Linking stages of life history:: How larval quality translates into juvenile performance for an intertidal barnacle (Balanus glandula)

Many marine invertebrates with complex life cycles produce planktonic larvae that experience environmental conditions different from those encountered by adults. Factors such as temperature and food, known to impact the larval period, can also affect larval size and consequently the size of newly settled juveniles. After documenting natural variation in the size of cyprids (the final larval stage) of the barnacle Balanus glandula, we experimentally manipulated temperature and food given to larvae to produce cyprids of differing sizes but within the size range of cyprids found in the field. In a set of trials in which larvae of B. glandula were raised on full or reduced rations in the laboratory and subsequently outplanted into the field as newly metamorphosed juveniles, we explored the effects of larval nutrition and size on juvenile performance. Larvae that received full rations throughout their feeding period produced larger cyprids (with more lipid and protein). These larger cyprids grew faster as juveniles and sometimes survived better in the field than juveniles from larvae that had their food ration reduced in the last feeding instar. For naturally settling barnacles brought into the laboratory within 2 days of settlement and fed, we found that initial juvenile size was a good predictor of juvenile size even after 2 weeks of growth. By manipulating food given to juveniles that were derived from larvae fed either full or reduced rations, we found that larval nutritional effects persisted in juveniles for 2-3 times the period that larvae experienced altered food rations.