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61.
The treatment efficiency, as toxicity removal, of complex effluents from the Industrial District of Cama?ari (BA, Brazil), after biological treatment with activated sludge was evaluated using Microtox. Samples of the equalised effluent (EE) were collected prior to treatment together with samples of the treated effluent (TE), which remained 24 h in the treatment plant. Rehydrated colonies of Vibrio fischeri were exposed to sequential dilutions of EE and TE to assess luminosity interference. Values for EC50 were calculated, together with the respective toxicity units. In all, twenty assays of each effluent type were carried out and the mean toxicity removal was 92.71%, while the chemical oxygen demand (COD) presented mean reduction of 83.04%. There was a variability of an order of magnitude between the Microtox results for the two types of effluents. The mean EC50 values were 2.12 for EE and 47.78% for TE. In spite of its weakness in some conditions, the Microtox system demonstrated to work adequately in assessing effluent toxicity removal in this treatment plant and therefore can be used for further toxicity removal programs. 相似文献
62.
Gisela García-Morales Renato Arturo Mendoza-Salgado Jaqueline García-Hernández Pedro Rosales-Grano Alfredo Ortega-Rubio 《Journal of Environmental Planning and Management》2018,61(1):161-175
Recreational beaches are strategic ecosystems for tourism and should be used in a sustainable manner. We studied three beaches in the municipality of Guaymas (NW Mexico), in order to assess their beach quality and identify key management issues. The evaluation was based on the perceptions of users concerning: (1) the user profile; (2) the recreational habits of users; and (3) the biophysical characteristics, infrastructure, services, and cleanliness of each beach. The results showed that the beaches were of different quality. The key management issues identified were the need to design and apply specific management programs for each beach, specifically in regards to improving infrastructure and services, and obtaining certification as a sustainable beach. The evaluation of the beaches as perceived by users suggests that it would be useful to assess beach quality in order to support management goals and be applicable to other beaches, both nationally and internationally. 相似文献
63.
64.
Cassiduloids are currently rare irregular echinoids with a highly conserved adult morphology. Aristotle’s lantern is present
only during the post-metamorphic stage, and little is known about the early development of species in this group. Cassidulus mitis produces eggs of about 375 μm in diameter, lecithotrophic larvae with four reduced arms with skeletal fenestrated rods, cilia
along the body surface, and a ciliated band on arms and lobes. Offspring is brooded among the female spines from embryo to
settler’s stage. The echinopluteus larval stage is reached 6 days after fertilization, and the settler’s stage is formed at
the age of 17 days. Aristotle’s lantern appears around the thirteenth day of development. The lantern is well developed and
functional in settlers. It remains until at least 62 days after fertilization and can be used to acquire food from the environment.
The early development of C. mitis is unusual concerning features of typical lecithotrophic larvae (such as reduced arms), but retains some features of planktotrophic
larvae (such as skeletal rods and a ciliated band). Regarding egg size, early development in C. mitis seems to be transitioning from facultative lecithotrophic to typical obligate lecithotrophic pattern in echinoid larval evolution. 相似文献
65.
66.
Renato A. M. Silvano John Valbo-Jørgensen 《Environment, Development and Sustainability》2008,10(5):657-675
Studies investigating the local ecological knowledge (LEK) held by fishermen about the fishing resources have indicated that
fishermen’s LEK may have the potential to improve fishery management, by providing new information about the ecology, behavior
and abundance trends of fish and other aquatic animals. Our major aim is to undertake a brief review of published ethnoichthyological
studies with a focus on coastal Brazilian fisheries and freshwater fisheries in both Brazil and Southeast Asia. Based on such
review, we provide 29 hypotheses on fish ecology based on fishermen’s LEK and compare them with what is already known from
the biological literature, using an arbitrary ‘likelihood’ measure: “Low likelihood” corresponded to unexpected hypotheses,
which contradict existing biological data. “Medium likelihood” corresponded to hypotheses that could not be compared to available
scientific knowledge. Hypotheses that agree with scientific data were considered as “High likelihood”. We therefore discuss
these three categories of hypotheses about several distinct topics, such as migration, reproduction, feeding habits, abundance
patterns, ecological relationships between fish and their predators, and fishing pressure. Our results may contribute to the
fisheries management and research in the studied regions and other similar places, besides raising the interest of biologists
to properly include fishermen’s LEK when planning and conducting fisheries surveys.
Readers should send their comments on this paper to: BhaskarNath@aol.com within 3 months of publication of this issue. 相似文献
67.
In Europe, coastal dune systems with Juniperus spp. (Natura 2000 habitat code 2250) are a priority habitat for conservation according to the Natura 2000 policies. Currently, anthropogenic pressure is threatening the biodiversity of this habitat. While the impact of human pressure on animals and vascular plants is already documented, information is still scanty for other organisms such as epiphytic lichens. The main aim of this study is to test the effect of human disturbance on the occurrence and abundance of the red-listed macrolichen Seirophora villosa. We also tested the effect of human disturbance on the whole community of epiphytic lichens in terms of species richness and composition. The study was performed along the coast of Tuscany by comparing both disturbed and undisturbed Juniperus stands according to a stratified random sampling design. Our results provided evidence that in coastal systems the long-term conservation of the red-listed macrolichen S. villosa and its characteristic community composed by several Mediterranean species of conservation concern depends on the maintenance of undisturbed Juniperus habitats. Results also support the possibility of using S. villosa as an indicator species of habitat conservation importance and habitat integrity since its occurrence is predicted on nestedness in term of species composition, assemblages of species poor disturbed stands being subsets of those of richer undisturbed stands. 相似文献
68.
Mirlaine R. Freitas Stella V.B.G. Matias Renato L.G. Macedo Matheus P. Freitas Nelson Venturin 《中国人口.资源与环境(英文版)》2015,13(4):324-331
Brazil is a central place in the international agricultural markets and this fact has been demanding environmentally oriented agricultural practices by Brazilian farmers and professionals involved in the agricultural market chain. A concise and structured questionnaire was applied to obtain the environmental perception of a group of Brazilian farmers in a town of the south Minas Gerais state, using herbicides as the topic for a case study. A highly variable opinion about taking the environment into account when choosing the most appropriate herbicide was found. Anyway, efficacy has been indicated as the most important factor when choosing an herbicide, followed by the environment and price. The outcomes from the questionnaires, i.e. the insufficient conception and importance given to environment when choosing the herbicide, motivated the creation of a teaching-learning model for the nonformal environmental education using the concept of socio-ecological resilience. This routine puts in practice the resilience thinking currently invoked as a major tool to achieve the conservation of the socio-ecological system, as well as it is complimentary to the outcome-oriented optimization for conservation theory. For the case study about farmers and the use of herbicides, we conclude that a complex reasoning and, ultimately, pro-environmental actions can be improved after experiencing the recommended model for environmental education. 相似文献
69.
Spatial patterns reveal negative density dependence and habitat associations in tropical trees 总被引:1,自引:0,他引:1
Bagchi R Henrys PA Brown PE Burslem DF Diggle PJ Gunatilleke CV Gunatilleke IA Kassim AR Law R Noor S Valencia RL 《Ecology》2011,92(9):1723-1729
Understanding how plant species coexist in tropical rainforests is one of the biggest challenges in community ecology. One prominent hypothesis suggests that rare species are at an advantage because trees have lower survival in areas of high conspecific density due to increased attack by natural enemies, a process known as negative density dependence (NDD). A consensus is emerging that NDD is important for plant-species coexistence in tropical forests. Most evidence comes from short-term studies, but testing the prediction that NDD decreases the spatial aggregation of tree populations provides a long-term perspective. While spatial distributions have provided only weak evidence for NDD so far, the opposing effects of environmental heterogeneity might have confounded previous analyses. Here we use a novel statistical technique to control for environmental heterogeneity while testing whether spatial aggregation decreases with tree size in four tropical forests. We provide evidence for NDD in 22% of the 139 tree species analyzed and show that environmental heterogeneity can obscure the spatial signal of NDD. Environmental heterogeneity contributed to aggregation in 84% of species. We conclude that both biotic interactions and environmental heterogeneity play crucial roles in shaping tree dynamics in tropical forests. 相似文献
70.
Daniela Bueno Sudatti Mutue Toyota Fujii Silvana Vianna Rodrigues Alexander Turra Renato Crespo Pereira 《Marine Biology》2011,158(7):1439-1446
Laurencia dendroidea shows high inter- and intrapopulation variability in the amount of the sesquiterpene elatol, caused by genetic variation
as well as environmental factors. To test the independent effect of physical and nutritional conditions, the growth and the
levels of elatol in L. dendroidea clones were evaluated under different conditions of temperature, salinity, irradiance, and culture medium in the laboratory.
Growth of L. dendroidea was clearly affected by all these factors, but elatol levels were influenced only by temperature and salinity. Better conditions
for growth did not produce a similar effect on elatol production in L. dendroidea, contradicting the carbon/nutrient balance and growth/differentiation balance models. On the contrary, severe conditions
of temperature and salinity promoted a decrease in elatol levels, as predicted by the environmental stress model. Our results
using clones indicated that abiotic factors clearly take part in fostering chemical variations observed in natural populations,
in addition to genetic factors, and can promote differential susceptibility of plant specimens to natural enemies. 相似文献