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Interciencia

versión impresa ISSN 0378-1844

Resumen

ORTAZ, Mario; MACHADO-ALLISON, Antonio  y  CARRILLO, Víctor. Fast ecological evaluation of the ichthyofauna in five localities of the Orinoco river delta, Venezuela. INCI [online]. 2007, vol.32, n.9, pp.601-609. ISSN 0378-1844.

A Rapid Ecological Assessment of the ichthyofauna was performed on five pilot areas (AP) of the Orinoco river delta. The pilot areas included the superior delta (AP1), middle delta (AP2 and AP5) and low delta (AP3 and AP4). All of them, except AP1, are included in the Orinoco Delta Biosphere Reserve (ODBR). Three campaigns were carried out from Sep/2002 to May/2003. Between 14 and 16 sampling stations were evaluated, including principal and secondary channels and lagoons. Fishes were collected using gillnets during daylight hours (8:00-18:30) with a total net effort of 23.2h for the first campaign and 37.6h for the second one. A total of 80 species were collected, 7 of them new records for the area. The Orinoco delta harbors ~394 species, 50% of which are within the ODBR. Diversity, evenness and species richness were high in AP1, where a series of lentic environments unique in the Orinoco river delta exist and could function as an important source of recruitments for other areas. Benthic invertebrates, nekton and organic allochthonous matter from terrestrial origin were the principal food resources used by fishes, with a varying spatial and temporal relative importance. This study increases the spatial distribution of the exotic cichlid Caquetaia kraussii. The anthropic environmental changes that could affect the ichthyofauna is considered low to this date but a moderate pressure was found on the upper delta area, without there being evidence of actions to reverse it.

Palabras clave : Delta del Orinoco ; Estructura Trófica ; Evaluación Rápida ; Ictiofauna ; Venezuela .

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