Food ingestion and digestibility of five unicellular algae by 1-day-old Strombus gigas larvae

This work presents food ingestion and digestibility analysis carried out by means of epifluorescence microscopy of 1‐day‐old Strombus gigas (Linnaeus, 1758) larvae fed five different algal cells: Tetraselmis suecica, T. tetrathele, Chlorella keslleri, Chlorella sp. and Chaetoceros cerastoporum. Absolute ingestion and digestion indices (AII and ADI) were used to compare larval feeding behaviour. Differences in efficiency of ingestion and digestion were observed, according to the diet: the highest AII and ADI were observed with T. suecica and T. tetrathele (>90% and 85–88% respectively). With C. cerastoporum and Chlorella sp. these indices were zero. We confirm the use of Tetraselmis as a suitable diet for S. gigas hatchery. On the contrary, Chlorella sp. and C. cerastoporum are not recommended during the early larval stage, due to their non‐ingestion and digestion.     

Hemocyte characteristics in families of oysters, Crassostrea gigas, selected for differential survival during summer and reared in three sites

High variability among individuals is often encountered when hemocyte characteristics are measured in bivalves. Such variability is suspected to result partly from genetic factors. In this study, hemocyte characteristics of six families of Crassostrea gigas were compared by flow cytometry at one sampling date in October 2001. These families were obtained from a nested, half-sibling cross design, and reared from July to October 2001 at three sites distributed along the French Atlantic coast from north to south: Baie des Veys (Normandy), Rivière d'Auray (Brittany) and Ronce (Marennes-oléron Basin, Poitou Charentes).

Among the 15 measured hemocyte characteristics, production of reactive oxygen species (ROS) of untreated hemocytes (maintained in filtered sterile seawater) and treated hemocytes (zymosan at 20 particles per hemocyte, and with Vibrio sp. S322 at 50 bacteria per hemocyte) was the most notable differences between families. This supports the existence of a genetic basis, at least partly, for the hemocyte characteristics of oysters, and especially for ROS production.

Among the six families analyzed, three have shown high survival during summer (named as “resistant”, mean mortality 5.2%) and three experienced high mortality during summer (named as “susceptible”, 30.6% mean mortality). Families showing high or low survival to summer mortality had similar hemocyte characteristics, regardless of the environmental conditions or reproductive state. Resistant families were observed to have higher total hemocyte counts and lower production of ROS than susceptible families. Moreover, ROS production of hemocytes from susceptible families was diminished significantly more by pathogenic Vibrio than that of resistant families. However, this study demonstrates also that rearing site strongly affected the hemocyte characteristics of all families of oysters, most notably hemocyte concentration and morphology (size and granularity), production of reactive oxygen species (ROS), and susceptibility to the cytotoxic activity of the pathogenic Vibrio sp. S322 (50 bacteria/hemocyte). Food availability and reproductive state are the most probable explanations for the site differences observed. Finally, it appeared difficult to link oyster survival during summer mortality to hemocyte profiles evaluated at one sampling date; other relevant indicators would probably help explaining oyster survival during summer mortality events.     

智利外海茎柔鱼角质颚微结构及其年龄与生长研究

文章利用2010年4-6月智利外海采集的148尾茎柔鱼(Dosidicus gigas)样品,分析了茎柔鱼角质颚微结构,并对其年龄和生长进行了研究。结果表明,茎柔鱼角质颚上颚喙部截面由头盖和脊突两部分向前延伸组合而成,周期性生长带明显,每条生长带由明、暗两条生长纹组成,头盖与脊突部的生长纹交汇于内轴成"<"形。标记轮与异常结构的形成与个体发育期的特殊事件以及外界的突发事件有关。根据角质颚生长纹估算茎柔鱼日龄,推测茎柔鱼样本孵化日期为2009年3-11月,主要为6-7月;胴长与角质颚日龄呈显著的幂函数关系,其中雌性茎柔鱼胴长的平均瞬时生长率(Instantaneous growth rate,IGR)和绝对生长率(Absolute daily growth rates,AGR)分别为0.14%·d^-1和0.60 mm·d^-1,雄性茎柔鱼胴长的平均IGR和AGR分别为0.11%·d^-1和0.47mm·d^-1。研究结果为柔鱼类年龄鉴定和生长估算提供了新方法,并为中国开展头足类相关研究奠定了基础。     

智利外海茎柔鱼渔获率及钓捕技术的初步研究

根据2006年4-6月我国鱿钓船对东南太平洋智利外海茎柔鱼资源探捕,对捕捞产量及其钓捕技术进行了分析。探捕期间,其产量以手钓为主,约占总产量的98%。试验表明,八角型手钓钩的脱钩率为6.5%-19.5%,平均为13.2%。船体后部和前部的手钓脱钩率较高,中部较低。机钓脱钩率为20.7%-46.2%,平均为32.9%。茎柔鱼对机钓钩的颜色具有选择性,其中荧白色机钓钩的钓获率为最高,其次为绿色,橙色为最低。集鱼灯为金属卤化物灯时（2kW×180盏）,八角型手钓钩的钓捕产量比四角型手钓钩高0.5倍;凌晨02：00-03：30时采用高压钠灯时（30盏×500W）,四角型手钓钩反过来比八角型手钓钩高0.35倍。     

东太平洋赤道海域茎柔鱼组织能量积累及其与海表面环境因子的关系

为了从能量积累角度掌握茎柔鱼 (Dosidicus gigas) 的生活史策略,利用组织能量密度测定技术和广义线性混合效应模型 (Generalized linear mixed-effects models, GLMM) 对东太平洋茎柔鱼的肌肉、性腺等组织的相对能量积累及其与栖息海域环境因子之间的关系进行了分析。结果显示,东太平洋茎柔鱼以肌肉组织能量积累为主 (相对能量积累占70%以上),性腺组织能量积累相对较低。在生理性发育期至功能性成熟期,肌肉组织相对能量积累下降显著,性腺组织相对能量积累明显;在功能性成熟期,肌肉组织相对能量积累回升显著。肌肉组织和性腺组织的相对能量积累与栖息海域海表温度无显著相关性,但与栖息海域叶绿素 a 质量浓度存在显著的效应关系,并与采样经度分布密切相关。研究表明,东太平洋茎柔鱼在性腺发育开始后能量积累逐渐增加对生殖发育的投入分配,但在繁殖产卵期保持较好的肌肉组织状态,肌肉、性腺组织的相对能量积累更多取决于栖息海域的初级生产力。     

厄尔尼诺对柔鱼亚科近缘种茎柔鱼与鸢乌贼营养生态位的影响

碳、氮稳定同位素技术 (δ¹³C和δ¹⁵N) 是海洋动物摄食生态学研究的主要方法之一。目前对海洋动物各组织的保存方法尚无统一的标准,这可能造成测定结果出现偏差,并产生误导性结论。以大洋性头足类茎柔鱼 (Dosidicus gigas) 为研究对象,开展了冷冻保存 (−20 ℃)、乙醇 (体积分数75%) 与甲醛 (体积分数38%) 溶液保存对肌肉、角质颚和性腺组织δ¹³C、δ¹⁵N和碳氮比 (C/N) 测定的比较研究。结果表明,冷冻保存在第30天时仅对肌肉和性腺组织δ¹³C和C/N值产生了显著性影响 (P<0.05),偏移量分别为(−0.89±0.30)‰和0.22±0.15,但相比于乙醇和甲醛方法偏移量较小。乙醇保存第30天时,肌肉δ¹³C、δ¹⁵N和C/N值均有显著性变化 (P<0.05),偏移量分别为(−0.41±0.50)‰、(0.76±0.79)‰和0.34±0.05;性腺δ¹³C和和C/N值存在显著性变化 (P<0.05),偏移量分别为 (−0.36±0.44)‰和 0.21±0.14;而角质颚的变化不显著 (P>0.05)。甲醛保存会导致3种组织的δ¹³C、δ¹⁵N和C/N值出现显著性变化 (P<0.05),30 d后 δ¹³C 、δ¹⁵N和 C/N值总偏移量分别为 (−3.03±1.87)‰、(−0.48±0.72)‰和0.86±0.73,但保存至第180天时仅角质颚和性腺的δ¹⁵N和C/N值仍持续增大 (P<0.05),可能与组织特异性有关。因此在分析稳定同位素时,应谨慎使用长时间保存后的软组织样品 (肌肉和性腺),而硬组织 (角质颚) 可采用冷冻或乙醇保存。

     

温度对大瓶螺心率与卵孵化速率的影响

水温对大瓶螺心率的影响,在7～38℃之间心率随温度上升而加快,超过40℃心率下降.致死温度的上、下限为47℃和3 ℃.卵发育的生物学零度为15.4℃,孵化的有效积温为161.3℃,孵化的最适温度范围25～30℃,温度≥34℃,孵化速度为零.     

^60Co-γ射线对成体长牡蛎生长的影响及致死效应

Effects of ionizing irradiation of ^60Co-γ ray on mortality and growth of one year-old Pacific oysters ( Crassotrea gigas ) were studied. Irradiation was conducted at 4℃ and without sea water, and the survival, shell length, shell width, whole wet weight and condition index of irradiated oysters were measured. A biphasic dose response effect of 6^60Co-γ irradiation on Pacific oyster with high stimulatory response dose range to 100 Gy, and strong hormesis effects had been observed. Gamma ray induced mortality happened within 90 days after irradiation, and the relation between dosage ( D ) and mortality at 90 days could be described by the equation of M90 = 0.0041D^2- 0. 1816D (R^2= 0. 9958) with an LD50/90 of 135 Gy, indicating that the Pacific oyster has strong resistance to ^60Co-γ irradiation. Growth in shell length, shell width and whole wet weight of Pacific oyster were also enhanced by 60 Gy of ^60Co-γ ray. The condition index was also enhanced by ^60Co-γ irradiation in the dosage range from 40 to 100 Gy, with the maximum stimulatory response of 2.5 fold of control value at the 40 Gy dosage, suggesting that the accelerating effects of γ ray on growth of the Pacific oyster led to increase in dry meat. Results of this study showed that ionizing irradiation might be useful in the improvement of production traits in shellfish.     

出口大瓶螺肉干的加工技术

详细介绍了出口无盐大瓶螺肉干和含盐大瓶螺肉干的加工工艺流程及操作要点，对破壳方法、蒸煮和烘烤过程中的温度控制，以及自然干燥工艺作了探讨。     

关于我国农田福寿螺生物入侵需要加以研究的生态学问题

福寿螺已成为我国南方稻区主要的入侵生物之一,近年来,对水稻等农作物以及农业生物多样性和生态环境的危害日趋加重。本文对我国农田福寿螺的生物入侵危害状况进行了概述,提出了今后关于农田福寿螺生物入侵需要加以研究的生态学问题,包括农田福寿螺的生态适应性与耐性规律、农田福寿螺的种群暴发规律与预测预警、福寿螺的生态风险、农田福寿螺的综合防治与生态控制等。