ABSTRACT
This study aimed to investigate the diet of the gecko Homonota fasciata (Duméril & Bibron, 1836) in a population from Monte of San Juan Province, Argentina, and to analyze possible temporal, sexual, and ontogenetic variations in feeding behavior. We determined the total volume, number, and occurrence frequency of each prey item and calculated the relative importance indexes. We also assessed trophic diversity and trophic equity. Homonota fasciata had a generalist and diverse diet based on arthropods, including insects and arachnids. Individuals adopted a passive 'sit and wait' foraging strategy. There were seasonal-, sex-, and age-related variations in the trophic spectra. The results of this study provide a valuable contribution to our understanding of the biology of this species, with implications for the establishment of management guidelines both for the species and its habitat.(AU)
El objetivo de este trabajo fue conocer y describir la dieta de Homonota fasciata (Duméril & Bibron, 1836) en una población del Monte de la provincia de San Juan Argentina, analizando posibles variaciones temporales, sexuales y ontogenéticas en la alimentación. Para examinar la dieta, se determinó volumen, numerosidad y frecuencia de ocurrencia para cada ítem-presa, y se calculó el Índice de Importancia Relativa (IRI). Se evaluaron diversidad y equidad trófica, además de variaciones estacionales, sexuales y etarias del espectro trófico. La dieta de H. fasciata es generalista, diversa, basada en artrópodos, incluyendo insectos y arácnidos. La estrategia de forrajeo exhibida fue pasiva ("sit and wait"). Se encontraron variaciones estacionales, sexuales y ontogénicas en la alimentación. Este estudio permite una valiosa contribución al conocimiento de la biología de esta especie, útil a la hora de fijar pautas de manejo para la misma, como así también para los ambientes que habita.(AU)
Subject(s)
Animals , Lizards , Diet/veterinary , Age Factors , Sex Factors , Seasons , Trophic LevelsABSTRACT
This study aimed to investigate the diet of the gecko Homonota fasciata (Duméril & Bibron, 1836) in a population from Monte of San Juan Province, Argentina, and to analyze possible temporal, sexual, and ontogenetic variations in feeding behavior. We determined the total volume, number, and occurrence frequency of each prey item and calculated the relative importance indexes. We also assessed trophic diversity and trophic equity. Homonota fasciata had a generalist and diverse diet based on arthropods, including insects and arachnids. Individuals adopted a passive 'sit and wait' foraging strategy. There were seasonal-, sex-, and age-related variations in the trophic spectra. The results of this study provide a valuable contribution to our understanding of the biology of this species, with implications for the establishment of management guidelines both for the species and its habitat.
El objetivo de este trabajo fue conocer y describir la dieta de Homonota fasciata (Duméril & Bibron, 1836) en una población del Monte de la provincia de San Juan Argentina, analizando posibles variaciones temporales, sexuales y ontogenéticas en la alimentación. Para examinar la dieta, se determinó volumen, numerosidad y frecuencia de ocurrencia para cada ítem-presa, y se calculó el Índice de Importancia Relativa (IRI). Se evaluaron diversidad y equidad trófica, además de variaciones estacionales, sexuales y etarias del espectro trófico. La dieta de H. fasciata es generalista, diversa, basada en artrópodos, incluyendo insectos y arácnidos. La estrategia de forrajeo exhibida fue pasiva ("sit and wait"). Se encontraron variaciones estacionales, sexuales y ontogénicas en la alimentación. Este estudio permite una valiosa contribución al conocimiento de la biología de esta especie, útil a la hora de fijar pautas de manejo para la misma, como así también para los ambientes que habita.
Subject(s)
Animals , Diet/veterinary , Seasons , Age Factors , Sex Factors , Lizards , Trophic LevelsABSTRACT
Resumen El objetivo de este trabajo fue conocer y describir la dieta de Homonota fasciata (Duméril & Bibron, 1836) en una población del Monte de la provincia de San Juan Argentina, analizando posibles variaciones temporales, sexuales y ontogenéticas en la alimentación. Para examinar la dieta, se determinó volumen, numerosidad y frecuencia de ocurrencia para cada ítem-presa, y se calculó el Índice de Importancia Relativa (IRI). Se evaluaron diversidad y equidad trófica, además de variaciones estacionales, sexuales y etarias del espectro trófico. La dieta de H. fasciata es generalista, diversa, basada en artrópodos, incluyendo insectos y arácnidos. La estrategia de forrajeo exhibida fue pasiva ("sit and wait"). Se encontraron variaciones estacionales, sexuales y ontogénicas en la alimentación. Este estudio permite una valiosa contribución al conocimiento de la biología de esta especie, útil a la hora de fijar pautas de manejo para la misma, como así también para los ambientes que habita.
Abstract This study aimed to investigate the diet of the gecko Homonota fasciata (Duméril & Bibron, 1836) in a population from Monte of San Juan Province, Argentina, and to analyze possible temporal, sexual, and ontogenetic variations in feeding behavior. We determined the total volume, number, and occurrence frequency of each prey item and calculated the relative importance indexes. We also assessed trophic diversity and trophic equity. Homonota fasciata had a generalist and diverse diet based on arthropods, including insects and arachnids. Individuals adopted a passive 'sit and wait' foraging strategy. There were seasonal-, sex-, and age-related variations in the trophic spectra. The results of this study provide a valuable contribution to our understanding of the biology of this species, with implications for the establishment of management guidelines both for the species and its habitat.
ABSTRACT
Menidia humboldtiana, a native species of Mexico, is a common inhabitant of local reservoirs. It represents a highly appreciated fish of economic importance in the central part of the country because of its delicate flavor. Trophic behavior of this species is important to understand the relationships with other fish species in reservoirs. With the aim to study this specific topic, the trophic spectrum, selectivity coefficient and overlap, were determined among different sizes of the Silverside M. humboldtiana. For this, both zooplankton and fish samples were taken during four different seasons of 1995. Zooplankton samples were taken through a mesh (125micron), and all organisms were identified to generic level. Fish were captured and grouped into standard length intervals per season, and the stomach contents were obtained and analyzed. Trophic interactions included the stomach contents analysis (Laevastu method), the coefficient of selection (Chesson) and the trophic overlap (Morisita index modified by Horn) between sizes. A total of 14 zooplankton genera were identified, of which Bosmina was the most abundant (29 625 ind./10L) followed by Cyclops (9 496 ind./10L), during the spring. Small size fishes (1-4.9cm) consumed high percentages of Cyclops in the spring (61.24%) and winter (69.82%). Ceriodaphnia was consumed by fish sizes of 3-10.9cm (72.41%) and 13-14.9cm (95.5%) during the summer; while in autumn, small sizes (1-4.9cm) ingested Mastigodiaptomus and Ceriodaphnia; Daphnia and Bosmina were consumed by fishes of 5-8.9cm and the biggest sizes (9-14.9cm) feed on Ceriodaphnia. M. humboldtiana makes a selective predation by the genera Ceriodaphnia, Daphnia, Mastigodiaptomus, Bosmina and Cyclops, depending on the size length interval. The trophic overlap was very marked among all sizes on spring, autumn and winter, unlike in summer fish of 1-2.9 and 11-12.9cm did not show overlap with other length intervals. M. humboldtiana is a zooplanktivore species, which performs a selective predation and a marked trophic overlap between the different fish sizes.
Menidia humboldtiana es una especie nativa muy apreciada por su delicado sabor. Se determinó el espectro trófico, selectividad y solapamiento trófico de ésta, durante 1995 (épocas del año), se obtuvieron muestras de zooplancton e identificaron a nivel genérico. Los peces capturados se agruparon en intervalos de longitud estándar para cada época. Se analizaron los contenidos estomacales (método volumétrico, Laevastu), selectividad (Chesson) y solapamiento trófico (Morisita). Se registraron 14 géneros de zooplancton; Bosmina el más abundante (29 625ind/10L) seguido por Cyclops (9 496ind/10L) ambos en primavera. Los peces pequeños (1-4.9cm) consumen a Cyclops en altos porcentajes en primavera e invierno, 61.24-69.82% respectivamente. Ceriodaphnia es consumida por peces de 3-10.9cm y de 13-14.9cm con 72.41-95.5% en verano; en otoño las tallas pequeñas ingieren a Mastigodiaptomus y Ceriodaphnia; Daphnia y Bosmina por peces de 5-8.9cm y los más grandes (9-14.9cm) a Ceriodaphnia. M. humboldtiana realiza una depredación selectiva por Ceriodaphnia, Daphnia, Mastigodiaptomus, Bosmina y Cyclops. El solapamiento trófico fue muy marcado entre todas las tallas en primavera, otoño e invierno, a diferencia en verano los peces de 1-2.9 y 11-12.9cm no registraron un solapamiento con otros intervalos de longitud. M. humboldtiana es una especie zooplanctófaga, que realiza una depredación selectiva y un marcado solapamiento trófico entre los intervalos de longitud.
Subject(s)
Animals , Food Chain , Feeding Behavior/physiology , Fishes/physiology , Body Size , Fishes/anatomy & histology , Fishes/classification , Gastrointestinal Contents , Mexico , SeasonsABSTRACT
The study reports the changes ocurred in feeding ecology of fish species during a tropical river reservoir formation. It was analysed the stomachal contents of 399 individuals belonging to four species of genus Leporinus (L. elongatus Valenciennes, 1849, n=157; L.friderici (Bloch, 1794), n=87; L. octofasciatus Steindachner, 1917, n=107; L.amblyrhynchus Garavello & Britski, 1987, n=48) during formation of Nova Ponte reservoir, State of Minas Gerais, Brazil, in 1993 and 1994. Specimens were separated by sampling period, according with the rate of filling of the reservoir, and standard lenght classes. The species had included in diet vegetal and animal items of autochtone and alochtone origin in several proportions. L. amblyrhynchus fed on basically dipterans in all the sampling periods and length classes. L. elongatus had presented a diverse diet, with predominance of dipterans and vegetal items, and changed the consumed items proportions along the sampling periods and between lenght classes. L. friderici diet was composed mainly by terrestrial insects during the rapid filling period, that were later substituted by fishes and vegetal items. Ontogenetic trophic changes were observed in this species. L. octofasciatus presented a well characterized herbivorous diet, without trophic ontogeny, but with a opportunistic character. Just three pair-species, L. amblyrhynchus-L. elongatus, L. friderici-L. octofasciatus and L. elongatus-L. octofasciatus, have presented some high value of trophic overlap in at least one sampling period. In spite of the fishes of the genus Leporinus being classified like omnivorous in a general way, the differences found between diets of these four species suggest that there is structuration of trophic niches in the reservoir.
ABSTRACT
The study reports the changes ocurred in feeding ecology of fish species during a tropical river reservoir formation. It was analysed the stomachal contents of 399 individuals belonging to four species of genus Leporinus (L. elongatus Valenciennes, 1849, n=157; L.friderici (Bloch, 1794), n=87; L. octofasciatus Steindachner, 1917, n=107; L.amblyrhynchus Garavello & Britski, 1987, n=48) during formation of Nova Ponte reservoir, State of Minas Gerais, Brazil, in 1993 and 1994. Specimens were separated by sampling period, according with the rate of filling of the reservoir, and standard lenght classes. The species had included in diet vegetal and animal items of autochtone and alochtone origin in several proportions. L. amblyrhynchus fed on basically dipterans in all the sampling periods and length classes. L. elongatus had presented a diverse diet, with predominance of dipterans and vegetal items, and changed the consumed items proportions along the sampling periods and between lenght classes. L. friderici diet was composed mainly by terrestrial insects during the rapid filling period, that were later substituted by fishes and vegetal items. Ontogenetic trophic changes were observed in this species. L. octofasciatus presented a well characterized herbivorous diet, without trophic ontogeny, but with a opportunistic character. Just three pair-species, L. amblyrhynchus-L. elongatus, L. friderici-L. octofasciatus and L. elongatus-L. octofasciatus, have presented some high value of trophic overlap in at least one sampling period. In spite of the fishes of the genus Leporinus being classified like omnivorous in a general way, the differences found between diets of these four species suggest that there is structuration of trophic niches in the reservoir.
ABSTRACT
The study reports the changes ocurred in feeding ecology of fish species during a tropical river reservoir formation. It was analysed the stomachal contents of 399 individuals belonging to four species of genus Leporinus (L. elongatus Valenciennes, 1849, n=157; L.friderici (Bloch, 1794), n=87; L. octofasciatus Steindachner, 1917, n=107; L.amblyrhynchus Garavello & Britski, 1987, n=48) during formation of Nova Ponte reservoir, State of Minas Gerais, Brazil, in 1993 and 1994. Specimens were separated by sampling period, according with the rate of filling of the reservoir, and standard lenght classes. The species had included in diet vegetal and animal items of autochtone and alochtone origin in several proportions. L. amblyrhynchus fed on basically dipterans in all the sampling periods and length classes. L. elongatus had presented a diverse diet, with predominance of dipterans and vegetal items, and changed the consumed items proportions along the sampling periods and between lenght classes. L. friderici diet was composed mainly by terrestrial insects during the rapid filling period, that were later substituted by fishes and vegetal items. Ontogenetic trophic changes were observed in this species. L. octofasciatus presented a well characterized herbivorous diet, without trophic ontogeny, but with a opportunistic character. Just three pair-species, L. amblyrhynchus-L. elongatus, L. friderici-L. octofasciatus and L. elongatus-L. octofasciatus, have presented some high value of trophic overlap in at least one sampling period. In spite of the fishes of the genus Leporinus being classified like omnivorous in a general way, the differences found between diets of these four species suggest that there is structuration of trophic niches in the reservoir.