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1.
球形棕囊藻是我国沿海常见有害藻华物种,生活史中包括囊体和单细胞两种形态,藻华爆发时的优势形态是囊体,游离单细胞很少被发现,但是球形棕囊藻囊体形成的机制目前还不清楚。本研究通过分析桡足类、纤毛虫和异养甲藻及其化学信号对囊体形成的影响,以探究摄食压力对球形棕囊藻生活史转变的影响。实验结果表明:3种摄食者的直接摄食均引发了球形棕囊藻囊体直径的扩大,摄食者的粒径越大,球形棕囊藻的囊体直径增大越显著,安氏伪镖水蚤的化学信号也能引发球形棕囊藻囊体显著增大,但是游仆虫和海洋尖尾藻的化学信号并未引发类似响应。囊体形成和直径的扩大保护了囊体内细胞免受摄食,有助于球形棕囊藻藻华的发生。 相似文献
2.
球形棕囊藻(Phaeocystis globosa)是中国近海常见的有害藻华原因种,游离单细胞和球形囊体是其异型生活史的两种形态。本研究通过添加KH2PO4(PO43-)、卵磷脂(LEC)、三磷酸腺苷二钠(ATP)、葡萄糖-6-磷酸钠盐(G-6-P)、和核糖核酸(RNA)5种不同磷源进行室内培养,以阐明不同磷源对球形棕囊藻生长及囊体形成的影响。结果表明,5种磷源培养条件下皆可形成囊体,以G-6-P为磷源的球形棕囊藻生长最优,囊体密度最大可达(5.7±0.5)×105colonies·L-1,在培养中后期诱导产生较高的碱性磷酸酶活性(181.1±41.6)nmol·h-1·L-1有利于其高生物量及囊体形态的维持。以PO43-为磷源时,囊体密度最大可达(6.1±0.7)×105colonies·L-1,但对囊体形态的维持较G-6-P组差。以LEC或RNA为磷源时,囊体密度及叶绿素a含量较低,囊体单位表面积的细胞密度更高,结构更紧致。LEC组的囊体直径最大,可达(488.2±220.6)μm。以ATP为磷源时,囊体细胞分布稀疏,囊体衰退较快。4种有机磷源对球形棕囊藻囊体的构建存在不同程度的影响,在自然水体棕囊藻藻华形成及维持中,除无机磷源外部分形态的有机磷源可能会发挥重要作用。 相似文献
3.
球形棕囊藻(Phaeocystis globosa)是我国北部湾海域主要的有害藻华原因种,囊体的生长是藻华发生和持续的关键。为了研究在富营养化日趋严重的钦州湾海域中营养盐输入对球形棕囊藻藻华形成的影响,采集钦州湾含球形棕囊藻的表层海水进行了添加不同营养盐的室内培养实验。根据钦州湾历史调查数据,进行了不同营养盐、不同氮磷比和不同添加方式的培养。结果表明,同时添加氮和磷显著促进浮游植物的生长,球形棕囊藻囊体继浮游植物细胞密度高峰期后大量形成。一次性添加磷对囊体生长的刺激作用较添加氮时强,丰度最高可达4.8×103 colonies·L-1,囊体平均直径为(115±84)μm,且具有较高囊体细胞密度,但囊体衰退较快。单独添加氮时,囊体细胞分布稀疏,囊体数量及直径皆较低。每天添加磷的方式相比一次性添加更有利于囊体丰度的维持。总体上,磷营养的添加能刺激囊体数量、囊体细胞数和囊体直径的生长。在具有较高N/P比值的钦州湾,应加强磷的排放管理,避免突发性磷污染对球形棕囊藻囊体生长的刺激作用。 相似文献
4.
棕囊藻引发的有害藻华已经成为一种全球性的自然灾害,给海洋环境以及渔业经济带来了严重的损失。棕囊藻存在两种生活史形态:游离的单细胞形态和囊体形态,但是不同形态之间的转换和囊体形成机制尚不清楚。营养盐是浮游植物生长和藻华发生的物质基础,棕囊藻藻华以往多发生在硝酸盐限制海区。但是近年来,尿素等有机氮在河口区域浓度不断提高,有机氮源的增加可能对棕囊藻生长和生活史转换产生显著的影响。通过添加硝酸盐、铵盐、尿素三种氮源,研究不同氮源对球形棕囊藻生长和囊体形成的影响。研究表明:球形棕囊藻可以在硝氮、尿素中迅速生长,形成囊体,但是氨氮对其却有明显的抑制作用;球形棕囊藻单细胞在硝氮中丰度比较高,最大可达到(444.21±64.97)×10~3个·mL~(-1);在尿素中更容易形成囊体,最多能达到(12.61±6.5)个·mL~(-1)。球形棕囊藻可以利用硝酸盐和有机氮源使其具有更强的竞争力,尿素在海洋水体中浓度的提高,可能是近年来球形棕囊藻藻华在我国近海水域频发的原因之一。 相似文献
5.
广西北部湾近岸海域虽常年为磷限制状态,但球形棕囊藻（Phaeocystis Globosa）赤潮灾害频繁发生。球形棕囊藻暴发时主要以囊体形式存在,赤潮衰退后,囊体破裂产生大量的透明胞外聚合颗粒物（Transparent Exopolymer Particles,TEP）,在海洋动力作用下形成高碳、高黏性泡沫,影响渔业和核电取水安全。本文通过设置氮磷比为32∶1和64∶1的半连续培养实验,探讨磷限制对球形棕囊藻的生长,以及透明胞外聚合颗粒物产量的影响。结果表明：在氮磷比为32∶1和64∶1的磷限制条件下,球形棕囊藻的细胞密度、叶绿素a浓度、囊体密度及囊体表面细胞数,在培养的后半期都受到了抑制。与控制组相比,两个磷限制的处理组在囊体直径上并没有表现出显著的差异（显著性水平p> 0.05）。在氮磷比为32∶1的条件下,球形棕囊藻的TEP生产量与控制组相比没有显著差异（p> 0.05）,在氮磷比为64∶1的条件下,TEP的生产量显著降低（p <0.05）,磷限制程度的加剧对球形棕囊藻细胞分泌TEP产生影响。研究结果为进一步研究环境胁迫下球形棕囊藻TEP形成机制提供了依据。 相似文献
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7.
2021年1月下旬深圳大鹏湾沿岸海域发生球形棕囊藻(Phaeocystis globosa)藻华。为了探究球形棕囊藻藻华发生动态特征及其影响因素, 于1月20日至2月1日系统调查分析了藻华发生过程中浮游植物优势种演替、球形棕囊藻囊体数量、营养盐水平以及其他环境因素的变化。结果表明: 1月20日, 中肋骨条藻(Skeletonema costatum)为绝对优势种, 1月21日球形棕囊藻囊体开始出现, 1月25日囊体数量达到最高, 达69colonies·L-1; 1月27日红色赤潮藻(Akashiwo sanguinea)藻华出现, 随后球形棕囊藻藻华逐渐消退。灰关联分析显示, 铵盐和硝酸盐是影响球形棕囊藻囊体丰度的最主要因素。水体扰动和球形棕囊藻在磷限制条件下的竞争优势也可能有利于球形棕囊藻藻华的发生。红色赤潮藻藻华可能是球形棕囊藻藻华消退的主要原因。球形棕囊藻藻华的发生和消亡是各种理化因素和生物因素共同作用的结果。 相似文献
8.
球形棕囊藻(Phaeocystis globosa)常在热带至温带近海海域形成有害藻华,该种具有种内遗传多态性,且有囊体大小、特征色素组成等性状分化。在我国南海形成有害藻华的球形棕囊藻可形成“巨型囊体”,以19''-丁酰氧基岩藻黄素(But-fuco)为特征色素,是一种独特的“巨囊”生态型。2021年11月底至12月初,南黄海青岛沿岸暴发大规模球形棕囊藻藻华。藻华发生期间,对青岛沿岸3个站位的水文和化学要素进行了观测,分析了球形棕囊藻囊体的数量、直径和色素组成,并应用一种高分辨率种下分子标记——叶绿体rbcS-rpl27基因间隔区分析了其遗传特征。结果表明,藻华发生期间青岛沿岸表层海水温度较低 (12~14℃),海域营养盐组成具有高溶解有机氮、低溶解无机氮的特征;球形棕囊藻囊体丰度超过20个/L,最大囊体直径为18 mm,以But-fuco为特征色素, rbcS-rpl27序列分析表明其与南海“巨囊”生态型球形棕囊藻具有相同的遗传特征。南黄海首次暴发的球形棕囊藻藻华是由“巨囊”生态型形成,该藻华可能对海洋生态系统、水产养殖业发展和核电设施运行等构成威胁,亟待开展藻华成因与监测预警对策研究。 相似文献
9.
本文首次对分离于我国广西北部湾的一株棕囊藻(Phaeocystis)纯培养进行了形态学研究。通过对其核糖体大亚基序列(LSU rDNA)进行了系统进化分析,并运用光学显微镜、扫描电镜和透射电镜等,对该藻的游动单细胞和囊体细胞表面结构和超微结构进行了详细的观察。结果表明,通过分子序列和形态学特征确证了该纯培养为球形棕囊藻(Phaeocystisglobosa)。通过分子系统进化分析,从北部湾获得的球形棕囊藻与同属的P. antarctica和P. rex的亲缘关系较近,但与P. jahnii的亲缘关系相对较远。我们发现该藻至少有两种类型的细胞:具鞭毛游动细胞和无鞭毛囊体细胞,其大小分别为2.30—3.98μm和3.69—6.49μm。具鞭毛游动细胞表面具有1—2个位置不固定但形状较为规则的圆盘状凸起,细胞表面的鳞片大小无明显差别;囊体细胞均匀地分布在囊体上,囊体细胞表面光滑,有三个较短的附属物。具鞭毛游动细胞和囊体细胞有2个或4个叶绿体,具鞭毛游动细胞的细胞核位于细胞的中下部,而囊体细胞的细胞核则位于细胞的中上部。细胞分泌物在扫描电镜样品处理过程后形成多数与细胞相连的丝状物,且丝状物形成较为规则的五角星形结构,每个角与一根丝相连,有些丝状体上有"瘤状"结构。研究结果填补了我国在球形棕囊藻形态学和超微结构研究上的空白,为深入认识其生物学特征及其成囊机理提供基础。 相似文献
10.
球形棕囊藻是一种具有复杂异型生活史的有毒有害赤潮生物,近年来在我国近海频繁暴发成灾,形成的巨大囊体为国内外罕见。迄今还未见到有效消除囊体型球形棕囊藻赤潮的方法报道。本文通过海上围隔实验和现场赤潮消除工程跟踪监测,考察了喷洒改性黏土消除囊体型球形棕囊藻赤潮的可行性与效率,并分析了改性黏土法治理赤潮时对水体及沉积环境的可能影响。围隔实验结果表明,喷洒改性黏土可以有效消除水体中过量的微藻细胞,其中以少量多次喷洒方法的效果最好,生物量(chl a)去除率90%。在对2016年2月广西防城港附近海域球形棕囊藻赤潮消除时的跟踪监测结果表明,改性黏土法适用于工程化消除赤潮作业,能够快速消除水体中的大量球形棕囊藻囊体,随改性黏土絮凝体沉入海底的赤潮藻可以快速分解而失去活性。喷洒改性黏土对于赤潮水体的主要理化指标影响不显著,所监测的水体COD、pH和不同形态氮、磷、硅等生源要素浓度都在原有水质水平范围内波动。 相似文献
11.
A straightforward ecophysiological characterization of Phaeocystis globosa is hampered by its complex polymorphic life cycle in whic flagellates and colonial cells express different physiological and morphological properties. There is also increasing evidence that, besides the existence of different species, the most widespread species Phaeocystis globosa (Scherffel) has to be subdivided into at least five different ecotypes which again differ in their ecophysiological properties. Most research has been performed on the P. globosa ecotype North European (English Channel/ North Sea isolates). From the available literature it must be concluded that flagellate cells are better competitors for light and phosphate than colonial cells, due to their superior uptake characteristics. To a limited extent this phenomenon is compensated in colonial cells by their ability to continue growth and cell division in the dark at the same rate as in the light, at the expense of extracellular colonial mucus. In contrast with other algal species, colonial cells of P. globosa are better competitors for nitrogen than for phosphorus.Flagellates transform into vegetative cells and form colonies in environments with irradiance levels of about 50 μE·m−2·s−1 or more and an optimum phosphate concentration of 1 μM. A solid substrate and the presence of calcium are prerequisites for colony formation. In environments where phosphorus is limiting no new colonies are formed. There is some evidence that nitrate stimulates colony formation, whereas high ammonium values (above 1 μM) tend to suppress colony formation. Massive blooms of P. globosa colonies can be attributed to a combination of environmental conditions that induce colony formation and smaller grazing losses of colonial cells than of flagellates, rather than to superior ecophysiological characteristics of colonial cells. 相似文献
12.
通过对13种藻不同组合后的集群进行室内一次性培养实验,探讨了浮游植物不同组合集群中物种丰富度及物种组成对其生物量及指数生长期比生长率的影响。实验结果表明,物种组成与物种丰富度均对集群生物量有一定的影响,其中物种组成的影响更大;且物种丰富度与生物量不具有线性相关性。随着物种丰富度增大,集群在指数生长期的比生长率有增加趋势。在本实验设定的营养盐条件下,营养盐水平高低对集群指数生长期的比生长率影响较小,但其对指数生长期的持续时间影响较大,进而对集群生物量产生影响。 相似文献
13.
Disturbance is a ubiquitous feature of ecosystems, and the ability of a species to persist in a habitat with frequent disturbance is largely determined by the ways in which individual organisms respond. In modular species, indeterminate growth by module addition allows recovery from colony damage through disturbance, and the number of modules – colony size – is a good predictor of colony success. A growing body of evidence suggests that the recovery capacity of a modular animal is related not only to its size, an important indicator of likely survivorship and reproductive potential, but also to the age structure of its component modules. We tested whether the age structure of modules altered the recovery capacity of colonies of the encrusting bryozoan Parasmittina delicatula at two sites in South‐eastern Australia that differed in their levels of cover by competing sessile invertebrates. Damage incurred at different colony regions had a negligible effect on the subsequent growth of colonies at both sites, but for different reasons. At one site, where competition from neighbouring sessile invertebrates was low, growth rates were very similar across colonies, regardless of colony size and amount of damage to the colony edge. At the second site, neighbouring sessile invertebrates were abundant, and competitive interactions were more important in determining a colony’s success than any history of damage. Colonies that were overgrown once or more had lower growth rates and lower numbers of embryos at the final census than those that were never overgrown. These results imply that the importance of the age structure of modules to a colony’s recovery rate is reduced in the presence of natural competition, and that these factors need to be considered when predicting the responses of modular animals to disturbance. 相似文献
14.
Abstract. Hermit crab shells are often encrusted with diverse communities of epibionts. To explore the effects of hermit crabs on the interactions of these encrusting species, two species of hydractiniid hydroids, Hydractinia symbiolongicarpus and Podocoryna carnea , were examined in the presence and absence of Pagurus longicarpus hermit crabs. Colonies growing on Littorina littorea snail shells with hermit crab hosts were compared to those growing on shells without crabs. These experiments suggest that hermit crabs variably affect colony polyp number, colony morphology and the outcome of interspecific competition, according to the size and number of crabs; other factors include water temperature, food availability and hydroid clonal genotype. In order to allow image analysis of perturbations of colony morphology, hydroids were grown on glass surfaces both exposed and unexposed to hermit crabs. Relative to colonies growing on unexposed surfaces, colonies growing on exposed surfaces exhibited larger within-colony patches, thus decreasing the total encrusted surface area and polyp number of colonies. Further, on glass surfaces, hermit crabs accelerated the time to the resolution of interspecific competition ( i.e. , the overgrowth of one colony by the other). While a number of factors may contribute to the relative abundance of these encrusting species, under most circumstances P. longicarpus have large effects on hydractiniid hydroids. Mechanisms underlying these effects likely include hydrodynamics and mechanical disturbance. 相似文献
15.
Sven Zea 《Marine Ecology》2011,32(2):162-173
The Caribbean sponge Cliona delitrix is among the strongest reef space competitors; it is able to overpower entire coral heads by undermining coral polyps. It has become abundant in reefs exposed to organic pollution, such as San Andrés Island, Colombia, SW Caribbean. Forty‐four sponge‐colonized coral colonies were followed‐up for 13 months to establish the circumstances and the speed at which this sponge advances laterally into live coral tissue and the coral tissue retreats. Cliona delitrix presence and abundance was recorded at seven stations to interpret current reef space and coral species colonization trends. The spread of C. delitrix on a coral colony was preceded by a band of dead coral a few millimeters to several centimeters wide. However, the sponge was directly responsible for coral death only when live coral tissue was within about 2 cm distance; coral death became sponge advance‐independent at greater distances, being indirectly dependent on other conditions that tend to accelerate its retreat. Cliona delitrix advanced fastest into recently killed clean coral calices; however, sponge spread slowed down when these became colonized by algae. The lateral advance of C. delitrix was slower than other Cliona spp. encrusting excavating sponges, probably owing to the greater depth of its excavation into the substratum. Cliona delitrix prefers elevated portions of massive corals, apparently settling on recently dead areas. It currently inhabits 6–9% of colonies in reefs bordering San Andrés. It was found more frequently in Siderastrea siderea (the most abundant local massive coral), which is apparently more susceptible to tissue mortality than other corals. Current massive coral mortality caused by C. delitrix could initially change the relative proportions of coral species and in the long‐term favor foliose and branching corals. 相似文献
16.
《African Journal of Marine Science》2013,35(3-4):697-704
From 1987 to 2005, numbers of African penguins Spheniscus demersus breeding in South Africa's Western Cape Province increased by about 50%. Numbers decreased at the four northernmost colonies in the region: Lambert's Bay and the three colonies in Saldanha Bay, although at Jutten Island the decrease is inferred from an estimate for 1987, derived from interpolation. Numbers also decreased at Geyser Rock and Dyer Island on the South Coast. At five colonies between Saldanha Bay and Dyer Island there were large increases. At a sixth colony in that region, Seal Island, where Cape fur seals Arctocephalus pusillus pusillus limit breeding space, numbers remained stable. At two colonies that were initiated in the early 1980s, Robben Island and Boulders, increases were initially rapid (>20% per annum) and matched growth of the South African stock of sardine Sardinops sagax. Strong growth at Dassen and Vondeling islands, between Robben Island and Saldanha Bay, was observed from about 1996–2002, when there was a large increase in the biomass of pelagic fish off South Africa. Increases at colonies between Saldanha Bay and Boulders slowed after 2002, whereas the colony at Dyer Island stabilised at that time. In 2003, a new colony was initiated east of Dyer Island at De Hoop Nature Reserve. These latter trends followed an eastward shift in the distribution of sardine. Small penguin colonies may act as foci for growth in a period when the distribution of prey is changing. Hence, it is important that they be maintained, especially those that, if lost, would increase the isolation of regional populations. Some of the small colonies are less susceptible to oil spills than colonies in the proximity of harbours, and for that reason also are important. 相似文献
17.
《African Journal of Marine Science》2013,35(1):111-119
This paper reports on growth of the Boulders colony of African penguins Spheniscus demersus from inception in 1985 to the present. More than 900 pairs now breed there. Growth of the colony slowed in 1995 and 1996 and reversed in 1998, coinciding with periods of low abundance of Cape anchovy Engraulis capensis off South Africa. In December 1996, penguins were excluded from a portion of land where they had formerly bred. They responded by increasing the density of their nests in other areas and expanding their area of breeding longshore. These patterns indicate that food and not space are currently controlling colony growth rate. Much of the colony growth probably results from immigration of first-time breeders from other colonies. Of immigrants, 70–80% may be from Dyer Island to the south-east, where numbers of penguins have decreased. Boulders also is frequently visited by penguins from other colonies, and by rehabilitated birds. 相似文献