中国渤海海域甲藻孢囊的种类多样性和生态地理分布

在渤海湾24个站位采集0–10 cm表层沉积物144份样品, 进行甲藻孢囊的种类多样性和生态地理分布研究, 并分析渤海海域水体的富营养化趋势。在渤海海域共采集鉴定出6类32种甲藻孢囊, 包括原多甲藻类孢囊11种、裸甲藻类孢囊6种、膝沟藻类孢囊7种、钙质类孢囊5种、翼藻类孢囊2种及Tuberculodinioid类孢囊1种。其中, 自养型甲藻孢囊17种, 优势种为锥状斯氏藻(Scrippsiella trochoidea)孢囊, 丰富的孢囊库为锥状斯氏藻赤潮提供种源, 可作为该海域发生锥状斯氏藻赤潮的参考依据; 异养型甲藻孢囊15种, 优势种为无纹多沟藻(Polykrikos schwartzii)和锥形原多甲藻(Protoperidinium conicum)孢囊; 发现1种产麻痹性贝类毒素的孢囊--塔玛亚历山大藻(Alexandrium tamarense)孢囊, 但是仅在S6、S8和S14三个站位发现, 且孢囊数量较少。渤海甲藻孢囊组成与世界其它海域相似, 异养型甲藻孢囊种类丰富, 提示渤海海域富营养化程度较高。每个站位沉积物样品分为3层(每层约3 cm), 春夏两季表层、中层和底层之间孢囊组成差异不大, 平均种类数为5.58–7.29, 孢囊的平均密度范围在58.82–103.57 cysts·g^–1 DW之间; 孢囊种类丰富的站点, 孢囊密度也较高, 如S9、S14站位。对渤海海区表层沉积物中甲藻孢囊的生物多样性进行了统计分析, 发现表、中、底3层甲藻孢囊的平均种类多样性指数在春季(5月)分别为1.69、1.61和1.52; 略低于夏季(8月)的1.83、1.89和1.60。     

我国东南沿海亚历山大藻休眠孢囊的分布和萌发研究

对4个海域的塔玛亚历山大藻(Alerandrium tamarense)和链状亚历山大藻(A．catenella)休眠孢囊的分布及萌发进行了研究．结果表明,厦门港仅在X1和X2站位有分布,且密度很小(0．4个·g-1);广西只在G2站位有发现,密度较少(2．5个·g-1泥样)．闽江口有3个站位有分布,M4站位的4～6cm层密度最大,达到6个·g-1泥样;长江口的孢囊分布广、密度大,DG-26站位的8～10cm层孢囊密度达到了23．2个·g-1泥样．孢囊的分布与沉积物底质类型、沉积速率、海流都有一定的关系．光照对孢囊萌发没有影响,温度升高导致萌发率和存活率均增大,而萌发时间缩短;在低氧条件下(0．01mgO2L-1),孢囊萌发率为0．亚历山大藻孢囊在合适的环境条件下终年都会萌发     

深圳湾表层沉积物中甲藻孢囊的垂直分布

采集了深圳湾3个采样点约20cm的表层沉积物样品,研究了甲藻孢囊的垂直分布。共分析鉴定出孢囊类型37种,其中5种为我国沿海未报道的新记录类型,原多甲藻类孢囊是该海域种类最丰富的孢囊类型。除上表层沉积物外,深圳湾甲藻孢囊密度较低,孢囊密度大多在500cysts／gDWt以下,总孢囊密度变化范围为83～4036cysts／gDWt之间。锥状斯氏藻是深圳湾甲藻孢囊的优势种类,上表层沉积物中该孢囊密度的急剧上升证实了2000年附近海域所发生的该藻赤潮。而裸甲藻类孢囊含量明显比南海其他海域高。孢囊的香农-威弗种类多样性指数为1．50～3．96之间,并且在非养殖区、离岸海域及较深层次沉积物中较高,而孢囊密度则呈相反的变化趋势。种类多样性的下降及孢囊密度的上升在一定程度上说明深圳湾污染的变化趋势,富营养化程度非养殖区大于养殖区,近岸海域大于离岸海域,并且近年来污染逐渐加剧。     

2004年春季长江口海域甲藻孢囊的分布研究

于2004年4月初,采集长江口(E122°～123°30',N29°～32°)10个站点0～15cm底泥样品,研究甲藻孢囊在这10个站点的水平和垂直分布情况。在30个样品中共鉴定出6大类24种甲藻孢囊。孢囊组成以异养型原多甲藻类孢囊为主,有13种,平均密度为157cysts·g^-1DW,为调查海域的最优势种群。两种产麻痹性贝类毒素(Paralytic shellfish poisoning,PSP)的孢囊,塔玛亚历山大藻和链状裸甲藻,在海区分布广泛但数量较低。10个站点甲藻孢囊的种类数在11～18种之间,平均密度为189～846cysts·g^-1DW,在远离河口的D6站点有一个明显的最高峰,位于最北部的D1站点孢囊密度最低。与其它海湾相比,属于孢囊密度较低的海区。Shannon-Weaver生物多样性指数(H')变化范围在2.57～3.27之间。甲藻孢囊的密度分布与生物多样性相关系数r=-0.72。3个不同深度的甲藻孢囊密度分别为351cysts·g^-1DW、412cysts·g^-1DW、432cysts·g^-1DW;生物多样性指数分别为3.22、2.95、2.98。     

2006—2007年冬季长江口海域甲藻孢囊的分布及其与环境的关系

分析了2006—2007年冬季长江口海域(121°-127°E,30°-32.5°N)19个站位0-10cm沉积物中的甲藻孢囊,共检出27种甲藻孢囊类型,其中自养型10种,异养型17种,异养型孢囊数量比为0.70。各站位孢囊种数在1-15种之间,孢囊平均密度在干重0.7-89.0个/g之间。表层(0-3cm)、中层(3-5cm)和底层(5-10cm)之间孢囊组成差异不大,大多以原多甲藻类孢囊为主要优势种,孢囊密度表层大于中层,中层大于底层的分布趋势;在经度方向上,孢囊平均密度在近岸逐渐增高,到站位M4-13突然降到最低,然后再逐渐增高。与其它海湾相比,长江口属于孢囊密度较低的海域。亚历山大藻分布广泛但数量较低,最高密度为干重40.8个/g,其他种类如Polykrikos kofoidii、Gonyaulax spiniferacomplex(Spiniferites mirabilis)和G.spiniferacomplex(S.cf.ramosus)都在长江口海域有分布。沉积物类型是影响孢囊数量分布的重要因素,水深、温度、盐度与孢囊分布呈正相关性,溶解氧与孢囊分布呈负相关性。孢囊的分布格局对河口的富营养化与低氧区具有良好的指示意义。     

甲藻孢囊在长山群岛海域表层沉积物中的分布

2007年10月,在大连长山群岛海域采集了25个站点的表层沉积物,研究了甲藻孢囊的水平分布。在沉积物样品中共检测出甲藻孢囊46种,其中Pentaphasodinium dalei和Warowia rosea,在我国是首次报道。各站位孢囊种类数在7-20之间,平均14种;丰度在182-2960 个/g干重之间,平均为1201 个/g干重。香农-威纳指数(H')的变化范围为2.4-3.4。麻痹性贝毒藻--亚历山大藻的孢囊在调查海域分布广泛,最高密度达829个/g干重,可能是造成该海域虾夷扇贝贝毒超标的原因之一。     

大亚湾近代沉积物中甲藻孢囊的垂直分布

用TFO采泥器于 2 0 0 1年 8月采集了大亚湾大鹏澳海域 6个采样点 8— 18cm柱状沉积物样品 ,分层研究了甲藻孢囊在该海域表层沉积物中的垂直分布。在 35个沉积物样品中共分析鉴定出甲藻孢囊 4 8种 ,其中自养型 2 0种 ,异养型 2 8种 ,优势种类为锥状斯氏藻。每个样品中所分析鉴定的孢囊种类数为 12— 2 9种 ,孢囊的香农—威弗种类多样性指数 (Shannon WeaverDiversityIndex,H′)为 0 6 1— 4 13,并且在 2— 4cm层次处 ,随深度的增加 ,两者均有一个明显上升趋势。除鱼类养殖区的上表层较高外 ,孢囊丰度大多为 10 0 0— 2 0 0 0cysts/gDWt,最高为 2 38× 10 4cysts/gDWt。亚历山大藻孢囊分布广泛且密度较高 ,最高丰度为 5 0 3cysts/gDWt,同时表层沉积物中高密度的亚历山大藻孢囊为该藻赤潮的发生提供了丰富的种源 ,而且也是该海域贝类体内冬季PSP毒素积累及高含量的重要原因。     

2006年冬季长江口海域表层沉积物中甲藻孢囊的分类学研究

于2006年12月23日至2007年2月3日,采集长江口海域(121° ～127°E, 30°～32.5°N)19个站位0～10cm的底泥样品,根据孢囊的形态特征共鉴定出分属5大类的27种甲藻孢囊类型.其中自养型孢囊10种,异养型孢囊17种,9种为国内首次报道,它们是Scrippsiella sp.、Scrippsiella crystallina、Pentapharsodinium tyrrhenicum、Scrippsiella sp.1、Scrippsiella sp.2、Cochlodinium sp.cf.Geminatum、 P.sp.1、P.sp.2 和Gotoius abei,并发现了Alexandrium tamarense/A.catenella complex、 A.minutum/A.affine complex两种有毒种,Polykrikos kofoidii、Gonyaulax spinifera complex (Spiniferites mirabilis*)和Gonyaulax spinifera complex (Spiniferites cf.ramosus*)3种有害种.各站位孢囊物种数在1～15种之间,M4-13和N11-4最低,O7-6最高,且种类组成上基本以异养型甲藻孢囊为主.在长江口、苏北、杭州湾、舟山海域、外海海域分别鉴定出15、15、12、15、13种甲藻孢囊类型.对每种孢囊的分类学特征和分布情况进行了详细的描述,丰富了长江口海域甲藻孢囊种类记录,对研究该海区的甲藻群落结构及其目标赤潮生物的种群动力学具有重要意义.     

广东大亚湾甲藻孢囊及其与锥状斯氏藻赤潮的关系

1999年12月至2001年1月,在大亚湾澳头海域用沉积物捕捉器(Sediment trap)及TFO重力采泥器对甲藻孢囊进行每月一次的周年监测,并同时研究了浮游植物的季节变化.结果显示,晚秋孢囊形成率最高(3.48105 cysts/m2d),冬季形成率较低,年平均为1.28105 cysts/m2d.锥状斯氏藻(Scrippsiella trochoidea)是大亚湾沉积物孢囊中的绝对优势种,除个别季节外,其形成率一般占孢囊总形成率的50%以上.2000年8月至9月,该海域发生了一次较大规模的锥状斯氏藻赤潮,最高细胞密度达4.0104 cells/mL.赤潮中后期,锥状斯氏藻孢囊包括暂时性孢囊和休眠孢囊大量形成,孢囊的形成减少了水体中营养细胞数量,是赤潮消退原因之一.       

长江口附近海域春季浮游硅藻的种类组成和生态分布

2002年春季,在长江口附近海域典型赤潮高发区28个大面站位采集了53个样品,从中共鉴定出隶属于31个硅藻属的80个种和变种;其中种类多样性较高的属为圆筛藻属(Coscinodiscus),有17个种,斜纹藻属(Pleurosigma),有8个种和变种;数量上较优势的种为柔弱拟菱形藻(pseudo-nitzschia delicatissma),为3．48×10^3cells·L-1,占28．54％;具槽直链藻(Melosira sulcata),为1．43×10^3cells·L-1,占16．98％;尖刺拟菱形藻(Pseudo-nitzschia pungens),为0．71×10^3cells·L-1,占9．85％．它们在大部分站位中都有出现;柔弱拟菱形藻和尖刺拟菱形藻的高细胞密度区主要出现在1230E断面的站位,而具槽直链藻则主要出现在长江口的31～32°N断面的站位．浮游硅藻总细胞丰度变化于0．43×10^3～23．3×10^3cells·L-1,平均4．61×10^3cells·L-1;在123°E、30．5°N的DDl5站位,无论表层还是中层,浮游硅藻总细胞丰度均最高(表层,1．85×10^4cells·L-1;中层,2．33×10^4cells·L-1)．从水平分布看,浮游硅藻呈不均匀分布态势,从垂直分布看,大部分站位的表层浮游硅藻丰度高于中层．     

Seasonal distribution of dinoflagellate resting cysts in surface sediments from Changjiang River Estuary

In order to understand the distribution of dinoflagellate cysts, surface sediments were collected from 15 stations in Changjiang River Estuary from 122°E to 123.5°E and from 29°N to 32°N in four cruises from May 2002 to February 2003. In the present study, 38 different cyst morphotypes representing 21 genera and 6 groups were identified, while 1 type was not identified into genus level. Species number and cell density of dinoflagellate cysts ranged from 10 to 25 species and from 12 to 587 per gram of dry weight, respectively. There were no obvious differences in cyst composition and density among seasons. However, the highest cyst species number and density were recorded in summer and winter, respectively. Cysts of heterotrophic dinoflagellates, which held 55.7% of the overall cyst density averagely, dominated cyst assemblages. Cyst density and species number increased from the west to the east, from the north to the south within the study area. Cysts of toxic dinoflagellates Alexandrium cat‐enella and Alexandrium tamarense complex distributed widely and were observed in almost all stations, with the maximum cell density of 81 per gram of dry weight.     

Dinoflagellate cyst records in recent sediments from Daya Bay, South China Sea

Nine sediment cores of 8–26 cm in length were collected from two basins of Daya Bay, the South China Sea, by Tokyo University Fisheries Oceanography Laboratory core sampler in August 2001 to investigate the distribution of dinoflagellate resting cysts. In the present study, 51 different cyst morphotypes representing 22 genera were identified from 65 sediment samples. Among them, there were 21 autotrophic species and 30 heterotrophic ones. Cyst species richness in each sample varied from 12 to 29, while the values of Shannon‐Weaver diversity index (H′) were between 0.15 and 4.13. There were an obvious increase in both species richness and values of H′in 2–6 cm sediments. Cyst concentrations varied from 154 to 113 483 cysts per gram dry weight sediment, and were much higher in upper sediments. Scrippsiella trochoidea was the most dominant cyst type, which took up over 90% of cyst assemblages in the upper sediments. The abrupt increase of S. trochoidea cysts in the surface sediments reflected the bloom of this species in Daya Bay in 2000. The results from cyst assemblages showed some trend of changes in water quality in this area, and indicated a typical type of pollution caused by cultural eutrophication, which started in the 1980s and greatly accelerated in the middle of 1990s. Cysts of Alexandrium, mainly those of Alexandrium catenella and Alexandrium tamarense complex, occurred frequently and abundantly in this area, with the highest concentration and relative frequency of 503 cysts per gram dry weight sediment and 22.3%, respectively. The high abundance of Alexandrium cysts provided rich ‘seed bed’ for Alexandrium blooms and was also an important source of paralytic shellfish poisoning toxins, especially in winter.     

长江口赤潮高发区浮游植物与水动力环境因子的分布特征

报道了2002年春季长江口海域(30°50′～31°50′N,121°50′～123°00′E)的22个大面观察站和一个昼夜连续观察站的水样和网样浮游植物的种类组成、丰度分布与水动力环境因子、营养盐的关系．结果表明,长江口区共有浮游植物5门45属110种．主要赤潮生物优势种为中肋骨条藻(Skeletonema castaturn)和具齿原甲藻(Prorocentrum dentatum)等．浮游植物丰度的昼夜变化白天大于夜间,垂直分布不明显．浮游植物主要生态类型可划分为：沿岸河口低盐半咸水类群、沿岸偏低盐广布性类群、外海高盐暖水性类群等．长江口区浮游植物丰度在1．6×10^3～75．2×10^3个.dm-3．浮游植物的种类组成和丰度分布与长江冲淡水密切相关．在该区域存在三股不同性质的水,即长江河口水、长江冲淡水及外海水(台湾暖流)影响着浮游植物的分布．     

长江口塔玛亚历山大藻孢囊的形成、发展及其与赤潮动力学的关系

有毒甲藻棗塔玛亚历山大藻(Alexandrium tamarense(Leboru)Balech)在低氮的F\2培养液中会形成休眠孢囊.在试验的递度中,f\20NO3-诱导效率最高,一次性培养中孢囊形成率达到2%.大约73.2%和17.6%的孢囊在接种后的第八天和第九天形成.新形成的孢囊3d后红色体开始出现,并持续地分泌粘性物质,这可能有助于孢囊的扩散和生存.孢囊在15和20℃保存下的休眠期分别为15和10d.孢囊需要温度的改变就能萌发,在20℃条件下孢囊密度分别降到了4.5和0.9个\g,说明2002年亚历山大大藻孢囊在春季和各有一次萌发.赤潮发生过程中产生的孢囊会很快通过萌发回到水体中,无论季节和水温如何.2003年5月DG-26站位表层沉积物中亚历山大藻孢囊密度只有3.3个\g,但这些孢囊均是新形成的.在长江口,种群初始的大小不是决定塔玛亚历山大藻赤潮发生的关键因素.     

A comparative study of Alexandrium tamarense cyst distribution in Belfast Lough

Alexandrium tamarense is a cyst-forming dinoflagellate that can cause toxicity in shellfish. Belfast Lough, in northeast Ireland, has experienced toxicity events due to the presence of A. tamarense, which are monitored because of shellfish farms in the Lough. Since 1992 anthropogenic influences on the Lough have changed with the introduction of a ‘fast cat’ ferry service and an increase in mussel farming. In 2002 Belfast Lough was surveyed for A. tamarense cyst distribution in the sediments and the results are compared to a previous cyst survey carried out in the Lough in 1992. Cyst numbers were generally lower in 2002 than in 1992 (t-test, P < 0.01). The highest concentration found in 2002 was 1058 cysts g^?1 dry sediment compared with 3330 in 1992. Although sediment disturbance increased in the period between the surveys and plays a role in cyst distribution, A. tamarense cysts are still present in the seabed of the Lough. These cysts remain an important repository of inoculating cells for A. tamarense blooms that have not been removed by the recent anthropogenic activity in the Lough and therefore the requirement for monitoring remains. Comparisons between cyst counts per volume of wet sediment and per weight of dry sediment were carried out, and although the first is needed for ecological studies allowing a deeper analysis, it is also recommended that cyst counts per dry weight of sediment are always reported for wider comparative purposes.     

Dinoflagellate cysts in recent marine sediments of the western coast of the Bering Sea

The quantitative and qualitative composition of live dinoflagellate cysts was studied in the upper two-centimeter layer of recent marine sediments that were collected at 19 stations in the coastal waters of the western Bering Sea. A total of 28 types of identified cysts belonged to the following 11 genera: Alexandrium, Diplopsalis, Ensiculifera, Gonyaulax, Gyrodinium, Pentapharsodinium, Polykrikos, Preperidinium, Protocera- tium, Protoperidinium, and Scrippsiella. The morphology of dinoflagellate cysts from recent sediments of Russian seas, such as the shape, the size, and also the structure of the phragma, including the processes and the archeopyle, was described comprehensively for the first time. Cysts of the species Gonyaulax spinifera, Pentapharsodinium dalei, Protoceratium reticulatum, Protoperidinium americanum, P. conicoides, P. subinerme, Scrippsiella crystallina, and S. trochoidea were the most widespread. Those of the potentially toxic species Alexandrium tamarense were also widely distributed and prevailed in the studied area. Their concentration varied from 0 to 25 860 cells/cm³; the maximum concentration was recorded in Pavel Bay, Koryak Okrug, and Kamchatka.     

Effects of Birds Ingesting Heterodera rostochiensis Cysts on Viability of Eggs and Larvae

Rate of passage through the digestive systems and effects of ingestion on viability of contents of cysts of Heterodera rostochiensis were determined in feeding trials with pigeons, thrushes, starlings, cowbirds, sparrows, and quails. Depending upon species of birds, 12-82% of the cysts ingested passed through the digestive system within 0.5 h. Pigeons required 6 h for complete evacuation. All other birds cmnpletely evacuated ingested cysts from their digestive systems within 3 h. Contents of cysts were nonviable if they were retained in the digestive system of starlings for more than 1.5 h, pigeons more than 1 h, or other birds more than 0.5 h. Cyst contents were nonviable if they remained in contact with excreta from cowbirds or quails for 4 h, thrushes for 96 h, or other species for 72 h after passage. Viability of contents of cysts was inversely related to exposure to excreta-filtrate concentration. Larvae failed to emerge from cysts that were exposed to a 25% concentration of excreta filtrate from starlings, 50% concentration from pigeons or thrushes, or 100% concentration of excreta filtrates from each of the other species. Cysts that were subjected to 44 C (avg. body temperature of cowbirds) for more than 3.5 h were nonviable. Cysts that passed through birds and collected with excrement on polyethylene or soil produced no infective larvae on potato.