Food partitioning between species is a common strategy for avoiding resource competition which allows the coexistence of two or more species in the same place. In order to evaluate the feeding of four species of batoids regularly caught by artisanal fisheries in southern Brazil, the present study aimed to analyse and compare the diet of the four batoid species. The Chola guitarfish, Rhinobatos percellens, had a specialized diet, consisting predominantly of blue crabs Callinectes sp., followed by teleost fish. The Lesser guitarfish Zapteryx brevirostris also had a very specialized diet, consuming mainly on Polychaeta, followed by Caridea shrimp. The Cownose ray, Rhinoptera bonasus, fed mainly on Ophiuroidea, followed by Gastropoda and Bivalvia. Finally, the Rio skate Rioraja agassizi, fed on teleost fish, Gammaridae, Caridea shrimp and Dendrobranchiata shrimp. An analysis of similarity showed significant differences among species in their diet. The trophic levels of the batoids in this study are ,4.0, placing them in intermediate trophic levels. The analysis of the diets indicates that feeding differs substantially among the four species, suggesting a partitioning of food resources available in the environment.
Age and growth studies are fundamental to successful fisheries management. Zapteryx brevirostris (Müller & Henle, 1841) is distributed off the Brazilian continental shelf and this species is assessed as “Vulnerable” in the Red List of the International Union for the Conservation of Nature (IUCN). Thus, the objective of this study was to present previously unknown information about the age and growth of Z. brevirostris that can be used for its management, conservation, and fisheries. A total of 162 specimens were sampled, with total lengths (TL) varying between 35.7 cm and 56 cm. The vertebrae were embedded in resin, sectioned in cuts with 0.5 mm thickness and the growth bands of the vertebrae were read under a light microscope. In the studied area, Z. brevirostris ages were estimated from 4 to 10 years according to vertebrae patterns. The species reaches its maximum asymptotic size (Linf) around 56 cm (56 cm for females and 50.37 cm for males). This is the first estimate of age and growth for a species of the Zapteryx genus, and the results support the hypothesis that this ray requires future management conservation, particularly due to its slow growth rate and consequent susceptibility to overexploitation.
The chola guitarfish, Rhinobatos percellens, is one of the most-captured batoids on the Brazilian coast, and an important predator of benthic community. Stomachs from R. percellens were sampled in the Paranaguá estuarine complex (March/2006 to March/2007 and October/2008 to September/2009). The stomachs obtained were used for describing the diet of R. percellens, and verifying if there are seasonal and ontogenetic differences in their feeding into the estuarine area. The general analysis showed a specialized diet with a predominance of three species in food contents: Leptochela serratorbita, Caridea remains and Ogyrides alphaerostris. Ontogenetic and seasonal analysis did not reveal significant differences in the food consumption. These data reveal that R. percellens is a specialist predator of L. serratorbita, and this food component is consumed by all size classes.
ResumoEfeito do tamanho corporal na dieta de Rivulus haraldsiolii (Aplocheiloidei: Rivulidae) em um riacho litorâneo insular de Floresta Atlântica, sul do Brasil. Foi investigado o efeito do tamanho corporal no hábito alimentar de exemplares de Rivulus haraldsiolii coletados em um riacho litorâneo insular de Floresta Atlântica. Amostragens foram realizadas durante uma fase de campo realizada em 13 de julho de 2009, em um riacho de água salobra localizado na porção nordeste da Ilha do Mel, localizada em região meridional de distribuição da Floresta Atlântica no sul do Brasil. A dieta da espécie incluiu insetos imaturos aquáticos (pupas de Diptera e larvas de Chironomidae), insetos aquáticos (Hemiptera -Vellidae), microcrustáceos (Cladocera), ácaros aquáticos (Acarina), gastrópodes (Pomacea sp.), insetos terrestres (Coleoptera, Formicidae e Isoptera), fragmentos de insetos e de plantas. A espécie apresentou hábito onívoro, e diferenças na dieta foram relacionadas com as variações no tamanho corporal. Adultos (indivíduos maiores) alimentaram-se principalmente de Formicidae, fragmentos de plantas e ácaros aquáticos, enquanto que jovens (indivíduos menores) alimentaram-se basicamente de larvas aquáticas de insetos (Chironomidae) e ácaros aquáticos.Unitermos: ecologia alimentar, peixe-anual, peixes de água doce, região neotropical AbstractThe effect of body size on the feeding habits of the little-known killifi sh Rivulus haraldsiolii, collected in a coastal Atlantic Rainforest island stream, was investigated. Samples were collected during a study trip on Biotemas, 23 (4): 59-64, dezembro de 2010
ResumoEste trabalho teve como objetivo fazer um levantamento da fauna de vertebrados do campus da Universidade Estadual de Londrina (UEL), pela compilação da literatura, com vistas a auxiliar o seu manejo e preservação. Foram registradas 250 espécies, sendo nove de peixes, 15 de anfíbios, 16 de répteis, 32 de mamíferos e 178 de aves. Duas espécies, o gato-do-mato Leopardus tigrinus e a jandaia-de-testa-vermelha Aratinga auricapillus figuram em listas de fauna ameaçada de extinção. A maioria das espécies, no entanto, não é estenóica ou endêmica da área, o que condiz com um ambiente perturbado e muito freqüentado pela população humana. O assoreamento do ribeirão Esperança, a redução de áreas verdes e a impermeabilização do solo podem reduzir a diversidade de espécies em médio a longo prazos. Palavras-chave: Actinopterygii. Aves. Biodiversidade. Lissamphibia. Mammalia. Reptilia. AbstractThis work had the objective to make a survey of vertebrates' fauna from Universidade Estadual de Londrina (UEL) campus, for the compilation of literature, in order to help its management and preservation. 250 species were identified, being nine of fish, 15 of amphibians, 16 of reptiles, 32 of mammals and 178 of birds. Two species, the gato-do-mato Leopardus tigrinus and the jandaia-da-testavermelha Aratinga auricapillus, are in the list of species threatened by extinction. Most species, however, are not stenoecious or endemic to the area, which corresponds to an environment under stress and often visited by humans. Despite UEL's rich diversity of wild animals, the burying of stream Esperança, the reduction of green areas and waterproofing of the ground can reduce de diversity of species in a medium or long term.
This is the first report of morphological anomaly in embryos of Zapteryx brevirostris (Lesser guitarfish), a very common species in Brazil. The gills were absent, and the pectoral fins were not fully formed nor were they completely fused to the head. They were asymmetrical, with the larger left pectoral fin projecting more toward the head (almost at the height of the eyes). The pelvic fin was absent, making sexing impossible. The cause of the morphological deformity is uncertain, although a nutritional problem of the embryo is evoked. Este é o primeiro relato de anomalias morfológicas em embriões de Zapteryx brevirostris, espécie comum no Brasil. As brânquias estiveram ausentes, e as nadadeiras peitorais mostraram-se assimétri-cas e não totalmente formadas e fundidas à cabeça. A nadadeira esquerda, a maior, se projetou destacadamente em direção à cabeça, quase alcançando a altura dos olhos. A nadadeira pélvica esteve ausente, não foi possível a determinação do sexo do animal. A causa da deformidade morfológica é incerta, mas sugere-se que possa estar relacionada a problema nutricional durante o desenvolvimento do embrião. AbstrAct
ResumoTrichogaster leeri é considerado um peixe pacífico e muito utilizado em aquarismo pela beleza de suas cores. O presente estudo teve como objetivos avaliar a ocupação da coluna da água por machos adultos quando mantidos com outros machos da mesma espécie. Foram utilizados três aquários com as dimensões de 35 cm de comprimento, 22 cm de altura e 16 cm de largura, com substrato de cascalho e vegetação artificial. O vidro frontal foi dividido em 12 quadrantes, ordenados da esquerda para a direita e de cima para baixo. Três exemplares de aproximadamente 8 cm de comprimento total foram utilizados para observação das freqüências de ocorrência nos quadrantes, nas seguintes situações: isolados, agrupados em duplas e os três juntos. Os dados foram analisados pelo teste χ 2, ao nível de significância de 5%. Foi observado que, quando associados em um mesmo aquário, os indivíduos ocupam uma determinada posição na coluna da água. Isso significa que, apesar do comportamento aparentemente pacífico, os machos se evitam ocupando distintas posições espaciais. Palavras-chave: Aquário. Comportamento. Dominância. Peixe. AbstractTrichogaster leeri is considered a peaceful fish and widely used in aquariums for the beauty of its colors. This study aimed to evaluate the occupation of water column by adult males when kept with other males of the same species. Three 35 cm-long, 22 cm-high and 16 cm-wide aquariums were used, with grave as substrate and artificial vegetation. The front glass was divided in 12 quarters, arranged from left to right and from top to bottom. Three 8 cm-long specimens were used to observe the frequency of occurrence in the quarters in the following situations: isolated, grouped in pairs and all of them together. The data were analyzed by χ² test, at significance level of 5%. It was observed that, when the individuals are together in the same aquarium, they occupy a position in the water column. It means that, in spite of the apparently pacific behavior, the males avoid each other occupying distinct spatial positions.
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