Relaciones Tróficas en el Sistema Hídrico de la Provincia de los Ríos: Ichthyoelephas humeralis y Brycon alburnus
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2012
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Universidad de Guayaquil. Facultad de Ciencias Naturales
Resumen
Se analizaron los contenidos estomacales de 245 ejemplares del pez Ichthyoelephas
humeralis y 230 de Brycon alburnus, para determinar sus hábitos alimentarios y
relaciones tróficas en el sistema hídrico de la provincia de Los Ríos entre marzo y
diciembre de 2010. Se utilizó el Índice de Importancia Relativa, basado en los
métodos numérico, peso y frecuencia de ocurrencia, obteniéndose además los índices
de amplitud del nicho trófico de Levin y de traslapo de Morisita. Se determinó que I.
humeralis es un pez detritívoro-fitófago, consumiendo siete grupos alimenticios,
siendo los más importantes el detritus y las microalgas. B. alburnus se determinó
como un pez omnívoro, cuyos componentes alimentarios predominantes fueron
materia vegetal mixta, peces e insectos. La amplitud del nicho trófico determinó a I.
humeralis (Bi=0.06) y B. alburnus (Bi=0.09) como depredadores selectivos por
consumir un mayor porcentaje de pocas especies. Al comparar ambas especies
mediante el índice de traslapo trófico, se obtuvo un traslapo medio (Cλ 0.47), lo que
indicó que comparten el mismo espacio debido a que consumen algunas presas
similares aunque en diferentes proporciones.
The stomach contents of 245 specimen Ichthyoelephas humeralis and 230 of Brycon alburnus were analyzed for determination of feeding habits and trophic relationships in Los Rios province hydric system, between march and december, 2010. The Relative importance index was used, based in the numeric method, weight and occurrence frequency, also obtaining trophic niche breadth index of Levin and overlapping index of Morisita. I. humeralis was determinated as a detritivorousphytophagous fish, feeding from 7 food groups, being the most important of them the detritus and microalgae. B. alburnus was determinated as an omnivorous fish; the predominant food components were mixed plant material, fish and insects. The trophic niche breadth determinated to I. humeralis (Bi=0.06) and B. alburnus (Bi=0.09) as selective predators, feeding of a higher percentage of few species. Comparing both species by trophic overlapping index, a middle overlapping (Cλ 0.47) was obtained, and indicated that both species share the same space because they feed some similar preys but in different proportions.
The stomach contents of 245 specimen Ichthyoelephas humeralis and 230 of Brycon alburnus were analyzed for determination of feeding habits and trophic relationships in Los Rios province hydric system, between march and december, 2010. The Relative importance index was used, based in the numeric method, weight and occurrence frequency, also obtaining trophic niche breadth index of Levin and overlapping index of Morisita. I. humeralis was determinated as a detritivorousphytophagous fish, feeding from 7 food groups, being the most important of them the detritus and microalgae. B. alburnus was determinated as an omnivorous fish; the predominant food components were mixed plant material, fish and insects. The trophic niche breadth determinated to I. humeralis (Bi=0.06) and B. alburnus (Bi=0.09) as selective predators, feeding of a higher percentage of few species. Comparing both species by trophic overlapping index, a middle overlapping (Cλ 0.47) was obtained, and indicated that both species share the same space because they feed some similar preys but in different proportions.
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RELACIONES TRÓFICAS, ICHTHYOELEPHAS HUMERALIS, BRYCON ALBURNUS, DETRITÍVORO, FITÓFAGO