northwesterly direction along the coast of Perú to the Ecuadorian coast where it
joins the South Equatorial Current system (Fig. 6.1). This current system prevails
from May to November and it represents a ‘‘change of season’’ in Ecuador, as it
significantly decreases the sea surface and air temperatures. This system provides
favorable conditions for fisheries, because its waters are rich in nutrients. The
greatest intensity of this current is between July and September. It gradually
weakens and disappears completely in December, when the Panamá Current,
warm and low in nutrients, starts to dominate Ecuadorian waters (Fig. 6.1).
The Equatorial Undercurrent
This current runs eastwards along the equatorial Pacific right in front of Ecuador,
reaching speeds of approximately 1.5 m s
-1 . When it reaches the Galápagos
Islands it weakens and splits into two branches, one north and one south of the
archipelago. The southern branch moves to southeast and generates outcrops that
occur along the northern coast of Perú (Fig. 6.1).
The Ecuadorian Coastal Current (ECC)
The Ecuadorian Coastal Current (ECC) moves northwards, paralleling the coast of
Ecuador. The northern boundary of this current is linked to the position of the
ITCZ, and begins to descend toward the south during December (Moreano 1983).
An important aspect to consider is the influence of the Gulf of Guayaquil in the
area around its mouth, because it has a well defined circulation regime. Yet it
somehow alters the normal course of the circulation of the ECC, mainly through
the influence of tidal currents that are stronger into the Gulf (Allauca 1990;
Fig. 6.1). Two semidiurnal tides occur both along mainland Ecuador and at the
Galápagos. The ECC influences the local currents along the continental coast of
Ecuador, and the marine ecosystems and coastal geomorphology.
6.1.2 The Galápagos Islands
Geography and Climate
The Galápagos Islands are situated astride the equator, between 01°40
0 N and
01°25
0 S, and between 89°15
0 W and 92°00
0 W, about 1,000 km from the Ecuadorian
mainland. These oceanic islands have been in existence for at least 3.3 million
years. They are made up of 13 major islands, the smallest having an area of
14.1 km
2 (Genovesa Island), and the largest of 4,588 km
2 (130 9 40 km, Isabela
Island). There are also over 115 islets and rocks, most of which have vegetation.
The most recent islands, Fernandina and Isabela, are moving slowly from west to
186
J. Sonnenholzner et al.
joins the South Equatorial Current system (Fig. 6.1). This current system prevails
from May to November and it represents a ‘‘change of season’’ in Ecuador, as it
significantly decreases the sea surface and air temperatures. This system provides
favorable conditions for fisheries, because its waters are rich in nutrients. The
greatest intensity of this current is between July and September. It gradually
weakens and disappears completely in December, when the Panamá Current,
warm and low in nutrients, starts to dominate Ecuadorian waters (Fig. 6.1).
The Equatorial Undercurrent
This current runs eastwards along the equatorial Pacific right in front of Ecuador,
reaching speeds of approximately 1.5 m s
-1 . When it reaches the Galápagos
Islands it weakens and splits into two branches, one north and one south of the
archipelago. The southern branch moves to southeast and generates outcrops that
occur along the northern coast of Perú (Fig. 6.1).
The Ecuadorian Coastal Current (ECC)
The Ecuadorian Coastal Current (ECC) moves northwards, paralleling the coast of
Ecuador. The northern boundary of this current is linked to the position of the
ITCZ, and begins to descend toward the south during December (Moreano 1983).
An important aspect to consider is the influence of the Gulf of Guayaquil in the
area around its mouth, because it has a well defined circulation regime. Yet it
somehow alters the normal course of the circulation of the ECC, mainly through
the influence of tidal currents that are stronger into the Gulf (Allauca 1990;
Fig. 6.1). Two semidiurnal tides occur both along mainland Ecuador and at the
Galápagos. The ECC influences the local currents along the continental coast of
Ecuador, and the marine ecosystems and coastal geomorphology.
6.1.2 The Galápagos Islands
Geography and Climate
The Galápagos Islands are situated astride the equator, between 01°40
0 N and
01°25
0 S, and between 89°15
0 W and 92°00
0 W, about 1,000 km from the Ecuadorian
mainland. These oceanic islands have been in existence for at least 3.3 million
years. They are made up of 13 major islands, the smallest having an area of
14.1 km
2 (Genovesa Island), and the largest of 4,588 km
2 (130 9 40 km, Isabela
Island). There are also over 115 islets and rocks, most of which have vegetation.
The most recent islands, Fernandina and Isabela, are moving slowly from west to
186
J. Sonnenholzner et al.