Cross-shore and Vertical Distributions of Invertebrate Larvae Using Autonomous Sampling Coupled with Genetic Analysis

We present a new method to estimate the distribution of invertebrate larvae relative to environmental variables such as temperature, salinity, and circulation. A large volume in situ filtering system developed for discrete biogeochemical sampling in the deep-sea (the Suspended Particulate Rosette “SUPR” multisampler) was mounted to the autonomous underwater vehicle REMUS 600 for coastal larval and environmental sampling. We describe the results of SUPR-REMUS deployments conducted in Buzzards Bay, Massachusetts (2014) and west of Martha’s Vineyard, Massachusetts (2015). We collected discrete samples cross-shore and from surface, middle, and bottom layers of the water column. Samples were preserved for DNA analysis. Our Buzzards Bay deployment targeted barnacle larvae, which are abundant in late winter and early spring. For these samples, we used morphological analysis and DNA barcodes generated by Sanger sequencing to obtain stage and species-specific cross-shore and vertical distributions. We targeted bivalve larvae in our 2015 deployments, and genetic analysis of larvae from these samples is underway. For these samples, we are comparing species barcode data derived from traditional Sanger sequencing of individuals to those obtained from next generation sequencing (NGS) of bulk plankton samples. Our results demonstrate the utility of autonomous sampling combined with DNA barcoding for studying larval distributions and transport dynamics.