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Caraguatatuba, Brazil

Denadai M.R.,Centro Universitario Modulo | Santos F.B.,State University of Southwest Bahia | Bessa E.,Mato Grosso State University | Fernandez W.S.,University of Sao Paulo | And 2 more authors.
Pan-American Journal of Aquatic Sciences

This study examined the feeding habits of Eucinostomus argenteus and Diapterus rhombeus in Caraguatatuba Bay, through analysis of stomach contents, collected monthly between May 2003 and October 2004 with trawls in two areas. The fish were measured and the diet was identified and quantified. For E. argenteus, the total length ranged from 55 to 115 mm, and for D. rhombeus from 75 to 197 mm; all individuals of both species were sexually immature. E. argenteus consumed polychaetes and crustaceans. D. rhombeus had a more diverse diet, mainly polychaetes, crustaceans, amphipods, and shrimp. The DTL/SL ratio calculated for E. argenteus was 0.80 and for D. rhombeus, 1.12; therefore, the former species is classified as a carnivore and the latter as an omnivore, but with a relatively high overlap between them. Large amounts of organic material and detritus in the digestive contents of both species were associated with accidental ingestion, due to their benthivorous habit. Trematodes and nematodes found in the intestine of D. rhombeus were considered to be parasites. Source

Da Costa M.R.,Centro Universitario Modulo | Da Costa M.R.,Federal Rural University of Rio de Janeiro | Moreti T.,Federal Rural University of Rio de Janeiro | Araujo F.G.,Federal Rural University of Rio de Janeiro
Journal of Applied Ichthyology

The present work reports the length-weight relationships (LWR) for 20 fish species from the Guandu River basin, Southeastern, Brazil, a lotic system that supplies most of the water for Rio de Janeiro Municipality and nearby cities. Length-weight relationships for nine of these species were unknown to Fishbase, and new maximum lengths are given for eight of the species. © 2013 Blackwell Verlag GmbH. Source

da Costa M.R.,Centro Universitario Modulo | da Costa M.R.,Federal Rural University of Rio de Janeiro | Pereira H.H.,Federal Rural University of Rio de Janeiro | Neves L.M.,Federal Rural University of Rio de Janeiro | Araujo F.G.,Federal Rural University of Rio de Janeiro
Journal of Applied Ichthyology

Length-weight relationships of 23 fish species from the Guaratiba mangrove area in southeastern Brazil were estimated. The value of the parameter b ranged from 2.63 to 3.39 (median = 2.97). This study presents the first estimation of LWR for two species (Ctenogobius stomatus and Ctenogobius boleosoma). New maximum length records were obtained for two species (Poecilla vivipara and Ctenogobius stomatus). © 2013 Blackwell Verlag GmbH. Source

Pombo M.,University of Sao Paulo | Denadai M.R.,Centro Universitario Modulo | Turra A.,University of Sao Paulo
Estuarine, Coastal and Shelf Science

Knowledge of population parameters and the ability to predict their responses to environmental changes are useful tools to aid in the appropriate management and conservation of natural resources. Samples of the sciaenid fish Stellifer rastrifer were taken from August 2003 through October 2004 in shallow areas of Caraguatatuba Bight, southeastern Brazil. The results showed a consistent presence of length-frequency classes throughout the year and low values of the gonadosomatic index of this species, indicating that the area is not used for spawning or residence of adults, but rather shelters individuals in late stages of development. The results may serve as a caveat for assessments of transitional areas such as the present one, the nursery function of which is neglected compared to estuaries and mangroves. The danger of mismanaging these areas by not considering their peculiarities is emphasized by using these data as a study case for the development of some broadly used population-parameter analyses. The individuals' body growth parameters from the von Bertalanffy model were estimated based on the most common approaches, and the best values obtained from traditional quantification methods of selection were very prone to bias. The low gonadosomatic index (GSI) estimated during the period was an important factor in stimulating us to select more reliable parameters of body growth (L∞ = 20.9, K = 0.37 and Z = 2.81), which were estimated based on assuming the existence of spatial segregation by size. The data obtained suggest that the estimated mortality rate included a high rate of migration of older individuals to deeper areas, where we assume that they completed their development. © 2013 Elsevier Ltd. Source

Costa M.R.,Centro Universitario Modulo | Costa M.R.,Federal Rural University of Rio de Janeiro | Mattos T.M.,Federal Rural University of Rio de Janeiro | Borges J.L.,Federal Rural University of Rio de Janeiro | Araujo F.G.,Federal Rural University of Rio de Janeiro
Neotropical Ichthyology

We determined in this study the habitat preferences of seven native fish species in a regulated river in Southeastern Brazil. We tested the hypothesis that fishes differ in habitat preference and that they use stretches of the river differing in hydraulic characteristics and substrate type. We surveyed fishes in four 1-km long river stretches encompassing different habitat traits, where we also measured water depth, velocity, and substrate type. We investigated preference patterns of four Siluriformes (Loricariichthys castaneus, Hoplosternum littorale, Pimelodus maculatus, and Trachelyopterus striatulus) and three Characiformes (Astyanax aff. bimaculatus, Oligosarcus hepsetus, and Hoplias malabaricus), representing approximately 70% of the total number of fishes and 64% of the total biomass. We classified fishes into four habitat guilds: (1) a slow-flowing water guild that occupied mud-sand substrate, composed of two Siluriformes in either shallow (< 4 m, i.e., H. littorale) or deep (> 8 m, L. castaneus) waters; (2) a run-dwelling guild that occurs in deep backwaters with clay-mud substrate, composed of the Characiformes A. aff. bimaculatus and O. hepsetus; (3) a run-dwelling guild that occurs in sandy and shallow substrate, composed of T. striatulus; and (4) a fast-flowing guild that occurs primarily along shorelines with shallow mud bottoms, composed of H. malabaricus and P. maculatus. Our hypothesis was confirmed, as different habitat preferences by fishes appear to occur in this regulated river. © 2013 Sociedade Brasileira de Ictiologia. Source

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