The Estuary Ecosystem of Buenaventura Bay, Colombia

Abstract

Buenaventura Bay at the Central Pacific Coast of Colombia is classified as a drowned valley (Fig. 18.1). The bay is located between two faults (NE-SW and NW-SE) on Tertiary consolidated rocky and sedimentary cliffs and on Quaternary mobile sediment platforms (Cantera 1991; Martínez 1993). The NE-SW fault is responsible for uplifting the northern shore of the bay, which is dominated by rocky cliffs, occasional rocky shores and intrusions of sand and silt (Gálvis and Mojíca 1993). Many depositional beaches of northern shore embayments are formed by sediments which originated from cliff erosion and decomposing mangrove litter. Depositional fans around the mouth of the Dagua and Anchicayá rivers characterize the southern shore of Buenaventura Bay. The composition of the fans varies from silt to sand, depending on the origin of sediments and the balance between river discharge and tidal flow (Lobo-Guerrero 1993). The addition of sediments and their transport by rivers and tides also causes their continuous deposition in the navigation channel and leads to a prograding southern coast (CAE 1995; Univalle 1997).