Diet composition and food overlap of Acestrorhynchus britskii and A. lacustris (Characiformes: Acestrorhynchidae) from Sobradinho reservoir, São Francisco river, Bahia State - doi: 10.4025/actascibiolsci.v33i4.7240 / Diet composition and food overlap of Acestrorhynchus britskii and A. lacustris (Characiformes: Acestrorhynchidae) from Sobradinho reservoir, São Francisco river, Bahia State - doi: 10.4025/actascibiolsci.v33i4.7240

Fish diet studies contribute to understanding resource partitioning and community trophic structure. The present paper characterizes the diet of peixe-cachorro species Acestrorhynchus britskii and A. lacustris in Sobradinho reservoir, Bahia State, Brazil. Bimonthly samples (November 2006 to July 2008) were taken in the lotic, transition and lentic stretches of the reservoir, using gillnets overnight. A total of 899 A. britskii and 476 A. lacustris stomachs were analyzed, 70% of which were empty. Their content indicated the species are predominantly piscivorous, with 18 prey fish species identified. However, each prey occurred in a single month, except for Anchoviella vaillanti, recorded in 80% of months for A. bristski, and Tetragonopterus chalceus in 25% for A. lacustris. The species presented high food overlap (C = 0.992), owing to the occurrence of Actinopterygii (bits) and Actinopterygii in all months. Regarding prey fish alone, a differentiated intake and lower food overlap was detected, in the flood (C = 0.427) and drought (C = 0.172) seasons, in the lotic (C = 0.434), transition (C = 0.089) and lentic (C = 0) stretches, and in overall overlap (C = 0.236). The spatial and seasonal differences in the intake of different prey fish by both species suggest an opportunistic feeding habit and a competition reduction mechanism for food resources.

Fish diet studies contribute to understanding resource partitioning and community trophic structure. The present paper characterizes the diet of peixe-cachorro species Acestrorhynchus britskii and A. lacustris in Sobradinho reservoir, Bahia State, Brazil. Bimonthly samples (November 2006 to July 2008) were taken in the lotic, transition and lentic stretches of the reservoir, using gillnets overnight. A total of 899 A. britskii and 476 A. lacustris stomachs were analyzed, 70% of which were empty. Their content indicated the species are predominantly piscivorous, with 18 prey fish species identified. However, each prey occurred in a single month, except for Anchoviella vaillanti, recorded in 80% of months for A. bristski, and Tetragonopterus chalceus in 25% for A. lacustris. The species presented high food overlap (C = 0.992), owing to the occurrence of Actinopterygii (bits) and Actinopterygii in all months. Regarding prey fish alone, a differentiated intake and lower food overlap was detected, in the flood (C = 0.427) and drought (C = 0.172) seasons, in the lotic (C = 0.434), transition (C = 0.089) and lentic (C = 0) stretches, and in overall overlap (C = 0.236). The spatial and seasonal differences in the intake of different prey fish by both species suggest an opportunistic feeding habit and a competition reduction mechanism for food resources.

Diet composition and food overlap of Acestrorhynchus britskii and A. lacustris (Characiformes: Acestrorhynchidae) from Sobradinho reservoir, São Francisco river, Bahia State - doi: 10.4025/actascibiolsci.v33i4.7240 / Diet composition and food overlap of Acestrorhynchus britskii and A. lacustris (Characiformes: Acestrorhynchidae) from Sobradinho reservoir, São Francisco river, Bahia State - doi: 10.4025/actascibiolsci.v33i4.7240

Fish diet studies contribute to understanding resource partitioning and community trophic structure. The present paper characterizes the diet of peixe-cachorro species Acestrorhynchus britskii and A. lacustris in Sobradinho reservoir, Bahia State, Brazil. Bimonthly samples (November 2006 to July 2008) were taken in the lotic, transition and lentic stretches of the reservoir, using gillnets overnight. A total of 899 A. britskii and 476 A. lacustris stomachs were analyzed, 70% of which were empty. Their content indicated the species are predominantly piscivorous, with 18 prey fish species identified. However, each prey occurred in a single month, except for Anchoviella vaillanti, recorded in 80% of months for A. bristski, and Tetragonopterus chalceus in 25% for A. lacustris. The species presented high food overlap (C = 0.992), owing to the occurrence of Actinopterygii (bits) and Actinopterygii in all months. Regarding prey fish alone, a differentiated intake and lower food overlap was detected, in the flood (C = 0.427) and drought (C = 0.172) seasons, in the lotic (C = 0.434), transition (C = 0.089) and lentic (C = 0) stretches, and in overall overlap (C = 0.236). The spatial and seasonal differences in the intake of different prey fish by both species suggest an opportunistic feeding habit and a competition reduction mechanism for food resources.

Fish diet studies contribute to understanding resource partitioning and community trophic structure. The present paper characterizes the diet of peixe-cachorro species Acestrorhynchus britskii and A. lacustris in Sobradinho reservoir, Bahia State, Brazil. Bimonthly samples (November 2006 to July 2008) were taken in the lotic, transition and lentic stretches of the reservoir, using gillnets overnight. A total of 899 A. britskii and 476 A. lacustris stomachs were analyzed, 70% of which were empty. Their content indicated the species are predominantly piscivorous, with 18 prey fish species identified. However, each prey occurred in a single month, except for Anchoviella vaillanti, recorded in 80% of months for A. bristski, and Tetragonopterus chalceus in 25% for A. lacustris. The species presented high food overlap (C = 0.992), owing to the occurrence of Actinopterygii (bits) and Actinopterygii in all months. Regarding prey fish alone, a differentiated intake and lower food overlap was detected, in the flood (C = 0.427) and drought (C = 0.172) seasons, in the lotic (C = 0.434), transition (C = 0.089) and lentic (C = 0) stretches, and in overall overlap (C = 0.236). The spatial and seasonal differences in the intake of different prey fish by both species suggest an opportunistic feeding habit and a competition reduction mechanism for food resources.

Occurrence of early life stages of Hirundichthys affinis (Günther, 1866) and Cheilopogon sp. (Beloniformes, Exocoetidae) in a tropical estuary, northeastern Brazil

Ocorrência de estágios iniciais de Hirundichthys affinis (Günther, 1866) e Cheilopogon sp. (Beloniformes, Exocoetidae) num estuário tropical, nordeste do Brasil. Exocoetidae é uma família de peixes predominantemente oceânicos e epipelágicos, comumente conhecidos como peixes-voadores. Estes peixes de pequeno porte alcançam um tamanho máximo de 450 mm e têm ocorrência restrita em águas costeiras. O material analisado no presente estudo foi coletado no complexo estuarino de rio Formoso, no litoral sul de Pernambuco, nordeste do Brasil. O espécimens de Hirundichthys affinis foram coletados no estágio de pós-flexão, com um comprimento padrão de 9 a 15 mm. Os espécimens foram coletados em setembro, outubro e novembro/2001. Duas larvas do gênero Cheilopogon foram coletadas em novembro/2004, ambos no estágio de pós-flexão da notocorda, com umcomprimento padrão de 13,5 e 15,2 mm. Este registro da presença de larvas de Exocoetidae no estuário do rio Formoso demonstra sua ocorrência em ambientes estuarinos, ressaltando o papel destes ecossistemas tanto para a ictiofauna costeira como oceânica.

Occurrence of early life stages of Hirundichthys affinis (Günther, 1866) and Cheilopogon sp. (Beloniformes, Exocoetidae) in a tropical estuary, northeastern Brazil

Ocorrência de estágios iniciais de Hirundichthys affinis (Günther, 1866) e Cheilopogon sp. (Beloniformes, Exocoetidae) num estuário tropical, nordeste do Brasil. Exocoetidae é uma família de peixes predominantemente oceânicos e epipelágicos, comumente conhecidos como peixes-voadores. Estes peixes de pequeno porte alcançam um tamanho máximo de 450 mm e têm ocorrência restrita em águas costeiras. O material analisado no presente estudo foi coletado no complexo estuarino de rio Formoso, no litoral sul de Pernambuco, nordeste do Brasil. O espécimens de Hirundichthys affinis foram coletados no estágio de pós-flexão, com um comprimento padrão de 9 a 15 mm. Os espécimens foram coletados em setembro, outubro e novembro/2001. Duas larvas do gênero Cheilopogon foram coletadas em novembro/2004, ambos no estágio de pós-flexão da notocorda, com umcomprimento padrão de 13,5 e 15,2 mm. Este registro da presença de larvas de Exocoetidae no estuário do rio Formoso demonstra sua ocorrência em ambientes estuarinos, ressaltando o papel destes ecossistemas tanto para a ictiofauna costeira como oceânica.