18 The Estuary Ecosystem of Buenaventura Bay,
Colombia
J.R. CANTERA and J.F. BLANCO
18.1 Introduction
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; Martinez 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 (Galvis and Mojica 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 Anchicaya 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).
18.2 Environmental Settings
Buenaventura Bay is located within the Inter-Tropical Convergence Zone
(ITCZ). As the low pressure belt of the zone moves north and south between 10°N and 3°S, it passes over Buenaventura Bay and causes two rainy
periods from September to November and April to June with mean monthly precipitation exceeding 567 mm, interrupted by periods with lower precipitation (mean 374 mm; Eslava 1993). Furthermore, the high (3,500 m)
Ecological Studies, Vol. 144
U. Seeliger and B. Kjerfve (eds.)
Coastal Marine Ecosystems of Latin America
©Springer-Verlag Berlin Heidelberg 2001
Colombia
J.R. CANTERA and J.F. BLANCO
18.1 Introduction
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; Martinez 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 (Galvis and Mojica 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 Anchicaya 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).
18.2 Environmental Settings
Buenaventura Bay is located within the Inter-Tropical Convergence Zone
(ITCZ). As the low pressure belt of the zone moves north and south between 10°N and 3°S, it passes over Buenaventura Bay and causes two rainy
periods from September to November and April to June with mean monthly precipitation exceeding 567 mm, interrupted by periods with lower precipitation (mean 374 mm; Eslava 1993). Furthermore, the high (3,500 m)
Ecological Studies, Vol. 144
U. Seeliger and B. Kjerfve (eds.)
Coastal Marine Ecosystems of Latin America
©Springer-Verlag Berlin Heidelberg 2001