Comportamiento alimentario de tres especies de tiburones capturados ilegalmente en la reserva marina de Galápagos.
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2016
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Facultad de Ciencias Naturales. Universidad de Guayaquil
Resumen
El presente trabajo está enfocado en generar información referente a la ecología trófica de los tiburones: zorro pelágico (Alopias pelagicus), azul (Prionace glauca) y piloto (Carcharinus falciformis). La Reserva Marina de Galápagos a pesar de ser una de las mejores cuidadas del mundo, no deja de estar afectado por la pesca ilegal de tiburones.
El objetivo de este estudio es, describir el comportamiento trófico de tres especies de tiburones a partir del uso de isótopos estables de carbono y nitrógeno (δ 13C y δ15N). A
nivel inter-específico los valores isotópicos (n=91) no mostraron diferencias en cuanto a sus áreas de alimentación (δ
13C: Kruskal-Wallis: p=0.095); pero sí hubo diferencias en el nivel trófico del que se alimentan (δ15N: Kruskal-Wallis: p=0. 001). Los valores de δ 13C y δ15N en ambos sexos de cada una de las especies, no mostraron diferencias significativas (t-student: p > 0.005), sugiriendo que las especies utilizan las mismas zonas de alimentación y nivel trófico. Los valores calculados de amplitud trófica señalan a Prionace glauca (AT= 0.84) como un depredador de tipo especialista, a diferencia de las otra especies que resultaron generalistas. El nivel trófico con base en la señal isotópica de δ15N ubicó a las tres especies como depredadores terciarios, ratificando su importancia dentro de la cadena alimenticia como grandes consumidores.
Los resultados de este trabajo demuestran que las tres especies de tiburones mantienen una estrategia pelágica con un consumo diferencial de presas.
The present essay is focused on generating information about sharks feeding ecology on pelagic thresher (Alopias pelagicus), blue (Prionace glauca) and pilot (Carcharinus falciformis). The Galapagos Marine Reserve, despite being one of the best managed marine reserves in the world, still has problems related to illegal shark fishing. The aim of this study is to describe the feeding behavior of three species of sharks, the use of stable isotopes of carbon and nitrogen (δ 13C and δ 15N). At level inter-specific the isotopic values (n=91) showed no differences in their feeding area (δ 13C: KruskalWallis test, p = 0.095); but there were differences in the trophic level (δ 15N: KruskalWallis test, p = 0 001.). The values of δ 13C and δ 15N of both gender on each of the specie show no significant difference (t-student test, p>0.005), suggesting the use of the same foraging area and trophic level. The calculated values of trophic breadth located to Prionace glauca (AT = 0.84) as a specialist predator unlike other species were generalists. The trophic level based on the δ 15N values are located to the three species as “tertiary” consumer; confirming its importance in the food web as top predator. Our results suggest a pelagic strategy with a differential consumption of prey for these species.
The present essay is focused on generating information about sharks feeding ecology on pelagic thresher (Alopias pelagicus), blue (Prionace glauca) and pilot (Carcharinus falciformis). The Galapagos Marine Reserve, despite being one of the best managed marine reserves in the world, still has problems related to illegal shark fishing. The aim of this study is to describe the feeding behavior of three species of sharks, the use of stable isotopes of carbon and nitrogen (δ 13C and δ 15N). At level inter-specific the isotopic values (n=91) showed no differences in their feeding area (δ 13C: KruskalWallis test, p = 0.095); but there were differences in the trophic level (δ 15N: KruskalWallis test, p = 0 001.). The values of δ 13C and δ 15N of both gender on each of the specie show no significant difference (t-student test, p>0.005), suggesting the use of the same foraging area and trophic level. The calculated values of trophic breadth located to Prionace glauca (AT = 0.84) as a specialist predator unlike other species were generalists. The trophic level based on the δ 15N values are located to the three species as “tertiary” consumer; confirming its importance in the food web as top predator. Our results suggest a pelagic strategy with a differential consumption of prey for these species.
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ECOLOGÍA TRÓFICA, ALOPIAS PELAGICUS, PRIONACE GLAUCA, CARCHARINUS FALCIFORMIS