EMLET, R.B.; Univ. of Oregon, OIMB: Linking stages of life history: How larval quality translates into juvenile performance

Experimental manipulations of offspring quality combined with outplanting of juveniles in the natural environment allow strong tests of the influence of offspring quality on juvenile performance. By experimentally manipulating food given to larval barnacles (Balanus glandula) and the amount of lipid rich material in embryos of a sea urchin with nonfeeding larvae (Heliocidaris erythrogramma), we have produced cohorts of siblings that differ in organic content and size at metamorphosis. Field outplants of the young juveniles demonstrate that larger, more organically rich offspring grow faster and usually survive better in the first few weeks of benthic life than their smaller siblings. Control and reduced-lipid juvenile urchins showed little mortality in the laboratory but the latter were recovered in significantly lower numbers in the 1-3 weeks after being outplanted in a shallow subtidal habitat. The magnitude of the effect of larval nutrition on juvenile barnacle performance varies with height in the intertidal and over seasons. The primary cause of mortality appears to be desiccation or thermal stress associated with hot daytime low tides. Variation in performance among juveniles may influence evolution of egg size in species with nonfeeding development. Variation in larval nutritional history or parental investment may also effect recruitment in marine populations.