Several experiments were performed examining the e¡ect of di¡erent culture variables on the growth and survival of Argopecten nucleus and Nodipecten nodosus larvae. Higher growth and survival values were obtained at a low density (1larvae mL À 1 ) than at a high density (5 larvae mL À1 ), except for N. nodosus's survival, which was not a¡ected by density. Higher growth was obtained when feeding the larvae a diet of Isochrysis galbana, similar results occurred with the diet of Isochrysis galbana 1 Chaetoceros calcitrans in A. nucleus and with I. galbana combined with the lipid emulsion EmDHA in N. nodosus. Higher survival was obtained when the diet included a mixture of microalgae than when EmDHA was supplemented. Growth and survival of the larvae of A. nucleus were greater when fed continuously, while N. nodosus grew and survived better when food was given discontinuously. Higher growth and survival values were recorded at lower food concentrations ranging from 20 to 40 cells mL À 1 of I. galbana. Higher growth was observed with increasing temperature between 22 and 28 1C, although there was a simultaneous decrease in survival. No signi¢cant e¡ects on larval production parameters were found when the culture water was changed totally or partially, but higher larval growth of N. nodosus was veri-¢ed when a partial renewal of water was performed.

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Several suspended culture experiments of the Atlantic Pearl oyster, Pinctada imbricata, were carried out in the Colombian Caribbean. Seed was collected at two seasons of the year (rainy and dry) using onion bags collectors. Shell growth and survival of the oysters, as well as frequency and size of predators, were evaluated under different stocking densities (10, 20, 30, and 40% coverage of the bottom of the net), culture systems (pearl nets and pocket nets), seasons (rainy and dry), and depths (4 and 9 m). A greater amount of P. imbricata spat was collected during the dry season (297 ind./m2) than in the rainy season (72 ind./m2). Density influenced significantly the growth of P. imbricata but not its survival. The highest antero‐posterior measure (APM) values appeared at lower densities (10 and 20% bottom coverage). Growth and survival values of the pearl oysters were greater in pocket nets than in pearl nets. Culture season did not affect the survival of the oysters but their growth was greater in the dry season than in the rainy season. Culture depth influenced oyster growth but not their survival, with recorded shell APM being greater at 9 m than at 4 m. The following predators: Cymatiidae, Portunidae, Majidae, and Xanthidae were found inside the culture nets. Highest mortality values of the pearl oysters coincided with high frequency and/or size of predators. Frequency of cymatids was higher during the rainy season and in pearl nets with high oyster density. Xantids appeared mostly in pocket nets and majids during the dry season.

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Juveniles of the Caribbean scallops Argopecten nucleus and Nodipecten nodosus were suspended in pearl nets at densities of 25%,30% and 50% coverage of the bottom of the net (BC) during days. Additionally, adults of A. nucleus (435 mm) were placed in lantern nets at densities of 40%, 50% and 65% BC during days. Stocking density a¡ected the growth of animals, with higher growth rates obtained at the lower densities. Although the survival of the two scallops was not in£uenced at the densities studied, the 15-day net changes, and culture in water of o28 1C produced better survival of A. nucleus and N. nodosus respectively. Predators of the families Cymatiidae, Grapsidae, Portunidae, Majidae and Xanthidae were found in the culture nets of juvenile A. nucleus, but during the adult phase they were absent. Predators exhibited a dense-independent behaviour in relation to scallops. There was not any association between predator frequency and survival of A. nucleus.

Argopecten nucleus is a functional hermaphroditic pectinid species that exhibits self‐fertilization, whose natural populations have usually very low densities. In the present study, the genetic diversity of a wild population from Neguanje Bay, Santa Marta (Colombia), was estimated using microsatellite markers, and the effect of the presence of null alleles on this estimation was assessed. A total of 8 microsatellite markers were developed, the first described for this species, and their amplification conditions were standardized. They were used to determine the genotype of 48 wild individuals from Naguanje Bay, and 1,010 individuals derived from the offspring of 38 directed crosses. For each locus, the frequencies of the identified alleles, including null alleles, were estimated using the statistical package Micro‐Checker, and the parental genotypes were confirmed using segregation analysis. Three to 8 alleles per locus with frequencies from 0.001 to 0.632 were detected. The frequencies of null alleles ranged from 0.10 to 0.45, with Ho from 0.0 to 0.79, and He from 0.53 to 0.80. All loci were in H‐W disequilibrium. The null allele frequencies values were high, with lower estimations using segregation analysis than estimated using Micro‐Checker. The present results show high levels of population genetic diversity and indicate that null alleles were not the only cause of deviation from H‐W equilibrium in all loci, suggesting that the wild population under study presents signs of inbreeding and Wahlund effect.