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31.
The most recent intervention on the coastline of Espinho, located on the Portuguese West Atlantic coast, was part of the General Plan for Coastal Protection in 1980/81. As a result, two unusually large groins/headlands were built which were reinforced and enlarged in 1997, slightly changing their geometry and orientation. However, due to the decreased sediment supply from the north and the impact of energetic sea conditions common to the northwest coast of Portugal the coastal evolution has not developed as desired, although in general terms the initial expectations were fulfilled. The numerical modelling of the Espinho coastline using SMC software focused on both hydrodynamic and hydromorphological aspects. The purpose of this study is to analyse the most vulnerable areas of the Espinho seafront for current velocities and littoral drift, as well as to confirm the effectiveness of the two groins in terms of coastal protection. To achieve this, various simulations were performed, taking into account diverse sea conditions.  相似文献   
32.
The management of small-scale freshwater fisheries in Amazon has been based usually on surveys of urban markets, while fisheries of rural villages have gone unnoticed. We compared the fishing characteristics (catch, effort and selectivity) between an urban market and five small villages in the Lower Tocantins River (Brazilian Amazon), downstream from a large reservoir. We recorded 86 and 601 fish landings in the urban market and villages, respectively, using the same methodology. The urban fishers showed higher catch per unit of effort, higher amount of ice (related to a higher fishing effort, as ice is used to store fish catches) and larger crew size per fishing trip, but village fishers had a higher estimated annual fish production. Conversely, urban and village fishers used similar fishing gear (gillnets) and the main fish species caught were the same. However, village fishers showed more diverse strategies regarding gear, habitats and fish caught. Therefore, although it underestimated the total amount of fish caught in the Lower Tocantins River region, the data from the urban market could be a reliable indicator of main fish species exploited and fishing gear used by village fishers. Monitoring and management should consider the differences and similarities between urban and rural fisheries, in Amazon and in other tropical regions.  相似文献   
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Environmental Science and Pollution Research - The growing demand for products with lower environmental impact and the extensive applicability of cellulose nanofibrils (CNFs) have received...  相似文献   
35.
Environmental Science and Pollution Research - Copper (Cu) can be toxic to vegetables when it is absorbed and accumulated at large concentrations, a fact that increases the risk of excessive...  相似文献   
36.
Regional Environmental Change - The State of Mato Grosso in Brazil has undergone intensive land use changes over the past decades. Native ecosystems have been converted into agrosystems for the...  相似文献   
37.
Some conservation prioritization methods are based on the assumption that conservation needs overwhelm current resources and not all species can be conserved; therefore, a conservation triage scheme (i.e., when the system is overwhelmed, species should be divided into three groups based on likelihood of survival, and efforts should be focused on those species in the group with the best survival prospects and reduced or denied to those in the group with no survival prospects and to those in the group not needing special efforts for their conservation) is necessary to guide resource allocation. We argue that this decision-making strategy is not appropriate because resources are not as limited as often assumed, and it is not evident that there are species that cannot be conserved. Small population size alone, for example, does not doom a species to extinction; plants, reptiles, birds, and mammals offer examples. Although resources dedicated to conserving all threatened species are insufficient at present, the world's economic resources are vast, and greater resources could be dedicated toward species conservation. The political framework for species conservation has improved, with initiatives such as the UN Sustainable Development Goals and other international agreements, funding mechanisms such as The Global Environment Facility, and the rise of many nongovernmental organizations with nimble, rapid-response small grants programs. For a prioritization system to allow no extinctions, zero extinctions must be an explicit goal of the system. Extinction is not inevitable, and should not be acceptable. A goal of no human-induced extinctions is imperative given the irreversibility of species loss.  相似文献   
38.
Darrigran G  Damborenea C  Greco N 《Ambio》2007,36(7):575-579
The effects of global change and globalization of trade on the biosphere spur an increase in bioinvasions and their subsequent impact on ecosystems. Continental invading bivalves are important because of their impact on artificially-constructed structures. Limnoperna fortunei was first found in the Neotropical region in 1991. Since then it has dispersed upstream in the Plata and Guaíba basins at a rate of 240 km y(-1). This species causes macrofouling in a manner similar to that caused by Dreissena polymorpha. This paper describes the biology of L. fortunei larvae from a hydroelectric power plant in South America. We suggest the importance of knowing the biology of the invading species and the need to consider the settlement patterns and densities of larvae in each of the sectors of the facility in order to achieve a sustainable prevention/control of macrofouling. This study acquires a global significance under the assumption that L. fortunei will eventually invade North America and Europe.  相似文献   
39.
A honeybee queen normally mates with 10–20 drones, and reproductive conflicts may arise among a colony’s different worker patrilines, especially after a colony has lost its single queen and the workers commence egg laying. In this study, we employed microsatellite markers to study aspects of worker reproductive competition in two queenless Africanized honeybee colonies. First, we determined whether there was a bias among worker patrilines in their maternity of drones and, second, we asked whether this bias could be attributed to differences in the degree of ovary activation of workers. Third, we relate these behavioral and physiological factors to ontogenetic differences between workers with respect to ovariole number. Workers from each of three (colony A) and one (colony B) patrilineal genotypes represented less than 6% of the worker population, yet each produced at least 13% of the drones in a colony, and collectively they produced 73% of the drones. Workers representing these genotypes also had more developed follicles and a greater number of ovarioles per ovary. Across all workers, ovariole development and number were closely correlated. This suggests a strong effect of worker genotype on the development of the ovary already in the postembryonic stages and sets a precedent to adult fertility, so that “workers are not born equal”. We hypothesize a frequency-dependent or “rare patriline” advantage to queenless workers over the parentage of males and discuss the maintenance of genetic variance in the reproductive capacity of workers.Electronic supplementary material Supplementary material is available for this article at and is accessible for authorized users.  相似文献   
40.
Introduction. Wheelchair configuration is an important factor influencing the ergonomics of the user–device interface and, from a biomechanical point of view, small changes in chair setup may have a positive influence on the demand on the upper limbs during manual propulsion. This study aimed to investigate the influence of the position of the rear wheels’ axle and the use of accessories on the activity of upper limb muscles during manual wheelchair propulsion. Methods. Electromyography signals of the biceps, triceps, anterior deltoids and pectoralis major were collected for 11 able-bodied subjects in a wheelchair propulsion protocol with four different wheelchair configurations (differing in axle position and the use of accessories) on a straightforward sprint and a slalom course. Results. With accessories, moving the axle forward led to a decrease in the activity of all muscles in both the straightforward sprint (significant differences in triceps, anterior deltoids and biceps) and the slalom course (significant difference in anterior deltoids and biceps). However, when propelling the chair without accessories, no difference was found related to axle position. Conclusion. Changes in wheelchair configuration can influence the ergonomics of manual wheelchair propulsion. Reducing the biomechanical loads may benefit users’ mobility, independence and social participation.  相似文献   
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