Trace element signatures in larval soft tissues reveal transport, but not population connectivity

摘要

Trace elemental signatures incorporated into calcified structures in fish and molrusk larvae have been used to reveal population connectivity and larval dispersal trajectories. To determine whether trace element analysis could be applied to larvae that do not permanently retain calcified structures, we raised larvae of the porcelain crab Petrolisthes cinc-tipes from multiple locations along the northern California, USA, coast in a common water source for up to 8 wk. We analyzed 20 elements in extractions of soft tissues from embryos and the 2 larval and 1 postlarval stages. Elemental signatures of individuals in each developmental stage were compared to an atlas of signatures from each collection site using discriminant analysis to determine whether larvae could be accurately assigned to their site of origin in 2 ways. First, postlarvae were classified using a natal site atlas constructed using embryonic signatures from each site, and this classification had poor success (average 39.7% correct). Second, larvae of each stage were classified using a natal site atlas constructed using signatures of larvae from that same stage. This yielded considerably better classification success (81.7 % correct overall). Thus, the same trace element signatures were not consistently maintained from embryos to postlarvae, but differences in signatures among natal sites were maintained during the larval period. Trace element signatures in soft tissues could be useful in tracking dispersal between stages and determining how many sites, rather than which sites, contributed to a cohort of larvae or settlers.