克隆文库分析红树林土壤中放线菌的多样性

直接提取8个红树林土壤的总DNA,用放线菌门的特异性PCR引物进行扩增,通过构建16S rRNA文库,测序及系统发育分析,获取新颖放线菌菌株.结果发现,有酸微菌亚纲(Acidimicrobidae) (30.2％)、放线菌亚纲(Actinobacteridae) (68.0％)、红蝽菌亚纲(Coriobacteridae)(1.1％)和去腈基菌亚纲(Nitriliruptoridae)( 0.7％)成员,没有红色杆菌亚纲( Rubrobacteridae)成员.仙农指数和Chao1物种多样性指数(Schao1)表明,红树林土壤样品中含有丰富的放线菌多样性.以16S rDNA基因的相似率≥97％作为临界点,45.1％可能代表新候选种(candidate species)(未培养、分离).本研究为进一步获取新颖的红树林放线菌资源提供了基础.     

Severe hail damage to mangroves at Port Curtis, Australia

A hailstorm in October 1994 was found to have moderately or severely impacted on 5.3% of the mangrove forests in Port Curtis. All mangrove species showed evidence of hail damage, including the three most common species (Rhizophora stylosa, Ceriops tagal and Avicennia marina). Physical effects of hail damage included stripping of leaves from plants, holes punched through leaves, bruising to bark, divots removed from bark, branch and plant death. Speciesspecific differences in vulnerability to the effects of hail were observed with C.tagal experiencing relatively higher mortality rates than the other two common mangrove species. A delayed pattern of mortality was observed in two species _ C.tagal and A.marina. Alterations to mangrove community structure included: (1) reductions in stem density, stem diameter and basal area, (2) reductions in canopy cover (based on a photographic index of foliage projective cover) and (3) changes in relative abundance of species in mangrove zones. Recovery was observed in some stands but others had not recovered to prehail levels of canopy cover two years after the hailstorm. Recovery had occurred by regeneration of fresh leaves but no recruitment of young plants had been observed during the study. The forests in the impact area were dominated by either Ceriops tagal or Rhizophora stylosa with Avicennia marinaas a subdominant in places. C.tagal dominated forests within the impact area were relatively more severely affected (41.8% in the severe category) than R.stylosa dominated communities (only 17.4% in the severe category). This indicated that C.tagal dominated forests were more vulnerable to the effects of hail damage than R.stylosa dominated forests. In addition, hailimpacted C.tagal dominated forests represented a relatively high percentage of the area of C.tagal dominated forests in Port Curtis (44.3%). This percentage was much higher than hailimpacted R.stylosa dominated forests in Port Curtis (2.7%). These two factors – relatively severe impact on C.tagal communities and a relatively higher percentage affected within the Port Curtis area – illustrate that hailstorms, as a form of natural disturbance, are an important influence on the forest ecology of mangrove ecosystems in this region.     

Mangrove Habitat Formation and Response to Holocene Sea-level Changes on Kosrae Island,Micronesia

Mangrove habitats on Kosrae are divided into three types, i.e., an estuary or delta type, a backmarsh or lagoon type and a coral reef or tidal-flat type. Most of the mangrove forests of Kosrae have been developed during the last 2000 years by accumulating mangrove peat with the gradual sea-level rise of 1 to 2 mm/yr except the landward part of the estuary or delta type. On the other hand, during the period of rapid sea-level rise of about 10 mm/yr between 4100 and 3700 yr B.P., the mangrove forests ceased peat accumulation and retreated landward. Until 3500 yr B.P., mangrove forests were distributed only in narrow bands in the inlets. Therefore, the critical rate of mangrove peat accretion with sea-level rise is estimated at more than 2 mm/yr and less than 10 mm/yr. If the anticipated sea-level rise exceeds this critical rate, all of the mangrove forests of Kosrae will retreat landward and reduce rapidly.     

虾塘养殖对红树林沉积物和间隙水理化性质的影响

红树林湿地在近海水体营养控制和营养盐循环过程中扮演着重要的角色。沉积物、水体和植被相互作用共同维持其生态功能的运转,了解虾塘养殖对林下沉积物和间隙水养分特征影响对评价红树林生态功能具有重要指导意义。本研究以受虾塘养殖废水排放不同影响程度的红树林（无排放区、直排区、修复区）为研究样地,通过不同生境下沉积物与间隙水养分特征的分析,探讨虾塘养殖对他们的影响。结果如下：1）受虾塘养殖废水排放影响区中（直排区、修复区）红树林下沉积物TN与OM、TP呈正相关关系,虾塘养殖废水直排对林下沉积物具有明显酸化作用;2)NH4+-N是红树林下间隙水可溶性无机氮（DIN）的主要组成形式,无排放区沉积物还原性较强,更利于NH4+-N累积在间隙水中;NO3--N与DIN呈极显著相关,虾塘养殖废水排放增强了NO3--N、NO2--N和DIN的累积效应。研究结果表明沉积物和间隙水的理化性质可作为评价虾塘养殖区边邻红树林生境变化规律的定量指标之一。     

不同盐度海水对锯缘青蟹幼蟹生长变态的影响

实验室条件下比较了盐度为0、3.38‰、6.76‰、10.14‰、13.52‰、16.99‰条件下锯缘青蟹由二期幼蟹至六期幼蟹的生长变态情况。初步结果表明:青蟹幼蟹在变态为四期幼蟹之前,对环境盐度条件有较高的要求:盐度低于10‰,将延长其变态周期和降低成活率;四期幼蟹以后对盐度的适应能力明显增强,此阶段适当降低盐度,将有助于缩短其蜕壳周期。     

海南八门湾红树林丛枝菌根真菌物种多样性

调查了海南八门湾8种红树植物根际丛枝菌根真菌物种资源的分布。结果表明:8种红树均被丛枝菌根真菌侵染,但侵染程度各不相同;经初步分离、鉴定,共确定丛枝菌根真菌4属16种:分别为无梗囊霉属(Acaulospora)6种,巨孢囊霉属(Gigaspora)2种,球囊霉属(Glomus)7种,Fuscutata 1种。其中球囊霉属和无梗囊霉属为优势属,首次在红树植物根际分离到巨孢囊霉属和Fuscutata两属真菌,Fuscutata savannicola为我国丛枝菌根真菌新记录种。     

雷州半岛红树林盐土的某些理化性质

红树林盐土是红树植被下的一类特殊土壤。雷州半岛红树林盐土各土层pH值为3.08 ~ 5.98,绝大多数低于4。土壤有机质平均含量为24.1 g/㎏,在土壤剖面中有机质含量分布没有规律性。土壤阳离子代换量为3.83 ~14.53 cmol/kg,平均6.94 cmo1/kg。土壤水溶性盐分7.6 ~ 42.1g/㎏,平均18.4 g/㎏,水溶性盐分有向下淋溶的趋势。土壤中<0.01 mm粒级含量一般>200 g/kg,土壤质地大多为中壤土类至中粘土类。     

5种红树植物光合产量模型研究

以木榄、白骨壤、桐花树、秋茄和海漆为试材,以光合作用对环境因子的响应为主线,建立了叶片水平上的光合产量模型。就光合作用对环境因子(太阳辐射、温度及CO2浓度等)变化的响应特征及合理性进行了分析,使用整个生长季实测的叶片生理数据对所建模型进行了验证,结果表明,模型可以较好的模拟实测红树植物的光合速率,并确定了5种红树植物单叶片光合作用与环境因子之间的数量关系。     

我国红树林研究人员统计与分析

以1989～2005年《中国期刊全文数据库》、《中文科技期刊数据库》收录的红树林研究文献为依据,采用文献计量学的方法,对我国红树林研究人员的地区分布、人员数量及文献量的年际变化、核心作者群、核心机构、核心期刊等方面进行统计与分析。     

以海蛙作为红树林环境监测指示物种的初步研究

[目的]研究将唯一栖息于红树林的两栖动物——海蛙(Rana cancrivora)作为红树林环境质量监测指示物种的可行性。[方法]于2009年7月和8月在海南东寨港红树林国家级自然保护区的码头和红树林核心区(简称红树林)2个不同微生境中采集海蛙,检测分析其肝脏和肌肉中超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、乙酰胆碱脂酶(AChE)和诱导型一氧化氮合成酶(iNOS)活性及丙二醛(MDA)含量,同时测量计算其肝体指数、肾体指数和脾体指数,以综合评估海蛙所受环境胁迫大小,并用以评估红树林不同生境质量好坏。[结果]红树林生境中海蛙的肝脏、肾脏和脾脏系数均低于码头,但仅肾脏系数差异显著(p<0.05);该生境中海蛙组织的4种酶活性均高于码头,且SOD和CAT活性均表现出差异显著(p<0.05);同时MDA含量也显著低于码头(p<0.05)。结果表明红树林生境中海蛙的抗氧化酶活性高于码头个体,相应地脂质过氧化程度低,所受环境胁迫程度低于码头。[结论]由于人类干扰和旅游开发等因素使码头生境质量明显低于红树林核心区,而红树林生境中海蛙个体所受环境胁迫小于码头个体,与这2个微生境中的生境质量相一致,表明海蛙可作为红树林环境质量评价的指示物种。