Quantification of bivalve and decapod larvae from field plankton samples using novel molecular methods

Eugenio Raymond Alfonso

Decapods and bivalves not only have a strong economic impact in global fisheries and aquaculture, but also their ecological role in ecosystems make them worthy of study. Nonetheless, their planktonic stages are still poorly understood in terms of distribution and abundance in the wild. This knowledge gap is explained because of the time-consuming and research-expertise dependent factors of their identification using the current morphological approaches, which makes impossible to process the large number of samples needed for proper spatio-temporal covering of the monitoring programs. With the development of molecular methods over the years, the real time PCR (qPCR) together with high throughput and microfluidic technology, have proved to be a successful quantification tool for marine organisms.

In this study, High Throughput quantitative real-time PCR (HT-qPCR) and digital PCR (dPCR) techniques were tested to quantify bivalve and decapod larvae from field samples using taxa and species-specific assays. The output from dPCR matched satisfactorily the results from morphological cross validation. Using HT-qPCR, most assays appeared to yield suboptimal performance parameters (amplification efficiency), however a recognizable pattern was observed in describing the bivalve and decapod larvae sample composition, which proves the potential of future implementation of such novel molecular techniques in marine larvae monitoring programs.

Key words: bivalve, decapod, larvae, digital PCR, High Throughput quantitative real-time PCR.