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Revista chilena de historia natural

versión impresa ISSN 0716-078X


CACERES, CRISTIAN W.  y  OJEDA, F. PATRICIO. Foraging patterns of two species of intertidal herbivorous fishes: Effect of food abundance and chemical composition. Rev. chil. hist. nat. [online]. 2000, vol.73, n.2, pp. 253-260. ISSN 0716-078X.

Herbivores are organisms that must meet their energy and nutrients requirements from a food source that typically has been characterized as having low nutritional value given their low concentration of nutrients and energy. Two of the most important questions in relation to fish herbivory are: i) which are the factors that determine the selection or rejection of a given algal item? and ii) are herbivorous fishes capable of extracting the nutrients and energy of a macroalgal diet? In this work, we studied in two species of herbivorous intertidal fishes, Scartichthys viridis and Girella laevifrons, the patterns of food selectivity in the field and in laboratory experiments, the assimilation efficiency for different dietary algal items, and the relationship between the observed patterns and the chemical composition of the algae. The results showed that more than 90% of the diet of these organisms consisted of benthic macroalgae. In the field both species present a non-selective trophic behavior in summer and selective one in winter, characterized by the consumption of green algae in the later season. Furthermore, in the experiments of food selection both species showed a similar pattern characterized by the preference of green and red algae. The results of the assimilation experiments, indicate that Girella laevifrons presents higher values of this parameter than Scartichthys viridis, being in the former the green algae Ulva and Enteromorpha, the items that present a higher efficiency of assimilation. Finally, the results obtained suggest in this herbivorous species a strong relationship among the patterns of food selection and the relationship between food composition and digestive characteristics

Palabras clave : fishes; herbivory; diet selection; assimilation efficiency; Chile.

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