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151.
Since 1989, and in comparison to the global trend, inland aquaculture production of European finfish has declined. To date, the yearly European freshwater aquaculture production is 371,727 tons, valued at over US$1 billion. Indigenous species accounted for less than one-third of the production, whereas alien species (a species that has been moved beyond its natural range of distribution) accounts for the remainder. However, in general, indigenous species command a higher market price. Currently, food quality and food safety are leading concerns of consumers, and European consumers are also becoming alert to environmentally detrimental practices. Therefore, to aim at economic sustainability, the sector needs to satisfy consumer expectations of environmentally friendly practices. It is believed that farming alien finfish species can threaten local biodiversity through escapes, and this represents a current environmental concern relative to aquaculture. In this context, an attempt is made in this paper to understand and quantify the impacts of alien finfish cultivation in European inland waters, and to suggest remedial measures.  相似文献   
152.
  • 1. Boat surveys were conducted between 2002 and 2005 to study bottlenose dolphins living in the 400 km2 Amvrakikos Gulf, western Greece. During 116 survey days, 4705 km of total effort resulted in the individual photo‐identification of 106 animals, through long‐term natural markings on their dorsal fins.
  • 2. Mark–recapture analyses based on the Mth model provided estimates of 82 marked individuals in 2003 (95% CI=80–91), 92 in 2004 (95% CI=86–108) and 98 in 2005 (95% CI=94–110). To include the unmarked portion of the population, the proportion of unmarked individuals was computed based on the number of photographs of marked and unmarked dorsal fins. The mean proportion of unmarked animals in the population was 0.338 (95% CI=0.288–0.389). By adding this to the estimate for marked animals in 2005, considered as the most robust, a total population estimate of 148 individuals (95% CI=132–180) was obtained.
  • 3. Dolphin encounter rates in 2003–2005 did not show significant variations, and averaged 7.2 groups per 100 km or 72.5 individuals per 100 km. Encounter rates within the Gulf were about one order of magnitude greater than those found for bottlenose dolphins in nearby eastern Ionian Sea coastal waters.
  • 4. Mean dolphin density in the Gulf was 0.37 animals km?2. This relatively high density, together with high levels of site fidelity shown by most individuals, was thought to be related primarily to prey availability, particularly of epipelagic schooling fish.
  • 5. The importance of the semi‐closed Amvrakikos Gulf for bottlenose dolphins and other threatened species encourages the adoption of measures aimed to conserve its valuable ecosystems and raise the naturalistic profile of the area, while promoting environment‐conscious development. Meaningful action includes restoring natural hydrology (e.g. freshwater input from rivers), curtailing pollution from various sources, responsible fisheries and aquaculture management, and control of illegal fishing. Interactions between dolphins and fisheries also deserve careful quantitative investigation.
Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   
153.
In urban environments, green spaces have proven to act as ameliorating factors of some climatic features related to heat stress, reducing their effects and providing comfortable outdoor settings for people. In addition, green spaces have demonstrated greater capacity, compared with built-up areas, for promoting human health and well-being. In this paper, we present results of a study conducted in Italy and the UK with the general goal to contribute to the theoretical and empirical rationale for linking green spaces with well-being in urban environments. Specifically, the study focused on the physical and psychological benefits and the general well-being associated with the use of green spaces on people when heat stress episodes are more likely to occur. A questionnaire was set up and administered to users of selected green spaces in Italy and the UK (n=800). Results indicate that longer and frequent visits of green spaces generate significant improvements of the perceived benefits and well-being among users. These results are consistent with the idea that the use of green spaces could alleviate the perception of thermal discomfort during periods of heat stress.  相似文献   
154.
Two hundred and fifty soles (30 g initial weight) were randomly stocked in 12 tanks (recirculation system) at two different stocking densities (2.3 and 1.3 kg m?2) and fed on two different diets (50% and 54% of crude protein and 21% and 18% of total lipid, respectively, for diets A and B) with triplicate tanks for treatment. The trial lasted for 300 days. Fish stocked at low density showed a significantly higher weight gain than the fish reared at 2.3 kg m?2 density (94.1±7.4 vs. 78.9±8.2 g, P<0.01) with a specific growth rate (SGR) of 0.46±0.11 and 0.43±0.16 (P<0.01) respectively. Feed conversion ratio (FCR) was more favourable for lower density groups (2.50 vs. 2.64, P<0.01). Diet B led to a higher final weight (124.1 vs. 110.2 g, P<0.01) and a better feed utilization (FCR: 2.49 vs. 2.65, P<0.01). Except for the lipid content, which was higher in the low‐density group (2.6% vs. 2.3%, P<0.05), proximate composition of sole's muscle was not influenced by treatments. Dover sole reared at low stocking density showed higher monounsaturated fatty acid (35.27% vs. 34.40%, P<0.01) and lower saturated fatty acid (24.36 vs. 26.13%, P<0.01) contents, and lower atherogenic (0.67 vs. 0.75, P<0.01) and thrombogenic (0.28 vs. 0.32, P<0.01) indexes.  相似文献   
155.
Chemical characteristics and some parameters related to biological components were determined in 16 soils from a fairly homogeneous area in the north of Italy, contaminated with different levels of heavy metals. Correlation analysis of the parameters studied showed close positive relationships among the metals and with the organic C content in the soils studied. Negative relationships were observed among the heavy metals, soil respiration, and the ratio between evolved CO2–C and microbial biomass C per unit time (specific respiratory activity). This was ascribed to an adverse heavy metal effect on the soil microflora, which appeared to increase the accumulation of organic matter as the heavy metal content increased, probably because the biomass was less effective in mineralising soil organic matter under these conditions.  相似文献   
156.
热塑淀粉Mater-Bi可生物降解地膜的适用性与降解性能研究   总被引:1,自引:1,他引:1  
通过霉菌侵蚀法、田间考察法和受控掩埋试验法,对Mater-Bi可生物降解地膜在上海郊区的适用性及其生物降解性能进行了研究.结果表明,Mater-Bi可生物降解地膜由于其高达90%的淀粉含量,能够被霉菌等微生物作为碳源所利用,仅需数天,霉菌菌落即可在该膜表面旺盛生长.在上海崇明岛的气候条件下,Mater-Bi可生物降解地膜的诱导期为60~120d,在田间生产中具有良好的适用性,能够满足上海郊区作物生产的需要.Mater-Bi可生物降解地膜能够被崇明岛当地农田土壤中的微生物迅速降解,在土壤中埋藏90d后.失重率为58.6%.其降解速度在10~20cm耕作层土壤中的最快,90d后失重率即高达84.2%.因此种植季结束后,可生物降解地膜不需要人工或机械捡拾残膜,只需翻耕入土壤即可,最佳翻耕深度为10~20cm.  相似文献   
157.
The gut immune system has the challenge of responding to pathogens while remaining relatively unresponsive to food antigens and the commensal microflora. In the developed world, this ability appears to be breaking down, with chronic inflammatory diseases of the gut commonplace in the apparent absence of overt infections. In both mouse and man, mutations in genes that control innate immune recognition, adaptive immunity, and epithelial permeability are all associated with gut inflammation. This suggests that perturbing homeostasis between gut antigens and host immunity represents a critical determinant in the development of gut inflammation and allergy.  相似文献   
158.
Activity of quinones on colletotrichum species   总被引:4,自引:0,他引:4  
The antifungal activity of 1,4-naphthoquinones, 1,2-naphthoquinones, 1,4-benzoquinones, and anthraquinones from our natural products collection was tested by direct bioautography to identify natural products with potential use in agricultural fungal pathogen control. Quinones demonstrated good to moderate antifungal activity against Colletotrichum spp. Colletotrichum fragariae was the most sensitive species to quinone-based chemistry, Colletotrichum gloeosporioides had intermediate sensitivity, while Colletotrichum acutatum was the species least sensitive to these compounds.  相似文献   
159.
160.
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