Cameron (1986) found L. variegatus juveniles (\15 mm in test diameter) at
Tres Marias in all four 1982 samples, April 1983 and June 1984. At Caracoles
juveniles were present during April and August 1982, April 1983 and June 1984.
Settlement of L. variegatus occurred throughout the year. The recruitment pattern
of this species follows the expected and observed pattern of reproduction and
larval occurrence. Juveniles (20 mm in diameter) of T. ventricosus found in
January or February may have settled the previous September. They most likely
settle on the reef face and crest. The larvae of T. ventricosus were observed during
August 1982, a time that coincides with the expected fall recruitment. Seasonal
recruitment was not apparent for E. lucunter at Papayo. There were E. viridis
recruits several times during the year.
Cameron et al. (1985) measured the embryonic response to temperature and
salinity by four species of Caribbean sea urchins. They wanted to test if embryos
of highly synchronous species of echinoderms are more sensitive to physical
factors. They cultured embryos of four species of sea urchins, L. variegatus,
E. lucunter, E. viridis, and T. ventricosus in a 3 9 3 factorial experiment comparing temperatures of 20, 25, and 30 °C and salinities of 31.5, 35, and 38.5 % at
La Parguera. The responses to different temperatures and salinities differed among
the embryos of the four species. The asynchronous species, L. variegatus and
T. ventricosus exhibit a more gradual response to temperature at cleavage than the
synchronous Echinometra spp. Lytechinus variegatus developed more rapidly at
higher salinities and T. ventricosus at lower salinities. Echinometra spp. are less
affected by salinity changes and have a linear response to an increase in temperature. These results support the suggestion that species with a narrower reproductive season have greater responses in development rate of extreme
environmental conditions. Salinity proved to be less harmful at all development
stages than temperature. Significant mortality occurred during the blastula and
early gastrula stages. The development rate of all four species is temperature
dependent. At 20 °C the hatching interval was the shortest for L. variegatus and
longest for T. ventricosus; Echinometra spp. had an intermediate response.
At 25 °C all four species hatched at about the same time, 7.5 h. Tripneustes
ventricosus had 100 % mortality at extreme temperatures. All four species reached
the pluteus stage (18–24 h) at optimum temperature. Development of L. variegatus
was fastest (18.3 h), while L. variegatus was slowest (28.6 h). Most synchronous
species (Echinometra spp.) were the most responsive to temperature changes.
14.2.4 Reproduction, Larval Biology, and Settlement
of Diadema antillarum
Lugo (2004) described the population structure and reproductive biology of
D. antillarum in La Parguera. The average gonad index per month was used to
characterize the annual reproductive cycle. The gonad index ranged from 2.9
444
S. M. Williams et al.
Tres Marias in all four 1982 samples, April 1983 and June 1984. At Caracoles
juveniles were present during April and August 1982, April 1983 and June 1984.
Settlement of L. variegatus occurred throughout the year. The recruitment pattern
of this species follows the expected and observed pattern of reproduction and
larval occurrence. Juveniles (20 mm in diameter) of T. ventricosus found in
January or February may have settled the previous September. They most likely
settle on the reef face and crest. The larvae of T. ventricosus were observed during
August 1982, a time that coincides with the expected fall recruitment. Seasonal
recruitment was not apparent for E. lucunter at Papayo. There were E. viridis
recruits several times during the year.
Cameron et al. (1985) measured the embryonic response to temperature and
salinity by four species of Caribbean sea urchins. They wanted to test if embryos
of highly synchronous species of echinoderms are more sensitive to physical
factors. They cultured embryos of four species of sea urchins, L. variegatus,
E. lucunter, E. viridis, and T. ventricosus in a 3 9 3 factorial experiment comparing temperatures of 20, 25, and 30 °C and salinities of 31.5, 35, and 38.5 % at
La Parguera. The responses to different temperatures and salinities differed among
the embryos of the four species. The asynchronous species, L. variegatus and
T. ventricosus exhibit a more gradual response to temperature at cleavage than the
synchronous Echinometra spp. Lytechinus variegatus developed more rapidly at
higher salinities and T. ventricosus at lower salinities. Echinometra spp. are less
affected by salinity changes and have a linear response to an increase in temperature. These results support the suggestion that species with a narrower reproductive season have greater responses in development rate of extreme
environmental conditions. Salinity proved to be less harmful at all development
stages than temperature. Significant mortality occurred during the blastula and
early gastrula stages. The development rate of all four species is temperature
dependent. At 20 °C the hatching interval was the shortest for L. variegatus and
longest for T. ventricosus; Echinometra spp. had an intermediate response.
At 25 °C all four species hatched at about the same time, 7.5 h. Tripneustes
ventricosus had 100 % mortality at extreme temperatures. All four species reached
the pluteus stage (18–24 h) at optimum temperature. Development of L. variegatus
was fastest (18.3 h), while L. variegatus was slowest (28.6 h). Most synchronous
species (Echinometra spp.) were the most responsive to temperature changes.
14.2.4 Reproduction, Larval Biology, and Settlement
of Diadema antillarum
Lugo (2004) described the population structure and reproductive biology of
D. antillarum in La Parguera. The average gonad index per month was used to
characterize the annual reproductive cycle. The gonad index ranged from 2.9
444
S. M. Williams et al.