绿色巴夫藻培养条件的研究

研究了温度、光照强度、光照时间、酸碱度和相对密度对绿色巴夫藻生长繁殖的影响,结果表明:绿色巴夫藻在水环境pH6 0～9 5、相对密度1 005～1 020的范围内都能生长,pH6 5、相对密度1 015条件下生长率最高;温度在5～35℃范围内都能生长,20～30℃为适宜温度;光照强度在1000～10000Lx范围内都能生长,4000Lx为最适光照强度。光照强度<1000Lx时,绿色巴夫藻的生长速率与光照时间成正比。     

解剖采集的珠母贝精子的激活条件

解剖成熟珠母贝（Pinctada margaritifera)并采集其精子，在不同pH、盐度和温度条件下进行激活实验。结果显示，水温25℃、盐度34、pH8.5以下时，珠母贝精子的激活率与活力均很低，pH9.0-10时激活率与活力均较高，pH9.5时的激活率最高；在水温20℃，盐度34时珠母贝精子只能在pH9.5-10激活，且激活率与活力均比25℃时低。在水温25℃，pH9.5时，精子在盐度10-45能激活，盐度25-35时激活率和活力很高；在水温20℃,pH9.5时，精子只能在盐度20-40时激活。当盐度相同，20℃时的激活率与活力比25℃时低，在pH9.5或10的氨海水中，珠母贝精子在水温5-45℃时能激活，在25-30℃时激活率较高。当温度相同，pH9.5时的激活率比pH10.0时高。解剖得到的珠母贝精子的适宜激活pH9.5、适宜盐度为25-35、适宜温度为25-30℃。     

大鹏澳网箱养殖区沉积物硫酸盐还原菌（SRB）及其与环境因子关系的初步研究

实验采用MPN法测定了大鹏澳网箱养殖区沉积物中硫酸盐还原菌(SRB)的含量,布设的5个站位SRB检出率达100%,SRB平面分布特征是鱼类网箱区>对照区>浮筏贝类区;垂直分布特征为1cm层>5cm层>10cm层,SRB数量是由上向下逐渐减少。探讨了SRB含量与相应沉积物样品中的硫化物含量、氧化还原电位、pH等环境因子的关系。结果表明,沉积物中SRB数量与硫化物含量呈显著性正相关(R=0.96,P<0.05),与氧化还原电位(OPR)呈极显著性负相关(R=-0.97,P<0.01),与pH之间不具有显著性关系。     

Characteristics of burnt meat in cultured yellowtail <Emphasis Type="Italic">Seriola quinqueradiata</Emphasis>

ABSTRACT:   In order to understand the characteristics of burnt meat in cultured yellowtail Seriola quinqueradiata , fish were kept at two different temperatures (13 and 30°C) and slaughtered by either spinal cord destruction (SCD) or suffocation in air (SA). Early postmortem changes during storage at 32°C were analyzed by rheological, biochemical, and histological methods. The burnt meat (with lightness parameter, L* ≥ 55) was observed at 1-h storage in the SA 30°C group, at 2 h in SCD 30°C, and at 4 h in SA 13°C; meat was normal for the SCD 13°C group until 6 h of storage. Breaking strength scores were higher for the normal meat (200 g/cm²) than burnt meat (70 g/cm²) at 4 h of storage. Expressible water content was higher for the burnt meat than for the normal meat. Adenosine triphosphate concentrations for the SCD groups were higher than for the SA counterparts. Moreover, pH decrease was much faster in the 30°C groups, showing pH 5.6 at 2 h of storage. A negative correlation between the pH and lactic acid contents in muscle ( P  < 0.001) was found. Histological analysis evidenced a larger pericellular area (40%) in the burnt samples than in the normal samples (16%). It was confirmed that a higher fish-keeping water temperature and a stressful slaughter method (faster glycolytic process) were determinative factors that influence the occurrence of burnt muscle in yellowtail, and that the effect of the former is larger than the latter.     

Carbon dioxide reversibly inhibits sperm motility and fertilizing ability in steelhead (Oncorhynchus mykiss)

The effects of different carbon dioxide (CO₂) levels on the short-term storage of semen samples from hatchery-produced steelhead (Oncorhynchus mykiss) were evaluated. Sperm motility and fertilizing ability were significantly reduced following 4 h incubation under a relatively modest (0.9 kPa = 1%) amount of CO₂. The dose-dependent reductions, however, were not the result of cell death as sperm viability was unaltered even at the highest (5.2 kPa = 5.6%) CO₂ exposures. Reductions in sperm motility and fertilizing ability were reversible. Although previous work has indicated a direct relationship between salmonid sperm motility and sperm ATP content, the inhibitory effects of CO₂ on sperm motility were not the result of reduced sperm ATP levels. Decreasing the pH of the seminal fluid (to below 7.5) significantly reduced sperm motility. However, this effect was only observed after prolonged (4 h) exposure; short-term (1 min) exposure to this lowered pH did not alter sperm motility. Moreover, acetazolamide, a carbonic anhydrase inhibitor, attenuated the inhibitory effects of CO₂ on sperm motility. These results suggest that CO₂ inhibits steelhead sperm motility and therefore fertility in a dose-dependent manner, by reversibly lowering intracellular pH.     

The physiological response to capture and handling stress in the Atlantic sharpnose shark, Rhizoprionodon terraenovae

Secondary effects of capture and handling stress in the Atlantic sharpnose shark, Rhizoprionodon terraenovae, were investigated in this study. Twenty-four sharks were serially bled and changes in several hematological parameters were monitored over a 1-h time period, following capture by hook-and-line. Blood samples were obtained from each shark at 0, 15, 30, 45 and 60 min. All 0-min (initial) blood samples were obtained within 3 min of capture. Blood glucose (9.2–13.1 mmol l^–1), lactate (1.5–28.9 mmol l^–1), and plasma osmolality (871–929 mOsm kg^–1) all increased after capture, whereas blood pH (6.86–6.78) declined. Hematocrit values (initial = 25.1%) remained unchanged throughout the 1-h stress period. Due to the short amount of time it took to obtain the initial sample and the lack of a significant relationship between the initial time and the initial parameter levels, all initial samples are considered the best approximation of the predisturbance resting levels. The use of repeated measures in this study enables us to describe the dynamics of the secondary stress response in the Atlantic sharpnose shark.     

Extracellular fluid volume measurements in tissues of the rainbow trout (Oncorhynchus mykiss)in vivo and their effects on intracellular pH and ion calculations

Extracellular fluid volume (ECFV) estimates were determined in various tissues and whole body of resting, chronically cannulated rainbow trout (Oncorhynchus mykiss). Fish were infused with¹⁴C-inulin,³H-polyethylene glycol (PEG, M.W. 4000),³H-mannitol, or¹⁴C-mannitol, and values of ECFV determined from tissue: plasma water distribution ratios after 6 h or 13 h equilibration. Overall,³H-PEG provided the most conservative and reliable estimates after 13 h equilibration, with ECFV values in the order: brain < white muscle < red muscle < liver < heart < gill tissue.¹⁴C-inulin yielded generally similar values to³H-PEG at 13 h, but probably overestimated ECFV in liver.³H-mannitol and¹⁴C-mannitol spaces were similar to each other and far greater than³H-PEG or¹⁴C-inulin values in most tissues.³H-mannitol values increased significantly between 6 h and 13 h, in contrast to¹⁴C-inulin. Mannitol clearly overestimated ECFV in liver and gill, and probably also heart and whole body, but may have provided more realistic estimates in brain due to better penetration of the blood-brain barrier. The Cl^–/K⁺ space technique overestimated ECFV in gills, but was satisfactory in white muscle. Measurements and model calculations evaluated sources of error in intracellular pH (by¹⁴C-DMO) and ion determinations. Trapped red cells in the gills have negligible influence. Errors in ECFV are much more influential in a tissue with a high ECFV (gills) than a low ECFV (white muscle).³H-PEG is the marker of choice for intracellular pH determinations. However, even when³H-PEG is used, the potential for absolute errors in intracellular ion concentrations remains high.     

昆明裂腹鱼淀粉酶活性研究

用碘─淀粉比色法研究鱼类离体消化器官淀粉活性,测得在最适pH和最适温度条件下,昆明裂腹鱼胃、前肠、中肠、后肠和肝等主要消化器官淀粉酶活性分别为669.5、789.23、796.86、786.15和733.15个淀粉酶活性单位,淀粉活性最高的是中肠,最低的是胃。其最适pH为7.4~8.6,最适温度为30~45℃。     

施用10％草甘膦水剂对土壤环境的影响

本文通过三地田间试验,研究了长期施用草甘膦水剂对土壤性质的影响。结果表明,湖北罗田、潜江和广水三地土壤的电导率、钠碱化度、钠吸附比、pH值和总碱度均呈现增加的现象,虽然根据国内对盐碱土的分类标准指标三地均属于非盐化和碱化土,但有盐化和碱化的趋势。     

Effects of Wood Ash Dose and Formulation on Soil Chemistry at Two Coniferous Forest Sites

Harvesting stem biomass from the forest inevitably involves exporting nutrients from the ecosystem. The amount exported is increased when the logging residues are also removed for use as fuel. Recycling of the resulting wood ash has been advocated as a measure to compensate for the nutrient losses and to sustain future forest production. The physical formulation of the wood ash may have an important influence on its effects on soil properties. In this paper, we report effects of two different types of wood ash (one self-hardened and crushed, the other pelleted), with differences in solubility, on soil chemistry in the humus layer and upper 15 cm of the mineral soil, at two coniferous sites in south-central Sweden, 5 yr after their application. The crushed ash was applied at three doses (3, 6 and 9 ton ha^–1), while the pelleted ash was applied at only one dose (3 ton ha^–1). At both sites the soil was podzolized. The two sites differed with respect to soil conditions, despite being situated only a few kilometers apart. The application of wood ash increased both soil pH and base-cation content in the humus layer at both sites. In the mineral soil, the effects were less pronounced. Treatment effects on soil chemistry did not differ between the two ash formulations. The retention (i.e. the extractable amount of nutrients found in the soil that could be attributed to the ash application) of nutrients varied strongly between the two sites, and K retention (ca. 10%) was generally lower than that of Ca and Mg.