THE ON FARM UTILISATION OF A MOLECULAR QPCR TOOL FOR THE PREDICTIVE MANAGEMENT OF PARALYTIC SHELLFISH TOXIN-PRODUCING HARMFUL ALGAL BLOOMS FOR THE AQUACULTURE INDUSTRY

Paralytic shellfish toxins (PSTs) produced by marine dinoflagellates significantly impact shellfish industries worldwide. Early detection on-farm would allow additional time for management decisions to minimize economic losses. The development and validation of the Phytoxigene DinoDTec qPCR assay allows for the utilisation of a standardized workflow to quickly detect and quantify the presence of sxtA4. The sxtA4 gene is a critical gene in the biosynthesis of PSTs and is upstream from any tailoring enzymes that are responsible for the many PST variants. The workflow is simple and inexpensive and does not require a specialized laboratory. The workflow consists

1. water collection and filtration using a custom gravity sampler,
2. Cell lysis for DNA, and
3. Rehydrating the lyophilized reagents from the DinoDtec kit to prepare the master mix for the the quantitative polymerase chain reaction (qPCR) assay.
4. Add the lysed sample with the master mix and place in instrument, Results are generated in 60 minutes

Water samples spiked with Alexandrium catenella showed a cell recovery of >90% when compared to light microscopy counts. The performance of the lysis method (90.3% efficient), Longmire’s buffer, and the DinoDtec qPCR assay (tested across a range of Alexandrium species (90.7–106.9% efficiency; r2 > 0.99)) was found to be specific, sensitive, and efficient. We tested the application of this workflow weekly from May 2016 to 30th October 2017 to compare the relationship between sxtA4 copies L–1 in seawater and PSTs in mussel tissue (Mytilus galloprovincialis) on-farm and spatially (across multiple sites), effectively demonstrating an ∼2 week early warning of two A. catenella HABs (r = 0.95). Our tool provides an early, accurate, and efficient method for the identification of PST risk in shellfish aquaculture.