三亚天涯海角潮间带趋磁细菌特性

在三亚天涯海角潮间带沉积物中发现了一定量的海洋趋磁细菌,最大丰度可达100个/cm3。透射电子显微镜(TEM)观察发现该区域趋磁细菌绝大多数为趋磁球菌。磁小体形状单一,皆为棱柱形;磁小体排列方式多样,以链状排列为主,包括单链、双链,也有少数成簇排列。高分辨率透射电子显微镜(HRTEM)与X-射线能谱仪(EDXS)结果表明,磁小体成分为Fe3O4。趋磁细菌的铁含量平均为2.05%(0.70%~7.53%)。通过16S r RNA基因文库的构建与测序,在78个阳性克隆中得到了16个趋磁细菌序列,分属9个OTU。系统发育分析结果表明,其中8个OTU属于α-变形菌纲,1个OTU属于γ-变形菌纲。在全部9个OTU中,有8个OTU与已知趋磁细菌序列的相似性低于97%,有5个OTU与已知趋磁细菌序列的相似性低于93%,说明该区域存在可观的趋磁细菌资源。     

乐清湾口海域春秋季甲壳动物的群落结构特征研究

根据2012年春季和10月在乐清湾口海域开展渔业资源调查所获甲壳动物资料,对乐清湾口海域的甲壳动物的种类组成、优势种、物种数量分布、生物多样性和群落结构相似性等群落结构特征及其影响因素进行了研究。结果表明,调查海域共鉴定出34种甲壳动物,隶属于2目17科23属,春季优势种仅有三疣梭子蟹1种,秋季为日本、口虾蛄、中华管鞭虾、三疣梭子蟹4种,两季优势种更替较显著;秋季物种数较春季丰富,调查水域中心区域物种数较多;秋季甲壳动物生物多样性指数高于春季;甲壳动物群落结构与海洋环境密切相关。乐清湾口海域的甲壳动物以季节性的广温低盐种类为主,该海域位于河口,受瓯江径流影响较大;春季受瓯江径流淡水水团影响,物种较少,而秋季受交汇水团影响,物种丰富;春秋季组内并无明显规律,地形、水深和水系等外部因素对甲壳动物群落结构影响较大。     

Review of Methods for Simulating Land Surface Temperature at the Pixel Scale Based on Ground Measurements over Heterogeneous Surface

Remotely sensed Land Surface Temperature (LST) is a key parameter for studying the global climate changes and the exchanges of water and energy. Acquiring LST accurately is important to diagnose the change of environment on earth. Quantifying the uncertainty of remotely sensed LST is the first step of its application. However, due to the difficulties in obtaining the ground truth of LST at the pixel scale, it is difficult to validate the remotely sensed LST. Here, methods for simulating the LST at the pixel scale based on ground measurements over heterogeneous area were reviewed. From the way to construct the ground scene, these methods were classified into three types, including the Modified Geometric Projection model (MGP), realistic structural three-dimensional model, and other model. The advantages and disadvantages of these models were examined and compared. Finally, some issues in simulating LST at the pixel scale over heterogeneous area needed to be solved and on-going directions in the future were summarized.     

大洋桥石藻Gephyrocapsa oceanica对海水酸化与营养盐胁迫的复合响应

本文选取了大洋桥石藻(Gephyrocapsa oceanica)作为实验对象,通过CO₂加富实验模拟海水酸化环境,分析了氮充足和氮相对不足条件下海洋颗石藻对海水酸化的生理响应。结果发现在两种营养盐状态下,CO₂加富均能一定程度促进大洋桥石藻种群增长与Chl a浓度的增加。对比两种营养盐状态,氮相对不足条件下的大洋桥石藻细胞密度和叶绿素含量均有最显著的提高,表明低营养盐浓度和低的氮磷比可能更有利于大洋桥石藻的生长繁殖。电镜观测结果显示酸化对大洋桥石藻的钙化作用具有显著的负影响,并且在氮相对不足条件下,大洋桥石藻的细胞个体变小及比表面积升高。研究结果表明在未来寡营养的大洋上层水体,大气CO₂浓度升高会对大洋桥石藻的生理功能产生负面影响,但可能刺激大洋桥石藻的生长。