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1.
As basic research for the effect of heavy oil on the fish immune system, in this study, the number of leukocyte was counted in Japanese flounder Paralichthys olivaceus, after exposure to heavy oil at a concentration of 30 g/8 L for 3 days. To compare the numbers of bacteria in the skin mucus between oil-exposed and control fish, viable bacteria were enumerated by counting colony forming unit (CFU). Compared with 5.79 ± 1.88 × 107 leukocytes/mL in the controls, the exposed fish demonstrated higher counts, averaging 1.45 ± 0.45 × 108 cells/mL. The bacterial numbers of control fish were 4.27 ± 3.68 × 104 CFU/g, whereas they were 4.58 ± 1.63 × 105 CFU/g in the exposed fish. The results suggest that immune suppression of the fish occurred due to heavy oil stressor, and bacteria could invade in the mucus, resulting in the increasing leukocyte number to prevent infectious disease.  相似文献   

2.
Protein digestibility was determined via two feeding trials in glass aquaria by the indicator (Chromium oxide) method using a mixture of shrimp powder with oil cake and wheat bran respectively (1: 1 W/W) as food. Analyses of feed were made to calculate the crude protein, carbohydrate, lipid and ash contents. Feces were analysed to determine their total nitrogen and chromium oxide. Protein digestibility was studied in relation to salinity of the medium size and weight of the fish body. The apparent digestibility of crude protein of a corresponding die has shown that 1st: Younger fish do possess a lower capability of protein digestion than fish having a medium weight and medium size; 2nd: Older fish with a high weight and large size exhibit no improvement in efficiency to digest the food protein, though their weight and size are significantly greater than those of middle weight and medium size fish; 3rd: The replacement of oil cake by wheat bran decreases the protein digestibility of shrimp powder mixture with them; 4th: A salinity (NaCl) of the aquatic medium at or above 3 g/l depletes the protein digestibility when fish of the same size were experimented with; but a salinity up to 2 g/l does not result in a significant decrease in the protein digestion rate.  相似文献   

3.
低湿洼地鱼塘中异养细菌的矿化作用   总被引：3，自引：1，他引：2  
高光 《湖泊科学》1998,10(3):61-67
对黄淮海平原低湿洼地鱼塘中异常细菌的矿化作用进行了初步研究,结果表明：（１）鱼塘水体中异养细菌的呼吸强度与鱼塘水体中的有机物质含量及温度密切相关;（２）鱼塘水体中异养细菌的生物量表现出明显的季节性变化;异养细菌的生物量在表层水及底层水之间的差异不明显。（３）鱼塘水体中异常细菌分解有机物质的动力学特点如下：开始时,鱼塘水体中有机物质的转化较少,随温度的增高及异养细菌生物量的增加,水体中的矿化作用逐渐  相似文献   

4.
As basic research for the effect of heavy oil on the fish immune system, in this study, the number of leukocyte was counted in Japanese flounder Paralichthys olivaceus, after exposure to heavy oil at a concentration of 30 g/8L for 3 days. To compare the numbers of bacteria in the skin mucus between oil-exposed and control fish, viable bacteria were enumerated by counting colony forming unit (CFU). Compared with 5.79+/-1.88 x 10(7)leukocytes/mL in the controls, the exposed fish demonstrated higher counts, averaging 1.45+/-0.45 x 10(8)cells/mL. The bacterial numbers of control fish were 4.27+/-3.68 x 10(4)CFU/g, whereas they were 4.58+/-1.63 x 10(5)CFU/g in the exposed fish. The results suggest that immune suppression of the fish occurred due to heavy oil stressor, and bacteria could invade in the mucus, resulting in the increasing leukocyte number to prevent infectious disease.  相似文献   

5.
The spatial and seasonal distribution of the viable heterotrophic population and three heterotrophic physiological groups, i.e. ammonifyers, nitrate reducers and sulphate reducers, were studied in two reservoirs in the province of Vizcaya (Spain). Using indicative parameters, both reservoirs were classified as warm monomictics, one hypereutrophic and the other mesotrophic. A direct relation between the size of the bacterial populations and the trophic levels of the reservoirs was observed. Likewise, the distributions of the bacterial populations in the water column are basically different. In the hypereutrophic lake there is a direct relationship between the bacterial distribution and the physical-chemical environment of the reservoir that cannot be observed in the mesotrophic lake.  相似文献   

6.
Different experimental conditions (fed large, fed small, starved large, starved small groups, batch offered ration during experiment and low fish loading for a constant volume of water) of the carnivorous fish Clarias batrachus resulted in marked changes in the concentration of different N species (ammonium-N, nitrate-N, nitrate-N, organic-N as well as the sum of all forms of N) in aquaria water. Organic forms of nitrogen were the most important species of nitrogen excreted by the test fish. The maintenance nitrogen excretion rate was distinctly higher in larger fishes than in smaller ones. Different species of N were found to differ significantly depending upon the fed or starved conditions as well as small or large groups. A reduced level of oxygen in experimental aquaria inhibited the synthesis of nitrate which was maximum in control aquaria with considerably higher values of oxygen.  相似文献   

7.
In bioassays in aquaria, the dying of Escherichia coli was accelerated by Glyceria maxima, Schoenoplectus lacustris, Alisma plantago-aquatica as well as Mentha aquatia as compared with check tanks without any plants (initial concentration 15 × 103 colony-forming units per ml). As expected, by this the antibacterial effect of the limnic macrophytes attains its maximum effectivity within the first days of the period of investigation. The decimal time of reduction is shortened by one third to half, the centimal reduction time is shortened by one fourth to one third. Mean contact times of 7… 11 h are required for the decimation of bacteria by 90 %, and mean contact times of 16… 19 h are necessary for a 99 % reduction of the population. Possibly, the antibacterial effect in mixed stands of different plant species is increased additively or superadditively.  相似文献   

8.
Algae growing in an enclosed sea may inhibit eutrophication because they absorb nutrients in the water. However, dead algae often cause anaerobic conditions in the water just above and on sediment after they are deposited on the bottom. We found that Stichopus japonicus inhibited the anaerobic processes coupling water sulfite production in sediment. The present study investigates whether S. japonicus inhibits algal flourish and influences sediment properties such as organic matter contents. Aquarium experiments were carried out at Komatsushima port in Tokushima Prefecture, western Japan. The aquaria used in the experiments were supplied with water directly from the adjacent sea (6 L/min), laid with sand of 10 cm depths, and lighted at 12 h intervals. Six aquaria each containing a sea cucumber from Komatsushima port and six aquaria without any were used in the experiments. Water temperature ranged between 9 and 15 degrees C during December 2000 and April 2001. Salinity ranged between 32 per thousand and 34 per thousand. Algae began to cover the bottom of the aquaria without S. japonicus after 2 weeks, whereas no growth was evident in the aquaria containing sea cucumbers. Chlorophyll a concentration in the surface sediment of the aquaria with S. japonicus (6.1+/-3.6 microg/g, mean S.D.+/-standard deviation) was significantly lower than that without it (60+/-17 microg/g, U-test, p<0.05). Phaeophytin concentration in the surface sediment of the aquaria with S. japonicus (0.9+/-0.09 microg/g) was also significantly lower than that without it (4.5+/-1.0 microg/g, U-test, p<0.05). TOC concentration in the surface sediment of the aquaria with S. japonicus (2.6+/-1.3 microg/g) was slightly lower than that without it (4.0+/-1.2 microg/g). These results showed that algal biomass and organic matter concentration of the bottom were decreased in the presence of S. japonicus. Therefore, S. japonicus inhibits algal bloom and decrease the contents of organic matter deposited on the bottom of enclosed sea areas.  相似文献   

9.
Juveniles ofCoregonus lavaretus L. of a body weight (wet weight) between 0.5 and 11g were fed on pond reared livingDaphnia pulicaria. The fish were held in groups of 4 to 8 fish in tanks of a volume of 10 to 20 l at water temperatures of 8, 12, 16 and 20°C. After a deprivation time of 24 h the fish were fed an amount of livingDaphnia of about 1000 specimen/l. Fish of a body weight (wet weight) less than 1 g showed a continuous food intake until satiation, whereas the food intake of bigger fish was divided into three phases: During a first feeding period 50 to 73% of the satiation amount were consumed. This feeding period was followed by a period of no food intake, which was followed by a second feeding period. At the end of the second feeding period the fish were satiated. The period of no food intake is considered to be a specific adaptation to planctivory. The satiation time (min) increased with increasing body weight and increasing water temperature. The satiation amount, i.e. the amount of food eaten until satiation (mg stomach content, dry weight) increased with increasing body weight. The satiation amount expressed in % body weight (dry weight/dry weight) reached a maximum of 10% for fish of a body weight of 1 g. With increasing body weight it decreased to 5% for fish of 11 g b.wt. At 8°C the satiation amount was significantly lower than at 12°C. The experiments were performed at the Limnological Institute, University of Constance, D-7750 Constance, Federal Republic of Germany.  相似文献   

10.
Spatial and seasonal fluctuations in autotrophic picoplankton (APP) abundance in a eutrophic, dimictic lake (Lake Aydat, France) were measured concurrently with a variety of environmental variables. Cell number ranged from 0.03 to 2.36×106 cells·ml–1 (highest concentrations were >5-fold higher than in oligotrophic lakes) and averaged 24 ± 7% of total picoplankton abundance (APP + heterotrophic bacteria). APP abundance (1) peaked in spring simultaneously with heterotrophic flagellate and ciliate densities, (2) decreased during the nitrogen-limited and summer stratification period, and (3) increased with fall turnover. In summer-autumn, the contribution of single-cell eukaryotic (up to 66%) and colonial prokaryotic (18%) forms to total abundance peaked in the bottom waters. Multivariate regression analyses suggest that >40% variance in APP number changes may be explained by ciliate abundance (at 0–4 m depth-range), heterotrophic flagellate number and oxygen concentration (5–9 m), and ciliate carbon biomass (10–14 m). The model accounting for changes in heterotrophic bacterial abundance (5–9 m) indicates chlorophylla concentration (r 2=58%) and ciliate abundance (r 2=34%) as dominant covariates. The data presented here suggest that micrograzers control APP abundance in Lake Aydat.  相似文献   

11.
大口鲇幼鱼摄食、生长及驯化的初步研究   总被引：19，自引：4，他引：15  
根据1991年1～12月的调查,陆水水库的浮游植物共8门118属,以绿藻、硅藻、蓝藻门的种类为主,占总属数的86.44％;浮游动物198种,其中原生动物38种、轮虫68种、枝角类61种、桡足类31种。浮游植物年平均数量和生物量分别为3.1449×10~6cell/L和1.937mg/L,数量以蓝藻、隐藻、硅藻最多,占总数量的91.33％,生物量以隐藻、硅藻、绿藻最大,占总生物量的85.03％,浮游植物初级毛产量为3.4gO_2/m~2·d。浮游动物年平均数量和生物量分别为2323.8ind/L和1.4837mg/L,数量以原生动物和轮虫最多,占96.89％,生物量以枝角类和桡足类为主,占79.94％.陆水水库浮游生物种类组成和现存量在不同的水域差异较大,季节变化明显。按水化学分析结果及浮游生物特征判定,陆水水库的营养类型为中营养型。还讨论了环境因子对水库浮游生物的影响。  相似文献   

12.
An algal culture medium was developed which reflects the extreme chemical conditions of acidic mining lakes (pH 2.7, high concentrations of iron and sulfate) and remains stable without addition of organic carbon sources. It enables controlled experiments e.g. on the heterotrophic potential of pigmented flagellates in the laboratory. Various plankton organisms isolated from acidic lakes were successfully cultivated in this medium. The growth rates of a Chlamydomonas isolate from acidic mining lakes were assessed by measuring cell densities under pure autotrophic and heterotrophic conditions (with glucose as organic C‐source) and showed values of 0.74 and 0.40, respectively.  相似文献   

13.
The level of hydrocarbons present in the sediments of real estate canals on the east and west coast of Florida was determined using gas chromatography. Although the amount of alkanes present was found to be comparatively low, the ratio of the amount of odd carbon-numbered alkanes to even carbon-numbered alkanes suggested that canals on the Gulf of Mexico are receiving an influx of petroleum products. In addition, the most probable number technique was used to enumerate total aerobic heterotrophic bacteria, aerobic hydrocarbon-degrading bacteria, sulfate reducing bacteria, and sulfate-reducing hydrocarbon-degrading bacteria present in the canal sediments. Results showed significantly higher numbers of hydrocarbon degrading bacteria in the sediments of the west coast canals.  相似文献   

14.
The plants and animals that inhabit river channels may act as zoogeomorphic agents affecting the nature and rates of sediment recruitment, transport and deposition. The impact of benthic‐feeding fish, which disturb bed material sediments during their search for food, has received very little attention, even though benthic feeding species are widespread in rivers and may collectively expend significant amounts of energy foraging across the bed. An ex situ experiment was conducted to investigate the impact of a benthic feeding fish (Barbel Barbus barbus) on particle displacements, bed sediment structures, gravel entrainment and transport fluxes. In a laboratory flume changes in bed surface topography were measured and grain displacements examined when an imbricated, water‐worked bed of 5.6 to 16 mm gravels was exposed to feeding juvenile Barbel (on average, 0.195 m in length). Grain entrainment rates and bedload fluxes were measured under a moderate transport regime for substrates that had been exposed to feeding fish and control substrates which had not. On average, approximately 37% of the substrate, by area, was modified by foraging fish during a four‐hour treatment period, resulting in increased microtopographic roughness and reduced particle imbrication. Structural changes by fish corresponded with an average increase in bedload flux of 60% under entrainment flows, whilst on average the total number of grains transported during the entrainment phase was 82% higher from substrates that had been disturbed by Barbel. Together, these results indicate that by increasing surface microtopography and undoing the naturally stable structures produced by water working, foraging can increase the mobility of gravel‐bed materials. An interesting implication of this result is that by increasing the quantity of available, transportable sediment and lowering entrainment thresholds, benthic feeding might affect bedload fluxes in gravel‐bed rivers. The evidence presented here is sufficient to suggest that further investigation of this possibility is warranted. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

15.
Arsenotrophic bacteria contribute to the nutrient cycling in arsenic (As) affected groundwater. This study employed a culture‐independent and ‐dependent investigation of arsenotrophic microbiomes in As affected groundwater samples collected from Madhabpur, Sonatengra, and Union Porishod in Singair Upazila, Manikganj, Bangladesh. Total As contents, detected by Atomic Absorption Spectrophotometry (AAS) of the samples, were 47 µg/L (Madhabpur, SNGW‐1), 53 µg/L (Sonatengra, SNGW‐2), and 12 µg/L (Union porishod, SNGW‐3), whereas the control well (SNGW‐4; depths >150 m) showed As content of 6 µg/L. Denaturing Gradient Gel Electrophoresis (DGGE) analysis of the amplified 16S rRNA gene from As‐affected groundwater samples revealed the dominance of aerobic bacteria Pseudomonas within heterogeneous bacterial populations. DGGE of heterotrophic enrichments supplemented with arsenite [As (III)] for 4 weeks showed the dominance of Chryseobacterium, Flavobacterium, and Aquabacterium, whereas the dominant genera in that of autotrophic enrichments were Aeromonas, Acinetobacter, and Pseudomonas. Cultured bacteria retrieved from both autotrophic and heterotrophic enrichments were distinguished into nine genotypes belonging to Chryseobacterium, Acinetobacter, Escherichia, Pseudomonas, Stenotrophomonas, Janibacter, Staphylococcus, and Bacillus. They exhibited varying range of As(III) tolerance from 4 to 27 mM. As(III) transformation potential was confirmed within the isolates with oxidation rate as high as 0.143 mM/h for Pseudomonas sp. Sn 28. The arsenotrophic microbiome specifies their potential role in groundwater As‐cycling and their genetic information provide the scientific basis for As‐bioremediation.  相似文献   

16.
The fish fauna in the northern part of the upper river Rhine close to the city of Karlsruhe (Germany) was analyzed by collecting fish from the cooling-water intake of a power plant (impingement method) between 1989 and 2001. With this method a total of 36 fish species were recorded. The results were compared between the years as well as with other studies on the fish fauna in this area. Particularly with regard to the physical structure of the river bed and banks, the pre-technical situation of the river Rhine has not been restored. However, the number of fish species has been augmented since the 1970s mainly due to improvements in the water quality and almost all autochthonous fish species are present again. Altogether only three introduced fish species (Sander lucioperca L., Lepomis gibbosus L., and Carassius auratus gibelio were found in this study. Among the long-distance migrating species three freshwater spawners (Lampetra fluviatilis, Petromyzon marinus and Salmo trutta trutta) were detected in addition to the catadromous eel. The eudominant fish species varied between years, i.e. the European eel, Anguilla anguilla, was the eudominant species 1989, whereas this species occurred in much lower numbers during the subsequent sampling campaigns. This clearly indicates that the high dominance of eels is mainly caused by stocking activities in the upper Rhine. In the following years roach, Rutilus rutilus was the eudominant fish species. Overall a positive development of the fish fauna in the upper Rhine over the last 15 years could be observed in terms of fish populations as well as in terms of species richness.  相似文献   

17.
Foraging by benthivorous fish can affect bed material mobility and sediment flux. This paper collates evidence of benthic feeding effects at local scales and evaluates the possibility that large numbers of foraging fish, each of which accomplishes a small amount of geomorphic work when feeding, may have a cumulative effect across river systems. A first synthesis of research from several disciplines provides a deeper understanding of how fish disturb and condition bed materials with implications for sediment mobility. To evaluate the spatial extent of benthic feeding and therefore the potential for it to have a large-scale effect, the distribution of benthivorous fish is established across a large river network. After quality control, the dataset yields a comprehensive set of fish community information based on over 61 000 individuals and 30 species at 176 sites. The factors that are likely to mediate foraging and its geomorphological effectiveness are considered. A novel scoring system that incorporates three key controls (fish feeding behaviour, fish abundance and fish body size) is then applied across the river network to predict where geomorphologically effective benthic feeding is feasible and its possible relative magnitude. Our results demonstrate, for the first time, that the potential for zoogeomorphic impacts is widespread but variable in space as a function of community composition and the abundance of key benthivores. An initial calibration against measured field impacts suggests that benthic feeding may cause measurable geomorphological disturbance at more than 90% of sites in this large network. Together, previous work and this unique analysis suggest that benthic feeding is sufficiently effective and extensive to warrant additional research. Investigating the role of benthivorous fish in fluvial geomorphology is important because it may yield results that challenge the assumption that biota are irrelevant sources of energy in geomorphological systems. Key research questions and a roadmap to facilitate progress are identified. © 2018 John Wiley & Sons, Ltd.  相似文献   

18.
溶解氧对低洼盐碱地鱼塘物质循环的影响   总被引：1，自引：0，他引：1  
对黄淮海平原低洼盐碱地鱼塘中溶解氧与物质循环之间的关系进行了初步研究. 结果表明池塘水体中的溶解氧含量取决于水体中藻类的光合作用及其它生物的耗氧作用扰动的方式时间可显著改变水体中溶解氧的含量. 池塘水体中异养细菌的数量变动除与水体中的有机物质含量等有关外与水体中溶解氧的含量密切相关. 尤其在底泥中这种变化更加明显. 池塘水体中的氨化作用强度磷的转化强度明显地呈现出受水体中的溶解氧含量影响. 当水体中的溶解氧含量增加时导致细菌的现存量及活性的增加使得氨化作用强度磷的转化强度也显著增加这种情况在底泥中表现的更加明显. 池塘水体中反硝化作用强度反硫化作用强度的变化则与水体中溶解氧含量的变化相反. 当水体中溶解氧的含量减少时水体中的反硝化作用强度反硫化作用强度反而大大增加. 这种作用在底泥中表现得也非常明显.  相似文献   

19.
《Marine pollution bulletin》2009,58(6-12):889-894
As basic research for the effect of heavy oil on the fish immune system, in this study, the number of leukocyte was counted in Japanese flounder Paralichthys olivaceus, after exposure to heavy oil at a concentration of 30 g/8 L for 3 days. To compare the numbers of bacteria in the skin mucus between oil-exposed and control fish, viable bacteria were enumerated by counting colony forming unit (CFU). Compared with 5.79 ± 1.88 × 107 leukocytes/mL in the controls, the exposed fish demonstrated higher counts, averaging 1.45 ± 0.45 × 108 cells/mL. The bacterial numbers of control fish were 4.27 ± 3.68 × 104 CFU/g, whereas they were 4.58 ± 1.63 × 105 CFU/g in the exposed fish. The results suggest that immune suppression of the fish occurred due to heavy oil stressor, and bacteria could invade in the mucus, resulting in the increasing leukocyte number to prevent infectious disease.  相似文献   

20.
千岛湖水环境质量调查与保护对策   总被引：5，自引：0，他引：5  
1992年7～8月,对大口鲇幼鱼进行了不同饲料喂养和驯化试验,对其摄食、生长进行了研究。试验表明,大口鲇生长迅速,尤其投喂适口的活鱼,其生长速度极快,21天增重2.67～4.60倍,比投喂鱼肉组的体重增长快37.9％～84.3％。具有早晚摄食的习性,平均每克体重日摄食活鱼量为0.1～0.2g,摄食鱼肉量为0.18～0.29g,其饲料系数前者为2.32～3.12,后者为4.15～7.86。试验还表明,大口鲇幼鱼亦摄食人工混合饲料,5cm左右便可用人工饲料进行驯化,但驯化过程要逐渐过渡,驯化期间生长速度受到影响,饲料系数亦较高。  相似文献   

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