7.2.2 Ecology
Studies on populations and ecology of echinoderms have been made primarily in the
central-western and eastern coasts of the country. Most refer to abundance and
distribution of the species in the Class Echinoidea, Holothuroidea and Ophiuroidea.
With respect to the Class Echinoidea, six of the seven species known for the
Caribbean Sea have been reported locally (Hendler et al. 1995): Lytechinus
variegatus (Lamarck, 1816), Tripneustes ventricosus Lamarck, 1816, Diadema
antillarum Philippi, 1845, Arbacia punctulata (Lamarck, 1816), Echinometra
lucunter (Linnaeus, 1758) and Echinometra viridis Agassiz, 1863. These species are
distributed along the coast from Falcón to Sucre and Nueva Esparta states
(Cruz-Motta 2007). The sand dollar, Mellita quinquiesperforata (Leske, 1778) has
been reported from the coasts of Golfo Triste (Penchaszadeh and Molinet 1994).
Most records have been made between 0 and 50 m depth, especially on rocky
substrates and seagrass (Cruz-Motta 2007). For the Atlantic region, most species are
irregular urchins, among which are Agassizia excentrica Agassiz, 1869, Brissopsis
elongata Mortensen, 1907, Clypeaster euclastus Clark, 1941 and Schizaster orbignyanus A. Agassiz 1880 (Martínez 1969; Francisco and Pauls 2008).
Diadema antillarum is distributed along the entire continental coast and oceanic
islands of Venezuela, associated primarily with coral communities. The abundance
of this species in some coastal locations, before the massive mortality registered in
1984, was similar to those found in the rest of the Caribbean Sea. However, only in
the eastern zone of the country is there information at the population level before
and after the demise that this species underwent in the entire Caribbean Sea, which
also affected the populations present in Venezuela (Pauls 1982; Noriega et al.
2006). In Mochima Bay, eastern Sucre state, the average density before the
massive mortality varied between 0.28 and 4 ind m
-2 (Pauls 1982). After the mass
mortality, the average density decreased to 0.15 ind m
-2 in 2000 and 0.47 ind m
2
in 2002 (Noriega et al. 2006). On the other hand, there have been records of
densities from 0.28 ind m
-2 in 2002 to 1.05 ind m
-2 in 2003 in Oricao Bay, and
from 0.84 ind m
-2 (2002) to 0.74 ind m
-2 (2003) in Chichiriviche de la Costa,
both locations in the central coast of Venezuela (Noriega et al. 2006). The populations of D. antillarum in Morrocoy National Park and Cuare Wildlife Refuge
showed the highest average densities at Playuela (0.43 ind m
-2 ) and Cayo Sur
(0.95 ind m
-2 ), while the remaining areas showed densities \0.1 ind m
-2 . The
density found in Playuela in 2003 is lower than the one reported before the mass
mortality event (0.58–3.64 ind m
-2
) (Noriega et al. 2006). In Morrocoy National
Park, Weil et al. (1984) reported average densities between 2.6 and 3.7 ind m
-2 on
three reefs (Pescadores, Playuela and Caiman). The highest densities (4.0–7.0 ind
m
-2 ) were found in the shallow and frontal zones of the reefs, characterized by a
high structural complexity of the substrate. Low densities (1.5–4.0 ind m
-2 ) were
found in deep zones of the reef platform with low to intermediate structural
complexity. Densities of D. antillarum in Los Roques Archipelago National Park,
specifically in Herradura Reef, varied between 0.22 and 0.23 ind m
-2 (Noriega
240
C. Lodeiros et al.
Studies on populations and ecology of echinoderms have been made primarily in the
central-western and eastern coasts of the country. Most refer to abundance and
distribution of the species in the Class Echinoidea, Holothuroidea and Ophiuroidea.
With respect to the Class Echinoidea, six of the seven species known for the
Caribbean Sea have been reported locally (Hendler et al. 1995): Lytechinus
variegatus (Lamarck, 1816), Tripneustes ventricosus Lamarck, 1816, Diadema
antillarum Philippi, 1845, Arbacia punctulata (Lamarck, 1816), Echinometra
lucunter (Linnaeus, 1758) and Echinometra viridis Agassiz, 1863. These species are
distributed along the coast from Falcón to Sucre and Nueva Esparta states
(Cruz-Motta 2007). The sand dollar, Mellita quinquiesperforata (Leske, 1778) has
been reported from the coasts of Golfo Triste (Penchaszadeh and Molinet 1994).
Most records have been made between 0 and 50 m depth, especially on rocky
substrates and seagrass (Cruz-Motta 2007). For the Atlantic region, most species are
irregular urchins, among which are Agassizia excentrica Agassiz, 1869, Brissopsis
elongata Mortensen, 1907, Clypeaster euclastus Clark, 1941 and Schizaster orbignyanus A. Agassiz 1880 (Martínez 1969; Francisco and Pauls 2008).
Diadema antillarum is distributed along the entire continental coast and oceanic
islands of Venezuela, associated primarily with coral communities. The abundance
of this species in some coastal locations, before the massive mortality registered in
1984, was similar to those found in the rest of the Caribbean Sea. However, only in
the eastern zone of the country is there information at the population level before
and after the demise that this species underwent in the entire Caribbean Sea, which
also affected the populations present in Venezuela (Pauls 1982; Noriega et al.
2006). In Mochima Bay, eastern Sucre state, the average density before the
massive mortality varied between 0.28 and 4 ind m
-2 (Pauls 1982). After the mass
mortality, the average density decreased to 0.15 ind m
-2 in 2000 and 0.47 ind m
2
in 2002 (Noriega et al. 2006). On the other hand, there have been records of
densities from 0.28 ind m
-2 in 2002 to 1.05 ind m
-2 in 2003 in Oricao Bay, and
from 0.84 ind m
-2 (2002) to 0.74 ind m
-2 (2003) in Chichiriviche de la Costa,
both locations in the central coast of Venezuela (Noriega et al. 2006). The populations of D. antillarum in Morrocoy National Park and Cuare Wildlife Refuge
showed the highest average densities at Playuela (0.43 ind m
-2 ) and Cayo Sur
(0.95 ind m
-2 ), while the remaining areas showed densities \0.1 ind m
-2 . The
density found in Playuela in 2003 is lower than the one reported before the mass
mortality event (0.58–3.64 ind m
-2
) (Noriega et al. 2006). In Morrocoy National
Park, Weil et al. (1984) reported average densities between 2.6 and 3.7 ind m
-2 on
three reefs (Pescadores, Playuela and Caiman). The highest densities (4.0–7.0 ind
m
-2 ) were found in the shallow and frontal zones of the reefs, characterized by a
high structural complexity of the substrate. Low densities (1.5–4.0 ind m
-2 ) were
found in deep zones of the reef platform with low to intermediate structural
complexity. Densities of D. antillarum in Los Roques Archipelago National Park,
specifically in Herradura Reef, varied between 0.22 and 0.23 ind m
-2 (Noriega
240
C. Lodeiros et al.