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Feeding dynamics and ecomorphology of Oligosarcus jenynsii (Gunther, 1864) and Oligosarcus robustus (Menezes, 1969) in the Lagoa Fortaleza, southern Brazil
Nunes, D. M.;Hartz, S. M.;
Brazilian Journal of Biology , 2006, DOI: 10.1590/S1519-69842006000100016
Abstract: oligosarcus jenynsii and oligosarcus robustus are fishes of characidae family that occur in rio grande do sul, uruguay and northern argentina. this work purported to study the feeding dynamics (repletion and hepatosomatic indexes and condition factor) over time, and to investigate the coexistence of these two species by evaluating the partition of resources using qualitative and quantitative analyses of diet, temporal and spatial segregation throughout the water column and some ecomorphological aspects of the species in the lagoa fortaleza. specimens were sampled monthly, from may 2000 to april 2001 during 24 h/month, using stationary gill nets of different mesh sizes. the records of each individual included total and standard length; total, stomach and liver weight; sex and stomach repletion. the variation of the mean values of repletion index and relative frequencies of stomach repletion stages indicate that o. jenynsii and o. robustus do not present seasonal differences in feeding intensity. the hepatosomatic index shows an allocation of energy to the liver during every period except reproduction, when part of the energy is used for gonad maturation. the estimated condition factor for both species reveals an increase in the reproductive period, evidencing the influence of gonads upon the condition of the fish. the diet analysis revealed that o. robustus is piscivorous, whereas o. jenynsii is a generalist carnivore, tending to piscivory as well. the active period of o. robustus is more concentrated at sunrise and sunset, whereas o. jenynsii is continually active, a characteristic related to hunting for prey. the ecomorphological analysis revealed differences between the two species in the dimensions of the mouth. evidence suggests that the species coexist, sharing food sources, differing in oral morphology but ingesting similar prey, possibly because food is not a limiting factor in the environment.
Dinamica reprodutiva de Oligosarcus jenynsii e O. robustus (Characiformes, Characidae) na lagoa Fortaleza, Rio Grande do Sul, Brasil
Nunes, Daniela M.;Pellanda, Mateus;Hartz, Sandra Maria;
Iheringia. Série Zoologia , 2004, DOI: 10.1590/S0073-47212004000100001
Abstract: oligosarcus jenynsii (günther, 1864) and o. robustus menezes, 1969 are fish species distributed in rio grande do sul, brazil, uruguay, and northern argentina. the reproductive period and recruitment, sex ratio, absolute and relative fecundity, and body length at first gonadal maturation of the two carnivorous species from fortaleza lagoon were analized. the specimens were sampled monthly, from may 2000 to april 2001, with fishing effort of 24 hours/month, using stationary gillnets of different mesh sizes and seine net (three samples per edge). the records of each individual included total length, total weight, gonad weight, sex and gonadal maturity stage. the reproductive period of both o. jenynsii and o. robustus ranges from may/june to november/december, according to the bimonthly variation of the mean values of gonosomatic index, and the relative frequencies of the gonadal maturation stages. recruitment of new individuals to the population occurs from november/december to march/april. the sex ratio is different from 1:1 for o. jenynsii and similar to 1:1 for o. robustus. the mean absolute fecundity, calculated by counting sub-sampled oocytes from mature females, was 14,483 oocytes for o. jenynsii, and 16,308 oocytes for o. robustus. the first maturation curve shows that o. jenynsii begins to reproduce between 84 mm and 104 mm (total length), and o. robustus between 126 mm and 146 mm, probably at similar ages.
Pleistocene karyotypic divergence in Hoplias malabaricus (Bloch, 1794) (Teleostei: Erythrinidae) populations in southeastern Brazil
Jacobina, Uedson Pereira;Paiva, Edson;Dergam, Jorge Abdala;
Neotropical Ichthyology , 2011, DOI: 10.1590/S1679-62252011005000023
Abstract: the lacustrine system of the middle rio doce basin is considered a paradigm of pleistocene geomorphology. in these lakes, two hoplias malabaricus karyomorphs (2n = 42a and 2n = 42b) live in sintopy in carioca lake. cytogenetic analyses were performed on 65 specimens from 8 lakes (including carioca lake) to determine the distribution and relative frequency of these karyomorphs and the degree of cytogenetic divergence caused putatively by recent geographic isolation. all fish were 2n = 42b karyomorphs, except for 1 specimen from the marola lake, which was 2n = 42a. among-population variation was especially high for c-banding patterns. other characters such as x chromosome size and cma3/dapi also varied among populations. our results suggested that the karyotype of h. malabaricus is able to respond rapidly to geographic isolation, and revealed that heterochromatic variation may represent the lowest hierarchical level of chromosomal evolution.
Differential chromosomal markers between sympatric karyomorphs of the fish Hoplias malabaricus (Bloch, 1794) (Characiformes: Erythrinidae)  [cached]
Renata Rosa,Marceléia Rubert,L. Giuliano-Caetano,I Martins-Santos
Comparative Cytogenetics , 2010, DOI: 10.3897/compcytogen.v4i2.48
Abstract: Cytogenetic analyses were performed on Hoplias malabaricus (Bloch, 1794) from the Taquari River, Parana River drainage, revealing two sympatric karyomorphs. One karyomorph was characterized by 2n = 40 m/sm and 2n = 39 m/sm chromosomes for females and males, respectively, and an X1X1X2X2/X1X2Y sex chromosome system. In the second karyomorph, specimens showed 2n = 42 m/sm chromosomes, without sex-related heteromorphism. Both karyomorphs were characterized by a distribution of heterochromatin in the pericentromeric and telomeric regions. In addition to the differences in the diploid numbers and the sex chromosomes, the GC-rich sites and the nucleolar organizer regions also showed clear differences between the karyomorphs. Coupled with the occurrence of unique chromosomal features within each karyomorph, the fact that hybrids have not been identified in the sampled population provides additional support of the existence of a species complex in H. malabaricus.
Acute intraperitoneal mercury chloride contamination and distribution in liver, muscle and gill of a neotropical fish Hoplias malabaricus (BLOCK, 1794)
Jesus, Taise Bomfim de;Almeida, Priscila Gontijo Aguiar de;Vergílio, Cristiane dos Santos;Machado, André Luiz dos Santos;Carvalho, Carlos Eduardo Veiga de;
Brazilian Archives of Biology and Technology , 2011, DOI: 10.1590/S1516-89132011000200021
Abstract: the present study investigated with the distribution of mercury chloride in muscle, liver and gills of hoplias malabaricus contaminated through intraperitoneal injection (6 μg in 0.1ml of pbs) for a period of 24, 48, 72 and 96h. the liver, gill and muscle were analyzed for mercury content in an icp/aes (varian liberty ii) with vapor generating accessory (vga 77). the muscle and liver tissues presented the same contamination pattern increasing concentrations in 24 h of exposure with a decrease in hg concentration with 72 h and a new increase in hg concentrations with 96 h of exposure. the hg concentrations in contaminated organisms were always higher than the control although only for liver samples the difference was statistically significant. liver samples always presented higher hg contents when compared with gill and muscle samples.
Pleistocene karyotypic divergence in Hoplias malabaricus (Bloch, 1794) (Teleostei: Erythrinidae) populations in southeastern Brazil  [cached]
Uedson Pereira Jacobina,Edson Paiva,Jorge Abdala Dergam
Neotropical Ichthyology , 2011,
Abstract: The lacustrine system of the middle rio Doce basin is considered a paradigm of Pleistocene geomorphology. In these lakes, two Hoplias malabaricus karyomorphs (2n = 42A and 2n = 42B) live in sintopy in Carioca Lake. Cytogenetic analyses were performed on 65 specimens from 8 lakes (including Carioca Lake) to determine the distribution and relative frequency of these karyomorphs and the degree of cytogenetic divergence caused putatively by recent geographic isolation. All fish were 2n = 42B karyomorphs, except for 1 specimen from the Marola Lake, which was 2n = 42A. Among-population variation was especially high for C-banding patterns. Other characters such as X chromosome size and CMA3/DAPI also varied among populations. Our results suggested that the karyotype of H. malabaricus is able to respond rapidly to geographic isolation, and revealed that heterochromatic variation may represent the lowest hierarchical level of chromosomal evolution. O sistema lacustre da bacia do médio rio Doce é considerado um paradigma da geomorfologia do Pleistoceno. Nestes lagos, dois cariomorfos de Hoplias malabaricus (2n = 42A e 2n = 42B) vivem em sintopia na lagoa Carioca. Análises citogenéticas foram realizadas em 65 amostras de 8 lagos (incluindo lagoa Carioca) para determinar a distribui o e frequência relativa destes cariomorfos e o grau de divergência citogenética aparentemente causada pelo isolamento geográfico recente. Todos os peixes apresentaram o cariomorfo 2n = 42B, com exce o de 1 espécime da lagoa Marola, que foi 2n = 42A. Entre as popula es, a varia o foi especialmente elevada nos padr es de bandamento C. Outros caracteres como o tamanho do cromossomo X e os padr es de CMA3/DAPI também variaram entre as popula es. Nossos resultados sugerem que o genoma de H. malabaricus é capaz de responder rapidamente ao isolamento geográfico, revelando que a varia o de heterocromatina pode representar o nível hierárquico mais baixo de evolu o cromoss mica.
Biology of growth of Hoplias aff. malabaricus (Bloch, 1794) in a shallow pampean lake (Argentina)
Balboni, Leandro;Colautti, Dario César;Baigún, Claudio Rafael Mariano;
Neotropical Ichthyology , 2011, DOI: 10.1590/S1679-62252011000200022
Abstract: the trahira hoplias aff. malabaricus is a top predator in pampean shallow lakes and is highly appreciated by recreational anglers and artisanal fishermen. trahira growth from yalca shallow lake was determined by lepidological analysis and age validated by marginal increment. when growth was fitted to the von bertalanffy model, annual classes exhibited a bimodal pattern as a result of the presence of spring and summer annual cohorts associated with a three month spawning season, each period in turn showing different growth patterns. the trahira population-age structure at yalca shallow lake showed a truncated profile with very low numbers of large adults and few individuals older than three to four years, thus producing an unbalanced length-structure population. growth parameters and growth performance were similar to the corresponding parameters estimated for other shallow pampean lakes of the region, but strongly diverged from the data for those populations inhabiting subtropical and tropical environments. such differences could be accounted for by dissimilarity in metabolic rates associated with thermal differences accompanying seasonal variability among latitudes as well as by the development of adaptive physiologic and demographic responses to cope with the high thermal amplitude and hydrologic instability observed in pampean lakes.
Reproductive dynamics and population structure of Hoplias aff. malabaricus (Bloch, 1794) (Characiformes, Erythrinidae) in the dam lake of the Taperoá River Basin, Paraíba
Márcio Fraz?o Chaves,Jane Torelli,Carlos Henrique Targino,Maria Cristina Crispim
Biotemas , 2009,
Abstract: This work aims to verify the reproductive dynamics and growth of the Hoplias aff. malabaricus species in the Taperoá II dam lake (07o11’44”S, 07o13’44”S), located in the basin of the River Taperoá in the Cariri region of Paraiba. Sixty-seven individuals were collected (August-December 2002, January-February, May and June 2003) by means of gillnets and cast nets. The interference of the rain regimen in the reproductive behavior and the structure of growth of the species were observed after the macrocospic analysis of the gonads of the collected units.
Phylogeography and RAPD-PCR variation in Hoplias malabaricus (Bloch, 1794) (Pisces, Teleostei) in southeastern Brazil
Dergam, Jorge A.;Paiva, Samuel R.;Schaeffer, Carlos E.;Godinho, Alexandre L.;Vieira, Fabio;
Genetics and Molecular Biology , 2002, DOI: 10.1590/S1415-47572002000400005
Abstract: in the rio doce basin of southeastern brazil, the freshwater fish hoplias malabaricus (trahira) is a widespread predatory characin and one of the few resilient native fishes in a highly impacted lake system. in order to test for genetic differentiation in populations within this basin and for biogeographic relationships among populations of this species in other basins, a study was conducted using rapd-pcr analysis of rio doce samples (n = 63) and phylogeographic analyses with mitochondrial dna (mtdna) haplotypes, including the rio grande and macacu river basins. in the rio doce basin, the patterns of genetic similarity of rapd-pcr markers (individual fingerprinting and nei?s genetic distance) suggest the existence of two genetically different groups, one composed of the lacustrine populations carioca and dom helvécio, and the other of riverine and the remaining lacustrine populations. the differences in the rapd-pcr patterns may be explained by the existence of sub-basins within this lacustrine system. a maximum parsimony tree of cytochrome b fragment (383 base pairs) supports the view that trahiras of the rio doce share a complex biogeographic history with those of neighboring basins. the phylogeographic patterns may be explained by a common history of the watersheds of the rio doce, paraíba do sul, and rio grande basins, corroborating the hypothesis of a plio-pleistocene separation of these drainage systems, forming the mantiqueira "divortium aquarium".
Phylogeography and RAPD-PCR variation in Hoplias malabaricus (Bloch, 1794) (Pisces, Teleostei) in southeastern Brazil  [cached]
Dergam Jorge A.,Paiva Samuel R.,Schaeffer Carlos E.,Godinho Alexandre L.
Genetics and Molecular Biology , 2002,
Abstract: In the Rio Doce basin of southeastern Brazil, the freshwater fish Hoplias malabaricus (trahira) is a widespread predatory characin and one of the few resilient native fishes in a highly impacted lake system. In order to test for genetic differentiation in populations within this basin and for biogeographic relationships among populations of this species in other basins, a study was conducted using RAPD-PCR analysis of Rio Doce samples (N = 63) and phylogeographic analyses with mitochondrial DNA (mtDNA) haplotypes, including the Rio Grande and Macacu river basins. In the Rio Doce basin, the patterns of genetic similarity of RAPD-PCR markers (individual fingerprinting and Nei?s genetic distance) suggest the existence of two genetically different groups, one composed of the lacustrine populations Carioca and Dom Helvécio, and the other of riverine and the remaining lacustrine populations. The differences in the RAPD-PCR patterns may be explained by the existence of sub-basins within this lacustrine system. A maximum parsimony tree of cytochrome b fragment (383 base pairs) supports the view that trahiras of the Rio Doce share a complex biogeographic history with those of neighboring basins. The phylogeographic patterns may be explained by a common history of the watersheds of the Rio Doce, Paraíba do Sul, and Rio Grande basins, corroborating the hypothesis of a Plio-Pleistocene separation of these drainage systems, forming the Mantiqueira "divortium aquarium".
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