Analysis of environment-recruitment associations for a coastal red drum population reveals consistent link between year class strength and early shifts in nearshore winds

The identification of factors contributing to strong year classes of marine fishes has been a constant goal toward a mechanistic understanding of recruitment variability. Here, we explored a 26-year time series of the abundance of early juvenile red drum along the North Carolina coast to identify environmental features associated with variable recruitment success. The study location was near the northern edge of the species latitudinal range, and we hypothesized that consistent environmental forcing would be linked to the formation of strong red drum year classes. Patterns of variability in seasonal environmental features were disaggregated into multiple forms of temporal periodicity and analyzed using generalized additive models. We also contrasted patterns of environmental variation that occurred during the strongest recruitment events with those coinciding with the weakest red drum year classes. The early shift, during August, to favorable wind conditions was the most consistent environmental feature associated with red drum recruitment success. The combined duration and magnitude of N and NE winds during August of strong recruitment years was nearly double the level observed during weak recruitment years. Elevated nearshore sea surface temperatures early in the spawning season were also found to occur during years that produced strong year classes. Coastal productivity, indexed using chlorophyll a concentration, was positively associated with red drum recruitment, but also highlighted the need for more spatially resolved productivity data. Our findings highlight the importance of environment-recruitment linkages for marine fishes, especially near distributional boundaries where conditions to promote year class success can be brief.     

Coastal winds and larval fish abundance indicate a recruitment mechanism for southeast Australian estuarine fisheries

Coastal winds transport water masses and larval fish onshore or offshore which may influence estuarine recruitment, yet our understanding of the mechanism underlying this relationship is limited. Here, we combine datasets from a historical database of larval fish off southeast Australia with a high-resolution atmospheric reanalysis model to show that normalised abundance of coastally spawned larvae increased with weak to moderate upwelling favourable winds 14 days prior to sampling. The increase in abundance may reflect increased nutrient and plankton availability for larval fish. Normalised larval abundance decreased following strong upwelling favourable winds but increased after onshore (downwelling favourable) winds, due to wind-driven transport. By combining a commercial estuarine fisheries catch-rate dataset (4 species, 8 estuaries, 10 years) and the high-resolution atmospheric reanalysis model, we show that negative effects of upwelling favourable winds during the spawning period can be detected in lagged estuarine commercial fisheries catch rates (lagged by 2–8 years depending on species' growth rates), potentially representing the same mechanism proposed for larval fish. Upwelling favourable winds in the southeast Australian region have increased since 1850 while onshore winds have decreased, which may have reduced larval recruitment to estuaries. Coastal winds are likely an important factor for estuarine recruitment in the southeast Australian region and future research on the estuarine recruitment of fish should incorporate coastal winds.     

牙鲆胚后发育过程中Ⅰ型脱碘酶基因的原位表达谱

甲状腺激素T3在鱼类胚后发育与变态发育过程中发挥着重要作用,甲状腺激素T4通过Ⅰ型甲状腺氨酸脱碘酶(Dio1)生成T3,因此,调查Dio1基因在胚后发育包括变态发育过程中原位表达谱,有助于理解T3在胚后发育中的具体作用。利用RNA整体原位杂交技术,发现Dio1主要在牙鲆肠道、鳃、肝、肌肉、鳍、眼睛周围等器官和组织表达,鳃、肠道、奇鳍中的Dio1原位表达谱有一定的规律性,尤其在生骨肌细胞向鳍褶中迁移、臀鳍和背鳍(包括冠状幼鳍)的鳍条和支鳍骨的发生过程中,Dio1可能通过影响这些组织器官的T3水平而发挥重要作用。     

萧氏松茎象有虫株率与虫口密度关系的研究

通过对江西萧氏松茎象发生林区118块标准地的调查与分析，得出萧氏松茎象平均虫口密度与有虫株率之间的关系可用指数函数Y=15.6e^0.0313x来描述。     

牙鲆早期发育和变态期间Pitx2基因的表达

Pitx2基因被认为是脊椎动物中调节内脏器官左右不对称的关键转录因子。为进一步探讨牙鲆变态期间的左右不对称是否也受Pitx2的左特异活性调节,采用逆转录聚合酶链式反应(RT-PCR),拟在变态的牙鲆的头部组织中克隆编码Pitx2基因的部分cDNA序列,并通过以18s rRNA为内标的半定量RT-PCR研究其在牙鲆早期发育和变态期间的表达情况。克隆和测序的结果表明Pitx2在牙鲆早期发育和变态期间也存在基因表达;而半定量的结果表明它的左特异性功能很可能在变态的早期阶段发挥作用。但是,牙鲆变态期间的右眼移动是否受Pitx2的左特异活性调控,以及变态期间的左右不对称和内脏器官的左右不对称是否拥有相同的分子机制,仍需进一步研究。     

海湾扇贝“中科红”品种与普通养殖群体不同温度下早期性状的比较

采用自交、杂交和混交等不同的交配方式分别获得海湾扇贝“中科红”品种和普通养殖群体（对照组）的受精卵和幼虫,在20 ℃、23 ℃和26 ℃三个温度条件下培养,比较了两个群体在不同温度下的孵化率、10日龄幼虫存活率、1日龄和10日龄幼虫壳长。实验结果表明：“中科红”海湾扇贝自交系、杂交系和混交系的孵化率均大于对照组。自交系10日龄幼虫存活率显著高于对照组（P＜0.05）,而杂交系和混交系的10日龄幼虫存活率小于对照组,但差异不显著（P＞0.05）。“中科红”海湾扇贝自交系（P＜0.05）和混交系幼虫的1日龄壳长大于对照组,杂交系的显著小于对照组（P＜0.05）。幼虫生长10日后,“中科红”海湾扇贝自交系、杂交系（P＜0.05）和混交系幼虫壳长均比对照组大,表现了较强的生长优势。温度对4个性状均有显著影响（P＜0.05）。“中科红”海湾扇贝对低温（20 ℃）和高温（26 ℃）的耐受性均高于对照组。     

虎斑乌贼喷墨卵与正常卵的比较

为了探明虎斑乌贼喷墨卵对孵化及胚胎发育的影响,采用单因子实验研究了喷墨卵与正常卵的孵化率、培育周期、孵化周期、初孵幼体体质量,并比较了剥膜喷墨卵、剥膜正常卵、喷墨卵、正常卵4种类型卵的幼体生长和存活率。结果显示,虎斑乌贼喷墨卵和正常卵的孵化率无显著差异,喷墨卵的孵化率为90.1%±1.5%,正常卵的孵化率为87.9%±0.7%;两种卵的初孵幼体体质量也无显著差异,喷墨卵的初孵幼体体质量为(0.18±0.01)g,正常卵的初孵幼体体质量为(0.17±0.01)g;两种卵的培育周期、孵化周期均无显著差异,喷墨卵的培育周期为(34.67±0.89)d,孵化周期为(14.33±0.44)d,而正常卵的培育周期为(35.33±0.44)d,孵化周期为(14.67±0.67)d。而剥膜喷墨卵、剥膜正常卵、喷墨卵、正常卵4种类型卵的幼体存活率差异显著,剥膜喷墨卵和剥膜正常卵的存活率明显小于喷墨卵和正常卵,而剥膜喷墨卵和剥膜正常卵之间、喷墨卵和正常卵之间的存活率无显著差异;4种类型的幼体日均增长量和增重量差异显著,剥膜喷墨卵和剥膜正常卵的幼体日均增长量和增重量明显小于喷墨卵和正常卵,而剥膜喷墨卵和剥膜正常卵之间、喷墨卵和正常卵之间的幼体日均增长量和增重量无显著差异。     

Importance of dietary arachidonic acid for the growth,survival and stress resistance of larval European sea bass (Dicentrarchus labrax) fed high dietary docosahexaenoic and eicosapentaenoic acids

Together with docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), arachidonic acid (ARA) is being considered to be an essential fatty acid in marine fish larval diets. The objective of the present study was to determine the importance of dietary ARA levels for larval European sea bass performance, when EPA and DHA are also present in the diet. Eighteen‐day‐old larvae were fed, for 14 days, gelatine‐based microdiets containing the following ARA levels: 0.3%, 0.6% or 1.2%. Elevation of dietary ARA up to 1.2% showed a positive correlation with larval survival and a significant improvement in the specific growth rates, body weight and total length. Arachidonic acid was efficiently incorporated into larval lipids, even at a higher proportion than that in the diets. Increased accumulation of ARA did not affect the incorporation of DHA or EPA from the diet into larval total lipids. A significant positive correlation was found between dietary ARA levels and survival after handling stress, indicating the importance of this fatty acid in sea bass larvae response to acute stressors. The results show the importance of ARA for sea bass larvae, but higher dietary levels should be tested to determine whether there is a negative effect of ARA in sea bass as reported for other species.     

雅砻江硬刺松潘裸鲤的胚胎及仔鱼发育研究

研究硬刺松潘裸鲤(Gymnocypris potanini firmispinatus)早期生活史阶段的发育规律,为松潘裸鲤的亚种分化研究、规模化人工繁殖和苗种培育提供理论依据。松潘裸鲤亲鱼采自雅砻江支流安宁河流域。雌鱼6~13龄,全长12.1~24.2cm,体重16.1~115.8g;雄鱼3~9龄,全长8.2~14.5cm,体重5.2~23.8g。结果显示,硬刺松潘裸鲤受精卵呈圆形,黄色,卵径(2.82±0.10)mm;水温(16±1)℃下,硬刺松潘裸鲤的胚胎发育历时183h45min,胚胎发育过程分为受精卵、胚盘形成、卵裂、囊胚、原肠、神经胚、器官分化和出膜共8个阶段、31个时期;出膜仔鱼全长(7.82±0.19)mm;出膜10d后,仔鱼的鳃、口、胸鳍、尾鳍、鳔、肠道等功能器官先后形成;出膜13d后卵黄囊消失,全长(14.33±0.51)mm;出膜40d后各鳍基本长成,体型和体色接近成鱼,进入幼鱼阶段。硬刺松潘裸鲤为地区重要的小型经济鱼类,主要分布在雅砻江中游各大干支流中,在形态和生态上形成一系列的适应性,早期发育过程与其栖息的环境同样具有一定的适应性。