Uso de redes de espera no estudo de ritmos circadianos de algumas espécies de peixes nos lagos de várzea do rio Solimões

Abstract

Rhythmic activity patterns are demonstrated for 15 species of fish in várzea lakes of the Solimões river by analyzing catch per hour-of-day INTRODUÇÃORitmos diários já foram observados em muitas espécies, relacionados a mudanças dclicas de diversos fatores ambientais. Essa alteração diária do comportamento da espécie é associada a sua estratégia de sobrevivência, que apresenta vantagens adaptativas em possuir a capacidade de "antever" e de se preparar para as mudanças ambientais previsrveis (Schwassmann, 1980) . Dessa forma, cada espécie desenvolveu, dentro da história de sua evolução, um comportamento adaptado a explorar determinados ambientes nos perrodos em que o seu mecanismo de defesa fosse mais efetivo (Hobson, 1972) . Para os vertebrados, fatores abióticos, como luz, temperatura e umidade"tendem a serem menos importantes diretamente· na atividade diária do animal do que fatores bióticos (Cloudsley-Thompson, 1961) . A disponibilidade de alimentos, o peixe e o predador são os três principais componentes de que, dessa interação biológica, resultam os ritmos diários de atividade e alimentação dos peixes (Manteifel et aL, 1978) .

Feeding of Acestrorhynchus lacustris (Characidae): a post impoundment studies on Itaipu reservoir, upper Paraná River, PR

“…Several investigators have observed that piscivores ingest prey smaller than one-third of their own length (Goulding et al, 1988;MachadoAllison, 1990;Almeida et al, 1997). However, this is not a rule, since the traíra Hoplias malabaricus, as reported in a number of studies, can ingest fish nearly its own length (Barthem, 1987;Winemiller, 1989;Almeida, 1994;Loureiro & Hahn, 1996). In the present study, the largest prey recorded was a specimen of Crenicichla niederleinii 9.5 cm long, eaten by an individual 23.3 cm long.…”

“…Studies on the feeding of A. lacustris are limited to those of Catella & Torres (1984) in Três Marias Reservoir, State of Minas Gerais; Mesquiatti (1995) in an oxbow lake of the Mogi-Guaçu River, State of São Paulo; and Almeida et al (1997) in the floodplain of the Upper Paraná River, State of Paraná. Trophic studies of large ichthyofaunistic communities have made brief reference to this species or others of the same genus (Barthem, 1987;Meschiatti, 1995;Benneman, 1996;Resende et al, 1996;Hahn et al, 1997). This paper describes the diet of A. lacustris in the area influenced by Itaipu Reservoir, the spacial and annual variations of the diet, its degree of overlap and the relationships between predator and prey sizes.…”

Diet of Iheringichthys labrosus (Siluriformes, Pimelodidae) in the Ibicuí River, Southern Brazil

“…Such differences of results could have been determined by the influence of the food availability in the environments on the daily rhythms of feeding activity of fishes (BARTHEM, 1987). HAHN et al (1997) suggested that fishes that adopt a visual method of capturing organisms exhibit high feeding activity during the daylight.…”

Responses of the fish community to the flood pulse and siltation in a floodplain lake of the Trombetas River, Brazil

“…They showed a negative relationship with transparency and a positive one with bauxite tailings. These species are active during twilight and at night (Barthem, 1987;Halboth, 1995), and are bottom inhabitants (Lin, 2003) with elaborate systems of sound production and requirements and a welldeveloped lateral line (Moyle & Cech, 1988). Thus, low transparency limits neither their distribution nor, probably, their foraging abilities; they are more abundant in turbid waters, as also observed by Rodrı´guez & Lewis (1997).…”