Five hundred and ninety-nine primary producers and consumers in the Papahānaumokuākea Marine National Monument (PMNM) (22°N–30°N, 160°W–180°W) were sampled for carbon and nitrogen stable isotope composition to elucidate trophic relationships in a relatively unimpacted, apex predator–dominated coral reef ecosystem. A one-isotope (δ13C), two-source (phytoplankton and benthic primary production) mixing model provided evidence for an average minimum benthic primary production contribution of 65 % to consumer production. Primary producer δ15N values ranged from ?1.6 to 8.0 ‰ with an average (2.1 ‰) consistent with a prevalence of N2 fixation. Consumer group δ15N means ranged from 6.6 ‰ (herbivore) to 12.1 ‰ (Galeocerdo cuvier), and differences between consumer group δ15N values suggest an average trophic enrichment factor of 1.8 ‰ Δ15N. Based on relative δ15N values, the larger G. cuvier may feed at a trophic position above other apex predators. The results provide baseline data for investigating the trophic ecology of healthy coral reef ecosystems. 相似文献
Although the effectiveness of herbivores in mitigating the effects of nutrient enrichment is well documented, few studies have examined the effects of nutrient enrichment on components of consumer fitness. Enclosures were deployed in shallow turtle grass (Thalassia testudinum) beds in Florida Bay, Florida in fall 2003, spring 2004, and fall 2004 to measure the effects of nitrogen and phosphorous enrichment on the growth, fecundity, and stoichiometry of three invertebrate epiphyte grazers commonly associated with T. testudinum. The gastropod Turbo castanea exhibited significantly greater wet weight gain and lower C:P and N:P in enriched than in ambient treatments. Although nutrient enrichment did not have any significant effects on the growth of caridean shrimp (treatment consisted of several different caridean shrimp species), their C:N was significantly lower in enriched treatments. The final size and stoichiometry of the hermit crab Paguristes tortugae was not significantly affected by nutrient enrichment, nor did nutrient enrichment significantly affect the fecundity of P. tortugae, the only grazer in which gravid individuals or egg masses were present. Our study demonstrated that nutrient enrichment of primary producers can positively affect the growth of marine invertebrate grazers and alter their stoichiometry; however, these effects were species-specific and may be dependent upon the life stage, specific diets, and/or compensatory feeding habits of the grazers. 相似文献
Concentrations and distributions of selected fluoroquinolones (norfloxacin, ciprofloxacin and enrofloxacin) in water, sediments
and nine kinds of fish species collected from 6 sites in two marine aquaculture regions of the Pearl River Delta, China, were
analyzed by using high-performance liquid chromatography with fluorescence detector (HPLC). The results showed that the concentrations
of ciprofloxacin and enrofloxacin were below the limits of quantification (LOQ) in all water samples except for norfloxacin.
Norfloxacin and ciprofloxacin concentrations ranged from 1.88 to 11.20 ng g−1 dry wt, 0.76–2.42 ng g−1 dry wt in sediments collected from the Dapeng’ao region (sites 1–3) and ranged from 2.31 to 4.75 ng g−1 dry wt, 1.26–1.76 ng g−1 dry wt in sediments collected from the Hailing Island region (sites 4–6), respectively. However, no enrofloxacin was found
in all sediment samples. The three fluoroquinolones (FQs) were detected in all fish samples, and the concentrations were higher
in liver tissues than those in muscle tissues. The levels of norfloxacin were higher than ciprofloxacin and enrofloxacin in
both liver and muscle tissues. Among the nine marine fish species, Siganus fuscescens from Hailing Island had a significantly high level of norfloxacin in liver tissue (254.58 ng g−1 wet wt), followed by Sparus macrocephalus (133.15 ng g−1 wet wt) from Dapeng’ao, and the lowest value was Lutianus argentimaculatus (5.18 ng g−1 wet wt) from Hailing Island. The obtained results of FQs in present study do not represent a risk to the human health in
Guangdong coastal area, based on the maximum residue limits (MRLs) established by Chinese Government and the acceptable daily
intake (ADI) recommended by the Food and Agriculture Organization and World Health Organization (FAO/WHO). 相似文献
In contrast to other apes, humans have relatively greater amounts of armpit hair, which is thought to retain signaling molecules.
Although armpit shaving is widespread cross-culturally, its effect on body odor has been little investigated. In four experiments,
we tested the effect of shaving and the subsequent regrowth of axillary hair. Armpit odors were collected from men who regularly
shaved (group S) or who had never shaved (group N) their armpits before. The samples were subsequently rated by women for
intensity, pleasantness, and attractiveness. In Experiments I, II (group N) and III, subjects firstly shaved one armpit and then let the hair regrow over 6 or 10 weeks. In Experiments I, II (group S) and IV, subjects shaved both armpits before the sampling and subsequently shaved one armpit during the same period, leaving the
second armpit unshaved. Odors of the shaved armpits were rated more pleasant, attractive, and less intense compared to the
unshaved armpits (Experiment I (group N)). However, no significant differences found in Experiments II and III (group N) suggest the effect of shaving is relatively minor. Moreover, there were no significant differences in odor comparing
unshaved armpits with armpits after 1 week of regrowth (Experiments I, II (group N) and III) or comparing regularly shaved armpits with armpits after 1 or 3 weeks of regrowth (Experiments I, II (group S) and IV). The odor of shaved armpits was rated significantly more attractive compared to the armpits where hair
had been regrowing for 6 or 10 weeks. 相似文献
Extinction risk is inversely associated with maximum per capita population growth rate (r(max)). However, this parameter is not known for most threatened species, underscoring the value in identifying correlates of r(max) that, in the absence of demographic data, would indirectly allow one to identify species and populations at elevated risk of extinction and their associated recovery potential. We undertook a comparative life-history analysis of 199 species from three taxonomic classes: Chondrichthyes (e.g., sharks; n = 82), Actinopterygii (teleost or bony fishes; n = 47), and Mammalia (n = 70, including 16 marine species). Median r(max) was highest for (and similar between) terrestrial mammals (0.71) and teleosts (0.43), significantly lower among chondrichthyans (0.26), and lower still in marine mammals (0.07). Age at maturity was the primary (and negative) correlate of r(max). In contrast, although body size was negatively correlated with r(max) in chondrichthyans and mammals, evidence of an association in teleosts was equivocal, and fecundity was not related to r(max) in fishes, despite recurring assertions to the contrary. Our analyses suggest that age at maturity can serve as a universal predictor of extinction risk in fishes and mammals when r(max) itself is unknown. Moreover, in contrast to what is generally expected, the recovery potential of teleost fishes does not differ from that of terrestrial mammals. Our findings are supportive of the application of extinction-risk criteria that are based on generation time and that are independent of taxonomic affinity. 相似文献
Recycling of materials from municipal solid waste is commonly considered to be superior to any other waste treatment alternative. For the material fractions with a significant energy content this might not be the case if the treatment alternative is a waste-to-energy plant with high energy recovery rates. The environmental impacts from recycling and from incineration of six material fractions in household waste have been compared through life cycle assessment assuming high-performance technologies for material recycling as well as for waste incineration. The results showed that there are environmental benefits when recycling paper, glass, steel and aluminium instead of incinerating it. For cardboard and plastic the results were more unclear, depending on the level of energy recovery at the incineration plant, the system boundaries chosen and which impact category was in focus. Further, the environmental impact potentials from collection, pre-treatment and transport was compared to the environmental benefit from recycling and this showed that with the right means of transport, recyclables can in most cases be transported long distances. However, the results also showed that recycling of some of the material fractions can only contribute marginally in improving the overall waste management system taking into consideration their limited content in average Danish household waste. 相似文献
Urbanization decreases species diversity, but it increases the abundance of certain species with high tolerance to human activities.
The safe-habitat hypothesis explains this pattern through a decrease in the abundance of native predators, which reduces predation
risk in urban habitats. However, this hypothesis does not consider the potential negative effects of human-associated disturbance
(e.g., pedestrians, dogs, cats). Our goal was to assess the degree of perceived predation risk in house finches (Carpodacus mexicanus) through field studies and semi-natural experiments in areas with different levels of urbanization using multiple indicators
of risk (flock size, flight initiation distance, vigilance, and foraging behavior). Field studies showed that house finches
in more urbanized habitats had a greater tendency to flock with an increase in population density and flushed at larger distances
than in less urbanized habitats. In the semi-natural experiment, we found that individuals spent a greater proportion of time
in the refuge patch and increased the instantaneous pecking rate in the more urbanized habitat with pedestrians probably to
compensate for the lower amount of foraging time. Vigilance parameters were influenced in different ways depending on habitat
type and distance to flock mates. Our results suggest that house finches may perceive highly urbanized habitats as more dangerous,
despite the lower number of native predators. This could be due to the presence of human activities, which could increase
risk or modify the ability to detect predators. House finches seem to adapt to the urban environment through different behavioral
strategies that minimize risk. 相似文献
Chamber method is commonly used to measure the CO2 exchange from plant communities. Due to low time resolution, actual measurements reflect only momentary CO2 exchange rates. Therefore, a common way to derive seasonal or annual estimates is to establish models describing the response of CO2 exchange to environmental variables, and then to reconstruct the CO2 exchange over the desired time period. There are several alternative ways to obtain the CO2 balance for the entire mire: models can be parameterized by individual sample plots, plant communities or the entire site. Similarly, the CO2 balance can be reconstructed by plots, plant communities or the entire site. We tested how the choice of the modelling and reconstruction approach influences the CO2 exchange estimates for the entire mire and for individual sample plots and plant communities. We measured the CO2 exchange in a spatially heterogeneous sedge-dominated northern aapa mire for two growing seasons. We observed high spatial variation in CO2 balance between the plant communities. We noticed that when the CO2 balances of individual sample plots or plant communities are of interest, using a model appropriate for the entire site may result in biased estimates. In worst case the different modelling approaches may turn the CO2 balance of an individual sample plot from positive to negative. Further, while using the whole ecosystem approach in modelling, the superior ability of chamber method in acknowledging spatial variation is lost. While the modelled growing season CO2 balance of the mire ranged from 232 to 625 g CO2 m−2 depending on the chosen modelling and reconstruction approach, the average estimates still remained within the uncertainty range of one another. Acknowledgement of the spatial variation in plant community level makes the areal estimate more robust to varying weather conditions. Further, the reliability of estimates is improved by explicit formulation of the choices behind the modelling and reconstruction units reflecting the study objectives. 相似文献
Two-year old Ulmus laevis Pall (U. laevis) seedlings were cultivated in a three-month hydroponic experiment with inorganic (aresenite – As(III) and arsenate – As(V)) and organic (dimethylarsenic acid – DMA(V)) arsenic forms, at 0.06 and/or 0.6?mM concentrations. Further, the profile and content of total low molecular weight organic acids (LMWOAs) were investigated in the rhizosphere, roots and leaves of U. laevis. Obtained results showed that the addition of As(III) or As(V) individually or in a mixture led to increased LMWOAs concentration in the rhizosphere, especially of oxalic and malonic acids, in comparison to the control, while in roots the overall content of the profiled LMWOAs decreased. In both rhizosphere and roots, addition of the DMA(V) form resulted in the inhibition of LMWOAs exudation into the rhizosphere and their creation in plant roots. Leaves were characterised by a higher content of LMWOAs than in the rhizosphere and roots for all experimental systems, where the profile and content of LMWOAs was strictly correlated with the analysed As forms. Our study indicated that creation of LMWOAs in U. laevis organs and their exudation to the rhizosphere could be responsible for the As toxicity tolerance of the plants. 相似文献
This article discusses inter and post-war works of fiction written by Polish and German-speaking authors with biographical connections to Oder River regions. The literary texts provide insights into the vulnerability to and resilience constructions of floods, which are related to such cultural factors as migrant histories and traditions, regional beliefs and religion, and the political background of changing frontiers in 1919 and 1945 that affected residents of this cross-border area.
The capacity to cope with the flooding Oder, especially after the major flood in 1997, intertwines with the problematic Polish-German relationship, including Silesia. For Polish communities, whose environmental cultures have been distorted by wars, resettlement and communism, vulnerability and resilience perceptions lack representations of the tangible river. It is culturally bounded in the stigmatising image of the Oder as the border of division, revived after 1945 and exposed by the Polish communist party in the so-called ‘Polonisation’ of the ‘Recovered Territories’. Fiction detects the problem of overworking the difficult past in response to the Oder’s hazardous nature. Writers representing an emotional attachment to the river and an aquacritical approach express the need to learn about the river’s lively nature, both in cooperating and sharing space, which is called the environmental adaptation. 相似文献