Outdoor mass microalgae production in Bahia Kino, Sonora, NW Mexico

The diatom Chaetoceros muelleri was grown in outdoor mass cultures under the winter, spring and summer conditions of Bahia Kino, Sonora, NW Mexico. The solar irradiance in winter was close to 60% of that available in spring and summer, but the cell concentrations and the harvestable biomass were one order of magnitude higher in spring and summer than in winter. There was no difference between the biomass harvested after 2 and 3 days in winter and summer, whereas in spring it was higher after 3 days. The protein content was significantly lower in winter, and carbohydrates and lipids were higher in winter and spring. The number of cells and the amount of harvestable biomass of outdoor cultures of C. muelleri depend on the temperature prevailing in each season, which causes significant differences in growth rates and in biochemical composition.     

Growth and proximate composition of the Chaetoceros calcitrans f. pumilus under different temperature, salinity and carbon dioxide levels

The marine diatom Chaetoceros calcitrans f. pumilus has been examined for its potential source as live feed in aquaculture. The present study investigated effects of temperature (20, 25 and 30 °C), salinity (25 and 35) and carbon dioxide addition (air+CO₂) on the growth and proximate composition of C. calcitrans under laboratory conditions. The growth and biomass of C. calcitrans were primarily affected by carbon dioxide addition, and to a lesser extent by temperature and salinity. In general, lipid and carbohydrate contents were higher at lower temperatures (20 and 25 °C), while the protein content was unaffected. Carbon dioxide addition increased protein, while lowering carbohydrates, but had no effect on lipid content. Carbohydrates were increased while lipids and protein decreased at the highest salinity (35±0.9). These results should be taken into consideration when evaluating the dietary value of this micro alga for aquaculture.     

Migration of kawakawa Euthynnus affinis in the waters near Taiwan

ABSTRACT:   Kawakawa Euthynnus affinis is the most abundant species among the small tuna in the coastal waters of Taiwan. The migration pattern of kawakawa to Taiwan was determined in the present study based on the species' feeding habits and reproductive biology and on temporal variation of catch for kawakawa and its prey fishes. Schools of this species successively migrate to Taiwan from September to May, and then move away in June. They travel to the waters off Taiwan with the warm Kuroshio current, migrate toward coastal waters for feeding and move away for spawning. It is suggested in the present study that the kawakawa spawning ground is in the waters of the northern Philippines. The migration of kawakawa exhibits size-segregating behavior. Schools of immature young fish first arrive in the coastal waters around Taiwan, followed by the adults.     

慈竹制造Lyocell纤维可行性研究

通过研究慈竹的纤维素含量,尤其是研究和测试了影响纤维素分子量等各种因素,认为以慈竹为原料,制造Lyocell纤维是可行的,并用慈竹浆成功地纺制出了竹Lyocell纤维样品.     

重庆缙云山慈竹种群年龄的初步研究

慈竹(Neosinocalamus affinis)系四川分布面积最大和用途最广的合轴型竹种。作者在重庆缙云山慈竹种群年龄研究过程中,发现慈竹种群之无性系个体的年龄与其个体生物量和各器官生物量相关密切,其器官数量也呈显著相关;慈竹秆的形态学特征与其个体的年龄,地下茎和地上茎(秆)的分枝级数与其年龄均呈直线相关。地下茎分枝级数(RSB_x)与其年龄(A_(rs))的回归模型:A_(rs)=(RSB_x_(max) 1)-RSB_x,相关系数Υ_(rs)=-1.0000,O_(x-1)=0;秆分枝级数(CB_x)与其年龄(A_c)之相关模型为A_c=CB_x,相关系数Υ_c=1.0000(一年生个体除外),O_(x-1)=0。     

城市废水暴露对食蚊鱼肝脏EROD酶活性的影响

采用动力学酶标荧光法,检测了东莞市数所污水处理厂、制药厂和电子厂废水对食蚊鱼(Gambusia affinis)肝组织中7-ethoxyresorufin o-deethylase(EROD)酶活性的影响,评价了运用EROD酶活性监测水环境污染物的生物效应的可行性。结果显示,食蚊鱼分别暴露于经稀释为20%,40%,60%,80%不同梯度的废水液72 h后,肝脏EROD酶的活性分别与受试城市污水处理厂、制药厂和电子厂的废水之间存在剂量效应关系,EROD酶活性随污水浓度的增加而提高。电子厂废水的最大诱导倍数与对照组的比值可达到5.26,这表明其水体中存在的有机污染物较多,污水处理厂次之,制药厂的出水中污染物最少。研究表明,食蚊鱼肝组织EROD酶活性可以作为监测城市废水污染的理想生物标记物,后续的研究工作应使之标准化。     

Assessment of the performance of Pacific oyster (Crassostrea gigas) larvae fed with fresh and preserved Pavlova lutheri concentrates

The Prymnesiophycea Pavlova lutheriwas produced using a traditional technique (batch mode in carboys) and by an innovative technique (semi-continuous mode in alveolarphotobioreactor). Two experimental feedingtrials were carried out with Pacific oyster(Crassostrea gigas) larvae with freshand preserved (4 °C and 1 °C)P. lutheri concentrates used inmonospecific and bispecific diets, incombination with fresh Chaetoceroscalcitrans forma pumilum. Nodifferences in terms of gross composition andlarval performance were noticed between thefresh algae biomass produced by the twotechniques. The low temperatures allowedpreservation of the nutritionalcharacteristics of the P. lutheri freshculture for the time period considered (27days). The P. lutheri concentratespreserved at 4 °C or 1 °C didnot differ substantially in terms ofnutritional value. Larvae fed a monospecificdiet of P. lutheri, both fresh andpreserved, exhibited a modest growth rate (<2.1 µm day^–1), in some cases notsignificantly different from that observed inthe unfed larvae (the control), and a lowsurvival rate. In contrast, when Chaetoceros calcitrans forma pumilumwas used as a monospecific diet, good growthperformance (>4.5 µm day^–1) and ahigh survival rate (>86%) were observed inlarvae. A substitution of 50% (trial 1) or80% (trial 2) of fresh C. calcitransforma pumilum with the preserved P. lutheri concentrates did not adverselyaffect growth rate or survival of C.gigas larvae.     

桁杆虾拖网捕捞脊腹褐虾网囊网目选择性试验

采用套网试验法在长江口渔场对25 mm桁杆虾拖网网囊网目的选择性进行了试验。结果表明:当网囊网目内径为25 mm时,网囊与套网内脊腹褐虾的体长范围在30~80 mm之间,其中网囊内虾的优势体长在46~70 mm之间,套网内虾的优势体长在41~60 mm之间;50%选择体长L0.5为50.53 mm,选择范围SR为9.86 mm;逃逸虾的平均存活率为96.25%。     

食蚊鱼对水生昆虫的捕食选择性研究

为了解食蚊鱼Gambusia affinis对华南地区水生昆虫多样性的影响,在实验室条件下,以食蚊鱼栖境中有代表性的3种水生昆虫为猎物,研究食蚊鱼的捕食选择性.结果表明,在单捕食者-多种猎物作用系统中,当猎物密度较低时,食蚊鱼对不同猎物的捕食选择性差异不显著.但随猎物密度的增加,食蚊鱼对白纹伊蚊Aedes albopictus幼虫和蛹的捕食量明显增加,对摇蚊Chironomus kiiensis幼虫和蜉蝣Cloeon bengalense稚虫的捕食量下降.在单捕食者-2种猎物的作用系统中,在猎物比例相同的情况下,食蚊鱼更喜欢捕食白纹伊蚊幼虫;但是在猎物总数不变的情况下,改变猎物比例,对食蚊鱼总的捕食量影响不大.说明食蚊鱼喜欢捕食漂浮于水面上、会动的活体猎物,对死的或不动的猎物不敏感,且对蚊子幼虫具有明显的嗜好性.     

四川两种竹材理化性质及纤维形态分析

为有效利用四川的乡土竹种慈竹和绵竹,测定分析了2个竹种的理化性质和纤维形态,并与毛竹及常见的阔叶材和针叶材做了对比。结果表明：1）在化学成分上,2个竹种的抽提物含量均小于毛竹,而介于针叶材和阔叶材之间,2个竹种的综纤维素含量和纤维素含量均高于毛竹,木质素含量与毛竹接近,但灰分含量远高于毛竹、阔叶材和针叶材;2）在物理力学特性上,2个竹种竹材密度略低于毛竹,顺纹抗压强度均明显高于毛竹,且优于强度较高的阔叶材马占相思木,2个竹种的抗弯弹性模量和抗弯强度均明显高于毛竹,抗剪强度与毛竹接近,表明2个竹种力学强度均较大,可以用作结构用竹或建筑用竹;3）在纤维形态上,慈竹和绵竹的平均纤维长度分别为0.63和0.67 mm,均小于毛竹,且纤维长度多为500~1 000和1 000~1 500 μm,2个竹种的纤维长宽比均在45以下,表明慈竹和绵竹均不适于作为造纸原料。