5 The ltamaraca Estuarine Ecosystem, Brazil
C. MEDEIROS, B. KJERFVE, M. ARAUJO, and S. NEUMANN-LEITAO
5.1 Introduction
In northeastern Brazil (7°34'-7°55' Sand 34°48'-34°52' W), the tropical Itamaraca estuary system ( 824 km 2 ) was formed during the early Holocene. A
fault which gave origin to the Santa Cruz Channel was flooded by seawater
and connected with the South Atlantic Ocean by the Catuama and Orange
entrance (Fig. 5.1). Offshore regions typically have a series of two or three
parallel sandstone reefs (20-60 m wide) which consist of cemented sand
(20-80% of quartz and biogenic detritus) and become exposed during low
waters, as well as eight to ten permanently submerged reef lines (Mabesone
1964). Most of the exposed and submersed reefs were formed during
Holocene sea level still-stands (Morais 1970) and some are still being
formed. Remnant reefs on land were presumably formed during temporary still-stands of the Quaternary regression phase (Ottmann 1960).
The discontinuous sandstone ridges, as well as reefs and sand banks north
of the Catuama and south of the Orange entrance, form a semi-open elongated lagoon-like environment ("inner sea") which restricts the exchange
of water between the Santa Cruz Channel and offshore areas (Medeiros
and Kjerfve 1993; Fig. 5.1).
5.2 Environmental Setting
The wind regime in the Itamaraca area is determined by the position of the
semi-stationary anticyclone of South America (Ratisbona 1976). Prevailing
winds are southeast trade winds with a mean velocity of 3.2 m s- 1 that tends
to increase ( 4.0 m s- 1 ) during July. Owing to continental warming, barometric pressure decreases introduce a northerly component, and prevailing
winds (mean 2.6 m s- 1 ) during the dry season (September to January) blows
from the northeast mainly in December-January. The climate is tropical,
Ecological Studies, Vol. 144
U. Seeliger and B. Kjerfve (eds.)
Coastal Marine Ecosystems of Latin America
© Springer-Verlag Berlin Heidelberg 2001
C. MEDEIROS, B. KJERFVE, M. ARAUJO, and S. NEUMANN-LEITAO
5.1 Introduction
In northeastern Brazil (7°34'-7°55' Sand 34°48'-34°52' W), the tropical Itamaraca estuary system ( 824 km 2 ) was formed during the early Holocene. A
fault which gave origin to the Santa Cruz Channel was flooded by seawater
and connected with the South Atlantic Ocean by the Catuama and Orange
entrance (Fig. 5.1). Offshore regions typically have a series of two or three
parallel sandstone reefs (20-60 m wide) which consist of cemented sand
(20-80% of quartz and biogenic detritus) and become exposed during low
waters, as well as eight to ten permanently submerged reef lines (Mabesone
1964). Most of the exposed and submersed reefs were formed during
Holocene sea level still-stands (Morais 1970) and some are still being
formed. Remnant reefs on land were presumably formed during temporary still-stands of the Quaternary regression phase (Ottmann 1960).
The discontinuous sandstone ridges, as well as reefs and sand banks north
of the Catuama and south of the Orange entrance, form a semi-open elongated lagoon-like environment ("inner sea") which restricts the exchange
of water between the Santa Cruz Channel and offshore areas (Medeiros
and Kjerfve 1993; Fig. 5.1).
5.2 Environmental Setting
The wind regime in the Itamaraca area is determined by the position of the
semi-stationary anticyclone of South America (Ratisbona 1976). Prevailing
winds are southeast trade winds with a mean velocity of 3.2 m s- 1 that tends
to increase ( 4.0 m s- 1 ) during July. Owing to continental warming, barometric pressure decreases introduce a northerly component, and prevailing
winds (mean 2.6 m s- 1 ) during the dry season (September to January) blows
from the northeast mainly in December-January. The climate is tropical,
Ecological Studies, Vol. 144
U. Seeliger and B. Kjerfve (eds.)
Coastal Marine Ecosystems of Latin America
© Springer-Verlag Berlin Heidelberg 2001