Estrutura e ecologia trófica da Ictiofauna da microbacia do Córrego Beija-flor, Estação Ecológica de Jataí, Luiz Antônio, SP
Abstract
The objective of this study was to analyze the structure, composition, trophic ecology
and food items shared by the fish fauna in the stream Beija -Flor, located in Jataí
Ecological Station ( 21 ⁰ 36'32 .8 " S 47 ⁰ 48'0 .54 " W ), besides characterizing the
trophic ecology of the species Hemigrammus marginatus, one of the most abundant in
the Beija-Flor stream. The samples of fish were collected monthly from August 2011 to
July 2012, using gill nets, trawl nets and baited traps in five sampling stations
distributed along the Beija-Flor stream. The fish were fixed in 10% formalin in the field
and in the laboratory were identified and subjected to biometric measurements. The
stomachs were weighed and transferred to 70% alcohol and stomach contents were
examined under a stereomicroscope to the lowest possible taxonomic level. Forty four
fish species belonging to 33 genera, 16 families and 5 orders were collected. Most
species were accidental ( 43.18 % ), followed by constant species ( 38.64 % ) and
accessory (18.18 % ). The diet of 30 species was analyzed. The main dietary habit was
insectivorous, followed by omnivorous habits, herbivorous, piscivorous and detritivore.
The dietary overlap was high in several species during periods of dry and flood.
Hemigrammus marginatus was classified as an insectivore. Food items of
autochthonous origin of the orders Ephemeroptera and Trichoptera were more important
during the dry season, while the items of allochthonous origin of the order
Hymenoptera, were more important in the rainy season. The increase in the quantity and
variety of food items during the flooding causes some species of fish to become more
generalist and share food resources. Hemigrammus marginatus, Astyanax altiparanae,
Metynnis maculatus, Serrapinnus notomelas and Oligosarcus pintoi, have complex of
interactions with the food items and can be considered key species for stream Beija-
Flor. The results showed that the stream Beija-Flor is a preserved, with high species
diversity by being located within the Jataí Ecological Station, but is highly threatened
by being surrounded by sugar cane plantations.