Relative importance of parental and larval nutrition on larval development and metamorphosis of the sea urchin Strongylocentrotus droebachiensis

We examined the relative importance of parental nutritional condition and larval food ration on the rates of development, growth and metamorphosis of larvae of Strongylocentrotus droebachiensis (Muller) in a laboratory experiment. Parents were reared for 22 months on either a high ration of kelp (Laminaria spp., 6 days week^-1) supplemented with mussel flesh (Mytilus spp., 1 day week^-1) (KM), or a low ration of kelp (1 day week^-1) (KL). Larvae were fed either a high ration (5000 cells ml^-1) or a low ration (500 cells ml^-1) of microalgae (Dunaliella tertiolecta). Larval food ration had a strong effect on the rates of development, growth, and metamorphosis, which were all significantly greater in larvae fed the high ration. Test diameter of settlers also was significantly greater in the high than the low ration. Parental nutritional condition had little or no effect on the rates of development and growth, and no effect on settler size. The rate of metamorphosis was significantly higher in larvae from the KM than the KL treatment in the high but not the low ration (where rates of metamorphosis were similar). Although parental condition generally had a small effect on larval development, our results suggest that when planktonic food is abundant, larvae of adults from nutritionally rich habitats (such as kelp beds) may metamorphose sooner than those of adults from nutritionally poor habitats (such as barrens).