共查询到20条相似文献，搜索用时 46 毫秒
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实验结果表明,兰蛤的起始致死温度（TL50）值随着驯化温度的升高而增大。热冲击明显降低了酚对兰蛤的毒性,在20,25,30℃条件下,兰蛤的96hLC50值分别为14．0,18．5,20．0mg/L,随着温度的升高,兰蛤的耐酚能力明显增强,而在盐度－酚的联合影响中,兰蛤对盐度的变化反应不敏感。 相似文献
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鳜鱼[Siniperca chuatsi (Basilewsky)]作为一种商品价值很高的鱼类,由于成功地解决了人工繁殖和养殖技术的问题,已成为我国名优水产动物的重要养殖对象。然而,自然条件下的缘鱼常被河妒锚首 吸虫(Ancyrocephalus mogurndae Gussev)寄生,并可引起鳃组织病变[1]。关于这种吸虫的危害及其引起 鳃组织病理变化的研究尚未见诸报端。在高密度的人工养殖条件下,这种寄生虫在宿主之间的传播速率必定会增加,导致寄生虫种群数量的增加,给宿主带来危害,使级鱼养殖生产遭受损失.据了解,由于这种单殖吸虫的寄生,导致级鱼致病并大批死亡的情况,已在不少养殖场发生且呈发展趋势.研究这种单殖吸虫的种群生态、流行病学以及病原生物学,将有利于正确掌握河妒锚首吸虫对级鱼养殖生产的危害以及研究有效的控制技术和防治方法。本文报道光照、温度及宿主鳃粘液对河妒锚首吸虫虫卵孵化的影响。 相似文献
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酸性矿山废水中低的pH和高浓度的重金属对水生态系统影响巨大.依据\"参照(Control)-受损(Impaired)-恢复(Recovery)\"的设计方法,对高岚河受酸性矿山废水影响的河段、不受影响的河段及恢复河段进行对比分析.结果表明底栖藻类密度、叶绿素a浓度、无灰干重及自养指数等受酸性矿山废水影响明显,且枯水期酸性矿山废水的影响更显著.相关分析表明自养指数与各金属显著正相关而与pH值显著负相关,可以很好地指示矿山酸性废水对底栖藻类的影响. 相似文献
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由于直接测定藻类的光合速率耗时且不方便,研究者们常通过测定藻类光合电子传递速率的方式来间接反映其光合速率,理论上,以氧气产生来度量的总光合速率（PGross）与电子传递速率(ETR)之间应该存在很好的线性关系。然而,由于温度的变化会影响藻类的光呼吸等耗氧的生理过程从而影响光合作用中的氧气释放,因此温度可能会对PGross与ETR之间的线性关系产生影响。研究了温度变化对蛋白核小球藻（Cholorella pyrenoidosa）、菱形藻（Nitzschia sp.）和水生集胞藻（Synechocystis aquetilis Sauv.）的总光合放氧速率（PGross）与电子传递速率(ETR)之间比率的影响,结果表明PGross/ETR随温度的升高而降低,低温条件下PGross/ETR比值较高,说明在相同的电子传递速率的情况下水的光裂解产生的氧有更多的可以释放出来;在高温条件下PGross/ETR比值相对较低,说明高温条件下可能有相对更多的水光裂解产生的氧被用于耗氧的生理过程而没有释放出来。研究表明当温度发生变化时,光合放氧与电子传递之间并不呈线性关系,这说明将ETR作为实际光合生产的评价指标时要谨慎,不能不加分析地直接应用。 相似文献
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香溪河小水电的梯级开发对浮游藻类的影响 总被引：14，自引：3，他引：14
以香溪河干流上5个连续的小水电站为对象,于2005年10月20—22日分别对其浮游藻类和主要理化指标进行研究.结果表明：硅藻占绝对优势(95.54%),其中,线性曲壳藻(Achnanthes linearis)、披针曲壳藻椭圆变种(A. lanceolata var. elliptica)、扁圆卵形藻(Cocconeis placentula)为绝对优势种,其平均相对丰富度分别为23.96%、18.62%和12.48%;所有样点的平均藻类密度为6.29×105 ind·L-1,最高为1.81×106 ind·L-1,最低为2.35×105 ind·L-1.方差分析表明,流速变化是小水电站开发影响河流中浮游藻类的主要原因.电站取水坝的建立,使其下游生境(生境3)与其它4个生境显著不同,导致多个参数出现骤变,包括Margalef多样性指数、物种丰富度、属的丰富度、硅藻组成、硅藻百分含量等均受到显著影响. 相似文献
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富营养水体中肥活底质对沉水植物生长的胁迫 总被引：18，自引：0，他引：18
Ｓｕｂｍｅｒｓｅｄｍａｃｒｏｐｈｙｔｅｓａｒｅｒｅａｌｗａｔｅｒｐｌａｎｔｓｂｅｃａｕｓｅｔｈｅｙａｒｅｒｏｏｔｅｄｉｎｓｅｄｉｍｅｎｔａｎｄｃａｎｃｏｍｐｌｅｔｅｔｈｅｉｒｇｒｏｗｔｈａｎｄｒｅｐｒｏｄｕｃｔｉｏｎｉｎｓｉｄｅｔｈｅｏｖｅｒｌｙｉｎｇｗａｔｅｒ.Ｐｒｏｖｉｄｉｎｇａｌｉｎｋａｇｅｂｅｔｗｅｅｎｗａｔｅｒａｎｄｓｅｄｉｍｅｎｔ,ｔｈｅｙｈａｖｅｔｈｅｃｌｏｓｅｓｔｉｎｔｅｒａｃｔｉｏｎｗｉｔｈｗａｔｅｒｅｎｖｉｒｏｎｍｅｎｔ.Ｔｈｉｓｉｎｔｅｒａｃｔｉｏｎｉｓｖｅｒｙｃｏｍｐｌｉｃ… 相似文献
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D. P. Gillette† J. S. Tiemann‡ D. R. Edds M. L. Wildhaber§ 《Journal of fish biology》2006,68(5):1494-1512
The hypothesis that temperate stream fishes alter habitat use in response to changing water temperature and stream discharge was evaluated over a 1 year period in the Neosho River, Kansas, U.S.A. at two spatial scales. Winter patterns differed from those of all other seasons, with shallower water used less frequently, and low‐flow habitat more frequently, than at other times. Non‐random habitat use was more frequent at the point scale (4·5 m2 ) than at the larger reach scale (20–40 m), although patterns at both scales were similar. Relative to available habitats, assemblages used shallower, swifter‐flowing water as temperature increased, and shallower, slower‐flowing water as river discharge increased. River discharge had a stronger effect on assemblage habitat use than water temperature. Proportion of juveniles in the assemblage did not have a significant effect. This study suggests that many riverine fishes shift habitats in response to changing environmental conditions, and supports, at the assemblage level, the paradigm of lotic fishes switching from shallower, high‐velocity habitats in summer to deeper, low‐velocity habitats in winter, and of using shallower, low‐velocity habitats during periods of high discharge. Results also indicate that different species within temperate river fish assemblages show similar habitat use patterns at multiple scales in response to environmental gradients, but that non‐random use of available habitats is more frequent at small scales. 相似文献
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D. CAISSIE 《Freshwater Biology》2006,51(8):1389-1406
1. The thermal regime of rivers plays an important role in the overall health of aquatic ecosystems, including water quality issues and the distribution of aquatic species within the river environment. Consequently, for conducting environmental impact assessments as well as for effective fisheries management, it is important to understand the thermal behaviour of rivers and related heat exchange processes. 2. This study reviews the different river thermal processes responsible for water temperature variability on both the temporal (e.g. diel, daily, seasonal) and spatial scales, as well as providing information related to different water temperature models currently found in the literature. 3. Water temperature models are generally classified into three groups: regression, stochastic and deterministic models. Deterministic models employ an energy budget approach to predict river water temperature, whereas regression and stochastic models generally rely on air to water temperature relationships. 4. Water temperature variability can occur naturally or as a result of anthropogenic perturbations, such as thermal pollution, deforestation, flow modification and climate change. Literature information is provided on the thermal regime of rivers in relation to anthropogenic impacts and such information will contribute to the better protection of fish habitat and more efficient fisheries management. 相似文献
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太湖流域宜兴片河流生境质量评价 总被引：7，自引：0，他引：7
建立包含河道生境、河岸生境和滨岸带生境3方面共10项的河流生境质量评价指标体系,对太湖流域宜兴片42个样点进行生境评价及空间差异比较,分析不同土地利用类型下河流生境各参数的差异性,探讨河流生境质量指数与富营养化综合指数的相关关系。结果表明:河流生境质量指数分值介于29～79,31.0%样点生境质量处于较差和很差等级,57.1%样点为一般等级,表明整体上生境退化明显;南部丘陵山区河流的生境质量状况好于广大的平原河网区;不同土地利用类型下河流生境质量差异显著,林地区域的生境质量明显好于耕地和建设用地;河流生境质量指数与富营养化综合指数显著负相关,说明水质状况对河流生境质量具有较大贡献。 相似文献
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and use and urban activity in the catchment of the Scheldt river system have deeply changed during the last 50 years, modifying in turn the water quality of the drainage network and the fluxes of nutrient transferred to the estuary and to the sea. Based on the RIVERSTRAHLER model, developed for establishing the link between the biogeochemical functioning of large river systems and the constraints set by the meteorology, the morphology of the drainage network and the human activity in the watershed, we reassembled the data available to document these constraints in the Scheldt basin since the last half of the XXth century and we used them to reconstruct the variations of nutrient and oxygen concentrations at the outlet of the Scheldt drainage network. We compared the results with the water quality data at the entrance of the estuarine zone available since the 1960s. Both model results and observational data show a very severe deterioration of water quality (with deep oxygen depletion) in the beginning of the 1960s, while a clear trend to improvement is apparent since the late 1980s. The budget of nutrient loadings from the watershed, retention within the drainage network and delivery to the estuarine zone is established on an annual basis for the 50 last years. The yearly fluxes of nutrient delivered by the river to the estuary and the sea show a severe depletion of silica with respect to nitrogen compared with the requirements of diatoms, and a clear shift from the early 1990s from nitrogen to phosphorus potential limitation. Seasonal variations of nutrient delivery are however much more pronounced for nitrogen, with much less inputs during the dry seasons, while phosphorus inputs, mainly from point sources are more constant, so that nitrogen limitation can still occur during summer. Compared with similar budget estimations carried out for the Seine river system, the Scheldt basin, in spite of its much higher population density, does not deliver higher specific fluxes of nutrient (presently about 2000 kgN/km2/yr, 80 kgP/km2/yr and 1000 kgSi/km2/yr), owing to very efficient processes of nutrient retention. 相似文献
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Gross primary production, community respiration and reaeration coefficient were determined during an annual cycle on the Viroin
River (South Belgium), based on the daily variations of dissolved oxygen concentration.
Reaeration coefficient remains remarkably constant (0.26 h−1) during the year in spite of discharge variations. The autotrophic community is dominated by ‘Ranunculus fluitans’. Primary production parallels the variations of total solar radiations. It ranges from 0 in winter to 8 g O2 m−2 d−1 in summer. In spring and summer, respiration variations parallel those of primary production (average value: 10 g O2 m−2 d−1); in the dry autumn, decomposition of dying macrophytes considerably enhances the community respiration (15 g O2 m−2 d−1).
A P/R diagram is used to characterize the trophic state of the Viroin. 相似文献
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1. Winged stages of Ephoron shigae were collected every day during their emergence period during a 6-year period from 1989 to 1994, by net sweeps or a light trap along the Asahi-gawa River in western Japan. Emergence occurred mainly in September. 2. Coefficients of determination (r2) were calculated for the regression of the mean date of emergence against cumulative degree-days during various periods from late March to early September. 3. In both sexes the highest values of r2 were obtained for regression with degree-days from late June to late August. This indicates that thermal conditions during the late instars affected the emergence timing most strongly. The timing of emergence can be well predicted from the cumulative degree-days during summer. 相似文献
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- Rivers around the world are undergoing shifts in thermal regime due to climate change and human appropriation of water resources. The local impacts of thermal regime change are challenging to predict because water temperature can influence aquatic organisms and communities at multiple levels simultaneously. For example, thermal change can influence the phenology of periphyton blooms, primary consumer physiology and behaviour, and interspecific interactions with predators.
- Using tadpoles of the threatened river‐breeding foothill yellow‐legged frog (Rana boylii, Ranidae), their algal foods and their invertebrate predators, we mimicked dam‐induced changes in temperature and observed the outcome of consumer–resource interactions. In stream enclosures, we reared tadpoles across a gradient of cold to warm conditions, quantified the ash content of diet, digestive efficiency and growth rate, and assessed their vulnerability to hemipteran and odonate predators.
- Tadpoles reared in a cool stream (15.5°C daily mean) digested epilithic periphyton poorly (6.6 ± 0.4% assimilation efficiency). In contrast, average assimilation efficiency of tadpoles reared at 19°C was 11.6 ± 0.1%. Access to nutritious diatoms (i.e. dinitrogen‐fixing Epithemia spp., Rhopalodiaceae) increased assimilation efficiency to 10.1 ± 0.1% and 13.8 ± 0.1% in the cool and warm treatments, respectively. Assimilation efficiency correlated positively with tadpole growth rate (R = 0.66, p < .001).
- The effect of temperature on mortality due to predation was mediated by low tadpole growth rates at cool temperatures and not by the temperature of predator exposure. Non‐lethal effects of predators on tadpole growth and tail injury, however, depended on both rearing temperature and exposure temperature. Contrary to the expectation that the cost of predator avoidance behaviours may be greater at warmer exposure temperatures because basal metabolic rates are higher, our results indicated that the energetic cost of foraging less was amplified at cool temperatures.
- Our results show that when thermal conditions impair digestion in a species’ early life stages, recruitment bottlenecks are likely to arise due to the combined negative effects of cool temperatures on assimilation efficiency and growth, and increased predation by invertebrates.
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In this study, effects of stock origin, fish size, water flow and temperature on time of river ascent of adult Atlantic salmon Salmo salar were tested. Brood stocks were collected in eight Norwegian rivers situated between 59 and 69° N. The fish were reared to smolts, individually tagged and released in the River Imsa, south-west Norway (59° N). Adults from all stocks approached the Norwegian coast concurrently, but Atlantic salmon ≥70 cm in natural tip length entered coastal water slightly earlier during summer than smaller fish. Atlantic salmon <70 cm, however, ascended the river significantly earlier and at lower water flow and higher water temperature than larger fish. Although largest in size, the fish from the northern populations (62–69° N) ascended the River Imsa almost 1 month earlier than those from the south (59–60° N). They seemed less restricted by the environmental factors than the fish originating from the more southern rivers. There was no apparent trend among years in time of river ascent. Maximum ascent per day occurred at water discharges between 12·5 and 15 m3 s−1 and at water temperatures between 10 and 12·5° C. There was a significant positive correlation between water flow and river ascent during the first part of the upstream run from July to September with best correlation for September, when multiple regression analysis indicated that water temperature had an additional positive effect. Stock origin, fish size and water discharge were important variables influencing the upstream migration of Atlantic salmon in small rivers. 相似文献
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I. S. A. Nather Khan 《International Review of Hydrobiology》1992,77(3):391-419
An investigation of the chemical environment of the Linggi River Basin was carried out at 15 main and 27 supplementary stations between January 1983 and January 1984. Spatial and temporal changes in pH, specific conductivity, alkalinity, chloride, ammonia-nitrogen, nitrite-nitrogen, nitrate-nitrogen, orthophosphate, dissolved oxygen, BOD, and diurnal variations were studied in relation to influence of various kinds of pollutants. The chemical composition of natural water analysed at a few undisturbed forest stream stations in the basin can be considered very good. A drastic change in river water quality was noticed in downstream polluted stations. The pH in the basin varied from 4.05 to 10.5 units, conductivity from 23.0–1,500 umhos/cm, alkalinity from 6.0–1,388 mg/l, chloride from 0.9–160.9 mg/l, orthophosphate from 0.5–5.21 mg/l, ammonia-N from 0.001–53.75 mg/l, nitrite-N from 0.0–8.2 mg/l, nitrate-N from 0.03–6.77 mg/l and BOD3, from 0.32–384.0 mg/l and COD from 0.02 to 79.2 unit. Among all the rivers, very high values were recorded at Kundor, Simin and Linggi (sensu stricto). 相似文献
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I. S. A. Nather Khan 《International Review of Hydrobiology》1992,77(2):203-223
The Linggi River Basin is one of the most polluted river basins in Malaysia and drains an area of about 1,399km2 in the state of Negri Sembilan. An extensive multidisciplinary research was carried out to develop a predictive mathematical model to manage the Linggi River basin effectively. This paper reports only the morphometry and other physical environmental conditions of the Linggi River Basin which was carried out between January, 1983 and January, 1984. Topography, vegetation, landuse pattern, general geology and lithology, population distribution and water usage by the people are discussed. In addition, physical information such as air and water temperatures, precipitation, sunshine, discharge, suspended solids and dissolved solids data collected before and after the study period are discussed in detail. 相似文献