Hugo Bornatowski

Feeding ecology and trophic comparisons of six shark species in a coastal ecosystem off southern Brazil.

The diets of six shark species, Sphyrna lewini, Sphyrna zygaena, Carcharhinus obscurus, Carcharhinus limbatus, Rhizoprionodon lalandii and Galeocerdo cuvier, were investigated in a subtropical coastal ecosystem of southern Brazil. Stomach content data were obtained to assess foraging niche segregation and ontogenetic shifts in the diets of these sharks. Five of the shark species off the Paraná coast were ichthyophagous, with the exception of S. zygaena, which was teutophagous. With the exception of G. cuvier, which had a generalist diet, the other five species displayed specialization in their feeding. Ontogenetic shifts were observed in C. obscurus and S. lewini with large individuals consuming elasmobranchs. Owing to the diet overlap between C. obscurus and S. lewini, C. obscurus and C. limbatus and R. lalandii and C. limbatus, future studies on the spatial and temporal distributions of these species are needed to understand the extent of competitive interactions.

Elasmobranchs of the Paraná Coast, southern Brazil, south-western Atlantic

The present study provides a check list of elasmobranchs from the Parana State coast, southern Brazil. Information from fish collections, literature data, field surveys and personal communications were included. Results indicated that 83 species from seven orders and 28 families were recorded. According to the results 51 species belonging to six orders and 17 families of sharks; and 32 species belonging to one order and eleven families of rays occur in this region. The most species-rich families were Carcharhinidae (14 species) and Arhynchobatidae (eight species).

Feeding ecology of Rivulus luelingi (Aplocheiloidei: Rivulidae) in a Coastal Atlantic Rainforest stream, southern Brazil

collected in a black water stream of the Coastal Atlantic Rainforest in southern Brazilwere investigated. Eight samplings were made between April 2003 and January 2004. The diet, assessed through a similarity matri xwith the estimated contribution values of food items, included microcrustaceans, aquatic immature insects (larvae and pupae),aquatic adult insects, terrestrial insects, insect fragments, spiders, and plant fragments. Differences in the diet according totemporal variations (months) were registered, but changes related with size classes evaluated and high/low precipitation periodwere not observed. The species presented an insectivorous feeding habit, and its diet in the studied stream was composed ofautochthonous (mainly aquatic immature insects) and allochthonous (mainly insect fragments) material.Neste estudo foram investigados os habitos alimentares do peixe anual

Feeding ecology of fish in a coastal river of the Atlantic Rain Forest

Feeding ecology of fish assemblage in a costal river of the Atlantic Rain Forest in Southern Brazil was investigated. Monthly samples using different fishing techniques were completed on a section of the river characterized as a freshwater environment, and an adjacent tide-influenced estuarine section. Species were grouped into three major Feeding Mode Functional Groups: Zoobenthivore, Omnivore and Detritivore. The river section with the greatest occurrence was the site where the most abundant species are likely to feed most intensively. Freshwater strangler species (Cyphocharax santacatarinae - detritivorous, Rhamdia quelen and Oligosarcus hepsetus - zoobenthivorous) presented higher stomach repletion in the freshwater environment while marine migrants (Genidens genidens and Etropus crossotus - zoobenthivorous) and estuarine residents (Bairdiella ronchus - zoobenthivorous) presented higher repletion in the tide-influenced estuarine stretch. Use of food resources was influenced by spatial and temporal variations linked to environmental characteristics such as salinity, habitat heterogeneity, life history evolution, feeding specialization and resource partitioning. Hypotheses concerning potential keystone species, ecosystem engineers or strong interactors were also discussed.

SOBRE A ALIMENTAÇÃO DO TUBARÃO-MARTELO, Sphyrna zygaena (LINNAEUS, 1758), CAPTURADO POR ESPINHEL PELÁGICO NO SUDESTE E SUL DO BRASIL

The feeding diet of smooth hammerhead shark, Sphyrna zyganea, in oceanic waters off Southeastern and South Brazil was studied. The samplings was carried through the use of surface longlines during four cruises of the R.V. Soloncy Moura of IBAMA/CEPSUL, in the months of December, 2002 and March, April and July, 2003. The analysis of the diet was carried through calculating for each feeding item its numerical percentage (%N) in the stomachs, the percentage in weight (%P), and the frequency of occurrence (%FO), as well as the Index of Relative Importance (IRI). The feeding diet was based on Teleostei and Cephalopoda, mainly on the fi sh Aluterus sp., Balistes sp. and Diodon sp., and the squids Illex argentinus and Chiroteutis sp.