长江口南支水域刀鲚仔稚鱼资源量的年度变化

为了进一步探明长江口南支刀鲚(Coilia nasus)仔稚鱼的分布和丰度变化,2018年6-10月在长江口南支设置8个站点,采用大型仔稚鱼网(口径1.3m,网目0.5mm)在每月大潮期间按月进行表层水平拖网调查,研究结果与2014年、2015年同水域和同期的研究结果比较,旨在揭示长江口南支刀鲚仔稚鱼资源的年度变化。本研究共拖网58网次,采集刀鲚仔稚鱼4611尾,平均密度0.123 ind./m3,体长范围3.1～61.74mm,发育阶段从前弯曲期到稚鱼期,其中前弯曲期仔鱼(3.1～18.12mm)最多,占总数86.19%,其次是弯曲期仔鱼(4.9～24.05mm),占8.5%,后弯曲期仔鱼(9.75～30.36mm)和稚鱼(24.22～61.7mm),分别占4.6%和0.72%。白天涨潮采集刀鲚仔稚鱼4271尾,平均体长11.18mm,平均密度0.169 ind./m3,退潮时采集336尾刀鲚仔稚鱼,平均体长10.52mm,平均密度(0.029 ind./m3)低于涨潮密度;St.8夜间涨退潮调查显示,涨潮密度(0.005 ind./m3)大于退潮密度(0.002ind./m3)。三年间刀鲚仔稚鱼发育阶段组成,2014年以卵黄囊期仔鱼为主,2015年和2018年均以前弯曲期仔鱼为主。各年刀鲚仔稚鱼出现的持续时间和高峰期基本相似,主要在6-8月出现,9-10月出现量极少。三年仔稚鱼密度分布表明,各站位点以及各月平均密度差异均不显著(P＞0.05)。     

Mesoscale spatial variability of ichthyoplankton in the Southwest Atlantic during the autumn–winter period

To gain a better understanding of the mechanisms underlying spatial heterogeneity in ichthyoplankton communities in the SW Atlantic, we examined for the first time the latitudinal and continental shelf–slope gradients in ichthyoplankton structure and oceanographic features in the Campos Basin during the relaxation phase of coastal upwellings (late autumn to early winter). This region, located on SE Brazil's continental margin, is the most productive offshore oil basin in the country and has ecological relevance owing to the existence of areas that experiences mesoscale (tens to hundreds of kilometers) processes (eddies, filaments, and upwelling) caused by the interaction of continental shelf and slope circulation with deep water masses. The present study collected a total of 3892 fish eggs and 10,030 larvae from 36 sampling stations, averaging 22 eggs per 100 m³ and 56 larvae per 100 m³. A total of 250 taxa (5 for fish eggs and 248 for larvae) were identified, encompassing 80 families and 145 genera. Species distribution exhibited a considerable degree of spatial variability, which was related mostly to hydrological characteristics. In general, greater densities were associated with higher nutrient concentrations areas. Through distance-based Redundancy Analysis, some discriminating species were found to associate with certain areas of the continental shelf characterized by colder temperatures. The ichthyoplankton distribution patterns suggested a potential influence from mesoscale oceanographic fronts, specifically those that induce upwelling of the cold and nutrient-rich South Atlantic Central Water. Nonetheless, the methodologies used in this study faced challenges in distinctly identifying these processes.     

史氏鲟消化器官的分化对消化酶活性变化的影响

对1～10日龄(DPH)的史氏鲟仔鱼消化道发育进行了组织学观察和消化酶活性的测定.结果表明,史氏鲟仔鱼在内源营养期,消化酶活性变化的总趋势是随着消化道的逐步发育而逐渐增强,但随着不同消化组织器官的分化,各种酶活性变化有各自特点.另外,3种消化酶出现活性的先后顺序为蛋白酶、淀粉酶和脂肪酶.     

金鳟发眼卵孵化及苗种培育试验

本首次报道了金鳟发眼卵孵化技术，孵化水温5－11℃，积温达到140－180度日破膜孵出稚鱼，孵化率北京房山78．0％，黑龙江渤海75．8％，经20－40d胚后发育上浮平游开食。同时介绍了苗种培育技术和管理方法。     

甲胺磷、90-消毒剂对欧洲鳗仔鳗的急性毒性作用

采用静水实验法进行甲胺磷乳剂,９０－消毒剂对欧洲鳗仔鳗急性毒性试验研究。结果表明：在试验浓度３２－５６ｍｇ／Ｌ范围内,欧洲鳗仔鳗中毒死亡发生在３０－４４ｈ,对甲胺磷乳剂急性中毒死亡的时间集中且持续短促;甲胺磷乳剂对欧洲鳗仔鳗的半致死浓度为３５．９ｍｇ／Ｌ,安全浓度为３．６ｍｇ／Ｌ。     

草坪害虫中喙丽金龟幼虫的空间分布与理论抽样数

本文采用扩散指标法和Iwao、Taylor回归法测定了上海辰山植物园内‘矮生百慕大’Cynodon dactylon×C.transvaalensis‘Tifdwarf’和日本结缕草Zoysia japonica上的中喙丽金龟Adoretus sinicus越冬幼虫的空间分布型。结果表明,中喙丽金龟幼虫在两种草坪草根部土壤中不同区域的密度相差较大(5~139头/m~2);幼虫在两种草坪草土壤中空间分布型均为聚集型的负二项分布,分布的基本成分为个体群。根据空间分布型的参数,确定了理论抽样数和Kuno序贯抽样方法。     

长毛对虾幼体的食性

本文采用11种单细胞藻类、3种动物、2种人工饵料，分别喂养不同发育期的长毛对虾幼体，从其变态速度和存活率，比较各种饵料的效果．并对幼体口器与食性关系、溞状幼体死亡率与食性转化关系，以及人工投饵与生态系育苗相结合的问题作了初步探讨。     

KCl诱导虾夷马粪海胆幼体变态的研究

研究了不同浓度的KCl对于虾夷马粪海胆幼体变态的诱导作用及对变态后个体生长的影响。试验结果表明,KCl对虾夷马粪海胆是一种极好的变态诱导剂,0.05 mol/L的KCl作用5~10 h诱导效果最佳,在提高变态率的同时,大大地降低了死亡率。     

牛皮蝇蛆病间接ELISA诊断方法的建立

以纹皮蝇Ⅰ期幼虫粗提蛋白为包被抗原,通过方阵试验确定了血清最佳稀释倍数为80倍,抗原最佳包被浓度为26.64μg/mL,并对其特异性、敏感性和重复性进行了试验,建立了牛皮蝇蛆病间接ELSIA诊断方法。再以建立的ELISA诊断方法对采自内蒙古地区的233份牛血清进行了检测。结果表明,所建立的牛皮蝇蛆病间接ELISA诊断方法具有较好的特异性、敏感性和可重复性,可用于牛皮蝇蛆病的血清学检测。     

Analysis of sinking death using video images of the swimming performance of Pacific Bluefin tuna (Thunnus orientalis) larvae

In this study, we aimed to clarify the mechanism of sinking death during the larval stage of Pacific Bluefin tuna Thunnus orientalis by investigating the effects of swimming performance on sinking death, using a behavioral approach. Swimming performance was examined 3–9 days after hatching (DAH) under day and night light conditions in cuboid experimental tanks. Swimming behavior variables such as swimming speed and swimming angle were measured under both light conditions. Larvae in the daytime experiment and larvae with inflated swim bladders at night were distributed on the surface layer of the water column. In contrast, larvae with uninflated swim bladders at night were frequently observed swimming vertically or sinking to the bottom of the tank. Larvae with inflated swim bladders at night were always distributed beneath the surface until the next morning (survival rates were 100 %). However, larvae with uninflated swim bladders at night swam upward repeatedly and later sank to the bottom of the tank (survival rates were 60 % and 38 % at 5 and 9 DAH, respectively). Larvae with uninflated swim bladders were not always able to maintain their swimming depth by swimming until the next morning. Additionally, their swimming speed and vertical swimming frequency (ratio) depended on the illumination and swim bladder conditions. Our findings show that larvae with uninflated swim bladders at night were associated with a higher risk of sinking death. The swimming energy capacity of Pacific Bluefin tuna larvae, which indicates the total amount of the energy that enables individuals to swim throughout the night without feeding, was found to be linked to sinking death.