Production and growth of triploid Mytilus edulis larvae

Abstract

Triploidy induction trials were carried out on the eggs of Mytilus edulis using heat shock treatment at three temperatures (20, 25 and 30 °C) and cytochalasin B (CB) treatment at three concentrations (0.1, 0.5 and 1.0 mg CB · l −1). Heat shock was administered at meiosis I while CB treatments were applied at both meiosis I and II. Estimates of potential triploidy were obtained by counts of diploid eggs in heat shock experiments and also by chromosome counts in early embryos in CB experiments. Diploid eggs (potential triploid zygotes) were produced at all heat shock temperatures with best results (25%) at 25 °C but all CB treatments regardless of concentration or timing of application produced higher percentages of triploids (26–67%). Both heat shock and CB treatments significantly reduced yield and normality of 72 h larvae. Veliger larvae derived from eggs treated with CB at meiosis I had grown significantly larger after 36 days, than controls or larvae derived from any other treatments. We propose that this is a result of the higher overall genomic heterozygosity expected in meiosis I triploids compared to meiosis II triploids or diploid controls.