The Coastal Lagoon Cienaga Grande de Santa Marta, Colombia
39
mosa Gaertn., and the buttonwood mangrove Conocarpus erectus L. Three
mangrove physiographies can be recognized. The lagoon is dotted with
small islets of R. mangle and on the alluvial plain a 500-1,000-m-wide belt
of Avicennia-Laguncularia fringes the shores of the lagoon. On the coastal
sandbar, which separates the lagoon from the sea, all four mangrove
species are present. The average height of these stands is 15 m, but 25-mtall trees are common. The diameter at breast height ranges from 25 to
30 em in R. mangle, from 10 to 40 em in A. germinans, and from 12 to 13 em
in Laguncularia racemosa (Cardona and Botero 1995). About eight species
of algae (i.e., Cladophora, Vaucheria, Chaetomorpha, Oscillatoria lutea)
are associated with mangrove prop roots while hydrophilous plants
(Roystonea regia, Heliconia latisphata) are common on poorly drained
soils (slope <1 o/o) near the mangroves. Mangrove forests are habitat for
about 51 species of fish of which three ( Gymnothorax funerbris, Myrophis
platyrhynus, Gambusia sp.) are new additions to the list compiled by Santos-Martinez and Acero (1991). The barnacle Balanus eburneus is the most
abundant (59 o/o of all collected individuals) sessile organism though the
crabs Eurypanopeus dissimilis, Pachygrapsus gracilis, and Petrolisthes
armatus, the polychaete worm Nereis virens, and amphipods are also
abundant. Especially prop roots of red mangrove stands are an important
habitat for more than 44 invertebrates (e.g., bryozoans, mollusks, oysters)
and three fishes (Santos-Martinez and Acero 1991; Catano and GarzonPerreira 1994).
2.4 Trophic Structure
The CGSM is one of the most productive ecosystems among in- and offshore environments along the Caribbean coast (Hernandez and Gocke
1990). The production of both phytoplankton (990g Cm- 2 year- 1 ) and
mangrove litter (15.7tons ha- 1 year- 1 ), 95% of which degrades within
16 weeks, contributes to the carbon budget in the lagoon. Sequential pulses
of primary production by plankton communities and seasonal export of
mangrove detritus sustain high secondary production in the CGSM; thus
the proportion of plankton- or mangrove-derived carbon in tissues of
shrimp and fish varies with seasons and distance from mangrove habitats.
Among fish species, about 67 o/o are carnivores, 15 o/o omnivores, 10 o/o
plankton feeders, 6 o/o ingest detritus, and 2 o/o are herbivores. Some species
are opportunistic ( Centropomus ensiferus, C. undecimalis) and feed at all
levels, while others (i.e., Elops saurus, Tarpon atlanticus) change their diet
from insects to mainly juvenile of Mugilidae and Clupeidae as they grow
39
mosa Gaertn., and the buttonwood mangrove Conocarpus erectus L. Three
mangrove physiographies can be recognized. The lagoon is dotted with
small islets of R. mangle and on the alluvial plain a 500-1,000-m-wide belt
of Avicennia-Laguncularia fringes the shores of the lagoon. On the coastal
sandbar, which separates the lagoon from the sea, all four mangrove
species are present. The average height of these stands is 15 m, but 25-mtall trees are common. The diameter at breast height ranges from 25 to
30 em in R. mangle, from 10 to 40 em in A. germinans, and from 12 to 13 em
in Laguncularia racemosa (Cardona and Botero 1995). About eight species
of algae (i.e., Cladophora, Vaucheria, Chaetomorpha, Oscillatoria lutea)
are associated with mangrove prop roots while hydrophilous plants
(Roystonea regia, Heliconia latisphata) are common on poorly drained
soils (slope <1 o/o) near the mangroves. Mangrove forests are habitat for
about 51 species of fish of which three ( Gymnothorax funerbris, Myrophis
platyrhynus, Gambusia sp.) are new additions to the list compiled by Santos-Martinez and Acero (1991). The barnacle Balanus eburneus is the most
abundant (59 o/o of all collected individuals) sessile organism though the
crabs Eurypanopeus dissimilis, Pachygrapsus gracilis, and Petrolisthes
armatus, the polychaete worm Nereis virens, and amphipods are also
abundant. Especially prop roots of red mangrove stands are an important
habitat for more than 44 invertebrates (e.g., bryozoans, mollusks, oysters)
and three fishes (Santos-Martinez and Acero 1991; Catano and GarzonPerreira 1994).
2.4 Trophic Structure
The CGSM is one of the most productive ecosystems among in- and offshore environments along the Caribbean coast (Hernandez and Gocke
1990). The production of both phytoplankton (990g Cm- 2 year- 1 ) and
mangrove litter (15.7tons ha- 1 year- 1 ), 95% of which degrades within
16 weeks, contributes to the carbon budget in the lagoon. Sequential pulses
of primary production by plankton communities and seasonal export of
mangrove detritus sustain high secondary production in the CGSM; thus
the proportion of plankton- or mangrove-derived carbon in tissues of
shrimp and fish varies with seasons and distance from mangrove habitats.
Among fish species, about 67 o/o are carnivores, 15 o/o omnivores, 10 o/o
plankton feeders, 6 o/o ingest detritus, and 2 o/o are herbivores. Some species
are opportunistic ( Centropomus ensiferus, C. undecimalis) and feed at all
levels, while others (i.e., Elops saurus, Tarpon atlanticus) change their diet
from insects to mainly juvenile of Mugilidae and Clupeidae as they grow