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91.
- The freshwater fauna has been judged to be one of the most threatened biotic components in the world. In many tropical‐temperate freshwater habitats worldwide the largest invertebrates are crayfish, as is the case with the cambarid crayfish in Mexico. With 98% of endemic species, most of them with reduced distribution ranges, the Mexican crayfish have not been analysed to examine how diversity, endemism and threat are distributed.
- A data set was analysed containing 1419 locality records for the 56 species of crayfish occurring in Mexico arranged in a 251 cell grid. Spatial autocorrelation analyses using Moran's I and G* were conducted; species richness, endemism and threat indices were calculated and mapped. An integrated risk score was derived from the two indices.
- Spatial autocorrelation analyses revealed a pattern that significantly departs from a random arrangement. Moran's I showed a positive autocorrelation between cells that are less than 800 km apart; while G* analysis identified one hotspot of diversity. Four areas with high endemism and seven areas with intermediate endemism values were recognized. The western portion of the Trans‐Mexican Volcanic Belt, and some areas in the north are of special concern owing to the presence of threatened microendemic species.
- The areas where more threatened species occur differ from those with high endemism values. This distinction makes evident that for species with low dispersal capabilities the areas with high endemism are the product of historical and geological events, while the areas with high numbers of threatened species are those where human activities have had a major impact. The integrated risk score, however, resulting from the combination of endemism and threat, peaks along the Trans‐Mexican Volcanic Belt and where it joins the Sierra Madre Oriental.
- The integrated risk score proposed in this study, based on well known and frequently used indices in conservation biology, can be used with existing data to determine areas where crayfish species richness, endemism and threat peak to make conservation efforts more cost‐effective.
92.
Zachary J. Loughman Stuart A. Welsh Nicole M. Sadecky Zachary W. Dillard R. Katie Scott 《水产资源保护:海洋与淡水生态系统》2017,27(4):755-763
1. Crayfish represent one of the most imperilled animal groups on the planet. Habitat degradation, destruction and fragmentation, introduction of invasive crayfishes, and a lack of applied biological information have all been identified as agents thwarting crayfish conservation. 2. Cambarus callainus was warranted federal protection by the United States Fish and Wildlife Service (USFWS) in April, 2016. As part of the USFWS listing procedure, a survey for C. callainus in the Big Sandy River catchment was conducted to determine points of occurrence with a secondary objective of determining reach level physical habitat and physicochemical correlates of C. callainus presence and absence. 3. At each site, physicochemical and physical habitat data were collected to determine the influence of abiotic covariates on the presence of C. callainus. Cambarus callainus presence or absence and associated site covariates were modelled using logistic regression. 4. Survey results recorded C. callainus at 39 sites in the Upper Levisa Fork (ULF) and Tug Fork (TF) drainages of the Big Sandy River; no C. callainus were collected in the Lower Levisa Fork (LLF). An additive effects model of physical habitat quality (Basin + Boulder presence/embeddedness) was the only model selected, supporting an association of C. callainus with slab boulders, open interstitial spaces, and moderate to no sedimentation. All sites lacking C. callainus were experiencing some degree of sedimentation. Physicochemical covariates were not supported by the data. 5. Results indicated that good quality habitat was lacking in the LLF, but was present in the ULF and TF catchments, with ULF supporting the most robust populations and most suitable habitat. Effective conservation for C. callainus should focus on efforts that limit sedimentation as well as restore good quality instream habitat in the greater Big Sandy catchment. 相似文献
93.
《水产资源保护:海洋与淡水生态系统》2018,28(2):506-511
- Austropotamobius pallipes is an endangered decapod attracting much attention in freshwater conservation programmes. In some cases population transfers or reintroductions are carried out in lentic ecosystems such as ponds or quarries. Such conservation actions require rapid, low cost and powerful tools to census suitable habitat.
- Some species of the Characeae family (Chara spp.), share ecological needs with A. pallipes and are proposed as bioindicators of suitable habitat. Chara species were tested, among other plants, as bioindicators, and to see whether Chara species are a stronger indicator than water chemistry.
- The Pinail Nature Reserve, with 3000 permanent ponds, is inhabited by white‐clawed crayfish probably introduced historically into ponds used for fish production. This allows a replicated study of suitable habitats where plant communities are bioindicators of crayfish presence.
- Crayfish presence is associated with Chara species (such as Chara aspera, Chara virgata, Chara fragifera, Chara polyacantha and Chara vulgaris). Austropotamobius pallipes is present in ponds with Chara spp. (N = 10/10) while other ponds without crayfish are lacking charophytes (N = 1/23). Algae of the genus Chara are thus a simple and low‐cost additional tool for determining suitable habitat for crayfish introductions within enclosed waters protected from exotic invasive species and disease. Cladium mariscus also appears to be another useful bioindicator for crayfish habitat.
94.
Özden Barim‐Öz 《Aquaculture Nutrition》2018,24(1):492-503
This study investigated the effect of starvation (78 days) and refeeding (33 days) on the oxidative stress [malondialdehyde (MDA)] and the non‐enzymatic antioxidants [vitamin E (VE), vitamin C (VC), vitamin A (VA), beta carotene (βC) and reduced glutathione (GSH)] in the hepatopancreas, muscle and gill tissues of freshwater crayfish (Astacus leptodactylus). Crayfish were divided into three experimental groups: control (fed), starved (not fed) crayfish for 78 days and refeeding crayfish for 33 days after 78 days of starvation. The biochemical analysis of the tissues was conducted at 3, 18, 33, 48, 63 and 78 days of starvation and feeding and at 3, 18 and 33 days of refeeding. It was determined that crayfish can withstand starvation period of 78 days. In all of the periods, the MDA levels were significantly higher in the tissues of starved crayfish when compared with the control. The findings of this study demonstrate that starvation has a negative effect on the VE, VC, VA, βC and GSH levels in the crayfish. The measured parameters returned to control values after 33 days of the refeeding. Additionally, the starvation resulted in decreased levels of VE, VA and βC in the abdomen muscle of crayfish consumed by humans. 相似文献
95.
Jen Nightingale Paul Stebbing Nick Taylor Grainne McCabe Gareth Jones 《Aquaculture Research》2018,49(9):3116-3122
Crayfish growth rates can vary considerably among individuals from the same brood, and social dominance hierarchies in crustacean species occur frequently. These hierarchies can reduce growth and survival when rearing communal groups. Size‐grading and single‐sex culturing are the methods used to combat this. A 160‐day experiment took place on 288 young‐of‐the‐year captive‐born Austropotamobius pallipes, within a closed‐circuit, indoor aquaculture facility. Crayfish were reared in three treatments (a) equal numbers of large males + small females (LMSF); (b) equal numbers of small males + large females (SMLF); (c) individuals of the same size, equal sex ratio; plus two control groups of single‐sex, same sized individuals. Female survival in the LMSF was significantly reduced (52.8%, SD = 20.7%), whereas overall survival in all other groups was high (83.1%, SD = 15.1%). Male growth (6.3 mm, SD = 0.6 mm) was greater than female growth (4.9 mm, SD = 0.9 mm) across all groups. Cheliped autotomy was significantly greater (8.8%) in males (26.7%, SD = 8.9%) than females (17.9%, SD = 2.7%). This study suggests that young‐of‐the‐year juvenile male A. pallipes grow faster and are more aggressive than females. Large males will suppress and reduce survival in smaller females whereas small males, when housed with larger females, will still grow faster than the females. We suggest that it is sex and not size that is the main factor that causes dominance hierarchies and growth suppression within juvenile A. pallipes. Maintaining juvenile A. pallipes in single‐sex groups is optimal to ensure high survival and growth rates. 相似文献
96.
Chinese mitten crab (Eriocheir sinensis), freshwater shrimp (Macrobrachium nipponensis) and red swamp crayfish (Procambarus clarkii) are important culture species in China and have world‐wide introduced distributions. The trophic role of these three decapods has not been compared within a system although they consume plants, animals, and detritus and often co‐occur in freshwater ponds. A combination of stable isotope measurements and gut content analysis was used to determine the main food sources and trophic niche of three benthic decapods, in commercial crab ponds around Lake Gucheng, China. Observation of the gut contents reflected a variety of prey items ingested by three decapods. Macrophytes made up the highest contribution to the volume of their gut contents, followed by forage fish, corn and mollusks. Stable isotope analysis supported a stronger relationship between crayfish and vegetable matter than with animal matter, while both crab and shrimp were the opposite. An isotopic mixing model indicated that about 60% of crab and shrimp production originated from animal matter, while only 40% of crayfish production was ascribed to consumption of animal matter. Although results from the mixing model corroborate the gut content findings in most cases, stable isotope results showed that three decapods obtained more energy for growth from animal matter than what would be estimated if gut analysis was used alone. Estimates of niche overlap indices indicated a high degree of dietary overlap among the three decapods examined, suggesting that shrimp and crayfish density should be controlled if considering economic benefits of pond aquaculture. 相似文献
97.
98.
淡水螯虾传染性疾病的研究进展 总被引：1，自引：0，他引：1
陈昌福 《华中农业大学学报》2009,28(4)
克氏原螯虾(Procambarusclarkii)的人工养殖热潮正在我国部分地区兴起,由于养殖者缺乏饲养克氏原螯虾的经验和技术,随着养殖面积的迅速扩大,不明原因的疾病暴发性发生正在威胁着克氏原螯虾养殖的可持续发展.由致病性细菌、病毒和真菌引起的传染性疾病对人工养殖克氏原螯虾的危害严重.本文对克氏原螯虾传染性疾病和防治技术的国内外研究概况进行了综述,旨在为养殖者和研究人员提供借鉴. 相似文献
99.
100.
农产品品牌的形成,对农产品的市场流通和消费量的增长具有显著的带动作用。针对我国农产品品牌缺失的问题,分析农产品品牌建设中存在的主要问题,结合盱眙龙虾品牌建设的经验,提出农产品品牌构建的对策。 相似文献