aggregations and a higher number of urchins per aggregation were correlated with
low complexity (rugosity) habitats. This supports the idea that this behavior provides protection. They also concluded that recruitment is not limited to highly
complex, calcium carbonate habitats. Although average densities were well below
pre-mass-mortality densities in Puerto Rico, results of this study indicate that
D. antillarum seem to be making a slow come back in La Parguera.
More recently, Ruiz-Ramos et al. 2011) measured the population recovery of
D. antillarum at 26 locations around Puerto Rico during 2003–2004. Seven sites
were surveyed in the northern region, five in the western region, four in the
southern and eastern regions and six around Culebra Island. Adults were absent in
11 of the 26 localities measured. The highest densities of D. antillarum occurred in
Culebra and in the northern region. Arrecife El Banderote, Culebra had the highest
densities of D. antillarum (0.91 ind m
-2
) followed by Bahía Tamarindo and Bahía
Sardinas, with 0.70 and 0.51 ind m
-2 , respectively. They believe that the continued low densities could be due to a number of factors such as diminished larval
supply, recruitment failure, post-recruitment mortality, currents or lack of an
appropriate habitat due to chronic environmental degradation. Also, larger individuals were more common in Culebra and the northern region. As for water
transparency, the mean value around the island was 6.2 m. Water transparency was
greater at the northern sites and sea urchin density was positively correlated with
water transparency. The benthic communities of the northern region differed
significantly from the other locations. They found the highest mean percent cover
of coral was in Culebra (12.6 ± 8.4) and the lowest to the east (0.1 ± 0.3). Cover
of macroalgae was greater on reefs in more turbid areas. A positive relationship
was observed between D. antillarum density and percent coral cover. In conclusion, they found that densities in their study were relatively higher than many other
wider Caribbean reef systems. However, they believe that population recovery of
D. antillarum seems remote.
There is also another important member of order Diadematoida, the magnificent
urchin, Astropyga magnifica (Clark). This is a very rare species in shallow water
areas. It can be often found at depths well below 30 m, but occasionally occurs in
shallow water (depth of 1 m) across seagrass communities. There are also two
species in the family Echinidae (order Temnopeuroida), Lytechinus variegatus,
and Tripneustes ventricosus. Both species are common on shallow seagrass habitats and protected backreef lagoons. Lytechinus variegatus appears to be more
abundant on seagrass habitats of the northern coast (e.g., Condado Lagoon, Vega
Baja), while T. ventricosus is more ubiquitous. Both species tend to cover their test
with fragments of algae and seagrass blades. There is a single member of family
Cidaridae, the pencil urchin, Eucidaris tribuloides (Lamarck). This is a fairly
common reef urchin that often hides under sheltered zones It can often be observed
on rubble and seagrass areas. There are two members of the family Brissidae
(order Spatangoida), Meoma ventricosa ventricosa (Lamarck), and Clypeaster
rosaceus (Linnaeus). Meoma v. ventricosa can be commonly found buried under
sandy bottoms or sparse seagrass bottoms, while C. rosaceus often camouflages its
body under seagrass blades, algae and seagrass blade fragments.
14 Review of Echinoderm Research in Puerto Rico
459
low complexity (rugosity) habitats. This supports the idea that this behavior provides protection. They also concluded that recruitment is not limited to highly
complex, calcium carbonate habitats. Although average densities were well below
pre-mass-mortality densities in Puerto Rico, results of this study indicate that
D. antillarum seem to be making a slow come back in La Parguera.
More recently, Ruiz-Ramos et al. 2011) measured the population recovery of
D. antillarum at 26 locations around Puerto Rico during 2003–2004. Seven sites
were surveyed in the northern region, five in the western region, four in the
southern and eastern regions and six around Culebra Island. Adults were absent in
11 of the 26 localities measured. The highest densities of D. antillarum occurred in
Culebra and in the northern region. Arrecife El Banderote, Culebra had the highest
densities of D. antillarum (0.91 ind m
-2
) followed by Bahía Tamarindo and Bahía
Sardinas, with 0.70 and 0.51 ind m
-2 , respectively. They believe that the continued low densities could be due to a number of factors such as diminished larval
supply, recruitment failure, post-recruitment mortality, currents or lack of an
appropriate habitat due to chronic environmental degradation. Also, larger individuals were more common in Culebra and the northern region. As for water
transparency, the mean value around the island was 6.2 m. Water transparency was
greater at the northern sites and sea urchin density was positively correlated with
water transparency. The benthic communities of the northern region differed
significantly from the other locations. They found the highest mean percent cover
of coral was in Culebra (12.6 ± 8.4) and the lowest to the east (0.1 ± 0.3). Cover
of macroalgae was greater on reefs in more turbid areas. A positive relationship
was observed between D. antillarum density and percent coral cover. In conclusion, they found that densities in their study were relatively higher than many other
wider Caribbean reef systems. However, they believe that population recovery of
D. antillarum seems remote.
There is also another important member of order Diadematoida, the magnificent
urchin, Astropyga magnifica (Clark). This is a very rare species in shallow water
areas. It can be often found at depths well below 30 m, but occasionally occurs in
shallow water (depth of 1 m) across seagrass communities. There are also two
species in the family Echinidae (order Temnopeuroida), Lytechinus variegatus,
and Tripneustes ventricosus. Both species are common on shallow seagrass habitats and protected backreef lagoons. Lytechinus variegatus appears to be more
abundant on seagrass habitats of the northern coast (e.g., Condado Lagoon, Vega
Baja), while T. ventricosus is more ubiquitous. Both species tend to cover their test
with fragments of algae and seagrass blades. There is a single member of family
Cidaridae, the pencil urchin, Eucidaris tribuloides (Lamarck). This is a fairly
common reef urchin that often hides under sheltered zones It can often be observed
on rubble and seagrass areas. There are two members of the family Brissidae
(order Spatangoida), Meoma ventricosa ventricosa (Lamarck), and Clypeaster
rosaceus (Linnaeus). Meoma v. ventricosa can be commonly found buried under
sandy bottoms or sparse seagrass bottoms, while C. rosaceus often camouflages its
body under seagrass blades, algae and seagrass blade fragments.
14 Review of Echinoderm Research in Puerto Rico
459