Ontogenetic variations and feeding habits of a Neotropical annual fish from southern Brazil.

Tatiana S. Dias, Ricardo J. Stein & Clarice B. Fialhoresearchgate logo

ABSTRACT. Knowing the feeding biology of a population and its ontogenetic aspects can help in understanding the functioning of fi sh assemblages, essential to the conservation of the habitat biodiversity in which these species are found. Annual fi shes complete their life cycle in temporary aquatic environments, existing in adult stage only for brief annual periods. Changes in the feeding habits between different size classes could indicate that a species belongs to diff erent feeding groups in diff erent growth phases. The aim of this work was to characterize the diet of Cynopoecilus fulgens Costa, 2002 in a temporary flooded area in the coastal plain of southern Brazil, taking into consideration possible alterations in feeding habits in different body size classes caused by ontogenetic changes, to explain the coexistence of these individuals in a short space of time. The diet analysis indicated that C. fulgens is a generalist, consuming small crustaceans and autochthonous insects. Intraspecific differences in diet were determined when compared between nine classes of standard length. Adults fed mainly on autochthonous insects, and juveniles ingested mostly crustaceans, with the population being separated into two trophic groups: invertivores and invertivores with a tendency towards zooplanktivory. It is possible to conclude that the ontogenetic changes in the diet of C. fulgens are related to morphological restrictions due to the size of the individuals, since feeding competitive relations are probably not so evident.

link: http://www.scielo.br/pdf/isz/v107/1678-4766-isz-107-e2017020.pdf

Fig. 2. General view of the sampling points of Cynopoecilus fulgens Costa, 2002 in a temporary flooded area in the coastal plain of State of Rio Grandedo Sul, Brazil

Fig. 4. Costello graphics showing the proportion of food items found in the diet of nine standard length classes of Cynopoecilus fulgens Costa, 2002 in a temporary flooded area in the coastal plain of State of Rio Grande do Sul, Brazil.


Length-weight relationships of four freshwater fish species from the coastal drainage system in Peru

D. Faustino-Fusterresearchgate logo, J. Chuctaya researchgate logo, R. Quispe and J. Espino

The morphometric relationships of three native and one exotic freshwater fish species from the Lower San Juan and Lower Pisco River basins, central Coast of Peru, are presented. Specimens were collected in May and November 2010 using seine nets and electrofishing. Length-Weight (LWR) relationships for Andinoacara stalsbergi, Trichomycterus punctulatus, Basilichthys archaeus and Poecilia reticulata are provided for the first time, contributing information towards the effort to conserve freshwater fishes.

Artigo: http://onlinelibrary.wiley.com/doi/10.1111/jai.13458/full

TABLE 1 Descriptive statistics and estimated parameters of the length weight relationships for four small freshwater fish species from Pisco and San Juan River, Peru. N = sample size; SL = standard length (cm); W = weight (g); Min = minimum; Max = maximum; CL = confidence limits; r2 = Pearson coefficient

Genomic signatures of paleodrainages in a freshwater fish along the southeastern coast of Brazil: genetic structure reflects past riverine properties.

A T Thomaz researchgate logo L R Malabarba researchgate logo and L L Knowles.

Past shifts in connectivity in riverine environments (for example, sea-level changes) and the properties of current drainages can act as drivers of genetic structure and demographic processes in riverine population of fishes. However, it is unclear whether the same river properties that structure variation on recent timescales will also leave similar genomic signatures that reflect paleodrainage properties. By characterizing genetic structure in a freshwater fish species (Hollandichthys multifasciatus) from a system of basins along the Atlantic coast of Brazil we test for the effects of paleodrainages caused by sea-level changes during the Pleistocene. Given that the paleodrainage properties differ along the Brazilian coast, we also evaluate whether estimated genetic diversity within paleodrainages can be explained by past riverine properties (i.e., area and number of rivers in a paleodrainage). Our results demonstrate that genetic structure between populations is not just highly concordant with paleodrainages, but that differences in the genetic diversity among paleodrainages correspond to the joint effect of differences in the area encompassed by, and the number of rivers, within a paleodrainage. Our findings extend the influence of current riverine properties on genetic diversity to those associated with past paleodrainage properties. We discuss how these findings may explain the inconsistent support for paleodrainages in structuring divergence from different global regions and the importance of taking into account past conditions for understanding the high species diversity of freshwater fish that we currently observe in the world, and especially in the Neotropics.

Artigo: http://www.nature.com/hdy/journal/vaop/ncurrent/full/hdy201746a.html?foxtrotcallback=true

Figure 1 Map of the 11 studied paleodrainages that formed during sea-level retreats of the LGM along the southeastern coast of Brazil, with an image of H. multifasciatus (99.5 mm standard length). The paleodrainage area is shown in different colors and populations sampled for genomic analyses are marked by black dots. Note that one dot in paleodrainage 10 represents three populations on Florianópolis Island. The gray shaded area marks the exposed area during the sea-level retreat in the LGM. The gray dots identify populations excluded from analyses (see Materials and Methods for detail; also Thomaz et al., 2015). A full color version of this fi gure is available at the Heredity journal online.

Resource partitioning among syntopic Characidae corroborated by gut content and stable isotope analyses

Karine Orlandi Bonatoresearchgate logo , Edward D. Burress, Clarice B. Fialho researchgate logo, Jonathan W. Armbruster

We aim to test the hypothesis that an assemblage of characid fishes coexist by partitioning food resources. We calculated dietary niche overlap of four syntopic species of the Characidae using gut content analysis. Secondly, we used a carbon (13C) and nitrogen (15N) isotope Bayesian mixing model to estimate relative assimilation. All characids consumed large proportions of plant material and aquatic insects; however, Pianka’s index indicated low dietary overlap among species throughout most of the sampling period. The low degrees of dietary overlap were due to discrepancies in the relative consumption of Ephemeroptera and aquatic insect remains. Secondly, there was high correspondence between the gut content analyses and isotope mixing model estimates. Astyanax xiru and Bryconamericus iheringii were the only species that ingested and assimilated large fractions of aquatic plants and algae, respectively. Astyanax procerus consumed and assimilated large fractions of terrestrial invertebrates, whereas Bryconamericus sp. assimilated mainly aquatic invertebrates. Therefore, we demonstrate that the assimilated nutrients were consistent with the relative consumption of food items. These results are consistent with the hypothesis that this characid assemblage may coexist via resource partitioning.

Artigo: https://link.springer.com/article/10.1007/s10750-017-3314-0

Fig. 2 Bi-plot (mean ± SD) depicting the isotopic relationships among Astyanax procerus, Astyanax xiru, Bryconamericus iheringii, and Brycomamericus sp. and their potential prey items. Note that some items are shown that were not included in the mixing models (Table 3) because they are not prey items of the characids. For references to color, see the online version.

Fig. 3 Density plots depicting the relative isotopic contribution of prey items to Astyanax xiru (a), Astyanax procerus (b), Bryconamericus iheringii (c), and Bryconamericus sp. (d) as estimated by a SIAR Bayesian mixing model. Note that the yaxes are not standardized across panels. For references to color, see the online version

Intrapopulational variation in color pattern of Trichomycterus davisi (Haseman, 1911) (Siluriformes: Trichomycteridae) corroborated by morphometrics and molecular analysis

Raul Henrique Cardoso Nascimento, Wilson Frantine-Silva, Lenice Souza-Shibatta, Silvia Helena Sofia, Juliano Ferrerresearchgate logo, Oscar Akio Shibatta.

Color patterns of the body are commonly used to distinguish and identify species of Trichomycterus. Therefore, variation in color pattern in a population can cause doubt concerning species identification. With the purpose to test the hypothesis of high variation in color pattern of Trichomycterus davisi (Haseman, 1911), 118 specimens were collected in a stream of a private Ecological Park in southern Brazil, of which 88 were used in the morphological analysis and 30 for DNA barcoding analysis. Three phenotypic classes were determined analyzing the distribution, size and shape of dark brown spots and blotches. The results of morphometric analysis indicate a tendency of association of those pigmentation patterns with the standard length, evidencing ontogenetic variation of color pattern in the species. The results of K2P intraspecific genetic distance (<0.72%), haplotypes network and Bayesian phylogenetic tree corroborate the existence of only one species with a high variable color pattern.

Artigo: https://biotaxa.org/Zootaxa/article/view/zootaxa.4290.3.5

FIGURE 3. Color pattern variation in T. davisi of Ribeirão João Pinheiro, Telêmaco Borba, state of Paraná, Brazil. MZUEL 11776, Phenotype I (specimens A, 84.56 mm SL, and B, 43.91 mm SL), Phenotype II (specimens C, 68.24 mm SL, D, 49.28 mm SL and E, 73.56 mm SL) and Phenotype III (specimens F, 53.11 mm SL, and G, 34.83 mm SL). Scale bars represent 10 mm.



Living in the waterfalls: A new species of Trichomycterus (Siluriformes: Trichomycteridae) from Tabay stream, Misiones, Argentina

Guillermo Enrique Terán, Juliano Ferrerresearchgate logoMauricio Benitez, Felipe Alonso, Gastón Aguilera  & Juan Marcos Mirande.


A new species assigned to the genus Trichomycterus from the area of the waterfalls of Tabay stream, Paraná River basin, Misiones, Argentina, is described. Trichomycterus ytororo sp. nov. is distinguished from all other species in the genus by the presence of 31–35 dorsal procurrent caudal-fin rays and the combination of some external characters such as: coloration, number of pectoral–fin rays and pores of the laterosensory canals. The new taxon belongs to a presumably monophyletic group of species composed of TcrassicaudatusTigobi, and Tstawiarski based on the presence of 24 or more thickly ossified and rigid procurrent caudal-fin rays with a slender distal tip extending along the tips of at least ten neural spines.

Artigo completo: http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0179594


Fig 1. Trichomycterus ytororo, holotype, CI–FML 7240, 94.2 mm SL; Argentina, Misiones Province, Jardín América, Tabay stream, Paraná River basin.


Fig 4. Geographic distribution of the species assigned to the Trichomycterus stawiarski group: T. crassicaudatus (green symbols), T. igobi (white symbols), T. stawiarski (yellow symbols) and T. ytororo (red symbol). Stars represent the type localities. Some triangles symbols represent more than one collection locality. Numbers 1, 2, 3 indicate the Paraguay, Paraná and Iguazú Rivers, respectively.


Laboratório de Ictiologia da UFRGS participando do evento PORTAS ABERTAS.

Alunos de iniciação científica, mestrado, doutorado, Pós-doutorado e professores, participaram de um evento muito importante, que ocorre anualmente em nossa Universidade, que é o de abrir as portas do laboratório e mostrar à comunidade todas as pesquisas que o grupo vem fazendo durante sua vida acadêmica. Visitantes de diferentes idades, desde crianças até famílias inteiras e, principalmente, alunos do ensino médio que estão prestes a participar do Enem e vestibular, vieram até o laboratório  e mostraram todo o interesse em aprender um pouco mais sobre os peixes, passando por diferentes experiências.

Em um primeiro momento houve a apresentação dos integrantes do laboratório, que é formado por alunos de diferentes nacionalidades, seguido de uma explicação de como se faz uma correta coleta de peixes com diferentes metodologias como: rede de espera, rede de arrastro, puçá, tarrafa e pesca elétrica. Em continuação às coletas, foi mostrado também como se faz a  triagem e catalogação das espécies que são depositadas na coleção científica da UFRGS.   Posteriormente se mostrou as diferentes técnicas para estudar os peixes em trabalhos de taxonômica e evolução, desde como estudar a osteologia com a técnica de diafanização até os trabalhos utilizando DNA. Além disso, o grupo também mostrou como se fazem pesquisas relacionadas à biologia alimentar e reprodutiva de peixes que incluem, respectivamente, análises da dieta e definição do período reprodutivo utilizando técnicas de cortes histológicos. Foi chamada a atenção dos visitantes que todos esses resultados de pesquisas do laboratório são publicados em congressos, revistas científicas e relatórios, ficando, portanto, disponíveis à sociedade. E, para finalizar foi enfatizada a importância que essas pesquisas apresentam, uma vez que aportam um melhor e maior conhecimento de nossa biodiversidade e nos capacitam a propor medidas de manejo e conservação dos mais variados tipos de ambientes aquáticos.


A new predatory herring-like fish (Teleostei: Clupeiformes) from the early Cretaceous of Brazil, and implications for relationships in the Clupeoidei


Cynoclupea nelsoni gen. et sp. nov., is described from Lower Cretaceous (Barremian-Aptian) sediments of the Morro do Chaves Formation in north-eastern Brazil. Diagnostic characters of the Clupeomorpha, such as abdominal and dorsal scutes, a pre-epiotic fossa, and an otophysic connection, were identified in C. nelsoni. The presence of the recessus lateralis furthermore indicates that the species is a member of the Clupeiformes. Given the absence of odontodes covering the skull bones, which are synapomorphic to the Denticipitoidei, and the apparent presence of a postorbital branch of the supraorbital sensory canal located deep within the body of the lateral wing of the frontal, C. nelsoni is assigned to the suborder Clupeoidei. In this suborder, derived character states of the suspensorium indicate that Cynoclupea is the sister group of a clade composed of the Chirocentridae (wolf-herrings) and Engraulidae (anchovies). The evolution of abdominal scutes and of microphagy vs. macrophagy in the Clupeoidei are discussed in light of this hypothesis. The discovery of Cynoclupea supports not only the existence of a diversified freshwater clupeiform fauna as early as in the Barremian-Aptian, but also indicates that the divergence between the Clupeoidei and Denticipitoidei must have occurred before this interval.Artigo completo: https://academic.oup.com/zoolinnean/article/180/1/175/3799580

Figure 2. Cynoclupea nelsoni gen. et sp. nov., MCP3447-PV (holotype), part (A) and counterpart (B). Scale bars = 1 cm.