Biodiversity and Association of Dinoflagellates in Coral Reef Rubble,Carrie Bow Cay,Belize

The species diversity and distribution of benthic dinoflagellates are illustrated from the back reef sand habitats at Carrie Bow Cay. Sand appears an ideal environment for nurturing a variety of species. Sand supported blooms of toxic, nontoxic, and parasitic assemblages of dinoflagellates. Morphology of dinoflagellates is illustrated in SEM and LM pictures; including the life cycle of a parasitic dinoflagellate's vegetative stage, sporogenetic stages, and the morphology of the feeding organelle. The feeding organelle of the primary dinoflagellate cysts is a hold fast and a peduncle‐like infestation tube, a ‘sucker organelle’, that inserts itself into copepod eggs. The parasitic dinoflagellate continues feeding on crustacean eggs since it is the only food source during vegetative cell division within the cyst. This is the first observation of the presence of parasitic dinoflagellates in shallow coral reef water. The study attempts to provide new knowledge on dinoflagellate associations and morphology of sand‐welling species in the microscopic food web of shallow warm tropical waters. Even, sand‐inhabiting invertebrates are not exempt from parasitic dinoflagellates.     

A quantitative review of the lifestyle,habitat and trophic diversity of dinoflagellates (Dinoflagellata,Alveolata)

This study reviews the trends in the lifestyle, habitat distribution and trophic diversity of the 2377 described species of dinoflagellates (Dinophyceae). Most of the dinoflagellates inhabit marine waters, whereas 17% of the total species have colonized continental waters. Dinoflagellates are dominated by planktonic species, while benthic forms represented 8% of the species. From the total number of species, 49% are heterotrophic (devoid of plastids), while 51% of the species have been reported with plastids (that does not strictly imply autotrophy). All the basal dinoflagellates (ellobiopsids, Duboscquodinida, Syndiniales) are heterotrophic, with the exception of a few Noctilucales (Spatulodinium). The continental waters are highly dominated by plastid-containing species (88%), while in marine environments there is a slight dominance of heterotrophic species (58%). Most of the dinoflagellates are free-living forms; only 7% of the total species are parasites. The dinokaryotic parasites appear in separate clades, and about 40% of them contain plastids. The beneficial or mutualistic symbionts (21 species, 1%) are photosynthetic species dispersed into at least three clades.     

Molecular Phylogeny of the Ocelloid-Bearing Dinoflagellates Erythropsidinium and Warnowia (Warnowiaceae, Dinophyceae)

ABSTRACT. Members of the family Warnowiaceae are unarmored phagotrophic dinoflagellates that possess an ocelloid. The genus Erythropsidinium (= Erythropsis ) has also developed a unique dynamic appendage, the piston, which is able to independently retract and extend for at least 2 min after the cell lyses. We provide the first small subunit ribosomal RNA gene sequences of warnowiid dinoflagellates, those of the type Erythropsidinium agile and one species of Warnowia . Phylogenetic analyses show that warnowiid dinoflagellates branch within the Gymnodinium sensu stricto group, forming a cluster separated from the Polykrikos clade and with autotrophic Pheopolykrikos beauchampii as closest relative. This reinforces their classification as unarmored dinoflagellates based on the shape of the apical groove, despite the strong ecological and ultrastructural diversity of the Gymnodinium s.s. group. Other structures, such as the ocelloid and piston, have no systematic value above the genus level.     

Phagotrophic Mechanisms and Prey Selection in Free-living Dinoflagellates1

Three types of feeding mechanisms are known in dinoflagellates: pallium feeding, tube feeding, and direct engulfment. Pallium feeding has only been described for heterotrophic thecate species (Protoperidinium, Diplopsalis group). Tube feeding is commonly found among both naked and thecate species of mixotrophic and heterotrophic dinoflagellates (e.g. Amphidinium, Dinophysis, Gyrodinium, Peridiniopsis). Direct engulfment is mainly found among naked species (e.g. Gymnodinium, Gyrodinium, Noctiluca): recently, however, some thecate species have been shown to use this feeding mechanism as well. Feeding behavior in dinoflagellates involves several steps prior to actual ingestion, including precapture, capture, and prey manipulation. As feeding mechanisms allow the ingestion of relatively large prey or parts thereof, dinoflagellates are regarded as raptorial feeders. While prey size plays an important role in the ability of dinoflagellates to ingest food, this alone cannot explain observed prey preferences. Some dinoflagellate species can be very selective in their choice of prey, while others show a remarkable versatility.     

Unique carotenoid lactoside, P457, in Symbiodinium sp. of dinoflagellate

The dinoflagellates are a large group of unicellular alge in marine and fresh water. Some are an endosymbiont of marine animals. Photosynthetic dinoflagellates have peridinin, a light-harvesting carotenoid. In addition, a unique carotenoid, P457, was found from Amphinidium. The presence of P457 in Symbiodinium derived from marine animals has not been reported. We reconfirmed the molecular structure of P457, a neoxanthin-like carotenoid with an aldehyde group and a lactoside, from Symbiodinium sp. NBRC 104787 isolated from a sea anemone. In addition, we investigated the distribution of P457 and peridinin in various Symbiodinium and scleractinian coral species, and possible biosynthetic pathways of these carotenoids are proposed.     

Parasitic Life Styles of Marine Dinoflagellates1

Several genera of marine dinoflagellates contain species that have evolved parasitic life styles. Dinoflagellate infections have been reported for a wide range of host organisms including sarcodines. ciliates, free-living dinoflagellates, various invertebrates, and a few vertebrates. Some dinoflagellates even parasitize other parasitic dinoflagellates. Most species are obligately parasitic and rely on heterotrophy as their sole means of nutrition; however, some are mixotrophic, as they possess chloroplasts during part or all of their life cycle. Many are ectoparasites that use highly specialized structures to attach to their host and feed, while others are intracellular parasites that feed by osmotrophy. Parasitic dinoflagellates often have adverse effects on their host that can lead to reproductive castration or death. The ecological importance of parasitic dinoflagellates is particularly evident during epidemic outbreaks that cause mass mortality of host organisms. Species that infect fish can pose threats to aquaculture. while other species can make commercially important crustacea unpalatable. In the planktonic realm, parasitic dinoflagellates influence the structure and function of the microbial food web. They compete with copepods and other grazers by utilizing ciliates as hosts and can stimulate rapid recycling of nutrients by causing the decline of toxic and non-toxic red tides.     

Parasites and phytoplankton, with special emphasis on dinoflagellate infections

Planktonic members of most algal groups are known to harbor intracellular symbionts, including viruses, bacteria, fungi, and protozoa. Among the dinoflagellates, viral and bacterial associations were recognized a quarter century ago, yet their impact on host populations remains largely unresolved. By contrast, fungal and protozoan infections of dinoflagellates are well documented and generally viewed as playing major roles in host population dynamics. Our understanding of fungal parasites is largely based on studies for freshwater diatoms and dinoflagellates, although fungal infections are known for some marine phytoplankton. In freshwater systems, fungal chytrids have been linked to mass mortalities of host organisms, suppression or retardation of phytoplankton blooms, and selective effects on species composition leading to successional changes in plankton communities. Parasitic dinoflagellates of the genus Amoebophrya and the newly described Perkinsozoa, Parvilucifera infectans, are widely distributed in coastal waters of the world where they commonly infect photosynthetic and heterotrophic dinoflagellates. Recent work indicates that these parasites can have significant impacts on host physiology, behavior, and bloom dynamics. Thus, parasitism needs to be carefully considered in developing concepts about plankton dynamics and the flow of material in marine food webs.     

甲藻的异养营养型

综述了甲藻的异养类型。目前已知异养营养型在甲藻中广泛存在,只有很少几种甲藻营严格自养营养方式。有近一半的甲藻物种是没有色素体的,还有很多甲藻即使具有色素体也会有异养营养需求,称为兼养营养类型。这些兼养类群不一定主要以有机物作为其获取碳的来源,而仅仅是补充一些生长必需的有机物如维生素、生物素等。兼养类群以渗透营养和腐食营养方式进行,同时也可以寄生方式和共生方式进行兼养生活。无色素体的甲藻以有机物作为碳的唯一来源,仅仅依靠异养方式生存,属于严格异养营养方式,又称有机营养型。它们是甲藻异养营养型的主体,其主要类型有寄生、渗透营养和吞噬营养。由于吞噬营养是甲藻异养的主要类型,因此论述了3种吞噬营养型:吞噬营养方式、捕食茎营养方式和捕食笼营养方式。吞噬营养方式在无甲类和具甲类甲藻中都有存在,主要通过甲藻细胞的纵沟或底部对猎物进行吞噬,也有研究发现吞噬部位为顶孔或片间带。捕食茎营养方式是通过捕食茎刺穿猎物细胞膜并吸食其细胞质来获取营养,在异养甲藻中也较常见。捕食笼营养方式只在原多甲藻属(Protoperidinium)和翼藻属(Diplopsalis)里发现,是甲藻通过鞭毛孔分泌细胞质到胞外形成捕食笼将猎物包裹并进行消化来摄食的。甲藻摄食对象尺寸范围变化较大,小至几微米,大至几百微米。有些甲藻具有摄食选择性,通过感应猎物释放的化学物质来判断猎物的位置并进行摄食,摄食完成后由于体积的增加经常会发生细胞分裂和蜕鞘。对于甲藻异养的其他形式如拦截摄食营养方式、伪足摄食营养方式、口足摄食营养方式、触手摄食营养方式等只作简单介绍。还就甲藻异养的研究方法、其生态学意义和进化学意义进行简要论述,并对相关研究进行展望。     

Presence of the dinoflagellates Ceratium dens, C. fusus and C. furca (Gonyaulacales: Ceratiaceae) in Golfo de Nicoya, Costa Rica

Harmful Algae Blooms (HAB) are a frequent phenomenon in the Gulf of Nicoya, Costa Rica, as in other parts of the world. The morphology and physiology of these microalgae are important because HAB species have adaptive characteristics. The production of high concentrations of paralytic toxins by Ceratium dinoflagellates has only been documented at the experimental level. However, this genus has been associated with the mortality of aquatic organisms, including oyster and shrimp larva, and fish, and with decreased water quality. Recently, fishermen reported massive mortality of encaged fish near Tortuga Island (Gulf of Nicoya). Samples were taken from an algal bloom that had produced an orange coloration and had a strong foul-smelling odor. Ultrastructural details were examined with scanning electron microscopy. The dinoflagellates Ceratium dens, C. furca and C. fusus were found in samples taken at the surface. The cell count revealed four million cells of this genus per liter. The morphological variability of these species is high; therefore electron microscopy is an useful tool in the ultrastructural study of these organisms. This is the first time that three Ceratium species are reported concurrently producing harmful blooms in Costa Rica.     

One,two, three: nature's tool box for building plastids

Summary. Plastids were acquired by different strategies. While in primary endosymbiosis a cyanobacterium was engulfed by a eukaryotic cell and reduced to a plastid, secondarily evolved plastids trace back to an enslaved red or green alga. Nature's recent playground in merging organisms together can be detected in dinoflagellates, which developed additional strategies to acquire their solar-powered factory. Some dinoflagellates possess secondary plastids, other species temporarily use “stolen plastids” of different origin. The highest degree of complexity is reached in dinoflagellates with chloroplasts originating from the uptake of a photosynthetic symbiont with secondary plastids, a process termed tertiary endosymbiosis. Received June 18, 2001 Accepted January 11, 2002     

Description of two species of early branching dinoflagellates, Psammosa pacifica n. g., n. sp. and P. atlantica n. sp

In alveolate evolution, dinoflagellates have developed many unique features, including the cell that has epicone and hypocone, the undulating transverse flagellum. However, it remains unclear how these features evolved. The early branching dinoflagellates so far investigated such as Hematodinium, Amoebophrya and Oxyrrhis marina differ in many ways from of core dinoflagellates, or dinokaryotes. Except those handful of well studied taxa, the vast majority of early branching dinoflagellates are known only by environmental sequences, and remain enigmatic. In this study we describe two new species of the early branching dinoflagellates, Psammosa pacifica n. g., n. sp. and P. atlantica n. sp. from marine intertidal sandy beach. Molecular phylogeny of the small subunit (SSU) ribosomal RNA and Hsp90 gene places Psammosa spp. as an early branch among the dinoflagellates. Morphologically (1) they lack the typical dinoflagellate epicone-hypocone structure, and (2) undulation in either flagella. Instead they display a mosa?c of dinokaryotes traits, i.e. (3) presence of bi-partite trychocysts; Oxyrrhis marina-like traits, i.e. (4) presence of flagellar hairs, (5) presence of two-dimensional cobweb scales ornamenting both flagella (6) transversal cell division; a trait shared with some syndineansand Parvilucifera spp. i.e. (7) a nucleus with a conspicuous nucleolus and condensed chromatin distributed beneath the nuclear envelope; as well as Perkinsus marinus -like features i.e. (8) separate ventral grooves where flagella emerge and (9) lacking dinoflagellate-type undulating flagellum. Notably Psammosa retains an apical complex structure, which is shared between perkinsids, colpodellids, chromerids and apicomplexans, but is not found in dinokaryotic dinoflagellates.     

Confirmation of the wide host range of Parvilucifera corolla (Alveolata,Perkinsozoa)

Marine parasites of the genus Parvilucifera have been described as endoparasitoids of dinoflagellates. Recently, the species Parvilucifera corolla was described, but its host range was not examined. Here, the host selectivity of P. corolla was screened, including 110 strains of dinoflagellates (24 genera) and other microalgal groups as potential hosts. Infections and the full life cycle of the parasitoid were observed in 73 strains (16 genera) of dinoflagellates. Parvilucifera corolla did not infect most chlorophytes, cryptophytes, chrysophytes, diatoms, haptophytes and raphidophytes but one strain of Pyramimonas (chlorophyte) was infected, although without viable sporangia. In Symbiodinium natans, a transition to the coccoid stage was induced above a certain parasite:host ratio. These results confirm P. corolla as a generalist parasitoid of dinoflagellates, with important differences in host range regarding other species of the genus.     

Sinophysis and Pseudophalacroma are distantly related to typical Dinophysoid dinoflagellates (Dinophysales, Dinophyceae)

Dinophysoid dinoflagellates are usually considered a large monophyletic group. Large subunit and small subunit (SSU) rDNA phylogenies suggest a basal position for Amphisoleniaceae (Amphisolenia,Triposolenia) with respect to two sister groups, one containing most Phalacroma species plus Oxyphysis and the other Dinophysis,Ornithocercus, Dinophysoid dinoflagellates are usually considered a large monophyletic group. Large subunit and small subunit (SSU) rDNA phylogenies suggest a basal position for Amphisoleniaceae (Amphisolenia,Triposolenia) with respect to two sister groups, one containing most Phalacroma species plus Oxyphysis and the other Dinophysis,Ornithocercus, Histioneis,Citharistes and some Phalacroma species. We provide here new SSU rDNA sequences of Pseudophalacroma (pelagic) and Sinophysis (the only benthic dinophysoid genus). Molecular phylogenies support that they are very divergent with respect to the main clade of Dinophysales. Additional molecular markers of these two key genera are needed to elucidate the evolutionary relations among the dinophysoid dinoflagellates. Histioneis,Citharistes and some Phalacroma species. We provide here new SSU rDNA sequences of Pseudophalacroma (pelagic) and Sinophysis (the only benthic dinophysoid genus). Molecular phylogenies support that they are very divergent with respect to the main clade of Dinophysales. Additional molecular markers of these two key genera are needed to elucidate the evolutionary relations among the dinophysoid dinoflagellates.     

Diversity, distribution, and new phylogenetic information of calcareous dinoflagellates from the China Sea

Calcareous dinoflagellates have been recorded from subarctic to tropical areas, inhabiting both neritic and oceanic regions. In the present study we analyse 12 sediment samples from the China Sea to establish the existence of calcareous dinoflagellates in this area. A total of 11 calcareous dinoflagellate species were recorded, among them, three genera (Calciodinellum, Leonella, Posoniella) and seven species (Calciodinellum albatrosianum, C. levantinum, C. operosum, Leonella granifera, Posoniella tricarinel...     

THECATE HETEROPHIC DINOFLAGELLATES: FEEDING BEHAVIOR AND MECHANISMS1

The feeding of 18 species of thrcale hetrophi dinoflagellates from three genera (Protoperidininm, Oblea, Zygabikodinium) can all be described within one general framework. These species engulf diatoms and other prey with a pseudopod (herein terned a “Pallium”)which originates at the flagellar pore in the sulcus. The pallium is a highly plastic, membranous organ which rasily strethes to accommodate spines and many as 58 diatom cells in a chain. The contents of the phytoplanklon prey are liquified and transporued throughthe pallioum typically within 7 to 30 minutes of capture (although feeding may last 2 h) teaving an intact but empty cell wall or frustule. Thus far, with few exceptions, Protoperidinium specises have been observed feeding inly on diatoms, whereas two diplopsaloid species feed on dinoflagellates and prasinophytes as well. In four species from the three genera studied. a capture filament has been observed that connects the food to the dinoflagellate prior to extension of the pallium, sometimes allowing the cell to pull the food while swimming. A distinctive precapture swimming behavior is also deseribed foe six species, suggesting that the dinoflagellates are selective grazers.     

Spatio-temporal dynamics and biotic substrate preferences of benthic dinoflagellates in the Lesser Antilles,Caribbean sea

Epibenthic dinoflagellates were monitored monthly over an 18 month period in Guadeloupe and Martinique (Lesser Antilles, Caribbean Sea). These islands are located in the second most affected ciguatera fish poisoning (CFP) region of the world. Guadeloupe presented five times more total epibenthic dinoflagellates and two times less abundant Gambierdiscus spp. compared to Martinique, although the area of frequent CFP outbreaks covers Guadeloupe and not Martinique. Results did not show any clear seasonal variations of benthic dinoflagellates abundances. Temperature and salinity were not driving parameters in the evolution of total benthic dinoflagellate abundances. Preferential associations were found between macrophyte species and epibenthic dinoflagellates. The Phaeophyceae Dictyota spp. hosted the highest abundances of total epibenthic dinoflagellates, composed mainly of Ostrepsis and Prorocentrum genera. The seagrass Halophila stipulacea hosted the highest abundances of Gambierdiscus spp. and Sinophysis spp. whilst the highest abundance of Coolia was determined on Galaxaura spp. The pelagic Sargassum spp. hosted the lowest abundances of benthic dinoflagellates including the genus Gambierdiscus.     

Simulating motile algae using a mixed Eulerian-Lagrangian approach: does motility promote dinoflagellate persistence or co-existence with diatoms?

Dinoflagellates are characterized by low maximum photosynthetic rates and high respiratory costs. Recent evidence also suggests that dinoflagellates are disproportionately abundant in the diets of many copepods. This suggests that at least some species are preferred prey types. This begs the question: 'How do dinoflagellates co-exist with other, seemingly competitively superior, algal taxa'? Their motility may enable them to maintain position better in the light-rich surface waters, and more successfully make the return journey into deeper waters in order to replenish their internal nutrient stores when surface nutrients become depleted. This theory is examined using a depth-resolved model of algal dynamics. Nutrients and organic detrital matter are represented on a Eulerian grid, whilst a Lagrangian approach is used to represent dinoflagellates and diatoms. The model indicates that strictly autotrophic dinoflagellates have difficulty balancing their metabolic budgets. Even in the absence of competition from diatoms, motility is almost essential to dinoflagellate persistence. Only extremely motile dinoflagellates are able to compete successfully with diatoms. In reality, an increasing number of dinoflagellate species are being found to be mixotrophic. This model suggests that mixotrophy may often be an obligatory, rather than optional, behaviour.      

大亚湾澳头水域浮游植物群落结构及周年数量动态

对1997年至1998年广东省大亚湾澳头水域的浮游植物群落进行调查和分析。结果发现浮游植物65属198种;硅藻在种类组成和数量上都比甲藻占有优势,存在春季和秋季高峰,主要优势类群依次是角毛藻、骨条藻、拟菱形藻等;甲藻只存在春季高峰,代表种类有裸甲藻、原甲藻等。主要优势种类的生长与调查水域的盐度没有明显关系,但全年水温的季节性变化对优势种类的消长影响显著。Simpson多样性指数、Shannon-Weaver多样性指数、均匀度的年平均值分别是0.611、2.107、0.557,多样性指数没有明显的季节变化规律和水平分布规律。       

Microphytoplankton of the Pitchavaram mangals,southeast coast of India: species composition and population density

Species richness of phytoplankton of the Pitchavaram mangals was high. There were 82 species constituted by 67 species of diatoms, 12 species of dinoflagellates and 3 species of bluegreen algae. The diatoms formed the bulk with 72% followed by the dinoflagellates with 15%, in which there were autochthonous (temporary and permanent) and allochthonous forms. Phytoplankton population density exhibited a wide seasonal fluctuation with the minimum during monsoon and the maximum during summer, suggesting the possible differential influence of various environmental factors.     

THE PHYCOBILIN SIGNATURES OF CHLOROPLASTS FROM THREE DINOFLAGELLATE SPECIES: A MICROANALYTICAL STUDY OF DINOPHYSIS CAUDATA, D. FORTII, AND D. ACUMINATA (DINOPHYSIALES, DINOPHYCEAE)

The absorbance and fluorescence emission spectra for three species of Dinophysis, D. caudata Saville-Kent, D. fortii Pavillard, and D. acuminata Claparède et Lachmann, were obtained through an in vivo microanalytical technique using a new type of transparent filter. The pigment signatures of these Dinophysis species were compared to those of Synechococcus Nägeli, a cryptophyte, and two wild rhodophytes, as well as those of another dinoflagellate, a diatom, and a chlorophyte. Phycobilins are not considered a native protein group for dinoflagellates, yet the absorption and fluorescence properties of the three Dinophysis species were demonstrated to closely resemble phycobilins and chlorophylls of Rhodomonas Karsten (Cryptophyceae). Analyses of Dinophysis species using epifluorescence microscopy found no additional nucleus or nuclear remnant as would be contributed by an endosymbiont.