A. cingulatus and L. ludwigi scotti are most frequent at a depth of 60 m (from well
to moderated-well sorted fine sand) and also at a depth of 45 m. Analysis of
population size structure of these three species showed that individuals of the same
size range did not occur at the same depth, especially for Astropecten species.
Studies on feeding biology are more frequent for paxillosid sea stars, particularly the genera Astropecten and Luidia because these species show intra-oral
digestion and the stomach content analysis provides reliable information about
their diet. In general, studies have shown that species of Astropecten (A. cingulatus,
A. marginatus and A. brasiliensis) and Luidia (L. senegalensisi and L. ludwigi
scotti) play a wide range of trophic roles in soft-bottom environments along the
Brazilian coast. They can be non-selective deposit feeders (feeding on organic
matter from sediments), non-selective predators (feeding on the most frequent prey
in the environment, generally mollusks and crustaceans) and also selective predators (showing preferences for some species of prey, especially when there are
competitors like other sea stars). Ventura et al. (2001) reported that A. brasiliensis
and A. cingulatus can shift their food niche breadth when they occur together. Also
specimens of both species of same size range have broader food niche at depths
where they do not occur together.
Calil et al. (2009) carried out field experiments to test the effectiveness of
predation of the sea star Asterina stellifera in a rocky-shore environment in the
south of Brazil. They increased the density of A. stellifera in order to evaluate its
predation pressure on the community. Their results showed that this starfish has a
small effect on the barnacle population (Chthamalus bisinuatus) and has a minimal
effect on this rocky-shore community of a subtropical region, in contrast to other
asteroid species.
Studies on reproduction of echinoderms, especially of common sea urchins and
sea stars species from Brazilian shallow waters, have been carried out. Regarding
echinoids, in general, continuous gametogenesis occurs throughout the year, but in
some cases a long spawning period of three or four months has been detected. That
is the case for E. lucunter, whose spawning time occurs from December to June in
populations from northeastern, southeastern and southern coasts (Tavares et al.
2004; Ventura et al. 2004; Lima et al. 2009).
9.3 Echinoderm biodiversity
9.3.1 Distribution Patterns and Biogeographic Remarks
Echinoderm fauna in Brazilian waters is composed essentially of species with
three principal distribution patterns: 1) species ranging from North–South Carolina
(USA) or from Caribbean to Argentine; 2) species ranging from North–South
Carolina or Florida (USA) to Cabo Frio or São Paulo (Southeastern Brazilian
coast); and 3) species ranging from Cabo Frio to the Rio de la Plata mouth
(Uruguay/Argentine). However, very few studies on biogeography of echinoderms
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C. R. R. Ventura et al.
to moderated-well sorted fine sand) and also at a depth of 45 m. Analysis of
population size structure of these three species showed that individuals of the same
size range did not occur at the same depth, especially for Astropecten species.
Studies on feeding biology are more frequent for paxillosid sea stars, particularly the genera Astropecten and Luidia because these species show intra-oral
digestion and the stomach content analysis provides reliable information about
their diet. In general, studies have shown that species of Astropecten (A. cingulatus,
A. marginatus and A. brasiliensis) and Luidia (L. senegalensisi and L. ludwigi
scotti) play a wide range of trophic roles in soft-bottom environments along the
Brazilian coast. They can be non-selective deposit feeders (feeding on organic
matter from sediments), non-selective predators (feeding on the most frequent prey
in the environment, generally mollusks and crustaceans) and also selective predators (showing preferences for some species of prey, especially when there are
competitors like other sea stars). Ventura et al. (2001) reported that A. brasiliensis
and A. cingulatus can shift their food niche breadth when they occur together. Also
specimens of both species of same size range have broader food niche at depths
where they do not occur together.
Calil et al. (2009) carried out field experiments to test the effectiveness of
predation of the sea star Asterina stellifera in a rocky-shore environment in the
south of Brazil. They increased the density of A. stellifera in order to evaluate its
predation pressure on the community. Their results showed that this starfish has a
small effect on the barnacle population (Chthamalus bisinuatus) and has a minimal
effect on this rocky-shore community of a subtropical region, in contrast to other
asteroid species.
Studies on reproduction of echinoderms, especially of common sea urchins and
sea stars species from Brazilian shallow waters, have been carried out. Regarding
echinoids, in general, continuous gametogenesis occurs throughout the year, but in
some cases a long spawning period of three or four months has been detected. That
is the case for E. lucunter, whose spawning time occurs from December to June in
populations from northeastern, southeastern and southern coasts (Tavares et al.
2004; Ventura et al. 2004; Lima et al. 2009).
9.3 Echinoderm biodiversity
9.3.1 Distribution Patterns and Biogeographic Remarks
Echinoderm fauna in Brazilian waters is composed essentially of species with
three principal distribution patterns: 1) species ranging from North–South Carolina
(USA) or from Caribbean to Argentine; 2) species ranging from North–South
Carolina or Florida (USA) to Cabo Frio or São Paulo (Southeastern Brazilian
coast); and 3) species ranging from Cabo Frio to the Rio de la Plata mouth
(Uruguay/Argentine). However, very few studies on biogeography of echinoderms
316
C. R. R. Ventura et al.