Polyculture of the lined seahorse, Hippocampus erectus Perry, 1810 with two species of macroalgae in aquaria   总被引：1，自引：0，他引：1  

XU Yongjian  LIN Jun  CHEN Shun 《海洋学报(英文版)》2010,29(1):26-32

A two-month study was conducted to test the e?ects of macroalgae on the growth and survivorship of juvenile lined seahorse (Hippocampus erectus) in aquaria. Twenty-day old seahorses were cultured in the tanks with green alga Chaetomorpha linum, red alga Gracilaria tikvahiae, green plastic artiˉcial plant (stargrass), and black plastic net, respectively. Increases in wet mass and standard length for the seahorses were signiˉcantly higher in the tanks with macroalgae than those without macroalgae. The seahorse survivorships in the two macroalgal treatments were also signiˉcantly higher than those of the two treatments without macroalgae. In the treatments with macroalgae, the DO and pH were higher than those without marcoalgae. During the experiment, the color of seahorses was changed to certain extent. In the green background (the treatments with C. linum and stargrass), 24.1%{28.4% of black seahorses decreased over time; whereas in the black (plastic net) or brown (G. tikvahiae) background treatments, 14.1%{16.3% of yellow seahorses decreased over time, for matching that of the background. Furthermore, the survival rate of seahorse was correlation with DO and pH, and strong correlation with standard length, wet mass and CF. Polyculture with macroalgae, survival rates of seahorse were higher than without macroaglae.  相似文献   

温度操作对褐牙鲆幼鱼的生长和能量分配的影响   总被引：1，自引：0，他引：1  

黄国强  韦柳枝  张秀梅  张沛东 《中国海洋大学学报(自然科学版)》2010,40(2)

实验对褐牙鲆(Paralichthys olivaceus)幼鱼在温度胁迫及温度调整后的生长与能量分配进行了研究。驯养于17.5℃的褐牙鲆幼鱼分别在8.5℃(T8.5),13.0℃(T13.0),17.5℃(T17.5),22.0℃(T22.0)和26.5℃(T26.5)养殖10 d后,除T22.0处理的褐牙鲆幼鱼除以干重表示时与T17.5和T26.5处理差异不显著外,以湿重、蛋白质和能量表示的鱼体重均显著大于其他处理。所有处理调整养殖温度至22.0℃继续养殖,由于不同温度造成的生长差异在30 d内可获得完全补偿。在不同温度养殖期间,摄食量少和分配于生长的能量减少是导致低温处理(T8.5和T13.0)生长慢的主要原因,而T17.5和T26.5生长慢的主要原因是分配在生长的能量较少。低温处理分配于生长的能量较少主要是由于其粪便损失和用于呼吸的能量比例较多,而高温处理则主要是由于排泄损失的能量比例较高导致生长能减少。温度调整后的第2个10 d,T8.5,T13.0,T17.5和T26.5的摄食量都显著比T22.0多,而温度调整后的30 d内不同处理的总摄食量没有显著差异,个体水平上的摄食能在生长、粪便、排泄、呼吸上的分配也没有显著差异。因此,补偿生长的获得主要依靠阶段性的提高摄食量。在温度调整后的30 d内,T8.5,T13.0,T17.5和T26.5的幼鱼单位体重日摄食能和生长能都比T22.0多,表现出明显的补偿生长现象。对于整个实验期间而言,T8.5的幼鱼摄食比其他处理少,但由于其排泄和呼吸损失的能量比例较少,因此分配于生长的能量比例比其他处理略多。养殖在不同温度的褐牙鲆幼鱼会在身体蛋白质和能量含量上产生差异,在实验结束时T8.5和T26.5的能量含量与对照组仍有显著差异。本研究的结果表明褐牙鲆幼鱼对温度变动具有较强的适应能力,短期的温度变动不会对其长期生长产生显著影响。  相似文献   

贫困山区农户人力资本对生计策略的影响研究——以四川省凉山彝族自治州为例     

何仁伟  方方  刘运伟 《地理科学进展》2019,38(9):1282-1893

人力资本是构建农户生计的关键要素,从人力资本视角探讨农户生计选择对于推动农户生计转型、实现乡村振兴具有重要意义。论文以西南贫困山区四川省凉山彝族自治州为案例区,采用2018年508个农户样本数据,应用回归模型,估算了人力资本对农户生计策略的影响。结果表明：人力资本是山区农户生计选择的重要影响因素,不同类型人力资本对农户生计策略的影响不同,且具有明显的空间差异。教育文化、健康状况对非农生计策略的选择具有正向影响,且高山区>二半山区>河谷区,健康状况对河谷区农户生计选择影响不显著;非农技能培训对非农生计策略选择具有显著的正向影响,且高山区>二半山区>河谷区;农业技能培训对非农生计策略选择具有负向影响,且高山区<二半山区<河谷区,但其对高山区农户生计选择并不显著;青壮年劳动力倾向于选择非农生计,务农人口老龄化问题严峻,高山区表现最为突出,二半山区次之,河谷区较不明显。最后,根据研究结论,探讨了人力资本、劳动力转移与乡村发展之间辩证关系及相关政策建议。  相似文献   

Colony growth in the harvested octocoral Pseudopterogorgia acerosa in a Caribbean coral reef     

Nini Johana Cadena  Juan Armando Sánchez 《Marine Ecology》2010,31(4):566-573

Pseudopterogorgia acerosa is the tallest gorgonian octocoral found in the Caribbean. In the Cartagena area, Colombia, P. acerosa is commonly harvested as raw material for handicrafts, rendering important the study of its growth and population dynamics. Growth measurements of branches from multiple colonies at two different reefs during 1 year revealed that the main growth was due to rapid elongation of the main (‘mother’) branch and production of daughter branches from the same (or just a few) mother branch(es). Some small colonies doubled their original size in a year. The branches’ absolute growth rate was weakly correlated with size, with no significant relationships between branch size and percent growth. While the pinnate branching pattern in P. acerosa is similar to its congeners Pseudopterogorgia elisabethae and Pseudopterogorgia bipinnata, it produces taller colonies due to the faster growth rate in the primordial mother branch. This growth mode seems advantageous as it augments exposure to light and higher fluxes of suspended food in the benthic boundary layer. Post‐harvesting, clipped colonies exhibited clear signs of regeneration, even in cases where only the holdfast remained. Pseudopterogorgia acerosa seems to have similar regeneration capabilities respect to other Pseudopterogorgia species, where regenerating colonies may grow faster than intact ones.  相似文献   

Current and future use of indicators for ecosystem based fisheries management     

Joseph E. Powers  Melissa H. Monk 《Marine Policy》2010

Implementing ecosystem based fisheries management (EBFM) will require a suite of ecological indices to track the state of an ecosystem, in addition to monitoring species-abundance for both economically important species, as well as species that are not targeted for harvest. However, EBFM implementation requires an examination of current methods and applications of ecological indices that are being used. This paper identifies four key uses for ecosystem indices in the context of EBFM and discusses the implications of each: (1) motivation for socio-political action, (2) information for individual users to modify their behavior, (3) implementation of decision rules for management evaluation, and (4) discovery of ecosystem functions to advance scientific knowledge. In a fisheries management context, ecological indicators will be linked to decision rules based on the definitions of both “ecosystem overfishing” and the current single-species definitions of overfishing. Two components of common ecological indicators are species weightings (i.e. catch or abundance data by species) and the species-specific ecological attributes (e.g. mortality rates, body size, trophic level). We discuss statistical issues that arise from estimating the parameters in ecological index calculations from both fishery-dependent and independent data and the potential biases introduced by using catch-per-unit-effort (CPUE) data, catch data, and abundance estimates. Given the range of biases that arise, often the best estimates of species weightings (abundances) are those derived from fish stock assessments. This implies that progress in EBFM may be best served by increasing the number of species for which single-species assessments are done and to expand the list of species to include species which may not be economically important. The policy framework exists to carry out EBFM; however, future works needs to focus on empirical management strategy simulations, as well as theoretical works to identify management criteria based on those indicators.  相似文献   

Nd³⁺ :Gd₃ Sc₂ Al₃ O₁₂ 晶场能级及拟合     

肖进  张庆礼  周文龙  谭晓靓  刘文鹏  殷绍唐  江海河  夏上达  郭常新 《海洋学报》2010,32(10):7306-7313

Nd³⁺ :GSAG是性能优良的942 nm激光晶体.用提拉法成功生长Nd³⁺ :GSAG单晶,研究其室温透射光谱,辨认位置高达29967 cm^-1的68个Nd³⁺晶场能级.对这些能级拟合了自由离子及晶场Hamilton参量,拟合标准偏差为16.7 cm^-1,表明实验与计算能级符合很好.获得的Hamilton参量可用于计算Nd³⁺ :GSAG中Nd³⁺的  相似文献   

1990—2015年中国县市尺度人口收缩的演变特征及影响因素   总被引：1，自引：0，他引：1  

刘振  戚伟  齐宏纲  刘盛和 《地理研究》2020,39(7):1565-1579

近年来,区域人口收缩问题在全球范围内引起了广泛关注,并且在中国也日益明显。利用1990年、2000年和2010年人口普查数据以及2015年1%人口抽样调查数据,本文在县市尺度上分析了1990—2000年、2000—2010年和2010—2015年三个时期人口收缩区的空间特征及演化趋势,并定量探讨了其形成与演变的影响因素,主要发现如下：① 人口收缩现象在县市尺度非常明显,三个时期人口收缩区占比均超过20%;② 2000—2010年人口收缩区以大面积扩张为主要特征,东北地区、川黔渝地区、长江中游地区最为明显,而东部地区则主要集中在江苏北部和福建西部等局部范围;③ 2010—2015年人口收缩转缓慢增长成为主要特征,仅东北地区、河南等人口收缩区仍有所扩张;④ 人均GDP和非农就业占比等经济发展水平因素对人口收缩区的形成影响显著,而经济发展速度因素则与人口收缩的演变密切相关;⑤ 除经济因素外,人口自然增长因素对人口收缩区形成及演变的影响均非常显著,且其作用呈增强趋势。  相似文献   

地缘关系对中国出口增长的影响     

贺灿飞  胡绪千  杨文韬 《世界地理研究》2019,28(6):1-10

本文结合现有文献中的方法和自身思考构建了地缘关系指标体系，利用Google的GDELT数据库，探索地缘关系对中国出口贸易增长的作用。本文发现地缘关系在短期和长期维度上对国家出口贸易带来的涉及政治、地理、制度和文化等方面的多重影响。一方面，政治关系反映了短期政府间关系的波动，对中国出口的影响十分明显。其中较高的政府交往频度不利于中国出口增长，而政府亲密程度对中国出口的影响则是积极的，中国与出口目的国亲密程度越高，则越有向该国出口的倾向。另一方面，地理关系、制度关系和文化关系同样对中国出口有重要影响。在地理关系中，较大的地理距离会减小中国对一地区出口的倾向，而邻接关系会增大中国对一地区出口的倾向。不同制度关系对中国出口的影响存在差别，没有证据表明经济制度距离对中国出口有额外的影响，而法律制度距离的增大则会导致中国不向该地区出口的倾向。文化关系同样对中国出口有重大影响，其中较大的文化距离会抑制中国对一地区的出口倾向，而如果中国对一地区文化影响力较大，中国对其出口则更加容易。此外，进一步分行业研究的结果表明，不同行业的产品出口对地缘关系的响应程度既存在共性，也存在差异。其中，地区间的亲密程度对全类别产品和服装类、机械设备类、交通工具类三类产品的出口都有显著的影响。  相似文献   

Where do fishmeal and fish oil products come from? An analysis of the conversion ratios in the global fishmeal industry   总被引：1，自引：0，他引：1  

Guillaume Péron  Jean François Mittaine  Bertrand Le Gallic 《Marine Policy》2010

As a result of the stagnation of commercial fishery landings, aquaculture activities are expected to increase over the next decades to match the growing demand for marine protein. Overall, it is expected that the aquaculture sector could reduce some of the fishing pressure applied to wild stocks. However, this development is likely to be limited by the availability of key aquaculture inputs, specifically fishmeal and fish oil products (FMFOP). Aquaculture provided 60 % (fish meal) and 80 % (fish oil) of the world total consumption of these products in 2007. FMFOP are generally derived from small pelagic fish species, but can also be derived from other sources. Identifying the origin of FMFOP is crucial to understanding the effects of this new pressure on marine social-ecological systems. Two factors are of particular importance in the reduction sector transforming wild fish into fishmeal or fish oil: the two “conversion ratios” (i.e. the ratio between the quantity of wild fish harvested and the resulting quantity of FMFOP, and the ratio between the quantity of FMFOP and aquaculture production), and the type of raw material used by the reduction sector. Based on trade and production databases from FAO and the International Fishmeal and Fish oil Organisation (IFFO), this paper proposes an approach to identify the origin of FMFOP. It shows that whereas different countries use different pelagic resources to produce FMFOP, other countries use non-pelagic sources, and some countries use pelagic resources for human consumption.  相似文献   

Magma chamber growth models in the upper crust: A review of the hydraulic and inertial constraints     

Eugenio Aragón  Fernando J.D'Eramo  Lucio P.Pinotti  Manuel Demartis  José María Tubía  Roberto F.Weinberg  Jorge E.Coniglio 《地学前缘(英文版)》2019,10(3):1211-1218

Finite volumes of magma moving in confinement, store hydraulic potential energy for the generation,control and transmission of power. The Pascal's principle in a hydraulic jack arrangement is used to model the vertical and lateral growth of sills. The small input piston of the hydraulic jack is equivalent to the feeder dike, the upper large expansible piston equivalent to the magmatic chamber and the inertial force of the magma in the dike is the input force. This arrangement is particularly relevant to the case of sills expanding with blunt tips, for which rapid fracture propagation is inhibited. Hydraulic models concur with experimental data that show that lateral expansion of magma into a sill is promoted when the vertical ascent of magma through a feeder dike reaches the bottom contact with an overlying, flat rigid-layer. At this point, the magma is forced to decelerate, triggering a pressure wave through the conduit caused by the continued ascent of magma further down(fluid-hammer effect). This pressure wave can provide overpressure enough to trigger the initial hydraulic lateral expansion of magma into an incipient sill, and still have enough input inertial force left to continue feeding the hydraulic system. The lateral expansion underneath the strong impeding layer, causes an area increase and thus, further hydraulic amplification of the input inertial force on the sides and roof of the incipient sill, triggering further expansion in a self-reinforcing process. Initially, the lateral pressure increase is larger than that in the roof allowing the sill to expand. However, expansion eventually increases the total integrated force on the roof allowing its uplift into either a laccolith, if the roof preserves continuity, or into a piston bounded by a circular set of fractures. Hydraulic models for shallow magmatic chambers, also suggest that laccolith-like intrusions require the existence of a self-supported chamber roof. In contrast, if the roof of magmatic chambers loses the self-supporting capacity, lopoliths and calderas should be expected for more or less dense magmas, respectively, owing to the growing influence of the density contrast between the host rock and the magma.  相似文献