Bastiaan Knoppers . Bjorn Kjerfve
Coastal lagoons border more than 13%, or 32 000 km, of the world's continental
coasts, with lagoon coasts in South America occupying 12.2% (Cromwell 1971). Lagoons
playa substantial role in the transport, modification, and accumulation of matter at
the land-sea interface (Kjerfve and Magill 1989; Knoppers 1994). Allochthonous matter introduced by the atmosphere, rivers, ground water, the sea, and bordering vegetation, is efficiently retained and recycled as a result of the lagoon enclosure, restricted
tidal flushing, and close coupling between pelagic and benthic compartments. Primary
production rates usually range from 200-500 g C m- 2 yr- l (Nixon 1982; Knoppers 1994),
and tile global contribution of coastal lagoon primary production reaches 1011 kg C yr-I,
which is approximately the same as the production rate of global coastal upwelling
(Knoppers 1994). Fishery yields are commonly 50-120 t ha- l yr- l , and a variety of commercially valuable species breed in coastal lagoons (Nixon 1982; Pauly and YanezArancibia 1994). At present, the symptoms of demographic expansion, such. as material waste disposal, cultural eutrophication, engineering works, and uncontrolled
management of watersheds, are adversely affecting coastal lagoons (Bruun 1994), including those of Brazil. It is our objective to characterize some of the salient physical
and biogeochemical features of the major and most intensely studied coastal lagoons
of southeastern and southern Brazil.
3.2
Coastal Lagoons in Brazil
The Brazilian coast stretches for 7700 km from 4°N to 34°S latitude. It can be divided
into four geological sections (Guerra 1962):
1. the northern Quaternary coast (4°N to 3°S),
2. the eastern Tertiary coast (3°S to 20 0 S),
3. the southern Granitic coast (20
0
S to 29°S), and
4. the southern Quaternary coast (29°S to 34°S) (Fig. 3.2).
Fig. 3.2. The four main divisions of the Brazil coast (north
Quaternary, east Tertiary, south
granitic, and south Quaternary)
and distribution of macro, meso,
and micro tides; dark shading
indicate Quaternary deposits
.-~-.------,-------.------.-----------4 · N
Nonh Quaternary
coast
- - 4' S
EastTeniary
coast
- - - 20 ' S
South Granitic
coast
- - 2 9 ' S
South Quaternary
coast
~-------------------------------------34 ' S
Coastal lagoons border more than 13%, or 32 000 km, of the world's continental
coasts, with lagoon coasts in South America occupying 12.2% (Cromwell 1971). Lagoons
playa substantial role in the transport, modification, and accumulation of matter at
the land-sea interface (Kjerfve and Magill 1989; Knoppers 1994). Allochthonous matter introduced by the atmosphere, rivers, ground water, the sea, and bordering vegetation, is efficiently retained and recycled as a result of the lagoon enclosure, restricted
tidal flushing, and close coupling between pelagic and benthic compartments. Primary
production rates usually range from 200-500 g C m- 2 yr- l (Nixon 1982; Knoppers 1994),
and tile global contribution of coastal lagoon primary production reaches 1011 kg C yr-I,
which is approximately the same as the production rate of global coastal upwelling
(Knoppers 1994). Fishery yields are commonly 50-120 t ha- l yr- l , and a variety of commercially valuable species breed in coastal lagoons (Nixon 1982; Pauly and YanezArancibia 1994). At present, the symptoms of demographic expansion, such. as material waste disposal, cultural eutrophication, engineering works, and uncontrolled
management of watersheds, are adversely affecting coastal lagoons (Bruun 1994), including those of Brazil. It is our objective to characterize some of the salient physical
and biogeochemical features of the major and most intensely studied coastal lagoons
of southeastern and southern Brazil.
3.2
Coastal Lagoons in Brazil
The Brazilian coast stretches for 7700 km from 4°N to 34°S latitude. It can be divided
into four geological sections (Guerra 1962):
1. the northern Quaternary coast (4°N to 3°S),
2. the eastern Tertiary coast (3°S to 20 0 S),
3. the southern Granitic coast (20
0
S to 29°S), and
4. the southern Quaternary coast (29°S to 34°S) (Fig. 3.2).
Fig. 3.2. The four main divisions of the Brazil coast (north
Quaternary, east Tertiary, south
granitic, and south Quaternary)
and distribution of macro, meso,
and micro tides; dark shading
indicate Quaternary deposits
.-~-.------,-------.------.-----------4 · N
Nonh Quaternary
coast
- - 4' S
EastTeniary
coast
- - - 20 ' S
South Granitic
coast
- - 2 9 ' S
South Quaternary
coast
~-------------------------------------34 ' S