Abstract (en):
To evaluate the impacts of water flow restriction and regulation caused by the construction of a dike across Manamo Channel, variations in the benthic fish communities were studied in the mouths of three streams or channels (Pedernales, Angostura and Manamo) of the Orinoco River Delta and one stream (Venado) that flows directly into the Gulf of Paria, during one (annual) hydrological cycle. Fishes were sampled with a shrimp trawl net. Of the 78 species collected, five were resident, 12 temporary and 62 occasional. Juvenile phases of all species were collected. Species with greater IVI values were Cathorops sp., Achirus achirus, Stellifer naso and Colomesus psittacus. No significant differences were obtained for the physical and chemical habitat parameters measured: depth, salinity and transparency, nor in the water levels of the streams even in different hydro-phases of the year. Salinity never dropped to zero and no changes in fish species composition were detected. These results lead us to hypothesize that the impacts of the dike constructed in Manamo Channel also extend to other streams of the Orinoco River Delta and even the one studied (Venado) that empties into the Gulf of Paria, where estuarine conditions prevailed during the entire study period of one year, with no observed changed in the hydrological regimen.
Abstract (es):
Con el objetivo de evaluar el efecto de la regulación de las aguas del caño Manamo (por la construcción de un dique), sobre la ictiofauna bentónica de algunos caños del delta del río Orinoco y Golfo de Paria, se estudió la variación de la estructura comunitaria de peces bentónicos en la desembocadura de tres caños del delta del río Orinoco (Pedernales, Angostura y Manamo) y un caño del golfo de Paria (Venado) durante un ciclo hidrológico anual. De las 78 especies colectadas, cinco fueron residentes, 12 temporales y 61 ocasionales; todas registraron ejemplares en estado juvenil. Las especies con mayores valores de IVI fueron Cathorops sp., Achirus achirus, Stellifer naso y Colomesus psittacus. No se observaron diferencias significativas entre los parámetros físico-químicos analizados (profundidad, salinidad y transparencia), ni a nivel de caños, ni entre hidrofases. La salinidad nunca registró valores menores de 4 % y no se observaron cambios en la composición de especies de la comunidad. Con los resultados obtenidos se plantea la hipótesis de que la construcción del dique sobre el caño Manamo en los años 60, afectó el comportamiento natural de este sistema y de otros caños del delta e incluso del golfo de Paria (caño Venado), registrando en las desembocaduras de todos los caños características de un estuario continuo (sin cambios en el régimen hidrológico y salinidad) durante todo el año.
Keywords:
Community structure, Estuary, Fishes, Manamo Channel, Shrimp trawl (en)
How to Cite
Sánchez-Duarte, P., & Lasso, C. A. (2016). Benthic fish community structure in the Orinoco River Delta andGulf of Paria (Venezuela), fifty years after the construction of adike across Manamo Channel. Biota Colombiana, 17(1). https://doi.org/10.21068/C2016v17r01a06
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