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Paolo Burighel - One of the best experts on this subject based on the ideXlab platform.
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evolutionary diversification of secondary mechanoreceptor cells in tunicata
BMC Evolutionary Biology, 2013Co-Authors: Francesca Rigon, Paolo Burighel, Thomas Stach, Federico Caicci, Fabio Gasparini, Lucia ManniAbstract:Background: Hair cells are vertebrate secondary sensory cells located in the ear and in the lateral line organ. Until recently, these cells were considered to be mechanoreceptors exclusively found in vertebrates that evolved within this group. Evidence of secondary mechanoreceptors in some tunicates, the proposed sister group of vertebrates, has recently led to the hypothesis that vertebrate and tunicate secondary sensory cells share a common origin. Secondary sensory cells were described in detail in two tunicate groups, ascidians and thaliaceans, in which they constitute an oral sensory structure called the coronal organ. Among thaliaceans, the organ is absent in salps and it has been hypothesised that this condition is due to a different feeding system adopted by this group of animals. No information is available as to whether a comparable structure exists in the third group of tunicates, the Appendicularians, although different sensory structures are known to be present in these animals. Results: We studied the detailed morphology of Appendicularian oral mechanoreceptors. Using light and electron microscopy we could demonstrate that the mechanosensory organ called the circumoral ring is composed of secondary sensory cells. We described the ultrastructure of the circumoral organ in two Appendicularian species, Oikopleura dioica and Oikopleura albicans, and thus taxonomically completed the data collection of tunicate secondary sensory cells. To understand the evolution of secondary sensory cells in tunicates, we performed a cladistic analysis using morphological data. We constructed a matrix consisting of 19 characters derived from detailed ultrastructural studies in 16 tunicate species and used a cephalochordate and three vertebrate species as outgroups. Conclusions: Our study clearly shows that the circumoral ring is the Appendicularian homologue of the coronal organ of other tunicate taxa. The cladistic analysis enabled us to reconstruct the features of the putative ancestral hair cell in tunicates, represented by a simple monociliated cell. This cell successively differentiated into the current variety of oral mechanoreceptors in the various tunicate lineages. Finally, we demonstrated that the inferred evolutionary changes coincide with major transitions in the feeding strategies in each respective lineage.
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alimentary tract of kowalevskiidae Appendicularia tunicata and evolutionary implications
Journal of Morphology, 2003Co-Authors: Carlo Brena, Francesca Cima, Paolo BurighelAbstract:The alimentary tract of Kowalevskia tenuis and K. oceanica, the only species of the Appendicularian family Kowalevskiidae, was studied both at the light and electron microscope levels and compared with species belonging to the other two families of the class. Kowalevskids show interesting specializations: 1) the pharynx opens on both sides through two opposing spiracles, modified into long ciliated fissures, and possesses an original filtering system of ciliated combs arranged in two pairs of opposing longitudinal rows; 2) the endostyle is absent, its place being taken by a ciliated groove without any glandular cell; 3) posterior to the esophagus, the globular stomach and rectum form a digestive nucleus comprising a few, large cells including two well-developed, specialized valves, cardiac and pyloric; 4) special apical junctions bearing characteristics of both gap and adherens junctions are diffuse along the gut epithelium; 5) the heart is absent. Our data suggest that Kowalevskiidae underwent a high degree of specialization for food filtering and are more closely related to Fritillariidae, with which they share several characters, rather than Oikopleuridae, the latter probably representing the most primitive family of Appendicularians.
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The highly specialised gut of Fritillariidae (Appendicularia: Tunicata)
Marine Biology, 2003Co-Authors: Carlo Brena, F. Cima, Paolo BurighelAbstract:The morphology and some functions of the gut of Fritillaria pellucida and Fritillaria formica (Fritillaridae) were investigated by light and electron microscopy, and also by means of histochemical and immunohistochemical techniques. Fritillarids, very important for their abundance and ecological impact in marine ecosystems, have a very simplified gut: a straight oesophagus connects the pharynx to the digestive nucleus, composed of globular stomach and rectum, connected dorsally through a very short proximal intestine. The latter is characterised by a few (two to four) extremely specialised cells, completely filled with mitochondria associated tightly with membrane infoldings showing strong ATP-ase activity, and probably involved in the osmoregulation of internal body fluids. The gut is formed of an extremely low number of cells, which, although poorly diversified, are very large in the stomach and rectum. Food transfer along the gut depends on and is regulated by well-developed cardiac and pyloric valves, and signs of general digestive and absorptive activity are recognisable all along the brush border of the main tracts. The macroscopic organisation and cytological characters of the gut in fritillarids are completely different from those of the oikopleurids. In particular, fritillarids lack specialised cells for endocytosis and intracellular digestion, like those described in the genus Oikopleura . The general simplification and specialisation observed in Fritillaria gut may account for their elevated growth rate and abundant diffusion in all oceans.
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the exceptional blind gut of Appendicularia sicula Appendicularia tunicata
Zoologischer Anzeiger – A Journal of Comparative Zoology, 2003Co-Authors: Carlo Brena, Francesca Cima, Paolo BurighelAbstract:Abstract In this work, we studied for the first time the histology and ultrastructure of the gut of Appendicularia sicula and demonstrated the absence of any trace of anus. Appendicularians are small holoplanktonic tunicates, characterised by very fast ingestion and quick food transfer along their gut. The high production of faecal pellets released in the aqueous environment, associated with a high filtration rate, highlights their important role in marine ecosystems. Due to the absence of an anus, in contrast with other Appendicularians, A. sicula , one of the smallest species, accumulates undigested faecal material within its body, with consequent extreme enlargement of its rectum. The gut, the epithelium of which is generally extremely reduced, is formed of an oesophagus, a globular stomach, thin proximal and mid-intestine, and a huge rectum. The latter, when filled with faecal material, may occupy most of the volume of the trunk in fully grown specimens. Although profoundly altered, the gut of these animals does show several similarities to that of Fritillaria (a genus of the same family, Fritillariidae), with which it has in common many features such as specialised mitochondrial pump cells. In A. sicula , the structural simplifications of organs seem to reach their extreme condition in comparison to other Appendicularians.
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multifarious activities of gut epithelium in an Appendicularian oikopleura dioica tunicata
Marine Biology, 2002Co-Authors: Francesca Cima, Carlo Brena, Paolo BurighelAbstract:The functions of the various gut regions of Oikopleuradioica (oesophagus, left and right gastric lobes, vertical intestine, mid-intestine and rectum) were investigated by means of histochemical, histoenzymatic and immunohistochemical techniques at light and electron microscopes. Ciliary food progression is evidenced by the presence of ATPases on cilia, along the entire gut, with the exception of the cardiac valve, a passive device controlling food direction. Absorptive processes (alkaline phosphatase), active transport (ATPases) and nitrogen excretion (D-amino acid oxidase) occur along the entire gut, in both ciliated microvillar and globular cells. The latter, typical of the left gastric lobe and rectum, are also involved in endocytotic processes (exogenous peroxidase as tracer) and intracellular digestion (α-amylase, aminopeptidase M, acid phosphatase, 5′-nucleotidase, non-specific esterase). The giant cells of the gastric band participate in extracellular digestion; they contain secretory granules positive to various hydrolytic enzymes, the activity of which is also recognisable in faecal pellets inside the intestinal lumen. Lipid storage occurs mainly in the right gastric lobe and vertical intestine, whereas protein storage takes place in the rectal granular cells. Epithelial transport and possible osmoregulation occur along the entire gut, especially at the level of diffuse baso-lateral interdigitations, which increase the plasmalemma surface enormously, are often associated with mitochondria and possess numerous ATPase pumps. Data extend previous histological observations and hypotheses on the physiological role of the various gut regions. The remarkable and specific location of enzymatic activities and nutrient storage are in agreement with the high capacity of O. dioica to process a great quantity of food very rapidly and efficiently.
Nori Satoh - One of the best experts on this subject based on the ideXlab platform.
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[ESSAY] An Advanced Filter-Feeder Hypothesis for Urochordate Evolution
2016Co-Authors: Nori SatohAbstract:Chordates consist of cephalochordates, urochordates, and vertebrates. They originated from a common ancestor(s) by evolving a novel type of tadpole-like larva characterized by a notochord and dorsal neural tube. Urochordata or Tunicata comprises three classes, Ascidiacea (ascidians), Thaliacea (salps), and Appendicularia (larvaceans); are extremely diverse in morphology, life his-tory, and mode of reproduction; and may include either free-swimming or sessile adults. Recent molecular phylogenies support the notion that cephalochordates are basal among chordates, with urochordates the sister group to vertebrates. This revitalized evolutionary scenario compels us to explain how the huge variety of lifestyles of extant urochordates evolved from a cephalochordate-like ancestor. Here, an advanced filter-feeder hypothesis is presented, in which, although the taxonomic position of larvaceans is enigmatic, it is argued that among urochordates, free-living lar-vaceans are basal, while sessile ascidians are derived. Urochordates might have evolved their traits in response to strong evolutionary advantages as specialists of suspension filter feeding. Never-theless, the molecular mechanisms involved in the formation of the notochord and several other organs in ascidian embryos are more comparable to those of vertebrates than cephalochordates. Thus, urochordates are close relatives to vertebrates
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An Advanced Filter-Feeder Hypothesis for Urochordate Evolution
Zoological Science, 2009Co-Authors: Nori SatohAbstract:Chordates consist of cephalochordates, urochordates, and vertebrates. They originated from a common ancestor(s) by evolving a novel type of tadpole-like larva characterized by a notochord and dorsal neural tube. Urochordata or Tunicata comprises three classes, Ascidiacea (ascidians), Thaliacea (salps), and Appendicularia (larvaceans); are extremely diverse in morphology, life history, and mode of reproduction; and may include either free-swimming or sessile adults. Recent molecular phylogenies support the notion that cephalochordates are basal among chordates, with urochordates the sister group to vertebrates. This revitalized evolutionary scenario compels us to explain how the huge variety of lifestyles of extant urochordates evolved from a cephalochordate-like ancestor. Here, an advanced filter-feeder hypothesis is presented, in which, although the taxonomic position of larvaceans is enigmatic, it is argued that among urochordates, free-living larvaceans are basal, while sessile ascidians are derived. Urochordates might have evolved their traits in response to strong evolutionary advantages as specialists of suspension filter feeding. Nevertheless, the molecular mechanisms involved in the formation of the notochord and several other organs in ascidian embryos are more comparable to those of vertebrates than cephalochordates. Thus, urochordates are close relatives to vertebrates.
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Brachyury (T) gene expression and notochord development in Oikopleura longicauda (Appendicularia, Urochordata).
Development genes and evolution, 2001Co-Authors: Atsuo Nishino, Masaaki Morisawa, Yutaka Satou, Nori SatohAbstract:Appendicularia (Larvacea) is a subgroup of Urochordata (Tunicata) comprised of holoplanktonic organisms that retain their tailed architecture throughout their life history, while other tunicates, including ascidians and doliolids, resorb the tail after metamorphosis. In order to investigate the characteristics of the Appendicularian unresorbed notochord, we isolated a partial genomic clone and a full-length cDNA sequence homologous to the mouse Brachyury (T) gene from the Appendicularian Oikopleura longicauda. Brachyury is known to be predominantly expressed in the notochord cells and plays an important role in their differentiation in other chordates. While phylogenetic analysis robustly supports the orthology of the isolated Brachyury gene, the exon–intron organization found in the genomic clone was distinct from that well-conserved among other T-box genes. In addition to a detailed observation of notochord development in living specimens, whole-mount double in situ hybridization was carried out using a Brachyury probe along with a muscle actin probe. The Brachyury transcripts were found in the notochord of the tailbud embryos and persisted into later stages. The present study highlights characteristics of notochord development in the Appendicularian. Furthermore, these results provide basic knowledge for comprehensive understanding of the cellular- and molecular-based mechanisms needed to build the characteristic cytoarchitecture of notochord that varies among tunicate species.
Sérgio Luiz Costa Bonecker - One of the best experts on this subject based on the ideXlab platform.
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o uso da classe Appendicularia como bioindicadora de regioes e massas de agua superficiais na area da bacia de campos rio de janeiro brasil
Iheringia Serie Zoologia, 2016Co-Authors: Pedro Freitas Carvalho, Sérgio Luiz Costa BoneckerAbstract:Estudos sobre a variacao espacial das especies de apendicularias e sua relacao com as massas de agua sao raros, principalmente no Atlântico Sul. O atual estudo pretende preencher a lacuna de conhecimento sobre a abundância, composicao especifica e a funcao de bioindicadora das apendicularias, em diferentes regioes (plataforma continental e talude) e massas de agua, no Atlântico Sul Ocidental. As coletas foram realizadas no periodo chuvoso (de fevereiro a abril de 2009) e no periodo seco (de agosto a setembro de 2009) na camada subsuperficial. As massas de agua encontradas na superficie na plataforma continental da area de estudo foram a Agua Tropical (AT), que predominou no periodo chuvoso, e a Agua Costeira (AC), que predominou no periodo seco. Em ambos os periodos de coleta nao foram registradas a presenca da Agua Central do Atlântico Sul (ACAS) na superficie na plataforma continental. As apendicularias foram mais abundantes na regiao de plataforma continental influenciada pela AC. Foi identificado um total de 12 especies da classe Appendicularia. Oikopleura longicauda e O. fusiformis foram as especies mais abundantes. Oikopleura dioica foi encontrada exclusivamente na plataforma continental na AC. Apesar nao ser observado a presenca de ACAS na superficie, altos valores da densidade de apendicularia em frente a Cabo Frio sugerem a influencia de uma pos ressurgencia no local. Tambem foram observados valores elevados na abundância das apendicularias em frente ao rio Paraiba do Sul com influencia da AC. Este fato sugere a alta capacidade de incremento de nutrientes desse aporte fluvial. A variacao espacial e as diferentes massas de agua influenciaram a abundância e a composicao das apendicularias. Dentre as especies identificadas, somente O. longicauda foi considerada como bioindicadora da AC.
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analysis of the Appendicularia class subphylum urochordata as a possible tool for biomonitoring four estuaries of the tropical region
Environmental Monitoring and Assessment, 2016Co-Authors: Pedro Freitas Carvalho, Sérgio Luiz Costa Bonecker, Cristina Aparecida Gomes NassarAbstract:This study aims to characterize the differences between physical and chemical parameters of water quality indicators and eutrophication in four estuaries of the state of Rio de Janeiro and relate them to full density of the species that belong to the Appendicularia class with the purpose of seeking bioindicators for estuarine areas. The estuaries studied were from the rivers Macae, Sao Joao, Bracui, and Pereque-Acu. The physicochemical parameters monitored for evaluation of the water bodies and used for the correlation with the Appendicularians were pH, temperature, nitrite, nitrate, N-ammonia, total nitrogen, phosphate, total phosphorus, dissolved oxygen (DO), suspended particulate matter (SPM), chlorophyll a, heterotrophic bacteria, and fecal coliform. The estuaries Bracui and Sao Joao showed enhanced qualities of water and lower degrees of eutrophication than Macae and Pereque-Acu estuaries. The species of the Appendicularia class found in this study were Oikopleura longicauda (Vogt, 1854), Oikopleura dioica Fol, 1872, Oikopleura fusiformis Fol, 1872, and Fritillaria haplostoma Fol, 1872. The density of Appendicularians and O. longicauda was inversely related to the nutrient values and SPM; nonetheless, no species of Appendicularians could be used as a bioindicator of any estuary in the current study. Studies on the quality of estuary waters and the search for other bioindicators belonging to other zooplankton groups are recommended to confirm the obtained results and to expand the knowledge of these coastal environments.
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variacao da composicao e abundância das especies da classe Appendicularia e seu uso como potenciais bioindicadoras de regioes e massas de agua superficiais na area da bacia de campos rio de janeiro brasil
Iheringia Serie Zoologia, 2016Co-Authors: Pedro Freitas Carvalho, Sérgio Luiz Costa BoneckerAbstract:Studies about the relationship of the species of Appendicularians with spatial gradients and water masses are rare, especially in the South Atlantic. The present study aims to fill the knowledge gap about the abundance of the community of Appendicularians and on their bioindicator function in different regions (continental shelf and slope), with influence of different water masses in the South Atlantic. Sampling was conducted in the rainy season (February-April 2009) and the dry season (August-September 2009) in the subsurface layer. The water masses found on the continental shelf of the study area were the Tropical Water (AT), which was prevalent during the rainy season, and the Coastal Water (AC), which was prevalent in the dry season. In both sampling periods has not registered the presence of SACW on the surface over continental shelf. The Appendicularians were more abundant in the region of the continental shelf influenced by the CW. A total of 18 species of Appendicularian was registered. Oikopleura longicauda Vogt, 1854 and O. fusiformis Fol, 1872 were the most abundant Appendicularian. Oikopleura dioica Fol, 1872 was found exclusively in the continental shelf on the CW. In despite of the SACW water had not registered on the surface, the presence of, high values of density of Appendicularians in front of Cabo Frio region suggest the influence of an upwelling event in a anterior period in the region. In relation to the Appendicularians abundance, high values were also observed in front of the Paraiba do Sul river with the CW influence. This fact suggests a high nutritional contribution of this river in the coastal marine area adjacent. The spatial variation and different water masses influenced the abundance and the composition of Appendicularians. Among the species identified, only O. longicauda was considered as a bioindicator of the CW.
Xabier Irigoien - One of the best experts on this subject based on the ideXlab platform.
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carotenoid metabolic profiling and transcriptome genome mining reveal functional equivalence among blue pigmented copepods and Appendicularia
Molecular Ecology, 2014Co-Authors: Nazia Mojib, Maan Amad, Manjula Thimma, Naroa Aldanondo, Mande K Kumaran, Xabier IrigoienAbstract:The tropical oligotrophic oceanic areas are characterized by high water transparency and annual solar radiation. Under these conditions, a large number of phylogenetically diverse mesozooplankton species living in the surface waters (neuston) are found to be blue pigmented. In the present study, we focused on understanding the metabolic and genetic basis of the observed blue phenotype functional equivalence between the blue-pigmented organisms from the phylum Arthropoda, subclass Copepoda (Acartia fossae) and the phylum Chordata, class Appendicularia (Oikopleura dioica) in the Red Sea. Previous studies have shown that carotenoid-protein complexes are responsible for blue coloration in crustaceans. Therefore, we performed carotenoid metabolic profiling using both targeted and nontargeted (high-resolution mass spectrometry) approaches in four different blue-pigmented genera of copepods and one blue-pigmented species of Appendicularia. Astaxanthin was found to be the principal carotenoid in all the species. The pathway analysis showed that all the species can synthesize astaxanthin from β-carotene, ingested from dietary sources, via 3-hydroxyechinenone, canthaxanthin, zeaxanthin, adonirubin or adonixanthin. Further, using de novo assembled transcriptome of blue A. fossae (subclass Copepoda), we identified highly expressed homologous β-carotene hydroxylase enzymes and putative carotenoid-binding proteins responsible for astaxanthin formation and the blue phenotype. In blue O. dioica (class Appendicularia), corresponding putative genes were identified from the reference genome. Collectively, our data provide molecular evidences for the bioconversion and accumulation of blue astaxanthin-protein complexes underpinning the observed ecological functional equivalence and adaptive convergence among neustonic mesozooplankton.
Pedro Freitas Carvalho - One of the best experts on this subject based on the ideXlab platform.
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o uso da classe Appendicularia como bioindicadora de regioes e massas de agua superficiais na area da bacia de campos rio de janeiro brasil
Iheringia Serie Zoologia, 2016Co-Authors: Pedro Freitas Carvalho, Sérgio Luiz Costa BoneckerAbstract:Estudos sobre a variacao espacial das especies de apendicularias e sua relacao com as massas de agua sao raros, principalmente no Atlântico Sul. O atual estudo pretende preencher a lacuna de conhecimento sobre a abundância, composicao especifica e a funcao de bioindicadora das apendicularias, em diferentes regioes (plataforma continental e talude) e massas de agua, no Atlântico Sul Ocidental. As coletas foram realizadas no periodo chuvoso (de fevereiro a abril de 2009) e no periodo seco (de agosto a setembro de 2009) na camada subsuperficial. As massas de agua encontradas na superficie na plataforma continental da area de estudo foram a Agua Tropical (AT), que predominou no periodo chuvoso, e a Agua Costeira (AC), que predominou no periodo seco. Em ambos os periodos de coleta nao foram registradas a presenca da Agua Central do Atlântico Sul (ACAS) na superficie na plataforma continental. As apendicularias foram mais abundantes na regiao de plataforma continental influenciada pela AC. Foi identificado um total de 12 especies da classe Appendicularia. Oikopleura longicauda e O. fusiformis foram as especies mais abundantes. Oikopleura dioica foi encontrada exclusivamente na plataforma continental na AC. Apesar nao ser observado a presenca de ACAS na superficie, altos valores da densidade de apendicularia em frente a Cabo Frio sugerem a influencia de uma pos ressurgencia no local. Tambem foram observados valores elevados na abundância das apendicularias em frente ao rio Paraiba do Sul com influencia da AC. Este fato sugere a alta capacidade de incremento de nutrientes desse aporte fluvial. A variacao espacial e as diferentes massas de agua influenciaram a abundância e a composicao das apendicularias. Dentre as especies identificadas, somente O. longicauda foi considerada como bioindicadora da AC.
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analysis of the Appendicularia class subphylum urochordata as a possible tool for biomonitoring four estuaries of the tropical region
Environmental Monitoring and Assessment, 2016Co-Authors: Pedro Freitas Carvalho, Sérgio Luiz Costa Bonecker, Cristina Aparecida Gomes NassarAbstract:This study aims to characterize the differences between physical and chemical parameters of water quality indicators and eutrophication in four estuaries of the state of Rio de Janeiro and relate them to full density of the species that belong to the Appendicularia class with the purpose of seeking bioindicators for estuarine areas. The estuaries studied were from the rivers Macae, Sao Joao, Bracui, and Pereque-Acu. The physicochemical parameters monitored for evaluation of the water bodies and used for the correlation with the Appendicularians were pH, temperature, nitrite, nitrate, N-ammonia, total nitrogen, phosphate, total phosphorus, dissolved oxygen (DO), suspended particulate matter (SPM), chlorophyll a, heterotrophic bacteria, and fecal coliform. The estuaries Bracui and Sao Joao showed enhanced qualities of water and lower degrees of eutrophication than Macae and Pereque-Acu estuaries. The species of the Appendicularia class found in this study were Oikopleura longicauda (Vogt, 1854), Oikopleura dioica Fol, 1872, Oikopleura fusiformis Fol, 1872, and Fritillaria haplostoma Fol, 1872. The density of Appendicularians and O. longicauda was inversely related to the nutrient values and SPM; nonetheless, no species of Appendicularians could be used as a bioindicator of any estuary in the current study. Studies on the quality of estuary waters and the search for other bioindicators belonging to other zooplankton groups are recommended to confirm the obtained results and to expand the knowledge of these coastal environments.
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variacao da composicao e abundância das especies da classe Appendicularia e seu uso como potenciais bioindicadoras de regioes e massas de agua superficiais na area da bacia de campos rio de janeiro brasil
Iheringia Serie Zoologia, 2016Co-Authors: Pedro Freitas Carvalho, Sérgio Luiz Costa BoneckerAbstract:Studies about the relationship of the species of Appendicularians with spatial gradients and water masses are rare, especially in the South Atlantic. The present study aims to fill the knowledge gap about the abundance of the community of Appendicularians and on their bioindicator function in different regions (continental shelf and slope), with influence of different water masses in the South Atlantic. Sampling was conducted in the rainy season (February-April 2009) and the dry season (August-September 2009) in the subsurface layer. The water masses found on the continental shelf of the study area were the Tropical Water (AT), which was prevalent during the rainy season, and the Coastal Water (AC), which was prevalent in the dry season. In both sampling periods has not registered the presence of SACW on the surface over continental shelf. The Appendicularians were more abundant in the region of the continental shelf influenced by the CW. A total of 18 species of Appendicularian was registered. Oikopleura longicauda Vogt, 1854 and O. fusiformis Fol, 1872 were the most abundant Appendicularian. Oikopleura dioica Fol, 1872 was found exclusively in the continental shelf on the CW. In despite of the SACW water had not registered on the surface, the presence of, high values of density of Appendicularians in front of Cabo Frio region suggest the influence of an upwelling event in a anterior period in the region. In relation to the Appendicularians abundance, high values were also observed in front of the Paraiba do Sul river with the CW influence. This fact suggests a high nutritional contribution of this river in the coastal marine area adjacent. The spatial variation and different water masses influenced the abundance and the composition of Appendicularians. Among the species identified, only O. longicauda was considered as a bioindicator of the CW.