Variable timing of larval food has consequences for early juvenile performance in a marine mussel

For organisms with complex life cycles, larval history is increasingly being found to influence later juvenile or adult performance; however, most experiments maintain manipulations in the larval environment at a constant level. Here, I assess the effects of constant vs. variable larval food availability on the marine mussel Mytilus galloprovincialis. In the laboratory, I raised larvae in four food concentrations: constant high, constant low, initial low switched to high, and initial high switched to low. After settlement, I outplanted juveniles to the field for two weeks. Changes in food availability affected larval size and lipid stores, and covariance between the two. Losses of juveniles were greater, and juvenile growth was lower, for those that had been reared as larvae in constant low food compared to those reared in constant high larval food. For the switched treatments, losses were greater, and growth was lower, for juveniles that had experienced initial low larval food relative to those that had experienced initial high larval food, regardless of average larval size or lipid stores from the different treatments. Thus, the timing of pulses of larval food may impact dynamics of later stages.