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121.
Francisco Leitão Miguel N. Santos Karim Erzini Carlos Costa Monteiro 《Marine Biology》2008,153(6):1233-1244
There is a concern that artificial reefs (AR) may act purely as fishing aggregation devices. Predators attracted to ARs can
influence the distribution and abundance of prey fish species. Determining the role of predators in AR is important in advancing
the understanding of community interactions. This paper documents the effects of predation on fish assemblages of AR located
near a coastal lagoon fish nursery. The Dicentrarchus labrax is a very opportunistic species preying on juveniles (0+ and 1+ age classes) of several demersal fish species on the ARs. Reef prey and sea bass abundance were negatively correlated. The
mean numbers of prey per sea bass stomach increased with the increase of reef fish prey abundance, suggesting that predation
has a significant influence, resulting in a decrease in prey abundance. Prey mortality (4–48%) of demersal reef fish associated
species depends on bass density. Prey selection was related both with prey abundance and vulnerability. Results showed that
D. labrax predation on AR-fish associated species can increase prey natural mortality. However, the role of bass predation on the ecological
functioning of exploited ARs is not clear. There may be increases in local fishing yields due either to an increase in predator
biomass through aggregation of sea bass attracted to ARs or to greater production. In contrast, predation on juveniles of
economically important reef fish preys, especially the most frequent and abundant (Boops boops), can contribute to a decrease in recruitment to the fishery. Our results indicate that inter-specific interactions (predator–prey)
are important in terms of conservation and management, as well as for the evaluation of the long-term effects of reef deployment.
Thus, it is necessary to consider ecological interactions, such as predation, prior to the development and deployment of artificial
habitats as a tool for rehabilitation. 相似文献
122.
Giovanni A. P. dos Santos Sofie Derycke Verônica G. F. Genevois Luana C. B. B. Coelho Maria T. S. Correia Tom Moens 《Marine Biology》2009,156(4):629-640
Accurate prediction of the biodiversity–ecosystem functioning relationship requires adequate understanding of the interactions
among species in a community. Effects of species diversity on ecosystem functioning are usually considered more pronounced
with increasing functional dissimilarity, although species within functional groups may also perform non-identical functions
and interact with each other. Here we present results of a laboratory experimental study aimed at elucidating whether interspecific
interactions among species within a single nematode trophic group, bacterivores, (1) affect population development and community
structure, and (2) depend on food availability. We studied the population growth of Rhabditis (Pellioditis) marina, a rhabditid nematode known to favour very high food densities when in monoculture, and of Diplolaimelloides meyli and D. oschei, congeneric Monhysteridae known to perform better in monocultures at intermediate food availability. Both Diplolaimelloides species showed significantly different patterns of food-density dependence in combination culture compared to monoculture.
At very high food availability, the rhabditid nematode facilitated growth of both monhysterid species, probably as a result
of down-regulation of bacterial density. At the lowest food availabilities, the presence of even low numbers of monhysterid
nematodes lead to exclusion of the rhabditid, which at such low food availability has a very inefficient food uptake. At intermediate
food availabilities, abundances of both Diplolaimelloides species were strongly depressed in the combination culture, as a result of food depletion by the rhabditid, indirect inhibitory
interactions between the two congeneric species, or both. The complexity of the species interactions render predictions on
the outcome and functional consequences of changes in within-trophic-group diversity highly problematic. 相似文献
123.
Herbivory has a strong impact on algal distribution, abundance and community structure and may influence the establishment
and spread of introduced seaweed species. In this study, we assess the potential regulating role of herbivory on one of the
most invasive brown seaweeds: Sargassum muticum. Multiple choice feeding experiments were conducted with 13 native seaweeds, S. muticum and 5 herbivore species from the Northwest, Southwest and South of Portugal. S. muticum was always the least or among the least preferred seaweeds and attained one of the highest growth rates of the tested seaweeds,
with and without herbivores. The addition of herbivores increased the number of cases by 40% in which the invader had higher
growth rates. Our results suggest that low grazing pressure on S. muticum by the recipient herbivore community may give the invader a competitive advantage over at least part of the native seaweed
community, thereby contributing to the invasiveness of S. muticum along the Portuguese coast. 相似文献
124.
We give reasons why demographic parameters such as survival and reproduction rates are often modelled well in stochastic population simulation using beta distributions. In practice, it is frequently expected that these parameters will be correlated, for example with survival rates for all age classes tending to be high or low in the same year. We therefore discuss a method for producing correlated beta random variables by transforming correlated normal random variables, and show how it can be applied in practice by means of a simple example. We also note how the same approach can be used to produce correlated uniform, triangular, and exponential random variables. 相似文献
125.
De Vargas Jocelina Paranhos Rosa Bastos Marília Camotti Al Badany Maha Gonzalez Rolando Wolff Delmira Santos Danilo Rheinheimer Dos Labanowski Jérôme 《Environmental science and pollution research international》2021,28(24):30955-30974
Environmental Science and Pollution Research - The fate of pharmaceuticals during the treatment of effluents is of major concern since they are not completely degraded and because of their... 相似文献
126.
John E.L. Maddock Maria B.P. Dos Santos Sonia R.N. Alves de Sá Pedro L.O. de A. Machado 《Environment, Development and Sustainability》2004,6(1-2):175-182
Soil respiration rates of a clay-loam textured Acrisol under different uses (Atlantic forest, manioc, horticulture and pasture) from Rio de Janeiro State were measured. The relationship between carbon dioxide (CO2) emissions and soil physico-chemical properties were investigated. Rates of CO2 emission of two sites (Atlantic forest and horticulture) were also evaluated in different seasons in 1997 and 1998. In the forest site, monthly means of measured respiration rates showed good correlation with soil temperature in the range 19.6–24.1°C (r2 = 0.89). In the horticulture site, no change was observed with soil moisture alone, in the range 3.0–13.2 wt%. In the horticulture soil, even when the surface soil was very dry, respiration rates increased in the hot, wetter summer but remained higher than the mean flux from forest soil. The CO2 emission flux of the Acrisol under different use showed good correlation with soil temperature (r2 = 0.72) and moisture (r2 = 0.61). 相似文献
127.
Juvenile sea bass, Dicentrarchus labrax L., were exposed during 2, 4, 8, and 24 h to 0.9 microM beta-naphthoflavone (BNF), 131 nM 17 beta-estradiol (E(2)), 4.05 microM 4-nonylphenol (NP), as well as to BNF combined either to E(2) or NP (maintaining the previous concentrations). Liver cytochrome P450 content (P450), ethoxyresorufin-O-deethylase (EROD), and glutathione S-transferase (GST) activities were measured in order to evaluate biotransformation responses. Genotoxicity was assessed as erythrocytic nuclear abnormalities (ENA) frequency. The effects on endocrine function were evaluated as plasma cortisol and glucose. Cortisol was not affected by xeno/estrogens tested, either in single exposure or mixed with BNF. Nevertheless, the intermediary metabolism was affected since glucose concentration increased after 4 h exposure to E(2), and after all BNF+NP exposure lengths. Moreover, a synergism between BNF and NP was thoroughly demonstrated, whereas a sporadic antagonistic interaction was found at 4 h BNF + E(2) exposure. Liver EROD and GST activities were not significantly altered by single E(2) or NP exposure. However, both compounds were able to induce EROD activity in the presence of BNF. NP single exposure was able to significantly increase liver P450 content, while its mixture with BNF displayed an antagonistic interference. Considering the xeno/estrogens single exposures, only NP induced an ENA increase; however, both mixtures (BNF + E(2) and BNF + NP) displayed genotoxic effects. Fish responses to mixtures of xenobiotics are complex and the type of interaction (synergism/potentiation or antagonism) in a particular mixture can vary with the evaluated biological response. 相似文献
128.
Allelopathic potential and systematic evaluation of organic extracts from Canavalia ensiformis leaves (Jack beans) 总被引:1,自引:0,他引:1
Santos S de Moraes Mde L da Silva Souza Filho AP Rezende MO 《Journal of environmental science and health. Part. B》2005,40(1):77-84
This article describes the assessment of possible allelopathic potential of organic extracts obtained from leaves of Canavalia ensiformis under laboratory conditions. Furthermore, a systematic evaluation of these extracts was carried out using specific protocols developed in capillary electrophoresis (CE) to determine some groups of secondary metabolites. After the identification and quantification of compounds, the effects of compounds on germination of some common weeds was investigated, which are becoming a real problem in pastures in the state of Pará, Brazil. 相似文献
129.
E. P. dos Santos 《Marine Biology》1968,1(4):348-350
This paper presents a method of investigating the distributional pattern of a biological population, using a technique of simulation. The method consists of the comparison of the empirical frequency curve of a population, obtained using the Method of Quadrats, with a simulated one, since the pattern of the simulated curve depends on the simulated distribution. An example is given. 相似文献
130.
Population density of the onuphid polychaete Diopatra cuprea is poorly correlated with particle size distribution of the substratum. It varies directly, however, with current velocity. Measurements of the volume of oxygen drawn through the tube by the inhabitants' rhythmic activities, and the volume consumed under similar conditions, indicate that the rate of oxygen utilization is unusually low; therefore, the influence of current velocity cannot be exerted through its effect on oxygen supply. We suggest that the worm's tube, which protrudes several centimeters above the substratum in the form of an inverted hook, is a food-catching device whose efficiency is governed by the volume of water flowing past. This hypothesis is supported by the identity of many species found both in the gut and on the tube. We also suggest that the tube-irrigating activities permit the animal to test the medium for the presence of chemical stimuli emanating from food caught by the tube; supra-threshold concentrations of these stimuli elicit the feeding response. 相似文献