The effect of dietary protein on the growth and survival of the shrimp, Penaeus monodon in outdoor tanks

The comparative effect of reducing the protein content of formulated feed on the growth and survival of black tiger shrimp, Penaeus monodon, and on water quality was tested in outdoor tanks. Three diets, 300, 350 and 400 g kg^?1 crude protein (CP), were fed to P. monodon (3.1 g animals, 25 animals per m²) in each of eight replicated outdoor 2500 L tanks in an 8‐week trial. There was no statistical difference (P > 0.05) in shrimp growth rate (1.34–1.50 g week^?1), survival, or final biomass between the treatments. However, when tanks with lower survival were removed from the analysis (<60 and <80% were tested), shrimp growth rate was statistically higher (P < 0.05) in the 350 and 400 g kg^?1 CP diets than in the 300 g kg^?1 CP diet treatment. There were no differences in the nutritional condition of shrimp between treatments, as determined by moisture and protein content, and lipid content of the digestive gland. Using ¹⁵N‐nitrogen isotope tracers, it was determined that shrimp were consuming natural biota, although these were unlikely to have contributed substantially to their nutrition. Total nitrogen (TN) concentrations in the water column increased over the eight week experiment and were statistically different (P < 0.001) between treatments (3.60, 5.17 and 6.45 mg L^?1 in the 300, 350 and 400 g kg^?1 CP treatments, respectively). Concentrations of dissolved organic nitrogen (DON) were also statistically different between treatments and made up 35–40% of the TN in the water column. Concentrations of total ammoniacal nitrogen (TAN) and oxides of nitrogen, and fluorescence were not statistically different between treatments but there was a trend of higher concentrations in treatments with higher protein levels. There was no difference in sediment nutrients between treatments. This study has shown that there is scope to reduce the protein content of P. monodon diets but only by 5–10%. However, further validation of these results in commercial ponds is needed. Reducing the feed protein content may result in cost savings and also has the advantage of improving water quality and reducing nitrogen discharge.     

Phosphorus removal in a marine prototype, recirculating aquaculture system

Phosphorus dynamics were examined in a prototype, zero-discharge, marine-recirculating system. Operation of the system without discharge of water and sludge was enabled by recirculation of effluent water through two separate treatment loops. Surface water from the fish basin was pumped over a trickling filter in one loop, while bottom-water was recirculated through a sedimentation basin followed by a fluidized bed reactor in the other treatment loop. Ammonia oxidation to nitrate in the trickling filter and organic matter digestion together with nitrate reduction in the sedimentation basin and fluidized bed reactor were the main biological features of this treatment system. Orthophosphate concentrations did not exceed 15 mg PO₄–P/l in the culture water during more than 1 year of system operation. Much of the phosphorus was retained within the sedimentation basin and fluidized bed reactor. In these treatment stages, the phosphorus content of organic matter was as high as 17.5% and 19%, respectively. High concentrations of total phosphorus and low concentrations of soluble orthophosphate were measured in the initial stages of sedimentation under oxic and anoxic conditions, suggesting that most of the phosphorus was associated with organic matter. Depletion of oxygen and nitrate in the sludge layers of the sedimentation basin coincided with sulfate reduction to sulfide and a release of soluble orthophosphate. The observed phosphorus dynamics in this marine system supported findings from previous studies in which it was demonstrated that denitrifiers underlie phosphorus immobilization under these conditions.     

深沪湾海水、沉积物及贝类体内重金属的含量与评价

利用1998年5月和9月深沪湾海域环境调查资料，着重分析了深炉湾海水、表层沉积物及褶牡蛎和菲律宾蛤仔体内重金属的含量及分布，结果表明：深沪湾海水中Cu、Pb、Cd、Zn、Hg等含量均低于渔业水质标准，而表层沉积物的Pb、Zn含量大部分已超标，近岸水域海水和表层沉积物中Cu、Pb、Cd、Zn的含量明显高于湾中心水域，湾顶水域高于湾口水域。Hg的含量是湾南部水域高于北部水域。文中还根据全国海岸带污染综合调查专业组制定的海洋生物污染评价标准，对2种贝类的重金属污染程度进行评价，结果深沪湾的养殖贝类体内的重金属含量均未超标。     

Effect of water temperature and chlorophyll abundance on shell growth of the Japanese pearl oyster, Pinctada fucata martensii, in suspended culture at different depths and sites

To understand the relationships between shell growth and some environmental factors, we examined the relationships between water temperature or chlorophyll abundance and the shell growth of the Japanese pearl oyster, Pinctada fucata martensii, suspended at three different depths at two sites. Growth in height, length and thickness of the shells were limited by water temperature during winter (< 20 °C), whereas growth in thickness correlated with food abundance, measured as chlorophyll, during early summer (> 20 °C). These results suggest that the shell of P. fucata martensii could grow well at locations with greater abundance of food and adequate water temperatures (20–26 °C), resulting in a longer growing season.     

湛江港沙湾对虾养殖场虾池水质状况分析

2002年4～7月,对湛江港沙湾对虾养殖场虾池的水质及对虾的生长情况进行连续监测,应用单项指标评价、富营养化评价等方法,对该养殖场的水质状况进行了评价和营养分级。结果表明,该养殖场的水质呈高N低P状态,水温、DO和大部分池的pH、DRP符合第二类海水水质标准,DIN超标,超标率达70%,该养殖场目前处于P中等限制潜在性富营养水平阶段。     

饲粮中添加葵花籽油和茶油对泌乳水牛生产性能及乳脂脂肪酸组成的影响

本文旨在研究饲粮中添加葵花籽油和茶油对泌乳水牛生产性能及乳脂脂肪酸组成的影响。选取32头健康泌乳水牛(平均年龄为6.0岁,平均体重为620 kg),按产奶量(9 kg/d以上)、泌乳期(处于泌乳中期)相近原则随机分为4组,进行为期6周的饲养试验,其中预试期2周,正试期4周。基础饲料由精料和粗料组成。对照组饲喂基础饲粮;在试验组的精料中分别添加4%的葵花籽油(葵花籽油组)、4%的茶油(茶油组)、2%的葵花籽油+2%的茶油(混合组)。结果表明:与对照组相比,各试验组的产奶量均显著下降(P<0.05),乳脂率均显著提高(P<0.05),乳脂产量、乳蛋白率和乳糖率则无显著变化(P>0.05)。与对照组相比,葵花籽油组、茶油组和混合组的乳总固形物含量分别提高了5.22%、7.95%和6.17%,其中茶油组和混合组与对照组差异显著(P<0.05)。与对照组相比,葵花籽油组乳脂中cis9,trans11-C18∶2[共轭亚油酸(CLA)]的含量提高了44.54%(P<0.05),混合组乳脂中trans11-C18∶1的含量提高了22.68%(P<0.05)。葵花籽油组、混合组乳脂中C18∶2的含量均显著高于对照组(P<0.05);葵花籽油组、茶油组和混合组的多不饱和脂肪酸(PUFA)/饱和脂肪酸(SFA)均比对照组提高,且葵花籽油组和混合组显著高于对照组(P<0.05),其中混合组的PUFA/SFA最高。各组水牛的血液总胆固醇、甘油三酯、高密度脂蛋白、低密度脂蛋白、葡萄糖、总蛋白、尿素氮含量及谷丙转氨酶、谷草转氨酶活性差异不显著(P>0.05)。由此得出,泌乳水牛饲粮中添加精料饲喂量4%的葵花籽油、4%的茶油或2%的葵花籽油+2%的茶油合均可提高乳脂率和乳脂中CLA的含量,但会导致产奶量降低;优化乳脂脂肪酸组成上,以葵花籽油和茶油的混合添加效果较好。     

椒江口海域浮游动物群落季节变化特征

依据2010年4月、7月和11月对浙江鱼山渔场-椒江口近海海域的海洋调查资料,分析该海域浮游动物生物量、丰度、优势种和多样性指数等生态特征的季节变化及其与浮游植物丰度之间的关系。结果表明:浮游动物生物量、丰度、优势种和多样性指数均存在明显的季节变化,其中春季浮游动物生物量和丰度均是3个季节最高,丰度的高值区位于调查海域的南部,中华哲水蚤(Calanus sinicus)占绝对优势;夏季浮游动物生物量和丰度次之,丰度的高值区在大陈岛西南海域,以中华哲水蚤、太平洋纺锤水蚤(Acartia pacifica)、精致真刺水蚤(Euchaeta concinna)和海龙箭虫(Sagitta nagae)占优势;秋季浮游动物生物量和丰度最低,丰度分布较为均匀,以肥胖箭虫(Sagitta enflata)和双生水母(Diphyes chamissonis)占优势。浮游动物丰度调查结果与同时期浮游植物丰度的调查结果相比,3个季节浮游植物与浮游动物丰度的高值区并不一致,这是因为影响浮游植物丰度的主要因素是营养盐和光照,而浮游动物的分布主要是受水团和海流的影响。上述生态特性的季节变化规律与椒江口海域的季节性水团变化密切相关,春季以低温低盐性质的沿岸流为主,夏季受高温高盐性质的台湾暖流水影响,水团的转换使调查水域的营养盐、温度、盐度和透明度等发生变化,从而进一步影响到浮游动物的生态特征。     

通过刺槐的水力结构特征参数探讨管道理论

为了解刺槐Robinia pseudoacacia苗木对体内水分运输过程的调控机制,基于水力结构理论,在充分供水条件下,利用改良的"冲洗法"对2年生刺槐苗木的水力结构参数进行测定,并探讨了管道理论的合理性和适用范围。结果表明:在充分供水条件下,刺槐苗木茎段导水率、比导率、叶比导率和胡伯尔值均随被测茎段直径的增加而增大;苗木不同生长阶段,其导水率、比导率和叶比导率差异显著(P<0.05),且均为生长旺期>生长初期>生长末期,胡伯尔值为生长初期最大,生长旺期和生长末期差异不显著(P>0.05)。由此可推断,①在水分胁迫条件下,苗木更倾向于保护那些较粗茎段;②苗木水力结构特征与提体内生理活动呈正相关关系;③管道模型假说虽然有其存在的合理性,但也有其局限性和适用性,在对于水分在林木体内的运输过程以及调控机制的解释,管道模型假说过于简单化了。     

池塘放养密度对施氏鲟幼鱼生长、摄食和肌肉组分的影响

在水温为14 ～ 17℃条件下,将大规格施氏鲟Acipenser schrenckii幼鱼（225.69 g±32.28 g）随机放入9个四边形水泥池（池底面积为18.23 m2）中流水饲养,分别设置5.5、8.0、11.0 kg/m3 3个放养密度组,每组设3个平行,养殖试验共进行70 d,观察并研究放养密度对施氏鲟幼鱼生长、摄食和肌肉组分的影响.结果表明：施氏鲟幼鱼的终末体质量、特定生长率、日增重和摄食率等均随养殖密度的增大而显著降低（P＜0.05）,饲料系数随养殖密度的增大而显著升高（P＜0.05）,密度为8.0 kg/m3的组生长效率最高;肌肉中的粗蛋白质和粗脂肪含量随养殖密度的增大而显著降低（P＜0.05）,雨水分和灰分含量的变化不明显（P＞0.05）;试验期间,水体中的溶解氧浓度随养殖密度的增大显著降低（P＜0.05）,而氨氮和化学耗氧量浓度则随养殖密度的增大而显著升高（P＜0.05）.研究表明,8.0 kg/m3的放养密度更适合大规格施氏鲟幼鱼的养殖,过高的放养密度会对施氏鲟幼鱼生长及其肌肉品质产生不利影响.     

凤眼莲对重金属的吸收与其喂鱼后二次富集状况的初步研究

通过苏州东郊城河试验：凤眼莲对城河污水及其重金属具有很强的吸收积累和净化能力。经凤眼莲净化后，其污水中酚浓度从0．005～0．023毫克/升降到检不出来，总氮从5．330毫克／升降至2．330毫克／升，总磷从0．840毫克／升降至0．183毫克/升，COD从54．8毫克／升降至29．36毫克/升，水质透明度也有很大改善，从36．7厘米提高到90厘米左右。对重金属铜从0．57ppb降至0．32ppb，Pb0．14ppb降至0．06ppb，锌65．6ppb降至23．6ppb，镉0．14ppb降至O．03ppb等，从而使河水达到了渔业用水标准。根据实验结果，凤眼莲喂鱼后鱼类对重金属没有明显的二次富集现象，在鱼肉中重金属含量均在食品卫生标准(汞0．3毫克/公斤，铅2毫克/公斤、砷1毫克／公斤)以下。