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S. J. Laly Jeyakumari Annamalai K. Ashok Kumar T. V. Sankar Lalitha KV George Ninan 《Journal Of Aquatic Food Product Technology》2019,28(2):221-232
Sutchi catfish (Pangasianodon hypophthalmus) is a highly preferred farmed species that is produced in huge quantities. Meat from ice-stored (4 ± 2°C) whole Sutchi catfish was evaluated for formation of biogenic amines, such as putrescine, cadaverine, histamine (HIM), agmatine, tyramine, spermine, and spermidine, and compared with biochemical, microbial, and sensory attributes during 22 days. Analysis of content of biogenic amines in the meat was carried out by liquid chromatography with tandem mass spectrometry using a without derivatization method. Three amines, namely, tyramine, spermidine, and spermine, were only present on 0th day of storage. Presence of cadaverine was noticed from 9th day onwards, where the aerobic plate count (APC) reached 4.85 log CFU/g. Putrescine was detected on the 22nd day of storage, where the APC crossed 7 log CFU/g. HIM was detected in lower quantities from 3rd day onwards. A shelf life of 15 days was determined based on sensory and microbiological evaluation. Although the samples were biochemically acceptable throughout the storage period, APC exceeded the limit on day 19, and the gradual increase of H2S-producing bacteria, Brochothrix thermosphacta, Aeromonas, and Enterobacteriaceae, was observed during storage. 相似文献
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Qing Wang Baoshan Cui Meng Luo Dongdong Qiu Wei Shi Chengjie Xie 《水产资源保护:海洋与淡水生态系统》2019,29(8):1336-1346
- It is well known that establishment limitation is stronger than seed limitation in aquatic ecosystems. Therefore, it seems crucial during the recruitment recovery process to overcome this establishment limitation on bare or degraded patches.
- Microtopographic structures have been shown to act as trap agents in saltmarshes. They can facilitate establishment, but this effect has not been quantitatively examined and assessed. This study examined the facilitative effect of microtopographic structures on plant recruitment in a dynamic saltmarsh system by conducting a series of field experiments along a saltmarsh tidal gradient.
- A simple plant life‐cycle model was used to evaluate the dynamics of the plant recruitment process facilitated by microtopographic structure and the importance of each life stage. The influence of abiotic factors on each life stage was also assessed, to identify the determinants during the life history.
- It was revealed that seed retention was the limiting factor in a bare saltmarsh area, rather than seed dispersal. Microtopographic structures can provide trap agents to facilitate seed anchorage. During seed retention, the stability of the microtopographic structure, especially its relative surface elevation difference, can be influenced by tidal events and the associated sediment process, which then affects seed retention efficiency.
- Microtopographic structure has a strong environmental filtering effect that can revise the potential dispersed seed and emergence patterns, and the determinant of the final establishment pattern along a tidal gradient is the retention pattern resulting from the interactions between microtopographic structures and tidal events.
- Furthermore, it can be designed into the early stage of recovery or restoration process so that it facilitates pioneer plant establishment. These early recruitment patches will speed up the recovery or succession process by (1) providing local seed sources, (2) retaining more seeds via the established vegetative structures, and (3) modifying microhabitat factors.
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- Amphidromy is the most prevalent type of diadromous migration. Despite this, the conservation and management of amphidromous species is exceptionally challenging because this life history type, with larval development in a pelagic habitat (usually marine) and adult development in fresh water, is poorly resolved.
- The chronological properties of otoliths, together with a spatial and temporal analysis of post‐larval migration traits and adult reproductive traits, were used to reconstruct the life history of a widespread, yet declining amphidromous galaxiid, Galaxias maculatus, and to explore relationships between marine and freshwater life phases.
- A wide range of post‐larval migration traits were observed over the peak migratory period. Post‐larvae were smaller and younger at inward migration late in the migration season (November) and were derived from winter spawning events. Earlier migrants (September) were larger, older and derived from autumn spawning events.
- Age estimates confirmed that G. maculatus is largely an annual species, but back‐calculated hatch dates showed that spawning times are more extensive than previously known.
- Growth reconstructions revealed that winter‐hatched larvae were faster growing during marine and freshwater life and attained sexual maturity at a younger age than autumn‐hatched fish. However, no differences in body size or reproductive investment were detected between autumn‐ and winter‐hatched larvae.
- The first 50 days of marine growth were inter‐dependent, indicating that early larval growth may be the critical link to understanding intra‐ and inter‐annual recruitment variations of inward migrating post‐larvae. Furthermore, growth after 60 days of larval life propagated through to adult freshwater development, highlighting linkages between late marine and adult freshwater life.
- This study highlights the value of studying the marine and freshwater life phases of amphidromous species in tandem. This interconnected understanding must ultimately be achieved for the conservation and management of species with this poorly understood life history type.
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骑跨式机架的随机振动疲劳分析 总被引:1,自引:0,他引:1
为了提高矮化密植红枣收获机的工作性能,以骑跨式机架为研究对象,建立有限元模型。对机架进行模态分析,得出机架的固有频率与振型,并与各激励频率范围比较,可知机架的固有频率仍在发动机的激振频率范围之内。为避免机架产生共振,在发动机安装位置添加弹性元件,对机架采用减振方案的谐响应分析,计算得出应力、变形量变化曲线。结合机架结构材料的S-N曲线和线性累积损伤理论,对机架进行疲劳分析,验证机架的可靠性。研究结果表明:减振方案的谐响应分析使机架的最大变形量由2.977mm变到0.358mm,减小了87.974%,明显改善了机架的振动特性;在激振载荷的作用下对添加减振元件前后的机架分别计算疲劳寿命,得出添加减振元件后机架的疲劳寿命为1.84×10~8次,高于1.0×10~6次,满足机架疲劳强度设计要求。 相似文献
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Differences in early developmental rate and yolk conversion efficiency in offspring of trout with alternative life histories 下载免费PDF全文
Travis E. Van Leeuwen Shaun S. Killen Neil B. Metcalfe Colin E. Adams 《Ecology of Freshwater Fish》2017,26(3):371-382
Partial migration, in which some individuals of a population migrate while other individuals remain resident, is generally associated with ontogenetic shifts to better feeding areas or as a response to environmental instability, but its underlying mechanisms remain relatively unknown. Brown trout (Salmo trutta) exhibit partial migration, with some individuals remaining in freshwater (freshwater resident) while others undertake an anadromous migration, where they spend time at sea before returning to breed in freshwater (migrant). We reared full‐sibling groups of offspring from freshwater‐resident and anadromous brown trout from the same catchment in the laboratory under common garden conditions to examine potential differences in their early development. Freshwater‐resident parents produced eggs that were slower to hatch than those of anadromous parents, but freshwater‐resident offspring were quicker to absorb their yolk and reach the stage of exogenous feeding. Their offspring also had a higher conversion efficiency from the egg stage to the start of exogenous feeding (so were larger by the start of the fry stage) than did offspring from anadromous parents despite no difference in standard metabolic rate, maximal metabolic rate or aerobic scope. Given these differences in early development, we discuss how the migration history of the parents might influence the migration probability of the offspring. 相似文献
39.
Carolina M. Muniz Natália C. L. dos Santos Matheus T. Baumgartner Angelo A. Agostinho Luiz C. Gomes 《Ecology of Freshwater Fish》2020,29(2):241-251
One of the main impacts on aquatic environments is the alteration of flow regime, usually caused by dam construction. This impact changes the dynamics and functioning of the environment. We aimed to evaluate changes in the composition of functional traits of fish assemblages from 29 reservoirs of different chronological ages. We assessed if there were any alterations in trophic state of these reservoirs according to their ages (chronological variable). Then, we evaluated the relationship between functional traits and environmental/chronological variables. Results showed that reservoir age is a predictor of fish assemblage functional traits composition. In older reservoirs, there was a predominance of omnivorous species, with multiple spawning and parental care. However, herbivorous species, with total spawning and medium size, had their abundance reduced. Also, it was possible to identify the influence of depth and water retention time on the composition of functional traits. By showing that although age has an influence on composition, the intrinsic characteristics of each reservoir are very important in evaluating the impacts of these projects. Therefore, the findings presented provide insights into what may happen to functional traits of fish assemblages with ageing of reservoirs. 相似文献
40.
Qiaojian Wang Jinyan Mu Changjuan Shan Weiyan Wang 《The Journal of Horticultural Science and Biotechnology》2017,92(6):630-635
To study the role of cerium (Ce) in regulating the vase life of Rosa chinensis Jacq. cut flowers, the effects of cerium nitrate (Ce(NO3)3) on the activities of antioxidant enzymes, the contents of malondialdehyde (MDA) and hydrogen peroxide (H2O2) in the petals, and the contents of chlorophyll a, chlorophyll b and carotenoids in the calyces were investigated. The results showed that Ce(NO3)3 evidently enhanced the activities of peroxidase (POD), catalase (CAT), superoxide dismutase (SOD), ascorbate peroxidase (APX), glutathione reductase (GR), glutathione S-transferase (GST) and glutathione peroxidase (GPX), and evidently decreased the contents of MDA and H2O2 in the petals, compared with the control. Moreover, Ce(NO3)3 evidently increased the contents of chlorophyll a, chlorophyll b and carotenoids in the calyces. The results also showed that Ce(NO3)3 evidently increased the numbers of open flowers and decreased the numbers of wilted flowers. Our results suggest that Ce(NO3)3 extended the vase life of R. chinensis Jacq. cut flower by improving the antioxidant defence system in the petals and the contents of pigments in the calyces. 相似文献