Triploid lion-paw scallop (Nodipecten subnodosus Sowerby);: Growth, gametogenesis, and gametic cell frequencies when grown at a high food availability site

Triploidy was induced in lion-paw scallop, Nodipecten subnodosus evaluating different cytochalasin-B (CB) concentrations for treatment of eggs. Concentrations of 0.75 and 1.0 mg/l were those with the largest triploid success (87% and 95%, respectively). Gametogenesis, and shell and weight traits were evaluated during a grow-out period of 21 months, comparing triploids, treated diploids, and control diploids. Growth of triploids was not superior to either diploid group, and only adductor muscle index was larger in triploids when compared with both diploid groups. Lack of triploid growth advantage occurred in spite of triploids being unable to mature and form gametes, showing a sterility of 95% to 99% when compared with diploids. Analyses of frequencies of gametic cell types indicated that the arrest of oogenesis was at the previtellogenic oocyte stage, or before the diplotene stage of meiosis I. The lack of triploid growth advantage may be related to the reproductive strategy in this species at this site, where energy for maturation is not derived from stored resources but rather from newly ingested food, largely abundant at this site. Possible additional negative effects of high primary productivity at the evaluation site may occur on triploids. (C) 2004 Elsevier B.V. All rights reserved.