FUNCTIONAL PARTITIONING OF ENERGY RESERVES BY LARVAE OF THE MARINE BRYOZOAN BUGULA-NERITINA (L.)

The effects of extended swimming on short-lived lecithotrophic larvae of the marine bryozoan Bugula neritina (L.) were examined. Larvae were forced to swim for 2 or 24 h by bath application of serotonin. Settle ment and metamorphosis success were significantly reduced, larval dime nsions were unaffected and ancestrulae were smaller after 24 h of swim ming. Larvae settled predominantly on seawater-conditioned glass after 2 h, but became less discriminative after 23 h.Lipid content in intac t larvae and dissociated surface ciliated and interior cell fractions was analysed by thin-layer chromatography. Hydrophilic lipids were una ffected by swimming regime. The hydrophobic fraction contained triglyc eride, confirmed by proton nuclear magnetic resonance spectroscopy (H- 1-NMR) analysis and correlation spectroscopy (H-1-H-1 COSY) patterns, which was significantly depleted after 24 h, and diacylglycerol, which was not. NMR spectra suggested no differences in fatty acid chain com positions between larvae swimming for 2 and 24 h, Triglyceride depleti on was limited to the ciliated cell fraction. We propose that the func tional partitioning of lipid reserves has evolved in association with the costs and benefits linked with larval dispersal.