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 À1 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 À1 . 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 mm. 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, r 2 0.99, and L 44.09 17.81t, r 2 0.94 respectively. Accordingly, larval morphology and size disparities are discussed with respect to other tropical pectinids.
We compared the growth of the scallop Euuolu (Pecten) ziczuc (L.) in three situations whichpotentially could be used for commercial culture, in cages maintained in suspension, in cages on thebottom and in cages partly buried in a sediment bottom. The latter permitted the scallops to burythemselves as in their natural habitat. Throughout the 7-month study, growth, as measured by shelllength and muscle mass, was by far superior for scallops in the partly buried cages. Possible explanationsfor this are ( 1) that the scallops are stressed by enclosures which prevent them from buryingthemselves and (2) that organic material at the sediment/water interface is an important food resourceand E. ziczac has better access to this when it buries itself flush with the bottom. The timing of gonadalgrowth and spawning varied markedly among treatments. Some spawnings coincided with temperatureincreases but others did not. Differences between scallops in suspension compared to those in bottomtreatments suggested that reproduction is as much controlled by conditions in the immediate environmentof the scallops as by large-scale environmental factors. Survival was highest for the scallopsmaintained in partly buried cages.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.