risk estimation. A further future objective is the refinement of O3 flux modelling by further consideration of soil/water budget characteristics and the above mentioned improved estimations of crown and canopy transpiration. Further, the introduction of threshold ranges for forest trees in view of their specific regional climatic conditions and their validation in real forest stands is necessary for developing meaningful ozone risk predictions for forests. 相似文献
946.
Jorge A. Achcar Eliane R. Rodrigues Guadalupe Tzintzun 《Environmental and Ecological Statistics》2011,18(2):271-290
In this paper we make use of some stochastic volatility models to analyse the behaviour of a weekly ozone average measurements
series. The models considered here have been used previously in problems related to financial time series. Two models are
considered and their parameters are estimated using a Bayesian approach based on Markov chain Monte Carlo (MCMC) methods.
Both models are applied to the data provided by the monitoring network of the Metropolitan Area of Mexico City. The selection
of the best model for that specific data set is performed using the Deviance Information Criterion and the Conditional Predictive
Ordinate method. 相似文献
947.
948.
Lotfi Rabaoui Sabiha Tlig Zouari Stelios Katsanevakis Oum Kalthoum Ben Hassine 《Marine Biology》2007,152(3):537-548
The variability in absolute and relative growth of Pinna nobilis along the Tunisian coastline was investigated. Five populations of P. nobilis were sampled, three from northern and two from eastern Tunisia. The specimens were aged and ten morphometric characters were
measured on each individual. To test if differences existed in absolute and relative growth patterns among the different populations
an information theory approach was followed. For absolute growth, von Bertalanffy, Gompertz, the logistic and the power models
were fitted in combination with three assumptions regarding inter-population differences in absolute growth patterns: no differences,
differences among all five populations or just between northern and eastern populations. The assumption of common absolute
growth parameters among all five populations had the greatest support by the data, whereas the assumption of different growth
patterns among all five populations had no support. Von Bertalanffy growth model and the power model were both equally supported
by the data (while Gompertz had considerably less support and the logistic model had no support), and thus it may not be definitely
concluded whether P. nobilis grows asymptotically or not. The P. nobilis populations of the Tunisian coastline had a slow growth and up to an age of ∼ 9 years their shells were smaller than from
all other reported populations in the Mediterranean. For relative growth, apart from the classical allometric model Y = aX
b
, relating the size of a part of a body Y to another reference dimension X, more complicated models were used in combination with the three abovementioned assumptions regarding inter-population differences.
Those models, of the form logY = f (logX), either assumed breakpoints in the relative growth trajectories or non-linearities. For most morphometric characters, the
classical allometric model had no support by the data and more complicated models were necessary. In most cases, different
relative growth either among all five populations or between the northern and eastern population groups was supported by the
data. Further investigation is needed to relate the morphological differences observed among different populations of P. nobilis to environmental factors. 相似文献
949.
Carmen M. Rosskopf Gianluigi Di Paola David E. Atkinson Germán Rodríguez Ian J. Walker 《Journal of Coastal Conservation》2018,22(5):879-895
A study on the modern dynamics and shoreline changes from 1954 to 2014 of the Molise coast (central Adriatic Sea) has been carried out. Short to long-term shoreline changes and associated surface area variations have been assessed in GIS environment for the study coast, subdivided in nine coastal segments (S1-S9), by using 100-m regularly spaced transects. In addition, the possible influence of natural and anthropogenic factors, especially of climatic variability and engineered shoreline defense structures, has been investigated. The Molise coast has experienced notable long-term erosion (period 1054-2014) that caused an overall coastal land loss of approximately 940,000 m2. Erosion was, yet, limited to coastal segments S1 and S7, nearest to the mouths of major rivers, namely Trigno and Biferno, while the major part of the study coast has remained essentially stable or even advanced. Increased shoreline protection by defense structures has generally favoured shoreline stability and frequently generated shoreline advance, except for segments S1 and S7. Observed differences in shoreline change rates over time at the decadal to interannual scale, have not find a response in the analysis of available data on meteo-marine conditions of the Molise coast and climate variability indices, pointing out the need to improve knowledge on meteomarine conditions and on climatic variability forcing of the study area. From 2004 to 2014, the Molise shoreline remained essentially stable. Nonetheless, most recent shoreline changes (period 2011-2014) and modern shoreline dynamics indicate that erosion has become more widespread, involving at least part of segments S2-S3 and S8-S9, located south of the river mouth segments. The localized long-term shoreline retreat and most recent shoreline erosion appear to be primarily related to channel adjustments of the Biferno and Trigno rivers that occurred since the 1950s under the control of human interventions on the rivers, especially the construction respectively of a dam and a check dam along their lower courses, that trap of most of their solid load, affecting so adversely the sediment budget of the river mouths areas and adjacent beaches. Overall data acquired on the recent shoreline evolution and modern shoreline dynamics of the Molise coast and on related causal factors provide a good basic knowledge for regional coastal management purposes, and for further scientific purposes. Particularly, they suggest the opportunity to deepen a number of aspects such as the relationship between the coast and river catchments feeding it, the possible influences on the Molise shoreline dynamics of the neighbouring coasts, the efficiency/obsolescence of defense structures and the present-day vulnerability to coastal erosion of the Molise coast. 相似文献
950.
Jun Bi Yongliang Zhang Bing Zhang 《Frontiers of Environmental Science & Engineering》2010,4(3):361-372
In developing countries, there is controversy over the correct perception regarding environmental and developmental issues. Few studies have examined the perception of low-income nationals in regards to social and environmental issues. This paper looks at the relationship between socio-demographic factors and the groups’ perceived priority regarding environmental and social issues in Wujin County. The results indicated that most residents, specifically the young, government employed and the urban community consider environmental issues to be serious, especially in relation to air pollution and water pollution. Furthermore, many residents feel it is important to rank environmental problems that are related to other social and economic issues, and that environmental protection must be set as a priority in Wujin County. Compared to social issues, environmental concern was greater among the young, government employed, and the urban community, because of their higher education and affluence. In addition, 66.2% of residents consider environmental protection to be more important than economic development. Thus, environmental protection must be set as a high priority in Wujin County, in order to face the many social and environmental challenges inherent in development. 相似文献