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Vicenç Bros 《Forest Ecology and Management》2011,261(3):611-619
In fire-prone regions, understanding the response of species to fire is a major goal in order to predict the effects on biodiversity. Furthermore, postfire management can also model this response through the manipulation of environmental characteristics of the burnt habitat. We have examined the taxonomic and functional response to fire and postfire management of a Mediterranean snail community affected by a summer fire in 2003. After the fire, the area was logged, leaving wood debris on the ground, and three alternative practices were implemented in several plots within the burnt area: subsoiling, removal of trunks having branches, total removal of trunks and branches, as well as one area not logged. Our results indicated that fire exerted a major impact on the snail community, strongly reducing diversity and species richness, particularly for forest species living in the humus and having European distribution ranges. By contrast, we found slight differences within the postfire practices, presumably because of the strong initial impact of fire and subsequent xerophilous postfire conditions. However, the area with only trunk removal showed a positive response of generalist snail species, probably due to moist microhabitats provided by the accumulation of wood debris on the ground. The effects of postfire management should be further explored due to the expected increase of fire risk associated with climate change and land-use histories. 相似文献
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Freshwater species and ecosystems are gravely imperiled, particularly within urban landscapes of tropical Asia. In one of the region’s most urbanized landscapes (i.e., Singapore), we determined: (1) the importance of six different habitats (i.e., catchment reservoirs, estuarine reservoirs, forest streams, rural streams, ponds and monsoon canals) for conserving the diversity of freshwater molluscs; (2) key environmental factors (e.g., pH) affecting molluscan distribution; (3) important biogeographical determinants (e.g., area) of molluscan richness within each habitat; and (4) the habitat affinities of introduced species. High sampling saturation was achieved at most study habitats with minimal sampling effort, suggesting that the utilization of molluscs as bioindicators can expedite freshwater conservation initiatives. Estuarine reservoirs (6.0 ± 2.0) had the highest molluscan richness, vis-à-vis catchment reservoirs, forest streams, rural streams, ponds and monsoon canals (3.0 ± 1.5; 0; 3.3 ± 2.0; 1.8 ± 0.5 and 3.5 ± 0.5 respectively). Both reservoir types possessed species compositions distinct from other habitats and contained majority (76%) of the sampled species. Reservoirs therefore serve to conserve the bulk of local freshwater malacofauna, especially if they are maintained at near-neutral pH levels (i.e., ∼7.3) and contain large substrates (i.e., rocks). Area was the best predictor of molluscan richness across all habitats, implying that larger freshwater habitats require higher conservation priorities than smaller ones. Introduced (non-native) species (e.g., Pomacea canaliculata) had high affinities for reservoirs, which are in need of monitoring to curb population expansions. The interminable growth of human settlements urgently requires a reconciliatory approach, which includes the ecologically-sound design and management of modified habitats to complement reserves in sustaining native freshwater species. 相似文献
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An extensive literature survey on metazoan parasites from rainbow trout Oncorhynchus mykiss has been conducted. The taxa Monogenea, Cestoda, Digenea, Nematoda, Acanthocephala, Crustacea and Hirudinea are covered. A total of 169 taxonomic entities are recorded in rainbow trout worldwide although few of these may prove synonyms in future analyses of the parasite specimens. These records include Monogenea (15), Cestoda (27), Digenea (37), Nematoda (39), Acanthocephala (23), Crustacea (17), Mollusca (6) and Hirudinea (5). The large number of parasites in this salmonid reflects its cosmopolitan distribution. 相似文献
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Robert H. Cowie 《国际虫害防治杂志》2013,59(1):23-40
The use of snails as biocontrol agents against other snails and against aquatic weeds is reviewed, evaluating their success and their impacts on non-target organisms. The predatory snail Euglandina rosea (and other species), although widely used against Achatina fulica (the giant African land snail) on Pacific and Indian Ocean islands, has not been shown to control A. fulica but has seriously impacted endemic island species. The facultative predator Rumina decollata , used in California against Helix aspersa (brown garden snail), is widely considered to be environmentally benign. However, evidence of its effectiveness is weak and it will also consume native snails. Ampullariid and thiarid freshwater snails have been used as competitors (and incidental predators) of snail vectors of human schistosomes, the parasites causing schistosomiasis (bilharzia). Successful control has been reported but impacts on native biotas have been essentially ignored. Ampullariids have been used in attempts to control aquatic weeds, sometimes successfully, but again with little consideration of impacts on native biota. Most snails have generalist feeding habits. Thus they are inappropriate biocontrol agents because of their potential nontarget effects. Rarely has adequate pre-release testing of snails been undertaken and post-release monitoring of non-target impacts has always been incidental. The use of non-native snails for biocontrol purposes is poorly regulated; many introductions are unofficial and sometimes illegal. Use of snails as biocontrol agents, if implemented, must be based on adequate pre-release testing, post-release monitoring and genuine concern for preservation of native biodiversity. 相似文献
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DNA条形码旨在通过PCR技术获得一段DNA序列,在物种水平上对现存生物类群和未知生物材料进行识别和鉴定。线粒体细胞色素C氧化酶I(COI)基因是常用DNA条形码基因之一,为研究COI基因作为DNA条形码在贝类系统进化中的评估效果,本文利用PCR技术扩增获得了60个贝类物种的353条COI基因序列,通过聚类法构建了neighbor-joining(NJ)进化树,同时还对7个物种不同地理群体的遗传进化情况进行了分析。结果表明,选用的COI基因引物在大多数贝类中通用性较强,除在珍珠贝目中的扩增效率只有10%以外,在整个研究中扩增效率达到82.7%;60个物种中除太平洋潜泥蛤(Panopea abrupta)、沼蛤(Limnoperna fortunei)和魁蚶(Scapharca broughtoni)等8个物种在进化树中的进化地位与传统系统分类具有一定差别外,其他物种的聚类关系与传统分类基本一致;对7个物种、共26个地理群体的聚类分析发现,COI基因基本能对同一物种的不同地理群体进行聚类,只有极个别群体或群体中的某个个体存在聚类混乱现象。综上所述,COI基因在一定程度上适用于贝类物种鉴别和系统发育研究,丰富了COI基因在物种鉴别应用中的科学数据。 相似文献
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福建海岛潮间带软体动物鉴定248种,绝大多数为暖水性种类。种类组成以瓣鳃类(120种)和腹足类(114种)占绝对优势。不同底质生态类型的软体动物的种数依次为岩相93种,泥沙滩83种,泥滩55种,沙滩36种,红树林区6种;生物量大小依序为岩相943.89g/m~2、泥沙滩 51.64g/m~2、泥滩 38.68g/m~2和沙滩 9.07g/m~2;栖息密度大小依序为岩相956.8个/m~2、泥滩 92.5个/m~2、泥沙滩 25.9个/m~2、沙滩 22.1个/m~2。种类分布的总体特点是:南部海岛多于北部海岛,外海海岛多于近岸内湾河口的海岛;生物数量分布的总体特点是:近岸内湾、河口的海岛大于外海的海岛。本文还对海岛潮间带软体动物资源的开发作了若干探讨。 相似文献
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共记述河南省的丽蚌属12种,其中天津丽蚌Lamprotula tientsinensis（Crosse＆Debeaux,1863）为河南新记录,并编制了这些种类的检索表。 相似文献
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Satit Kovitvadhi Uthaiwan Kovitvadhi Pichan Sawangwong Premjai Trisaranuwatana Jorge Machado 《Aquaculture International》2009,17(1):57-67
The freshwater pearl mussel, Hyriopsis (Limnoscapha) myersiana (Lea, 1856), was cultured in the laboratory (0–120 days old), in an earthen pond in acrylic containers (120–270 days old)
and in pocket nets with frames (270–360 days old). Measurements were taken of the length–height and the total body weight–size
(shell length, shell height and shell width). It was found that the length–height in each period of culture showed a linear
relationship and that the shell height increased as the shell length increased, along with the same linear relationship. When
statistical analyses were performed, this linear regression line consisted of three distinct lines (P < 0.01). The general morphometric relationships between the length and height of mussels grown in the laboratory, in acrylic
containers and in pocket nets were Log H = −0.147 + 0.828Log L, Log H = −0.211 + 0.909Log L and Log H = −0.264 + 0.951Log L, respectively. The relationship between the total body weight–size in different culture phases was a positive allometric
equation and the two curved lines were not the same (P < 0.01). The general morphometric relationships between the length and the total body weight of the mussels cultured in acrylic
containers and pocket nets were Log W = −3.747 + 2.674Log L and Log W = −4.149 + 2.976Log L, respectively. Such measurements are useful in the management of different culture phases of H. (L.) myersiana. 相似文献