锥状施克里普藻孢囊的多种形态特征

休眠孢囊是某些甲藻生活史的重要阶段, 它被认为是甲藻赤潮爆发的种源。通过观察我国沿海海域采集的锥状施克里普藻(Scrippsiella trochoidea (Stein) Loebl ich)休眠孢囊的类型以及形态特征, 并将实验条件下形成的休眠孢囊与海区沉积物中休眠孢囊的形态特征进行比较, 结果表明, 锥状施克里普藻细胞在20°C、12小时光照/12小时黑暗、f/2培养基和f/2-N培养基中分别培养至第14天和第8天, 可以观察到休眠孢囊的产生。培养30天后, 培养液中有大量休眠孢囊, 将藻液避光保存90天后, 观察到培养基中有4种类型的休眠孢囊产生: (1)球形到椭球形(长25-39 μm), 钙质外壁, 稀疏或密被钙质附属物(长1-4 μm); (2)球形(直径为29-35 μm), 钙质外壁, 附属物非钙质(长0.5-1.5 μm); (3) 球形到椭球形(长29-35 μm), 钙质, 表面光滑, 无附属物; (4) 球形(直径24-35 μm ), 有机外壁, 无附属物。第1种类型的孢囊最为常见, 分别占到2种培养条件下所得全部孢囊的77.70%和95.18%。从沉积物中所得的孢囊多属于第1种类型。分析了实验条件下形成不同类型休眠孢囊的原因和比例, 同时探讨了海区沉积物中形成多种孢囊形态特征的原因, 为锥状施克里普藻孢囊的生态研究提供了依据。     

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。     

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.       

大亚湾海域锥状斯氏藻孢囊形成与萌发的季节变化

锥状斯氏藻(Scrippsiella trochoidea)是南海大亚湾海域优势甲藻。为了解该藻孢囊形成和萌发动态及其对营养细胞种群动态的影响,2001年1月-2002年1月在大亚湾澳头海域用沉积物捕捉器及TFO重力采泥器对其孢囊进行每月一次的周年监测,同时对浮游植物、水温、盐度、溶解氧等也进行了监测。孢囊形成和萌发分别以沉积物捕捉器中的孢囊形成率以及上表层沉积物中空孢囊的百分比来表示。钙质孢囊和非钙质孢囊年平均形成率分别为1.11×104 cysts m-2d-1和2.13×105 cysts m-2d-1。前者在冬季大量形成,而后者在夏季形成较多。孢囊多在春秋季节萌发,夏季萌发较少,而冬季几乎不萌发。在5月份和10月份营养细胞数量峰形成前,孢囊的萌发出现了高峰,而表层沉积物中的孢囊数量及孢囊形成率则在营养细胞数量峰后大幅度上升。由此可见,大亚湾沉积物中该藻孢囊的萌发给水体提供了丰富的营养细胞,反之水体中高密度营养细胞又促使孢囊的大量形成,从而造成了锥状斯氏藻赤潮在大亚湾海域接连发生。     

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。     

甲藻孢囊在长江口海域表层沉积物中的分布

为了了解长江口海域赤潮爆发潜势,于2002年4月至5月用采泥器采集了位于122°～123．5°E、29°～32°N之间12个站位的表层沉积物,分析沉积物中甲藻孢囊的分布．共分析鉴定出孢囊类型29种,其中自养型11种,异养型18种．每个站位的孢囊种类在10～21之间,孢囊密度为11．7～587孢囊·g-1干泥之间．远岸海域孢囊种类较为丰富,密度也较高．在调查区域内,孢囊密度及种类自西向东、自北向南逐渐增加．亚历山大藻孢囊分布广泛,最高密度为40．4孢囊·g-1干泥,其他赤潮种类的孢囊如链状裸甲藻、多边舌甲藻、锥状斯氏藻、科夫多沟藻和无纹多沟藻等都在长江口海域有分布．     

黑暗、温度对锥状斯氏藻暂时性孢囊形成、存活与萌发的影响

锥状斯氏藻(Scrippsiella trochoidea)是一种世界性的赤潮甲藻,暂时性孢囊是甲藻为了抵御瞬时不良环境条件而形成的不动细胞,暂时性孢囊在锥状斯氏藻生活史及其赤潮发生过程中充当着重要的角色。本文研究了黑暗和温度(8、20和25℃)对锥状斯氏藻暂时性孢囊形成、存活与萌发的影响。结果表明:暂时性孢囊在黑暗处理的第1天就开始形成,在第3～5天孢囊形成率达到最高,且常温下孢囊形成高峰延迟,8、20和25℃下孢囊的最终累积形成率分别为15.9%、20.1%和9.9%;同时,暂时性孢囊不耐保存,在形成后第1天即出现死亡,第8～16天后全部死亡;暂时性孢囊在低温下存活时间较长,8、20和25℃下半存活时间分别为5.9、2.9和2.7 d;暂时性孢囊不存在强制性休眠期,全部处理组的暂时性孢囊均在培养后的24 h内开始萌发,3～6 d内达到最大累积萌发率,为43.3%～65.6%,低温下形成的孢囊萌发率较高;锥状斯氏藻极易形成暂时性孢囊,当环境条件合适时能迅速萌发,说明暂时性孢囊在锥状斯氏藻种群动态以及赤潮形成和消亡过程中具有重要作用。     

利用F_v/F_m检测锥状施克里普藻N和P限制的局限

通过测定缺N和缺P的锥状施克里普藻(Scrippsiella trochoidea)在分别添加充足的NO3-N、PO4-P后,光系统Ⅱ(PSⅡ)最大光化学量子产量(Fv/Fm)的变化,来检验Fv/Fm能否用来检测锥状施克里普藻N、P限制的情况。实验表明,锥状施克里普藻分别在不加N、P元素的f/2-Si培养基培养过程中,缺N组叶绿素a(Chla)浓度先升高,在原培养液N耗尽后快速下降;缺P组Chla开始时升高,在原培养液P耗尽后缓慢下降。两组藻液Fv/Fm比值保持相对稳定,短时间内未见明显降低。当分别向藻液中重新添加充足的N和P后,缺N组藻液添加N后Chla浓度48h内明显上升,缺P组藻液添加P后Chla浓度48h内没有明显变化,两种培养液中Fv/Fm均未见明显升高。结果证明,利用Fv/Fm不能够快速检测锥状施克里普藻N、P限制的情况,该法在检测浮游植物营养盐胁迫时具有局限性。     

春末三峡大坝首次蓄水期长江口浮游植物群集

根据2003年6月三峡大坝第1次蓄水期长江口及其邻近水域(28°-33°N,120°-125°E)34个测站采集的浮游植物水样,报道了该水域浮游植物群集特征.结果表明:调查区浮游植物以硅藻和甲藻为主,伴有少量的绿藻和金藻.浮游植物细胞丰度介于0.2～1504.2 cells·ml-1,平均为72.7 cells·ml-1,主要优势物种为骨条藻(Skeletonema sp.)、具齿原甲藻(Prorocentrum dentatum)和锥状施克里普藻(ScrippsieUa trochoidea).调查区表层两个浮游植物密集区分别位于北部的冲淡水域和西南部近岸水域.浮游植物细胞丰度最大值出现在中层(10m层),最小值出现在底层.冲淡水域的优势物种是骨条藻,主要出现在表层;而在长江冲淡水与台湾暖流、黄海混合水交汇的水域,优势物种为具齿原甲藻,主要分布在表层和中层.     

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。     

A NEW SPECIES OF ENSICULIFERA,E. IMARIENSE (DINOPHYCEAE), PRODUCING ORGANIC-WALLED CYSTS1

We describe a new organic-walled resting cyst from surface sediments of Imari Bay in western Japan. The cysts are spherical, 23–29 pm in diameter, and their surface is covered with spinous to membranous ornaments that are 5–7 μm long and 1.5–2.2 μm wide. The ornaments vary from slender and bifurcate to membranous and multifurcate distal extremities. No archeopyle was observed. The cyst shape is variable in both natural samples and clonal cultures. Vegetative cells are small and ovoid, 17–25 μm long and 14–21 μm wide, and are yellow-brown in color. The epitheca is conical with a conspicuous apical horn, and the hypotheca is hemispherical. The cingular transitional plate has a needle-like spine at its anterior right corner. The plate formula is Po, X, 4″3a, 7″, 5c, 5s 5″and 2″. Although vegetative cells of the present species correspond to Ensiculifera, it is distinct from other species in producing no calcareous cysts. No species of Ensiculifera has been reported to produce cysts composed of only an organic wall. The present species is provisionally placed in the genus Ensiculifera as E. imariense sp. nov.     

VEGETATIVE REPRODUCTION AND SEXUAL LIFE CYCLE OF THE TOXIC DINOFLAGELLATE GYMNODINIUM CATENATUM FROM TASMANIA,AUSTRALIA1

The toxic, chain-forming dinoflagellate Gymnodinium catenatum Graham was cultured from vegetative cells and benthic resting cysts isolated from estuarine waters in Tasmania, Australia. Rapidly dividing, log phase cultures formed long chains of up to 64 cells whereas stationary phase cultures were composed primarily of single cells (23-41 pm long, 27-36 pm wide). Vegetative growth (mean doubling time 3-4 days) was optimal at temperatures from 14.5-20° C, salinities of 23-34% and light irradiances of 50-300 μE·m^?2·s^?1. The sexual life cycle of G. catenatum was easily induced in a nutrient-deficient medium, provided compatible opposite mating types were combined (heterothallism). Gamete fusion produced a large (59-73 μm long, 50-59 μm wide) biconical, posteriorly biflagellate planozygote (double longitudinal flagellum) which after several days lost one longitudinal flagellum and gradually became subspherical in shape. This older planozygote stage persisted for up to two weeks before encysting into a round, brown resting cyst (42-52 μm diam; hypnozygote) with microreticulate surface ornamentation. Resting cysts germinated after a dormancy period as short as two weeks under our culture conditions, resulting in a single, posteriorly biflagellate germling cell (planomeiocyte). This divided to form a chain of two cells, which subsequently re-established a vegetative population. Implications for the bloom dynamics of this toxic dinoflagellate, a causative organism of paralytic shellfish poisoning, are discussed.     

Scrippsiella trochoidea and scrippsiella regalis, nov. comb. (peridiniales, dinophyceae): a comparison

Culture experiments on dinoflagellates from the Atlantic Ocean revealed Scrippsiella regalis (Gaarder) Janofske, nov. comb., a calciodinelloid species with a spherical spiny calcareous cyst. This calcareous cyst was collected previously from plankton and sediment samples, where it was described as the coccolithophorid Discosphaera regalis Gaarder or was often mistaken for the cyst of Scrippsiella trochoidea (von Stein) Loeblich III. The morphological features of both the cellulosic theca and the calcareous cyst of S. trochoidea and S. regalis were compared with respect to their systematic position and the emendation of taxa. Both species were found to have different distribution patterns. Scrippsiella trochoidea is known only from the neritic environment, whereas S. regalis has been found mostly in oceanic samples. The preservation of these spiny calcareous dinocysts in the (fossil) sediment was dependent on the ultrastructure of the calcareous layer of the cyst wall.     

广东省淡水红藻弯枝藻属一种（Compsopogon sp．）的形态描述及分类地位探讨

2009年8月在广东省龙川县定南水河采集到一份弯枝藻属的标本,其形态特征介于弯枝藻（Compsopogon caeruleus）和疏枝弯枝藻（Csparsus）之间。植物体株高10～18cm,主轴直径180～270μm,微收缢;中轴细胞近球形和扁球形,横壁收缢明显,直径150-200μm,高100～110μm;皮层细胞1层,中轴细胞缢缩处为2—3层;多角形或卵形,长25~35μm,直径20-25μm;分枝直出至侧生,某些基部细胞特化为假根;分枝顶端渐尖、急尖或二叉状;单孢子球形,直径10—14μm。该标本可能为弯枝藻和疏枝弯枝藻在演化过程中的一种过渡类型。     

Spatial distribution of calcareous dinoflagellate cysts in surface sediments of the Atlantic Ocean between 13 degrees N and 36 degrees S

To enhance the limited information available about the palaeo-ecological significance of calcareous dinoflagellates, we have studied their lateral distribution in surface sediments of the equatorial and south Atlantic between 13 degrees N and 36 degrees S. Calcareous dinoflagellate cysts appear to be widely distributed throughout the studied area. In the surface sediments, concentrations (cyst per gram dry sediment) of the vegetative stage Thoracosphaera heimii are generally higher than that of the (presumably) calcareous resting cysts. Distribution patterns in surface sediments of Orthopithonella granifera (Fütterer) Keupp and Versteegh, Rhabdothorax spp. Kamptner., Sphaerodinella albatrosiana (Kamptner) Keupp and Versteegh S. albatrosiana praratabulated, Sphaerodinella tuberosa var. 1 (Kamptner) Keupp and Versteegh and S. tuberosa var. 2 and the ratios between these species have been compared with temperature, salinity, density and stratification gradients in the upper water column. Rhabdothorax spp. is characteristically present in sediments of more temperate regions characterized by high seasonality. Dinoflagellates producing these cysts are able to tolerate high nutrient concentrations, and mixing of the water column. S. albatrosiana is abundant in regions characterized by high sea surface temperatures and oligotrophic surface water conditions. In contrast, the distribution of S. tuberosa var. 2 is negatively related to temperature. The other cyst species did not show a characteristic pattern in relation to the studied environmental gradients.The ratio of Sphaerodinella tuberosa var. 2 to Orthopithonella granifera can be used for reconstructing the presence of stratification in the upper 50m of the water column, whereas the ratios of S. tuberosa var. 2 to Sphaerodinella albatrosiana and of O. granifera to Rhabdothorax spp. might be used for palaeotemperature reconstructions. Calcareous dinoflagellate cysts are abundant in oligotrophic areas and may be useful for the reconstruction of palaeoenvironmental conditions.     

The endogenous development of two new species of Isospora Schneider, 1881 (Apicomplexa: Eimeriidae) from Thai geckoes

Two new species of Isospora are described from Thai geckoes. I. platyurusi n. sp. in Cosymbotus platyurus from Chiang Mai and Khon Kaen and I. uptoni n. sp. in Hemidactylus frenatus from Chiang Mai. Oöcysts of I. platyurusi are spherical to subspherical, 19–22.5 × 16.5–21.5 μm and have two ovoid sporocysts of 11.5–14 × 7.5–9 μm. Oöcysts of I. uptoni are spherical to subspherical, 24–31.5 × 20–27.5 μm and have two ovoid sporocysts of 12.5–15 × 9–11.5 μm. Both species have sporocysts with Stieda bodies and undergo endogenous development in the nucleus of the host gut epithelial cells. On the completion of merogony and gamogony, the host nucleus is reduced to a thin envelope.     

Distributions of calcareous dinoflagellate cysts in surface sediments of the western equatorial Atlantic Ocean,and their potential use in palaeoceanography

Only very few studies focus on recent calcareous dinoflagellate cyst diversity, geographic distribution and ecology, so that information on the distribution patterns and environmental affinities of individual cyst species is extremely limited. This information is, however, essential if we want to use calcareous dinoflagellate cysts for palaeoenvironmental reconstruction. Surface sediment samples from the generally oligotrophic western equatorial Atlantic Ocean, offshore northeast Brazil, were therefore quantitatively analysed for their calcareous dinoflagellate cyst content, including the calcareous vegetative coccoid Thoracosphaera heimii. Seven calcareous dinoflagellate cyst species/morphotypes and T. heimii were encountered in high concentrations throughout the area. Substantial differences in the distribution patterns were observed. The highest concentrations of cysts are found in sediments of the more oligotrophic, oceanic regions, beyond the influence of Amazon River discharge waters. Dinoflagellates producing calcareous cysts thus appear to be capable of surviving low nutrient concentrations and produce large numbers of cysts in relatively stable and predictable environments affected by minimal seasonality. To test for the environmental affinities of individual species, distribution patterns in surface sediments were compared with temperature, salinity, density and stratification gradients within the upper water column (0–100 m) over different times of the year, using principal components analysis and redundancy analysis. T. heimii and four of the seven encountered cyst species (Sphaerodinella? albatrosiana, two morphotypes of Sphaerodinella? tuberosa and Scrippsiella regalis) relate to these parameters significantly and the variations in the cyst associations appear to be associated with the different surface water currents characterising the area. The results imply that calcareous dinoflagellate cyst distributions can potentially be used to distinguish between different open oceanic environments and they could, therefore, be useful in tracing water mass movements throughout the late Quaternary.