transportation towards storage places due to the eventual metal fatigue and rupture
of pipes, pumps and tanks (López et al. 1999). Populations of echnoids like
E. lucunter could be reduced by 80 % after an oil spill in the coasts of Panamá
(Jackson et al. 1989). Furthermore, oil spills (crude or refined) significantly affect
the early larval stages of echinoderms (Jangoux 1984). These effects vary
according to the composition of the hydrocarbon (Allen 1971).
More than 50 % of the human population in Venezuela is concentrated in or
near the coasts, increasing sedimentation considerably because of infrastructure
developments as well as the pollution by untreated sewage (Díaz-Martín 1995).
Other contaminants, sub-products of the industry and agriculture, can also become
a threat to the fauna in coastal marine environments of Venezuela (Díaz-Martín
1995; Penchaszadeh et al. 2000). Unfortunately, Venezuela does not have effective
and widespread sewage treatments and most contaminants reach the sea without
previous processing. This can produce high oxygen demand, eutrophication,
accumulation of heavy metals and other processes (Penchaszadeh et al. 2000). In
this sense, concentrations of some heavy metals, in particular mercury, have been
measured in asteroids like Luidia clathrata, L. bareimaes, L. senegalensis and
Tethyaster vestitus in the zone of Golfo Triste. Concentrations ranged between 3.8
and 8.87 lg g dry weight
-1 in the gonads (Iglesias and Penchaszadeh 1983).
Concentrations of the metals Al, Cu, Mn, Ni, Pb, and Zn were measured in the
eviscerated digestive tissue of two species of holothurians (I. badionotus and
H. mexicana) in Morrocoy National Park. Concentrations of Cu, Ni, Pb and Zn
were higher than in the surrounding sediments (Laboy-Nieves and Conde 2001).
Industrial trawl fishing, recently prohibited by the Venezuelan government
(actually in March 2009), was considered a threat to echinoderms. However,
echinoderms represented a minor portion (\1%) of the incidental capture in the
trawls in eastern Venezuela (Marcano et al. 2001), although their representation in
the catches from trawl fisheries has been little studied in other parts of the world
(Alverson et al. 1994; Kelleher 2005). Unpublished observations from one of the
authors (JA) indicate echinoderm discards by industrial trawlers in eastern
Venezuela included echinoids, asteroids, ophiuroids and, in a lesser proportion,
holothuroids and crinoids. Most of them, with the exception of ophiuroids due to
their fragile structure, were returned alive to the ocean. Hill and Wasemberg
(1990) examined the fate of discards from shrimp trawlers in Torres Strait,
northern Australia, and recorded an 88 % survival rate in the asteroid, Astropecten
sp. However, the trawl gear can modify the habitat and generate a reduction in the
density of populations of echinoderms and other groups of benthic animals
(Bergman and Hup 1992). In this sense, the interdiction of industrial trawling in
Venezuelan waters could have reduced the threat to a considerable number of
organisms whose capture was intended or not for consumption. It could also have
prevented a possible suspension of contaminants present in the sediment, like
DDT, PCBs and PAHs, reducing their incorporation into the trophic chains
through the plankton (Schiff 2000). The interdiction only affected industrial
trawling, because artisanal trawling is still actively practiced in shallow areas of
eastern Venezuela. For example, trawl fishing of the turkey wing, A. zebra
7 Echinoderms from Venezuela
263
of pipes, pumps and tanks (López et al. 1999). Populations of echnoids like
E. lucunter could be reduced by 80 % after an oil spill in the coasts of Panamá
(Jackson et al. 1989). Furthermore, oil spills (crude or refined) significantly affect
the early larval stages of echinoderms (Jangoux 1984). These effects vary
according to the composition of the hydrocarbon (Allen 1971).
More than 50 % of the human population in Venezuela is concentrated in or
near the coasts, increasing sedimentation considerably because of infrastructure
developments as well as the pollution by untreated sewage (Díaz-Martín 1995).
Other contaminants, sub-products of the industry and agriculture, can also become
a threat to the fauna in coastal marine environments of Venezuela (Díaz-Martín
1995; Penchaszadeh et al. 2000). Unfortunately, Venezuela does not have effective
and widespread sewage treatments and most contaminants reach the sea without
previous processing. This can produce high oxygen demand, eutrophication,
accumulation of heavy metals and other processes (Penchaszadeh et al. 2000). In
this sense, concentrations of some heavy metals, in particular mercury, have been
measured in asteroids like Luidia clathrata, L. bareimaes, L. senegalensis and
Tethyaster vestitus in the zone of Golfo Triste. Concentrations ranged between 3.8
and 8.87 lg g dry weight
-1 in the gonads (Iglesias and Penchaszadeh 1983).
Concentrations of the metals Al, Cu, Mn, Ni, Pb, and Zn were measured in the
eviscerated digestive tissue of two species of holothurians (I. badionotus and
H. mexicana) in Morrocoy National Park. Concentrations of Cu, Ni, Pb and Zn
were higher than in the surrounding sediments (Laboy-Nieves and Conde 2001).
Industrial trawl fishing, recently prohibited by the Venezuelan government
(actually in March 2009), was considered a threat to echinoderms. However,
echinoderms represented a minor portion (\1%) of the incidental capture in the
trawls in eastern Venezuela (Marcano et al. 2001), although their representation in
the catches from trawl fisheries has been little studied in other parts of the world
(Alverson et al. 1994; Kelleher 2005). Unpublished observations from one of the
authors (JA) indicate echinoderm discards by industrial trawlers in eastern
Venezuela included echinoids, asteroids, ophiuroids and, in a lesser proportion,
holothuroids and crinoids. Most of them, with the exception of ophiuroids due to
their fragile structure, were returned alive to the ocean. Hill and Wasemberg
(1990) examined the fate of discards from shrimp trawlers in Torres Strait,
northern Australia, and recorded an 88 % survival rate in the asteroid, Astropecten
sp. However, the trawl gear can modify the habitat and generate a reduction in the
density of populations of echinoderms and other groups of benthic animals
(Bergman and Hup 1992). In this sense, the interdiction of industrial trawling in
Venezuelan waters could have reduced the threat to a considerable number of
organisms whose capture was intended or not for consumption. It could also have
prevented a possible suspension of contaminants present in the sediment, like
DDT, PCBs and PAHs, reducing their incorporation into the trophic chains
through the plankton (Schiff 2000). The interdiction only affected industrial
trawling, because artisanal trawling is still actively practiced in shallow areas of
eastern Venezuela. For example, trawl fishing of the turkey wing, A. zebra
7 Echinoderms from Venezuela
263