Salish Sea Ecosystem Conference

Species-specific identification using molecular tools on planktonic field samples: complications and considerations

High throughput molecular methods provide valuable tools for species-specific identification and quantification especially in cases where research questions require large amounts of sampling. Specifically, studies have successfully adapted real-time polymerase chain reaction (RT-PCR) to detect and enumerate hatchery-reared pelagic larvae in hopes of developing methods to replace traditional techniques which are time intensive, costly, and demand high levels of taxonomic expertise. While these techniques show promise, field validation indicates that results may be confounded by a number of factors. The present study focuses on native Olympia oyster larvae, Ostrea lurida, to explore complications with the application of RT-PCR on field samples. Using RT-PCR, differences in amplification in copies of DNA were compared with the following treatments: two size classes of larvae (<200�m, >200�m), hatchery vs. wild reared larvae, presence of eDNA in plankton sample without the focal species, and presence of eDNA in preservation solution absent of all sample material. Preliminary results indicate differences in copies of DNA exist between size classes of bivalve larvae of the same species with larger larvae having a greater number of copies. Although lab-based studies have successfully utilized RT-PCR using hatchery-raised larvae, additional research is necessary before confidently applying RT-PCR to field samples. Application of molecular tools such as RT-PCR could benefit the scientific community by providing a precise and accurate, cost effective high throughput method if able to utilize the technique on field samples reliably.