(bioerosion). These cliffs have nearly vertical walls that fall directly into the sea or
may be separated from it by sandy beaches. Most of these are located in areas
exposed to strong waves and high hydrodynamic conditions. The erosion forms
caverns and abrasion terraces, which are inhabited by sea urchins of the family
Cidariidae (Eucidaris thouarsii and Hesperocidaris asteriscus), Diadematidae
(Centrostephanus coronatus), and Echinometridae (Echinometra vanbrunti). Some
ophiuroids can be found occasionally (Ophioderma teres, O. panamensis, and
Ophiocoma alexandri).
Rocky Shores
This habitat is located along the whole Pacific coast. It is characterized by igneous
and sedimentary rocks at different stages of fragmentation and by variability of
environmental conditions. Rocky platforms are covered with hard blocks of various sizes (20 cm to 1 m in diameter), pebbles (5–10 cm), or gravel (2–5 cm) or
are partially covered by sand or mud. In some cases these platforms only emerge
during the minimal astronomic tides. This ecosystem is one of the richest in
species, with 23 species (two asteroids, seven echinoids, nine ophiuroids, five
holothurians). The most common species of rocky shores, living under rocks or in
cavities or holes, are: Phataria unifascialis, Pharia pyramidata, E. thouarsii,
H. asteriscus, D. mexicanum, C. coronatus, Echinometra vanbrunti, O teres,
O. panamensis, Ophiothrix (Ophiothrix) spiculata (associated with clusters of
polychaetes and sponges), Ophiocoma aethiops, Ophionereis annulata, Ophiactis
savignyi, and Holothuria (Cystipus) inhabilis. O. savignyi and Ophiothela mirabilis are found associated with the gorgonian Leptogorgia alba (Neira and Cantera
2005).
Coral Reefs
The coral areas are found mainly in some localities of the Chocó (Cabo Marzo,
Cupica Gulf, Utría Bight) and the islands of Gorgona and Malpelo (Zapata and
Vargas-Ángel 2003). The major coral reefs are found on the island of Gorgona,
where there are true reefs 2 or 3 km long, and some coral patches with species of
scleractinian corals of the genera Pocillopora, Pavona, Porites, Psammocora.
These reefs have four areas: the backreef, comprising sandy areas and a platform
with dead coral and few living colonies (depth between 1 and 3.5 m); a platformcrest region, with the highest coralline coverage (but largely dead) and dominated
by Pocillopora coral (depth between 0.5 and 3 m); a reef front, with a decreased
coverage of Pocillopora and an increased number of massive coral colonies (depth
between 1 and 4 m at low tide, reaching 8 m at high tide); and finally, a reef slope,
depth to 12 m, characterized by low coral coverage, and some dead colonies
scattered on the sandy bottom. Patches also occur, with massive and branching
corals (Cantera et al. 2001; Zapata 2001). Malpelo Island has coral colonies
170
M. Benavides-Serrato et al.
may be separated from it by sandy beaches. Most of these are located in areas
exposed to strong waves and high hydrodynamic conditions. The erosion forms
caverns and abrasion terraces, which are inhabited by sea urchins of the family
Cidariidae (Eucidaris thouarsii and Hesperocidaris asteriscus), Diadematidae
(Centrostephanus coronatus), and Echinometridae (Echinometra vanbrunti). Some
ophiuroids can be found occasionally (Ophioderma teres, O. panamensis, and
Ophiocoma alexandri).
Rocky Shores
This habitat is located along the whole Pacific coast. It is characterized by igneous
and sedimentary rocks at different stages of fragmentation and by variability of
environmental conditions. Rocky platforms are covered with hard blocks of various sizes (20 cm to 1 m in diameter), pebbles (5–10 cm), or gravel (2–5 cm) or
are partially covered by sand or mud. In some cases these platforms only emerge
during the minimal astronomic tides. This ecosystem is one of the richest in
species, with 23 species (two asteroids, seven echinoids, nine ophiuroids, five
holothurians). The most common species of rocky shores, living under rocks or in
cavities or holes, are: Phataria unifascialis, Pharia pyramidata, E. thouarsii,
H. asteriscus, D. mexicanum, C. coronatus, Echinometra vanbrunti, O teres,
O. panamensis, Ophiothrix (Ophiothrix) spiculata (associated with clusters of
polychaetes and sponges), Ophiocoma aethiops, Ophionereis annulata, Ophiactis
savignyi, and Holothuria (Cystipus) inhabilis. O. savignyi and Ophiothela mirabilis are found associated with the gorgonian Leptogorgia alba (Neira and Cantera
2005).
Coral Reefs
The coral areas are found mainly in some localities of the Chocó (Cabo Marzo,
Cupica Gulf, Utría Bight) and the islands of Gorgona and Malpelo (Zapata and
Vargas-Ángel 2003). The major coral reefs are found on the island of Gorgona,
where there are true reefs 2 or 3 km long, and some coral patches with species of
scleractinian corals of the genera Pocillopora, Pavona, Porites, Psammocora.
These reefs have four areas: the backreef, comprising sandy areas and a platform
with dead coral and few living colonies (depth between 1 and 3.5 m); a platformcrest region, with the highest coralline coverage (but largely dead) and dominated
by Pocillopora coral (depth between 0.5 and 3 m); a reef front, with a decreased
coverage of Pocillopora and an increased number of massive coral colonies (depth
between 1 and 4 m at low tide, reaching 8 m at high tide); and finally, a reef slope,
depth to 12 m, characterized by low coral coverage, and some dead colonies
scattered on the sandy bottom. Patches also occur, with massive and branching
corals (Cantera et al. 2001; Zapata 2001). Malpelo Island has coral colonies
170
M. Benavides-Serrato et al.