Abstract

FUNES, Manuela; LIBEROFF, Ana Laura  and  GALVAN, David E.. Cambios tamaño-dependientes en la dieta de peces marinos y su estudio mediante análisis de isótopos estables. Ecol. austral [online]. 2014, vol.24, n.1, pp.118-126. ISSN 1667-782X.

Size-based dietary shifts in marine fishes assessed by stable isotopes analysis: Fish undergo significant morphological changes throughout their lives, like in the relative length of the digestive tube or the increase of mouth gape, and some of them can lead to changes in the trophic level. Studying these changes is important to understand fish trophodynamics, to verify the assumptions of size-structured trophic models and to assess community status by analyzing the size spectrum. In the present study we evaluated changes in the trophic positions of four reef-fish from northern Patagonia: Pagrus pagrus, Diplodus argentus argentus, Pinguipes brasilianus and Acanthistius patachonicus. Even though these four species share foraging areas and had similar trophic levels (trophic level ranged between 3.98 and 4.45), they exhibited specie-specifc isotopic trends related to changes in body size that could be meaning different trophic behavior. While P. pagrus and A. patachonicus presented an increase in their trophic level positively correlated with body size, D. argenteus and P. brasilianus did not show any isotopic trend along ontogeny. These results highlight the importance of including the species identity in size-structured trophic models, as well as to acknowledge that size-based feeding behavior might not be ubiquitous. However, these results support the assumption that as the maximum body size of a species increases, there are more probabilities to increase trophic level with size.

Keywords : Trophic level; Trophodinamics; Growth; Ontogenetic changes; Rocky reefs.

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