基于贝壳生长轮方法的平端深海偏顶蛤的生长和年龄结构研究

平端深海偏顶蛤(Gigantidasplatifrons)是广泛分布于西太平洋深海热液和冷泉生态系统中的优势种和共有种,也是深海化能生态系统中重要的生境营造种。以南海F冷泉平端深海偏顶蛤为研究对象,基于贝壳日生长轮方法,分析了平端深海偏顶蛤的年龄与生长速率,建立了其年龄与贝壳壳长关系的生长方程。同时,结合获得的生长方程,分析了南海F冷泉采样点(119.285 6°E,22.115 4°N)平端深海偏顶蛤种群的年龄结构。研究结果表明,采样获得的平端深海偏顶蛤种群的最大壳长为11.4 cm,最大寿命为13.5龄。研究区域的贝壳长度分布集中在4～7 cm,占比60%;年龄分布集中在2～4龄,占比49.7%。相关研究结果为进一步开展平端深海偏顶蛤的生长研究提供了基础数据,有助于深入了解冷泉区域的种群动态变化规律。     

平端深海偏顶蛤(Gigantidas platifrons)实验室蓄养过程鳃部含菌上皮细胞超微结构动态变化研究

平端深海偏顶蛤(Gigantidasplatifrons)是南海台西南冷泉区的典型优势物种,鳃丝上皮细胞内共生大量甲烷氧化菌,通过甲烷有氧氧化合成有机物为共生体系提供物质能量,是平端深海偏顶蛤赖以生存的重要能量来源器官,溶酶体在共生体系的营养互作和稳态维持中可能发挥重要作用,本研究使用电镜技术观测了常压培养过程中(0d,30d,90d)平端深海偏顶蛤共生体系中共生菌和溶酶体的动态变化,通过鳃上皮含菌细胞超显微结构的变化研究常压培养对深海共生体系的影响,并探讨溶酶体在宿主—共生菌营养传递和共生菌群稳态维持中的关键作用。研究发现,在原位状态样品中(0d)共生菌和溶酶体呈极化分布,细胞结构完整清晰;蓄养30d后,含菌细胞出现明显破碎,共生菌数量大幅降低,溶酶体数量、范围和消化程度大幅增加,对细胞顶端的甲烷氧化菌进行分解;而90d后,共生菌在溶酶体的作用下消失殆尽,鳃部有明显细胞脱落后留下的坑洞,细胞呈现空泡状,无法明确区分各种细胞组分。上述结果展示了长期常压蓄养过程中鳃上皮含菌细胞中溶酶体与甲烷氧化菌的动态变化,推测当共生菌丢失后溶酶体也同步降低活跃度,平端深海偏顶蛤在共生互作中通过溶酶体主导消化和调控共生菌。     

南海北部生源要素的垂直输运和保存及其与东太平洋的对比研究

通过对南海北部夏、冬两个季节的生源要素垂直输运剖面和时间系列沉积物捕获器的测量资料进行综合研究表明:南海北部颗粒物质主要是由钙质生物壳、生物硅、海洋浮游生物的有机质以及岩源物质组成,颗粒物质通量在1 000 m处大约为90.0 mg/(m2·d);研究还表明颗粒有机碳在进入沉积物保存之前被大量溶解,南海北部来自底层顺坡搬运的有机碳远大于垂直沉降;与开阔大洋(东太平洋海域)的对比研究表明,边缘海对于季节的变化更加敏感,而东太平洋调查区位于热带赤道高生产力带,生物作用十分明显,其海洋生物呼吸和物质转移同样也较活跃.     

南海东北部陆坡结核成因及对冷泉活动的指示

本文对2018年利用“海龙Ⅲ”ROV在南海东北部陆坡采集到的多金属结核样品进行了矿物学和地球化学分析。结果表明研究区结核以棒状为主,具有2层结构。结核外层的矿物学和元素组成特征与水成型多金属结核较为相似。结核内层多发育孔洞,以针铁矿为主,有黄铁矿残余,Fe、As元素含量高,Mn、REE等元素含量低。NH-2结核样品内部的碳酸盐组分的全岩δ¹³C为-30.91‰。所研究结核样品的早期形成过程与冷泉活动密切相关,结核生长后期冷泉活动停止或是减弱,在等深流作用下结核黄铁矿被氧化成针铁矿,之后锰铁氧化物继续在结核外部生长。     

南海冷泉区贻贝(Bathymodiolus platifrons)附生菌的分离培养与多样性分析

以采集后适应培养0~24 h以及添加甲烷和硫化钠培养24~240 h的南海冷泉区深海贻贝(Bathymodiolus platifrons)为材料,取其鳃部,分析附生菌的多样性与适应性变化状况。共分离鉴定出贻贝附生菌270株,对菌株的16S r DNA进行聚类分析,结果表明所分离菌株主要分布在4个门,21个属,其中变形菌的数量最多且多样性高。分析发现原位新采集的贻贝鳃部附生菌的多样性较高,6 h后附生菌的多样性明显降低。分别添加甲烷和硫化钠对深海贻贝进行培养,甲烷组与碳代谢有关的假单胞菌的数量逐渐增多,且在甲烷组240 h中发现2株食烷菌属菌株。硫化钠组的芽孢杆菌属所占比例升高。此外还发现4株潜在的新种。本研究实现了深海冷泉区贻贝的实验室培养,并对贻贝鳃部附生菌群结构进行了分析,丰富了海洋极端环境微生物资源库,并为深入解析贻贝与其附生菌之间的相互作用关系奠定了基础。     

南海北部亚热带滨珊瑚对低温的耐受能力

Marginal scleractinian corals growing at their latitudinal limits should be quite sensitive to variations in winter sea surface temperatures(SSTs). An extreme cold event occurring in early 2008 offered a unique opportunity to examine the effect of cold-water anomalies on Porites lutea corals and their physiological tolerance and acclimation in the subtropical northern South China Sea(NSCS). Besides in-situ observation, a subsequent aquarium-based experiment was designed for reproducing the chilling process and a 50-year-long Sr/Ca ratio profile from two P. lutea skeletal slabs was analyzed for reconstructed the historical annual minimum SSTs which ceased Porites calcification. The 2008 low-temperature anomaly caused the minimum daily mean SSTs dropped below 13°C in the Daya Bay. The stress symptoms displayed by local P. lutea colonies included polyp retraction, reduced coloration and pale, but none showed tissue sloughing. The ability of P. lutea to survive implied its tolerance of extreme low temperatures. Here we suggest a model on the tolerance of high-latitude Porites under low-temperature stresses, which is when SSTs drop below 18°C, Porites corals contract their tentacles(losing heterotrophic capability), then cease calcification(reducing energy consumption), and meanwhile maintain relatively high levels of zooxanthellae density(sustaining host's life via photosynthetic capacity of symbiotic zooxanthellae). This study revealed remarkable acclimatization of P. lutea corals to low temperature extremes. This acclimatization is beneficial for Porites corals in the NSCS to expand their living ranges towards the higher-latitude areas and have the potential to be the incipient reef former.     

中国南海表层叶绿素a季节内变化特征及成因

对中国南海表层叶绿素a季节内变化的研究有助于深入认识其海洋特征,满足渔情预报等实际应用需求。利用卫星观测资料分析南海表层叶绿素a不同季节的季节内变化特征,结果表明南海表层叶绿素a季节内振荡强度冬季最高。冬季和春季的季节内振荡最强区域都位于吕宋岛西北侧海区,夏季和秋季振荡较强的区域偏向菲律宾群岛一侧。分析表明研究海区表层温度和表层叶绿素a 存在负相关,冬强夏弱,北强南弱。大部分海区海面高度和叶绿素a 相关性不显著,但南海东南边缘海区海面高度和叶绿素a在季节内存在正相关。冬季海盆尺度逆时针旋转的环流结构应是这些现象产生的原因。除南海东南边缘海区、海南岛东南海区和吕宋岛西侧海区之外,风应力大小和热通量均与叶绿素a 在季节内呈正相关。这显示非局地风场和海流等因素、海洋动力调整过程可能在吕宋海峡以西和南海东南边缘的表层叶绿素a 季节内变化中起到重要作用。     

Effect of cadmium, copper and mercury on antioxidant enzyme activities and lipid peroxidation in the gills of the hydrothermal vent mussel Bathymodiolus azoricus

Metals are known to influence lipid peroxidation and oxidative status of marine organisms. Hydrothermal vent mussels Bathymodiolus azoricus live in deep-sea environments with anomalous conditions, including high metal concentrations. Although B. azoricus are aerobic organisms they possess abundant methano and thioautotrophic symbiotic bacteria in the gills. The enzymatic defences (superoxide dismutase (SOD), catalase (CAT), total glutathione peroxidase (Total GPx) and selenium-dependent glutathione peroxidase (Se–GPx)) and lipid peroxidation were determined in the gills of B. azoricus exposed to Cd (0.9 μM), Cu (0.4 μM) and Hg (0.1 μM) with different times of exposure. The experiments were performed in pressurized containers at 9 ± 1 °C and 85 bars.Results show that vent mussels possess antioxidant enzymatic protection in the gills. Cd and Cu had an inhibitory effect in the enzymatic defence system, contrarily to Hg. These enzymatic systems are not completely understood in the B. azoricus, since reactive oxygen species might be produced through other processes than natural redox cycling, due to hydrogen sulphide and oxygen content present. Also the symbiotic bacteria may play an important contribution in the antioxidant protection of the gills.     

热液和冷泉10种无脊椎动物基因组大小测定及比较

基因组大小(或称C值)作为生物单倍体细胞中全套染色体的DNA总量,在一定程度上是恒定的,因而C值可以作为生物物种的一个特定参数。深海热液和冷泉为更好地理解C值与不同环境之间的关系提供了一个特征性的模型。本文采用流式细胞术,测定了来自热液和冷泉环境中的10种深海无脊椎动物的C值,其分布范围从0.87 pg到12.28 pg,其中,相比于软体动物和多毛类,甲壳生物基因组大小及变异均较大。对比热液和冷泉两个群落中共有种(深海偏顶蛤Bathymodiolus platifrons、柯氏潜铠虾Shinkaia crosnieri以及长角阿尔文虾Alvinocaris longirostris)的基因组大小,发现C值差异并不显著。同时,综合已有的数据,对深海化能极端环境与其他环境条件下的物种C值进行对比分析,结果显示深海化能极端环境下生物的基因组大小并没有发现明确的变化趋势。     

Using sediment geochemistry to infer temporal variation of methane flux at a cold seep in the South China Sea

Release of methane from the seafloor throughout the world's oceans and the biogeochemical processes involved may have significant effects on the marine sedimentary environment. Identification of such methane release events in marine sediment records can hence provide a window into the magnitude of ancient seeps. Here, we report on analysis of the geochemical composition of samples in a 12.3 m long sediment core (DH-5) collected from a seep site in the South China Sea (SCS). Our aim has been to investigate whether the evidence for the presence of methane release event within sediments is discernible from solid-phase sediment geochemistry. We show that sedimentary total sulfur (TS), δ³⁴S values of chromium reducible sulfur (δ³⁴S_CRS) along with total organic carbon (TOC) and total inorganic carbon (TIC) content can be used to infer the presence of methane release events in cold seep settings. At least three methane release events were identified in the studied core (Unit I at 400–550 cm, Unit II at 740–820 cm, and Unit III at 1000–1150 cm). According to the characteristic of redox-sensitive elements (eg., Mo, U and Mn), we suggest that methane flux has been changed from relatively high (Unit I) to low (Unit II and III) rates. This inference is supported by the coupled occurrence of ³⁴S-enriched sulfides in Unit II and III. AMS ¹⁴C dates from planktonic foraminifera in Unit I suggest that high methane flux event occurred at ∼15.4–24.8 kyr BP, which probably resulted in locally-focused aerobic methane oxidation. Overall, our results suggest that TS, TOC, TIC and δ³⁴S_CRS have potential for identifying present and fossil methane release events in marine sediments.     

南海深海鱼类一新记录种——鞭尾鱼

2016年11月至2020年7月在南海海域采集管眼鱼6尾,经形态特征鉴定为月鱼目、鞭尾鱼科、鞭尾鱼属(Stylephorus)、鞭尾鱼(Stylephorus chordates)。鞭尾鱼主要鉴别特征为：体长,侧扁。眼大,呈望远镜状,朝前或朝上。吻小,管状,口有特别大的伸缩能力。背鳍从颈背部延伸至尾鳍基部。尾鳍分明显的上叶和下叶,下叶2鳍条极度延长。鞭尾鱼在南海海域的发现是该科、该属、该种鱼类在中国海域的首次纪录。     

南海腹突平头水蚤新记录(甲壳纲:桡足亚纲:平头水蚤科)

本文基于南海采集的浮游动物标本,详细描述了腹突平头水蚤Candacia varicans Giesbrecht,1892的雌雄个体形态分类特征。本文报道腹突平头水蚤雄性个体是中国海的首次记录。腹突平头水蚤雄性在形态上与武平头水蚤和短平头雄性个体相似,但腹突平头水蚤可以通过以下几个特征与上述两个物种区分：1）头胸部：末胸节后侧角尖锐,左右对称;2）生殖节：右侧下缘具一个指向后方的小突起;3）第五胸足：右足第3节近末端背面具1片状突起。