Resumen del producto

In this study we analyzed the resource partitioning of three species of sharks; Sphyrna lewini, Squatina californica and Rhizoprionodon longurio, within La Paz Bay, BCS. Resource partitioning was estimated from three ecological niche axes; their diet, the chemical signal and the level of a macronutrient. The stomach content, the stable isotopes analysis of Carbon and Nitrogen, and the level of fatty acids present in the sharks were analyzed for this purpose. The Index of Relative Importance Specific Prey showed that S. lewini has a more diverse diet, although the three shark species share prey items. ANOSIM determined that the diets of these sharks are different (R: 0.1894, p = <0.001). The Bayesian ellipses showed that these species have more resource partitioning than trophic overlap in their isotopic niche. At fatty acids levels, S. lewini and R. longurio showed a high similarity; however, both were different from S. californica. The partitioning at prey level and isotopic signal can be the result of ecological interactions of these species. However, the pattern found at the biochemical level responds more to the history of the biology of these organisms rather than to changes they may suffer during their lifetime. This species presents a trophic decrease with respect to the trophic web base and none essential fatty acids were retent when the trophic level increase.

Palabras clave: stable isotopes; trophic decrease; trophic overlap

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