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James C Tyler - One of the best experts on this subject based on the ideXlab platform.
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mass extinction in tetraodontiform fishes linked to the palaeocene eocene thermal maximum
Proceedings of The Royal Society B: Biological Sciences, 2017Co-Authors: Dahiana Arcila, James C TylerAbstract:Integrative evolutionary analyses based upon fossil and extant species provide a powerful approach for understanding past diversification events and for assessing the tempo of evolution across the Tree of Life. Herein, we demonstrate the importance of integrating fossil and extant species for inferring patterns of lineage diversification that would otherwise be masked in analyses that examine only one source of evidence. We infer the phylogeny and macroevolutionary history of the Tetraodontiformes (triggerfishes, pufferfishes and allies), a group with one of the most extensive fossil records among fishes. Our analyses combine molecular and morphological data, based on an expanded matrix that adds newly coded fossil species and character states. Beyond confidently resolving the relationships and divergence times of tetraodontiforms, our diversification analyses detect a major mass-extinction event during the Palaeocene–Eocene Thermal Maximum (PETM), followed by a marked increase in speciation rates. This pattern is consistently obtained when fossil and extant species are integrated, whereas examination of the fossil occurrences alone failed to detect major diversification changes during the PETM. When taking into account non-homogeneous models, our analyses also detect a rapid lineage diversification increase in one of the groups (tetraodontoids) during the middle Miocene, which is considered a key period in the evolution of reef fishes associated with trophic changes and ecological opportunity. In summary, our analyses show distinct diversification dynamics estimated from phylogenies and the fossil record, suggesting that different episodes shaped the evolution of tetraodontiforms during the Cenozoic.
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Electronic supplementary material from Mass extinction in tetraodontiform fishes linked to the Palaeocene Eocene thermal maximum
2017Co-Authors: Dahiana Arcila, James C TylerAbstract:Integrative evolutionary analyses based upon fossil and extant species provide a powerful approach for understanding past diversification events and for assessing the tempo of evolution across the Tree of Life. Herein, we demonstrate the importance of integrating fossil and extant species for inferring patterns of lineage diversification that would otherwise be masked in analyses that examine only one source of evidence. We infer the phylogeny and macroevolutionary history of the Tetraodontiformes (triggerfishes, pufferfishes and allies), a group with one of the most extensive fossil records among fishes. Our analyses combine molecular and morphological data, based on an expanded matrix that adds newly coded fossil species and character states. Beyond confidently resolving the relationships and divergence times of tetraodontiforms, our diversification analyses detect a major mass-extinction event during the Palaeocene Eocene Thermal Maximum (PETM), followed by a marked increase in speciation rates. This pattern is consistently obtained when fossil and extant species are integrated, whereas examination of the fossil occurrences alone failed to detect major diversification changes during the PETM. When taking into account non-homogeneous models, our analyses also detect a rapid lineage diversification increase in one of the groups (tetraodontoids) during the middle Miocene, which is considered a key period in the evolution of reef fishes associated with trophic changes and ecological opportunity. In summary, our analyses show distinct diversification dynamics estimated from phylogenies and the fossil record, suggesting that different episodes shaped the evolution of tetraodontiforms during the Cenozoic
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Supplementary Figure 3
2016Co-Authors: Roger A. Close, James C Tyler, Zerina Johanson, Richard C. Harrington, Matt FriedmanAbstract:Figure 3: Kernel probability-density estimates of divergence times for crown Tetraodontiformes and extant tetraodontiform families
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A new family of gymnodont fish (Tetraodontiformes) from the earliest Eocene of the Peri-Tethys (Kabardino-Balkaria, northern Caucasus, Russia)
2016Co-Authors: Alexandre F. Bannikov, Dahiana Arcila, James C Tyler, Giorgio CarnevaleAbstract:The environmental changes that occurred during the Paleocene–Eocene transition are crucial for the interpretation of the patterns and processes of diversification of vertebrate clades. A prominent increase of the number of vertebrate families occurred between the late Paleocene and early Eocene, resulting in the appearance of many in the earliest representatives of extant lineages, including a number of marine fish groups. Tetraodontiforms are a monophyletic group of derived teleost fishes encompassing a variety of bizarre morphologies. Even though the earliest members of this order appeared in the Late Cretaceous, most of the crown lineages date back to the Eocene. One of the crown tetraodontiform groups that appeared in the fossil record during the Eocene are the gymnodonts (pufferfishes, porcupinefishes, ocean sunfishes and their allies), which include a variety of species characterized by highly modified teeth incorporated into beak-like jaws and scales usually modified into prickly spines. Herein, we describe †Balkaria histiopterygia gen. et sp. nov., a gymnodont fish characterized by a strikingly peculiar morphology. The single available specimen in part and counterpart documented herein was recovered from the sapropelitic deposits that originated in the northern Peri-Tethys during the transition between the Paleocene and Eocene. Today, these deposits are exposed near the village of Gerpegezh, Republic of Kabardino-Balkaria, Russia. The skeletal structure reveals an extreme mosaicism of primitive and derived characters that result in a very bizarre and unexpected morphology. †Balkaria histiopterygia gen. et sp. nov. is unique among the extant and other fossil gymnodont fishes by, among many other features, the huge size of its spiny-dorsal fin and the position of these spines on the top of the head. †Balkaria histiopterygia gen. et sp. nov. is the earliest unequivocal gymnodont fish, representing the sole member of the new family †Balkariidae. More particularly, †Balkaria histiopterygia gen. et sp. nov. is shown herein to be the oldest and arguably the most informative fossil of the gymnodont suborder Tetraodontoidei. The phylogenetic placement of this new taxon has been assessed based on both morphology alone and on a combination of morphological and molecular data that strongly supports the close relationship of †Balkaria gen. nov. to the herein restricted Tetraodontoidei. However, its position within Tetraodontoidei is unstable depending on the type of method of phylogenetic inference. Significantly younger ages, during the Late Cretaceous, are estimated for the diversification of Tetraodontiformes than in previous tip-dating analyses (Jurassic and Early Cretaceous) using the fossilized birth-death process; these new age estimates are in better agreement with the tetraodontiform fossil record. http://zoobank.org/urn:lsid:zoobank.org:pub:41764800-B0D8-4CA4-A111-5F4C4A281C37
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2004. The importance of even highly incomplete fossil taxa in reconstructing the phylogenetic relationships of the Tetraodontiformes (Acanthomorpha
2015Co-Authors: Francesco Santini, James C TylerAbstract:SYNOPSIS. The use of fossils in the phylogenetics of extant clades traditionally has been a contentious issue. Fossils usually are relatively incomplete, and their use commonly leads to an increase in the number of equally most parsimonious trees and a decrease in the resolution of phylogenies. Fossils alone, however, provide certain kinds of information about the biological history of a clade, and computer simulations have shown that even highly incomplete material can, under certain circumstances, increase the accuracy of a phylogeny, rather than decrease it. Because empirical data are still scarce on the effects of the inclusion of fossils on phylogenetic reconstruc-tions, we attempted to investigate this problem by using a relatively well-known group of acanthomorph fishes, the Tetraodontiformes (triggerfishes, pufferfishes, and ocean sunfishes), for which robust phylogenies using extant taxa already exist and that has a well-studied fossil record. Adding incomplete fossil taxa of tetraodontiforms usually increases the number of equally most parsimonious trees and often decreases the resolution of consensus trees. However, adding fossil taxa may help to correctly establish relationships among lineages that have experienced high degrees of morphological diversification by allowing for a reinterpre-tation of homologous and homoplastic features, increasing the resolution rather than decreasing it. Fur-thermore, taxa that were scored for 25 % or more of their characters did not cause a significant loss of resolution, while providing unique biological information
Dahiana Arcila - One of the best experts on this subject based on the ideXlab platform.
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mass extinction in tetraodontiform fishes linked to the palaeocene eocene thermal maximum
Proceedings of The Royal Society B: Biological Sciences, 2017Co-Authors: Dahiana Arcila, James C TylerAbstract:Integrative evolutionary analyses based upon fossil and extant species provide a powerful approach for understanding past diversification events and for assessing the tempo of evolution across the Tree of Life. Herein, we demonstrate the importance of integrating fossil and extant species for inferring patterns of lineage diversification that would otherwise be masked in analyses that examine only one source of evidence. We infer the phylogeny and macroevolutionary history of the Tetraodontiformes (triggerfishes, pufferfishes and allies), a group with one of the most extensive fossil records among fishes. Our analyses combine molecular and morphological data, based on an expanded matrix that adds newly coded fossil species and character states. Beyond confidently resolving the relationships and divergence times of tetraodontiforms, our diversification analyses detect a major mass-extinction event during the Palaeocene–Eocene Thermal Maximum (PETM), followed by a marked increase in speciation rates. This pattern is consistently obtained when fossil and extant species are integrated, whereas examination of the fossil occurrences alone failed to detect major diversification changes during the PETM. When taking into account non-homogeneous models, our analyses also detect a rapid lineage diversification increase in one of the groups (tetraodontoids) during the middle Miocene, which is considered a key period in the evolution of reef fishes associated with trophic changes and ecological opportunity. In summary, our analyses show distinct diversification dynamics estimated from phylogenies and the fossil record, suggesting that different episodes shaped the evolution of tetraodontiforms during the Cenozoic.
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Electronic supplementary material from Mass extinction in tetraodontiform fishes linked to the Palaeocene Eocene thermal maximum
2017Co-Authors: Dahiana Arcila, James C TylerAbstract:Integrative evolutionary analyses based upon fossil and extant species provide a powerful approach for understanding past diversification events and for assessing the tempo of evolution across the Tree of Life. Herein, we demonstrate the importance of integrating fossil and extant species for inferring patterns of lineage diversification that would otherwise be masked in analyses that examine only one source of evidence. We infer the phylogeny and macroevolutionary history of the Tetraodontiformes (triggerfishes, pufferfishes and allies), a group with one of the most extensive fossil records among fishes. Our analyses combine molecular and morphological data, based on an expanded matrix that adds newly coded fossil species and character states. Beyond confidently resolving the relationships and divergence times of tetraodontiforms, our diversification analyses detect a major mass-extinction event during the Palaeocene Eocene Thermal Maximum (PETM), followed by a marked increase in speciation rates. This pattern is consistently obtained when fossil and extant species are integrated, whereas examination of the fossil occurrences alone failed to detect major diversification changes during the PETM. When taking into account non-homogeneous models, our analyses also detect a rapid lineage diversification increase in one of the groups (tetraodontoids) during the middle Miocene, which is considered a key period in the evolution of reef fishes associated with trophic changes and ecological opportunity. In summary, our analyses show distinct diversification dynamics estimated from phylogenies and the fossil record, suggesting that different episodes shaped the evolution of tetraodontiforms during the Cenozoic
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A new family of gymnodont fish (Tetraodontiformes) from the earliest Eocene of the Peri-Tethys (Kabardino-Balkaria, northern Caucasus, Russia)
2016Co-Authors: Alexandre F. Bannikov, Dahiana Arcila, James C Tyler, Giorgio CarnevaleAbstract:The environmental changes that occurred during the Paleocene–Eocene transition are crucial for the interpretation of the patterns and processes of diversification of vertebrate clades. A prominent increase of the number of vertebrate families occurred between the late Paleocene and early Eocene, resulting in the appearance of many in the earliest representatives of extant lineages, including a number of marine fish groups. Tetraodontiforms are a monophyletic group of derived teleost fishes encompassing a variety of bizarre morphologies. Even though the earliest members of this order appeared in the Late Cretaceous, most of the crown lineages date back to the Eocene. One of the crown tetraodontiform groups that appeared in the fossil record during the Eocene are the gymnodonts (pufferfishes, porcupinefishes, ocean sunfishes and their allies), which include a variety of species characterized by highly modified teeth incorporated into beak-like jaws and scales usually modified into prickly spines. Herein, we describe †Balkaria histiopterygia gen. et sp. nov., a gymnodont fish characterized by a strikingly peculiar morphology. The single available specimen in part and counterpart documented herein was recovered from the sapropelitic deposits that originated in the northern Peri-Tethys during the transition between the Paleocene and Eocene. Today, these deposits are exposed near the village of Gerpegezh, Republic of Kabardino-Balkaria, Russia. The skeletal structure reveals an extreme mosaicism of primitive and derived characters that result in a very bizarre and unexpected morphology. †Balkaria histiopterygia gen. et sp. nov. is unique among the extant and other fossil gymnodont fishes by, among many other features, the huge size of its spiny-dorsal fin and the position of these spines on the top of the head. †Balkaria histiopterygia gen. et sp. nov. is the earliest unequivocal gymnodont fish, representing the sole member of the new family †Balkariidae. More particularly, †Balkaria histiopterygia gen. et sp. nov. is shown herein to be the oldest and arguably the most informative fossil of the gymnodont suborder Tetraodontoidei. The phylogenetic placement of this new taxon has been assessed based on both morphology alone and on a combination of morphological and molecular data that strongly supports the close relationship of †Balkaria gen. nov. to the herein restricted Tetraodontoidei. However, its position within Tetraodontoidei is unstable depending on the type of method of phylogenetic inference. Significantly younger ages, during the Late Cretaceous, are estimated for the diversification of Tetraodontiformes than in previous tip-dating analyses (Jurassic and Early Cretaceous) using the fossilized birth-death process; these new age estimates are in better agreement with the tetraodontiform fossil record. http://zoobank.org/urn:lsid:zoobank.org:pub:41764800-B0D8-4CA4-A111-5F4C4A281C37
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an evaluation of fossil tip dating versus node age calibrations in tetraodontiform fishes teleostei percomorphaceae
Molecular Phylogenetics and Evolution, 2015Co-Authors: Guillermo Ortí, James C Tyler, Dahiana Arcila, Alexander R Pyron, Ricardo BetancurrAbstract:Time-calibrated phylogenies based on molecular data provide a framework for comparative studies. Calibration methods to combine fossil information with molecular phylogenies are, however, under active development, often generating disagreement about the best way to incorporate paleontological data into these analyses. This study provides an empirical comparison of the most widely used approach based on node-dating priors for relaxed clocks implemented in the programs BEAST and MrBayes, with two recently proposed improvements: one using a new fossilized birth–death process model for node dating (implemented in the program DPPDiv), and the other using a total-evidence or tip-dating method (implemented in MrBayes and BEAST). These methods are applied herein to tetraodontiform fishes, a diverse group of living and extinct taxa that features one of the most extensive fossil records among teleosts. Previous estimates of time-calibrated phylogenies of tetraodontiforms using node-dating methods reported disparate estimates for their age of origin, ranging from the late Jurassic to the early Paleocene (ca. 150– 59 Ma). We analyzed a comprehensive dataset with 16 loci and 210 morphological characters, including 131 taxa (95 extant and 36 fossil species) representing all families of fossil and extant tetraodontiforms, under different molecular clock calibration approaches. Results from node-dating methods produced consistently younger ages than the tip-dating approaches. The older ages inferred by tip dating imply an unlikely early-late Jurassic (ca. 185–119 Ma) origin for this order and the existence of extended ghost lineages in their fossil record. Node-based methods, by contrast, produce time estimates that are more consistent with the stratigraphic record, suggesting a late Cretaceous (ca. 86–96 Ma) origin. We show that the precision of clade age estimates using tip dating increases with the number of fossils analyzed and with the proximity of fossil taxa to the node under assessment. This study suggests that current implementations of tip dating may overestimate ages of divergence in calibrated phylogenies. It also provides a comprehensive phylogenetic framework for tetraodontiform systematics and future comparative studies.
Mutsumi Nishida - One of the best experts on this subject based on the ideXlab platform.
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a new perspective on phylogeny and evolution of tetraodontiform fishes pisces acanthopterygii based on whole mitochondrial genome sequences basal ecological diversification
BMC Evolutionary Biology, 2008Co-Authors: Yusuke Yamanoue, Keiichi Matsuura, Masaki Miya, Masaya Katoh, Harumi Sakai, Mutsumi NishidaAbstract:The order Tetraodontiformes consists of approximately 429 species of fishes in nine families. Members of the order exhibit striking morphological diversity and radiated into various habitats such as freshwater, brackish and coastal waters, open seas, and deep waters along continental shelves and slopes. Despite extensive studies based on both morphology and molecules, there has been no clear resolution except for monophyly of each family and sister-group relationships of Diodontidae + Tetraodontidae and Balistidae + Monacanthidae. To address phylogenetic questions of tetraodontiform fishes, we used whole mitochondrial genome (mitogenome) sequences from 27 selected species (data for 11 species were newly determined during this study) that fully represent all families and subfamilies of Tetraodontiformes (except for Hollardinae of the Triacanthodidae). Partitioned maximum likelihood (ML) and Bayesian analyses were performed on two data sets comprising concatenated nucleotide sequences from 13 protein-coding genes (all positions included; third codon positions converted into purine [R] and pyrimidine [Y]), 22 transfer RNA and two ribosomal RNA genes (total positions = 15,084). The resultant tree topologies from the two data sets were congruent, with many internal branches showing high support values. The mitogenomic data strongly supported monophyly of all families and subfamilies (except the Tetraodontinae) and sister-group relationships of Balistidae + Monacanthidae and Tetraodontidae + Diodontidae, confirming the results of previous studies. However, we also found two unexpected basal splits into Tetraodontoidei (Triacanthidae + Balistidae + Monacanthidae + Tetraodontidae + Diodontidae + Molidae) and Triacanthodoidei (Ostraciidae + Triodontidae + Triacanthodidae). This basal split into the two clades has never been reported and challenges previously proposed hypotheses based on both morphology and nuclear gene sequences. It is likely that the basal split had involved ecological diversification, because most members of Tetraodontoidei exclusively occur in shallow waters (freshwater, brackish and coastal waters, and open seas), while those of Triacanthodoidei occur mainly in relatively deep waters along continental shelves and slopes except for more derived ostraciids. This suggests that the basal split between the two clades led to subsequent radiation into the two different habitats.
N. Alice Lee - One of the best experts on this subject based on the ideXlab platform.
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Quantitative analysis of species specificity of two anti-parvalbumin antibodies for detecting southern hemisphere fish species demonstrating strong phylogenetic association.
Food chemistry, 2017Co-Authors: Ji Liang, Chui Choo Tan, Steve L. Taylor, Joseph L. Baumert, Andreas L. Lopata, N. Alice LeeAbstract:This study aimed to develop a novel approach to determine the correlation between the parvalbumin (PAV) contents and their corresponding immunoreactivity (detectability) in southern hemisphere fish species. The immuno-detected PAV contents of the test fish species were estimated by a quantitative SDS-PAGE. A quantitative Enzyme-Linked ImmunoSorbent Assay (ELISA) was formatted to assess relative immunoreactivity of PAV. Sixteen species (forty-three percent) displayed a positive correlation with the anti-cod PAV polyclonal antibody, but no correlation with the anti-carp PAV monoclonal antibody. There was a strong phylogenetic association of the PAV immunoreactivity. Species from the order of Perciformes showed strong binding with both antibodies; whereas species from Salmoniformes, Ophidiiformes, Scombriformes, Scorpaeniformes, and Tetraodontiformes showed weak or no binding. This approach showed for the first time a statistical correlation between the PAV content and the immunoreactivity and allowed to rank the relative species/order specificity of the two antibodies for the southern hemisphere fish PAV.
Amanda Carvalho De Andrade - One of the best experts on this subject based on the ideXlab platform.
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Guildas de Tetraodontiformes (Teleostei, Acanthopterygii) em um complexo estuarino tropical
Universidade Federal de São Carlos, 2009Co-Authors: Amanda Carvalho De AndradeAbstract:A ictiofauna demersal da Baía de Guanabara foi amostrada quinzenalmente, durante dois anos, em dez pontos de coleta distribuídos ao longo de um gradiente hidrobiológico. Utilizou-se uma rede de arrasto com portas, a uma velocidade de 2 nós, durante 30 minutos, totalizando 240 horas de esforço de pesca entre julho de 2005 e junho de 2007. Coletou-se 16.081 espécimes de Tetraodontiformes, pertencentes a dez espécies das famílias Ostraciidae, Monacanthidae, Tetraodontidae e Diodontidae. O arrasto foi considerado um aparelho adequado para amostrar o grupo, apesar de subestimar a abundância de espécies associadas a substratos consolidados (Acanthostracion sp.) e áreas marginais (Sphoeroides spp.). Tetraodontiformes demonstram ser bem adaptados às variações hidrológicas e condições inóspitas decorrentes da intensa eutrofização. Entretanto, fatores abióticos tradicionalmente considerados importantes na estruturação da comunidade estuarina desempenham um papel secundário na regulação da distribuição dos Tetraodontiformes. O sedimento aparece como o fator físico mais importante, mas é apenas um indicador de domínios ecológicos. A baixa explicabilidade das variáveis físicoquímicas, aliada à relativa estabilidade da ictiofauna na baía, sugere a atuação de parâmetros biológicos. Os principais fatores biológicos relacionados com as variações sazonais da ictiocenose são a disponibilidade de itens alimentares, competição intra- e interespecífica, e os ciclos reprodutivos das espécies. Os Tetraodontiformes exibem uma larga variação de usos da Baía de Guanabara, utilizando-a como área de repouso, alimentação e crescimento. Entretanto, não foi possível estabelecer uma relação de dependência de nenhuma das espécies com o estuário, uma vez que os mesmos estratos populacionais ocorrem na região costeira do Sudeste-Sul. Dentre as dez espécies de Tetraodontiformes capturadas, oito foram categorizados como espécies marinhas estuarino-oportunistas, e duas como marine stragglers. A explosão populacional de C. spinosus indica um desequilíbrio ecológico e deve ser cuidadosamente investigada. Recomenda-se que estudos subsequentes abordem melhor a biologia populacional dessas espécies, e busquem elucidar as relações entre os estoques marinhos e estuarinos.The demersal ichthyofauna of Guanabara bay was sampled bimonthly, during two years, in ten stations distributed along a hydrobiological gradient. An otter trawl was employed, conducting 30 minute trawls, at a speed of 2 knots, summing up to 240 hours of fishing effort from July 2005 to June 2007. A total of 16,081 Tetraodontiformes specimens were collected, representing ten species divided among the families Ostraciidae, Monacanthidae, Tetraodontidae and Diodontidae. The otter trawl was considered an adequate technique to sample the group, although it may underestimate the abundances of species associated with hard bottoms (Acanthostracion sp.) and marginal areas (Sphoeroides spp.). Tetraodontiformes fishes appear to be well adapted to hydrological variations and to inhospitable conditions prompted by intense eutrophication. However, abiotic factors traditionally considered important in the structuring of estuarine communities play a secondary role in regulating the distribution of Tetraodontiformes. The type of sediment appears as the most important physical factor, but acts only as an indicator of ecological domain. The low explicability of physical-chemical variables, in addition to the relative stability of the bays ichthyofauna, suggests the influence of biological parameters. The main biological factors related with the ichthyocenosis seasonal variations are food items availability, intra- and interspecific competition and the species reproductive cycles. Tetraodontiformes exhibited a wide variation of uses in Guanabara bay, utilizing it as a resting, feeding and growing area. However, it was not possible to establish a relation of dependence upon the estuary for any of the species, because the same population strata occur the in coastal regions of South-Southeastern Brazil. Among the ten species of Tetraodontiformes captured, eight were categorized as marine estuarine opportunists and two as marine stragglers. Chilomycterus spinosus population boom indicated an ecological misbalance and must be carefully investigated. Subsequent studies should adopt a population approach of these species and attempt to elucidate the relationships between estuarine and marine stocks
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Guildas de Tetraodontiformes (Teleostei, Acanthopterygii) em um complexo estuarino tropical
Programa de Pós-graduação em Ecologia e Recursos Naturais, 2009Co-Authors: Amanda Carvalho De AndradeAbstract:The demersal ichthyofauna of Guanabara bay was sampled bimonthly, during two years, in ten stations distributed along a hydrobiological gradient. An otter trawl was employed, conducting 30 minute trawls, at a speed of 2 knots, summing up to 240 hours of fishing effort from July 2005 to June 2007. A total of 16,081 Tetraodontiformes specimens were collected, representing ten species divided among the families Ostraciidae, Monacanthidae, Tetraodontidae and Diodontidae. The otter trawl was considered an adequate technique to sample the group, although it may underestimate the abundances of species associated with hard bottoms (Acanthostracion sp.) and marginal areas (Sphoeroides spp.). Tetraodontiformes fishes appear to be well adapted to hydrological variations and to inhospitable conditions prompted by intense eutrophication. However, abiotic factors traditionally considered important in the structuring of estuarine communities play a secondary role in regulating the distribution of Tetraodontiformes. The type of sediment appears as the most important physical factor, but acts only as an indicator of ecological domain. The low explicability of physical-chemical variables, in addition to the relative stability of the bay s ichthyofauna, suggests the influence of biological parameters. The main biological factors related with the ichthyocenosis seasonal variations are food items availability, intra- and interspecific competition and the species reproductive cycles. Tetraodontiformes exhibited a wide variation of uses in Guanabara bay, utilizing it as a resting, feeding and growing area. However, it was not possible to establish a relation of dependence upon the estuary for any of the species, because the same population strata occur the in coastal regions of South-Southeastern Brazil. Among the ten species of Tetraodontiformes captured, eight were categorized as marine estuarine opportunists and two as marine stragglers. Chilomycterus spinosus population boom indicated an ecological misbalance and must be carefully investigated. Subsequent studies should adopt a population approach of these species and attempt to elucidate the relationships between estuarine and marine stocks.Financiadora de Estudos e ProjetosA ictiofauna demersal da Baía de Guanabara foi amostrada quinzenalmente, durante dois anos, em dez pontos de coleta distribuídos ao longo de um gradiente hidrobiológico. Utilizou-se uma rede de arrasto com portas, a uma velocidade de 2 nós, durante 30 minutos, totalizando 240 horas de esforço de pesca entre julho de 2005 e junho de 2007. Coletou-se 16.081 espécimes de Tetraodontiformes, pertencentes a dez espécies das famílias Ostraciidae, Monacanthidae, Tetraodontidae e Diodontidae. O arrasto foi considerado um aparelho adequado para amostrar o grupo, apesar de subestimar a abundância de espécies associadas a substratos consolidados (Acanthostracion sp.) e áreas marginais (Sphoeroides spp.). Tetraodontiformes demonstram ser bem adaptados às variações hidrológicas e condições inóspitas decorrentes da intensa eutrofização. Entretanto, fatores abióticos tradicionalmente considerados importantes na estruturação da comunidade estuarina desempenham um papel secundário na regulação da distribuição dos Tetraodontiformes. O sedimento aparece como o fator físico mais importante, mas é apenas um indicador de domínios ecológicos. A baixa explicabilidade das variáveis físicoquímicas, aliada à relativa estabilidade da ictiofauna na baía, sugere a atuação de parâmetros biológicos. Os principais fatores biológicos relacionados com as variações sazonais da ictiocenose são a disponibilidade de itens alimentares, competição intra- e interespecífica, e os ciclos reprodutivos das espécies. Os Tetraodontiformes exibem uma larga variação de usos da Baía de Guanabara, utilizando-a como área de repouso, alimentação e crescimento. Entretanto, não foi possível estabelecer uma relação de dependência de nenhuma das espécies com o estuário, uma vez que os mesmos estratos populacionais ocorrem na região costeira do Sudeste-Sul. Dentre as dez espécies de Tetraodontiformes capturadas, oito foram categorizados como espécies marinhas estuarino-oportunistas, e duas como marine stragglers. A explosão populacional de C. spinosus indica um desequilíbrio ecológico e deve ser cuidadosamente investigada. Recomenda-se que estudos subsequentes abordem melhor a biologia populacional dessas espécies, e busquem elucidar as relações entre os estoques marinhos e estuarinos
