19 Eastern Pacific Coral Reef Ecosystems
P.W.GLYNN
19.1 Introduction
Although not as common as coastal soft bottom, estuarine and mangrove
ecosystems, reef-building coral communities and coral reefs occur in the
eastern tropical Pacific region, ranging from northern Mexico to southern
Ecuador, and are present on all offshore islands as well. Coral reefs are waveresistant limestone structures built dominantly by the vertical accumulation of coral skeletons. In contrast, coral communities are loosely spaced to
dense aggregations of coral colonies that veneer underlying substrates
whose origin is other than the actively growing corals they support. This
distinction is especially important in the eastern Pacific where coral communities can be easily confused with true structural coral reefs. Both coral
reefs and coral communities consist of coral colonies that host zooxanthellae (endosymbiotic dinoflagellates), which are dependent on solar energy,
and are thus confined to relatively shallow depths. Eastern Pacific coral reefs
do not dominate coastal seascapes because they are relatively small and patchy in distribution, their presence depending upon a combination of requisite hydrographic and geomorphologic conditions. Also, eastern Pacific
coral reefs are seldom visible to non-divers because they rarely build islands
or possess emergent algal ridges, and are exposed for only brief periods during extreme low tides. However, where reefs are present they boost local biodiversity, provide habitats for a variety of fishes and shellfish, and offer attractive vistas for diver-oriented ecotourism. With the increasing attention
and scientific interest directed toward eastern Pacific coral reefs since about
the 1970s, our knowledge of this ecosystem has grown immeasurably (Cortes 1997) but the scope of new information is highly imbalanced. While
much new understanding has been reached in the areas of systematics,
population and community ecology, biogeography and reef growth history,
no progress has been made at the ecosystem level focusing on trophic structure, nutrient cycling or productivity. Of necessity, therefore, the following
essay will emphasize our level of understanding in the former disciplines.
Ecological Studies, Vol. 144
U. Seeliger and B. Kjerfve (eds.)
Coastal Marine Ecosystems of Latin America
©Springer-Verlag Berlin Heidelberg 2001
P.W.GLYNN
19.1 Introduction
Although not as common as coastal soft bottom, estuarine and mangrove
ecosystems, reef-building coral communities and coral reefs occur in the
eastern tropical Pacific region, ranging from northern Mexico to southern
Ecuador, and are present on all offshore islands as well. Coral reefs are waveresistant limestone structures built dominantly by the vertical accumulation of coral skeletons. In contrast, coral communities are loosely spaced to
dense aggregations of coral colonies that veneer underlying substrates
whose origin is other than the actively growing corals they support. This
distinction is especially important in the eastern Pacific where coral communities can be easily confused with true structural coral reefs. Both coral
reefs and coral communities consist of coral colonies that host zooxanthellae (endosymbiotic dinoflagellates), which are dependent on solar energy,
and are thus confined to relatively shallow depths. Eastern Pacific coral reefs
do not dominate coastal seascapes because they are relatively small and patchy in distribution, their presence depending upon a combination of requisite hydrographic and geomorphologic conditions. Also, eastern Pacific
coral reefs are seldom visible to non-divers because they rarely build islands
or possess emergent algal ridges, and are exposed for only brief periods during extreme low tides. However, where reefs are present they boost local biodiversity, provide habitats for a variety of fishes and shellfish, and offer attractive vistas for diver-oriented ecotourism. With the increasing attention
and scientific interest directed toward eastern Pacific coral reefs since about
the 1970s, our knowledge of this ecosystem has grown immeasurably (Cortes 1997) but the scope of new information is highly imbalanced. While
much new understanding has been reached in the areas of systematics,
population and community ecology, biogeography and reef growth history,
no progress has been made at the ecosystem level focusing on trophic structure, nutrient cycling or productivity. Of necessity, therefore, the following
essay will emphasize our level of understanding in the former disciplines.
Ecological Studies, Vol. 144
U. Seeliger and B. Kjerfve (eds.)
Coastal Marine Ecosystems of Latin America
©Springer-Verlag Berlin Heidelberg 2001