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The growth, survival and influence of environmental factors were analysed in two cohorts of cultured Pteria sterna in Ayangue Bay, Province of Santa Elena, Ecuador (tropical Eastern Pacific). Juveniles representing cohorts I and II (8.4 ± 0.54 and 5.0 ± 0.17 mm in dorso-ventral axis) were deployed in November 2015 and February 2016, and grown in pearl nets suspended in a long line for 12 and 10 months respectively. The stocking density was monthly and bi-monthly reduced during sampling of individuals to determine growth in dorso-ventral shell axis, dry mass of shell, soft tissues and dry mass of fouling on shell. Water temperature, salinity, total seston and phytoplankton biomass (chlorophyll a) were determined at the culture site. Results showed that P. sterna reached ~100 mm in length during the first year of culture. Although little negative influence of environmental factors was detected, high temperatures during the reproduction period can be the most negative influential trait. The highest tissue mass (6 g), which occurred at the 10th month of cultivation, as well as a high availability of spat by artificial collectors in the coastal waters, showed that the species can be considered a good candidate for aquaculture in the tropical eastern Pacific.

Growth and survival of the scallop Lyropecten nodosus were studied in 1997 at two sites (inner and outer Turpialito Bay) during a non-upwelling period normally occurring between August and November. Individuals had an initial shell height of 4.86 cm (SD=1.64 cm). Both experimental groups were held in suspended plastic baskets at the same depth (4 m). Measurements of shell height and dry weights of shell, gonad, digestive gland, remaining tissues and shell biofouling were taken at monthly intervals. Environmental parameters, including temperature, phytoplanktonic biomass, total particulate material (TPM) and associated organic (POM) and inorganic (PIM) fractions, were recorded simultaneously. At the end of the study, significant differences in growth and survival of scallops were observed between the two experimental sites. Scallops maintained inside the bay showed a 22% greater increase in shell height (7.41 ± 0.27 cm) than those placed outside the bay (6.37 ± 0.41 cm). Survival of scallops inside the bay was 31% higher compared with scallops outside. The greater availability of food of phytoplanktonic origin during the first two experimental months (July and August) together with greater POM throughout the whole experimental period except September, at the inner bay site, probably explained survival and growth differences observed between the two locations. Results suggest that, during the non-upwelling period (characterized by low primary productivity and high water temperatures), POM of sedimentary origin may play an important role as an energy source required for metabolic and reproductive activities of L. nodosus.

This work describes for the first time the embryonic development of the tropical scallop Nodipecten nodosus. Larval and post-larval growth parameters and some characteristics of larvae shell morphology were also ascertained. The larvae were obtained from the induced spawning of a group of broodstocks under controlled laboratory conditions. After fertilization, larval cultivation was carried out in conical tanks at a temperature of 26–27 °C. Larval density was controlled as a function of larval growth to give 10, 5 and 3 larvae mL−1 from days 1, 3 and 8 respectively. The larvae were nourished with a 1:1 mix of Isochrysis galbana (clone T-ISO) and Chaetoceros gracilis in portions varying between 30 000 and 70 000 cells mL−1. Expulsion of polar groups was observed 5 and 15 min after fertilization, whereas the first cellular division occurred after 30 min. The first gastrule ciliates and trocophore larvae were noted after 8 and 18 h had elapsed, respectively, whereas prodissoconch I, or D-larvae, were discerned after 26 h. Subsequently, larvae with prodissoconch II or veliger-conch appeared at 30 h. Larval development continued for 10–12 days, followed by metamorphosis, at an approximate length of 208–230 µm. The growth of the post-larvae was evaluated for 9 days. Larval and post-larval growth corresponded to the linear equations L = 71.85 + 10.85t, r2 = 0.99, and L = 44.09 + 17.81t, r2 = 0.94 respectively. Accordingly, larval morphology and size disparities are discussed with respect to other tropical pectinids.