Abstract
The trophic relationships of 13 intertidal fish species collected in northern Chile (20 degrees 18' S and 20 degrees 54' S) from July 1997 to July 1998, the stomach content analysis of 820 specimens, were investigated. The importance of the prey items was assessed by means of gravimetric and frequency of ocurrence methods, together with the Shannon-Wiener (trophic diversity) and Pianka (trophic overlap) indexes. The results allowed to recognize a fish assemblage composed of: 46% of carnivorous species, preying mainly on porcelain crabs. polichaetes and minor crustaceans: 23% of herviborous species, preying mainly on chlorophitic algae: 31% of omnivorous species. preying mainly on chlorophitic algae. Copepoda and Gastropoda. The carnivorous fishes Cheilodactylus variegatus. Helcogrammoides chilensis. Labrisomus philippii and the omnivorous Oplegnatus insignis showed euriphagic tendencies (>2.0 bits), however, the major trophic overlap (>0.90) was observed among herbivorous and omnivorous fishes. Finally, the increase of fish species towards lower latitudes and the increase of herbivory and omnivory levels in the rocky intertidal shore were analyzed.
Highlights
The trophic relationships of 13 intertidal fish species collected in northern Chile
The importance of the prey items was assessed by means
La incorporación de especies en el área estudiada, así como también el aumento de las especies herbívoras y omnívoras con relación a la región central de Chile, concuerda con lo indicado por Moreno et al (1979) para la zona submareal, donde existe un incremento de especies ícticas hacia los trópicos, principalmente de hábitos herbívoros
Summary
En Chile, las investigaciones sobre la estructura y organización trófica de las asociaciones ícticas intermareales son en general escasas y referidas principalmente a la región central del país (Stepien 1990, Varas y Ojeda 1990, Muñoz y Ojeda 1997, 1998), a través de las cuales es posible observar que los niveles tróficos de estas asociaciones, se componen de aproximadamente 65% de carnívoros y 35% de omnívoros-herbívoros, estando los herbívoros representados exclusivamente por el blénido Scartichthys viridis (Valenciennes 1836) de acuerdo con Muñoz y Ojeda (1997). El objetivo de este estudio es caracterizar la estructura trófica de la asociación de peces en la zona intermareal rocosa del norte de Chile, como una forma de contribuir al conocimiento del incremento latitudinal de peces herbívoros en estos ambientes, respecto de lo observado para la región central de Chile por Stepien (1990), Varas y Ojeda (1990) y Muñoz y Ojeda (1997)
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