南海北部生态系统食物网结构、能量流动及系统特征

根据20072008年在南海北部(107°00'120°00'E、17°00'23°30'N)进行的海洋生态综合调查数据,应用Ecopath with Ecosim软件构建了南海北部生态系统的生态通道模型,并通过模型分析了南海北部海洋生态系统的食物网结构、能量流动和系统的总体特征,并简要总结过度捕捞生态系统的基本特征。结果表明,南海北部海洋生态系统以捕食食物链为主要能流通道,初级生产者是系统能量的主要来源。各功能群的营养级范围为13.99,哺乳动物占据了最高的营养层,平均渔获物营养级为2.93。利用生态网络分析,系统的能量流动主要有6级,来自初级生产者的能流效率为12.6%,来自碎屑的转换效率为10.4%,平均能量转换效率为11.5%。系统连接指数(Connectance Index,CI)和系统杂食指数(System Omnivory Index,SOI)分别为0.290和0.239;Finn’s循环指数(Finn’scy cling index,FCI)和系统平均路径长度(Finn’s mean path length,MPL)分别为4.380和2.476;总初级生产力/总呼吸为2.596,综合研究表明当前南海北部海洋生态系统处于不成熟阶段。     

Phytoplankton morphological response to the underwater light conditions in a vegetated wetland

This study analyses the influence of the underwater light climate on the morphometric characteristics of the phytoplankton at the population and community levels. The differences in light conditions across the floodplain were mainly defined by the patchiness of floating macrophytes and humic acids concentration. A morphometric response at the community level to the underwater PAR was registered. Sites with strong light constraints were characterised by non-flagellated organisms or with a small proportion of unicellular flagellates. Short organisms (<10 μm) with a unit volume of less than 1,000 μm³ and a high surface:volume ratio (S/V >2) were the morphotypes related to poorly illuminated environments. Moreover, the organisms showed forms more slender under these limiting conditions. This pattern was different to that registered in well-illuminated sites where longer and larger organisms, with a smaller S/V and frequently flagellated, coexisted with the previously mentioned organisms. The autotrophic picoplankton, the smallest phytoplankton fraction, revealed lower abundances at sites with higher humic substances. Short term morphological changes were additionally studied for the dominant species by means of mesocosm experiments simulating different light climates. Intraspecific morphological plasticity was observed with respect to the filament length and the vacuolization of cells. Electronic Supplementary Material Supplementary material is available for this article at and is available to authorized users.     

气候环境因子和捕捞压力对南海北部带鱼渔获量变动的影响

带鱼(Trichiurus japonicas)是南海北部的重要经济鱼类,其渔获量的变化不仅与捕捞压力有关,还与气候环境变化有关.为了研究气候变化和捕捞对南海北部带鱼渔获量变动的影响,使用长时间序列渔业统计资料和气候变化数据对1956-2006年的南海北部带鱼渔获量变动进行了分析.南海北部的带鱼渔获量变化可划分成因捕捞效应所产生的趋势变化和因气候环境变化所导致的渔获量变动.捕捞效应所产生的趋势变化可用Fox模型拟合,Fox模型拟合结果显示南海北部带鱼渔获量与捕捞努力量关系显著(P＜0.01),说明捕捞压力的增长显著影响到南海北部带鱼渔获量的变化.移除捕捞效应所产生的趋势变化后,渔获量变动与中国南方降雨、南海北部海表水温、南海北部夏季季风以及南海北部冬季季风等气候因子呈显著正偏相关(P＜0.04),与热带气旋影响指数呈显著负偏相关(P＜0.03),这种相关说明南海北部带鱼渔获量变动还受气候环境因子的影响.南海北部带鱼渔获量可用捕捞努力量和气候变量来拟合,且拟合效果显著(R2=0.958,P＜0.01),表明南海北部带鱼渔获量的变动归因于捕捞压力的单调增长和气候环境的变化.在南海北部的捕捞压力维持在现有水平下,未来的气候变化和人类活动引起营养盐的增加都可能有利于南海北部带鱼渔业产量的增加,且由于未来极端天气事件的频繁发生,可能还会引起带鱼渔获量的变动幅度加剧.     

长喙田菁-Azorhizobium caulinodans共生固氮体系在华南地区的生长、结瘤、固氮和种子生产

研究了长喙田菁－Ａｚｏｒｈｉｚｏｂｉｕｍｃａｕｌｉｎｏｄａｎｓ共生固氮体系在华南地区的生长、结瘤、固氮和种子生产．结果表明,长喙田菁－Ａ．ｃａｕｌｉｎｏｄａｎｓ共生固氮体系在华南地区生长正常,并具旺盛的茎根瘤结瘤作用．经６５天的生长,其在湛江地区的单位面积生物量（干物质）和单位面积Ｎ产量分别为２８７５２和６８１ｋｇ·ｈｍ－２,远优于普通田菁的１６５２０和３５２ｋｇ·ｈｍ－２;茎瘤菌Ａ．ｃａｕｌｉｎｏｄａｎｓ品系ＡＲ１１１和ＡＲ５６在华南地区混合接种效果良好,植株茎瘤结瘤率达到１００％,平均单株茎瘤个数为１８２个,单株茎瘤鲜重约为１．２ｇ,茎瘤生物量在茎根瘤总生物量中所占比重为７０％,而其根瘤生物量略高于普通田菁;长喙田菁在华南地区能够正常开花结实,在栽植密度为４×１０４株·ｈｍ－２的条件下,其种子产量达３２００ｋｇ·ｈｍ－２．     

鞘喙蝽总科（半翅目）在中国的首次发现

半翅目鞘喙亚目是一类具有重要演化意义的昆虫。该亚目包括三个科：鞘喙蝽科(Peloridiidae)和卡拉蝽科(Karabasiidae)同属于鞘喙蝽总科;原臭虫科(Progonocimicidae)属于原臭虫总科。鞘喙蝽科是唯一的现生类群,孑遗于南半球。卡拉蝽科化石较丰富,但只发现于中亚、西伯利亚和蒙古中生代地层。本文...     

Ontogeny of the eodiscoid trilobite Tsunyidiscus acutus from the Lower Cambrian of South China

Abstract: The morphology and ontogeny of the eodiscid trilobite Tsunyidiscus acutus Sun is described on the basis of numerous calcified specimens collected from the Lower Cambrian Shuijingtuo Formation in Yichang and Changyang, Hubei Province, South China. An ontogenetic series is established based on the articulated material including the previously unknown protaspides and meraspides (degrees 0 and 1). The material, revealing some prominent morphological changes such as the number of pygidial axial rings, genal spines retained throughout ontogeny and pygidial pleurae from furrowed to unfurrowed, enables a discussion on the trunk segmentation schedule, indicating that somitogenesis and tagmosis occurred independently during the ontogenetic development of T. acutus.     

颈斑尖猪鱼——中国南海隆头鱼科新纪录种

本文根据采自海南岛的标本描述了中国南海一新记录种:颈斑尖猪鱼(Leptojulis lambdastigma)。本种的主要形态特征为:体长形,体长为体高的3.7~4.0倍,为头长的3.1~3.6倍;头长为吻长的2.7~3.3倍,为胸鳍长的1.45~1.65倍;头裸露无鳞;两颌前端各具2对大犬齿,外侧1对犬齿弯向外后方;背鳍Ⅸ-12,臀鳍Ⅲ-12,胸鳍i(不分支)+11-12(分支);侧线完整,侧线鳞27;颈部具一个"V"形大黑斑,胸鳍后部的上方、侧线的下方具一小黑斑。新鲜标本头部具2条黄色纵带,沿体侧分别经眼和胸鳍基部向后达尾鳍基部;体侧背部具1条浅棕黄色条带;胸鳍基部棕红色,后部浅色;臀鳍浅蓝色;尾鳍下部淡蓝色,上部橙色。本种与尾斑尖猪鱼(L.urostigma)形态较为相似,主要差别在于颈斑尖猪鱼的颈部具有一显著的"V"形黑斑,尾鳍基部无黑斑(尾斑尖猪鱼具此黑斑)。     

末次冰盛期低海面时南海南北陆架上的植被

在探讨孢粉的传播、来源地的基础上,根据南海南北陆坡柱状剖面（１７９４０ ,１７９６４） 的孢粉资料推断末次冰盛期（包括氧同位素３ 期的上部） 低海面时,南北出露的大陆架上生长的植被。末次冰盛期时北部大陆架曾分布以蒿属（Ａｒｔｅｍｉｓｉａ Ｌ．） 为主的草原植被,气候较今日冷且干旱。南部称为“巽他古陆”,曾覆盖热带低地雨林,河口及海岸为红树林,在周围岛屿上高山雨林曾多次向山下迁移,表明当时温度可能较今日低,但湿度没有明显变化。南北大陆架末次冰期时在植被与气候演化上的巨大差异,可能与南部巽他陆架的特殊位置（ 西太平洋暖池） 有关     

华南兔组织乳酸脱氢酶同工酶的研究

本文以聚丙烯酰胺凝胶电泳法分析华南兔(Lepus sinensis sinensis)11种组织乳酸脱氢酶同工酶的分布待征。分析结果:骨骼肌和肝组织5条同工酶带俱全;脑、肺、卵巢和盲肠等组织各含有4条谱带(LDH-1,-2,-3和-4);胃和肾组织含有3条谱带(LDH-1,-2,和-3);眼晶状体和睾丸组织也含有3条谱带,但前者是LDH-3,-4和-5,后者是LDH-1,-2和-5;谱带最少的是心肌组织,只有2条(LDH-1和-2)。此外,还对各组织中的亚基活性分布及电泳图谱特征进行了分析。     

Vegetation:environment relationships and water management in Shark Slough,Everglades National Park

The hydrologic regime of Shark Slough, the most extensive long hydroperiod marsh in Everglades National Park, is largely controlled by the location, volume, and timing of water delivered to it through several control structures from Water Conservation Areas north of the Park. Where natural or anthropogenic barriers to water flow are present, water management practices in this highly regulated system may result in an uneven distribution of water in the marsh, which may impact regional vegetation patterns. In this paper, we use data from 569 sampling locations along five cross-Slough transects to examine regional vegetation distribution, and to test and describe the association of marsh vegetation with several hydrologic and edaphic parameters. Analysis of vegetation:environment relationships yielded estimates of both mean and variance in soil depth, as well as annual hydroperiod, mean water depth, and 30-day maximum water depth within each cover type during the 1990's. We found that rank abundances of the three major marsh cover types (Tall Sawgrass, Sparse Sawgrass, and Spikerush Marsh) were identical in all portions of Shark Slough, but regional trends in the relative abundance of individual communities were present. Analysis also indicated clear and consistent differences in the hydrologic regime of three marsh cover types, with hydroperiod and water depths increasing in the order Tall Sawgrass < Sparse Sawgrass < Spikerush Marsh. In contrast, soil depth decreased in the same order. Locally, these differences were quite subtle; within a management unit of Shark Slough, mean annual values for the two water depth parameters varied less than 15 cm among types, and hydroperiods varied by 65 days or less. More significantly, regional variation in hydrology equaled or exceeded the variation attributable to cover type within a small area. For instance, estimated hydroperiods for Tall Sawgrass in Northern Shark Slough were longer than for Spikerush Marsh in any of the other regions. Although some of this regional variation may reflect a natural gradient within the Slough, a large proportion is the result of compartmentalization due to current water management practices within the marsh. We conclude that hydroperiod or water depth are the most important influences on vegetation within management units, and attribute larger scale differences in vegetation pattern to the interactions among soil development, hydrology and fire regime in this pivotal portion of Everglades.