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. 2024 Apr 23;58(16):6924-6933.
doi: 10.1021/acs.est.3c10502. Epub 2024 Apr 12.

An On-Farm Workflow for Predictive Management of Paralytic Shellfish Toxin-Producing Harmful Algal Blooms for the Aquaculture Industry

Rendy Ruvindy  1 , Penelope A Ajani  1 , Sereena Ashlin  2 , Gustaaf Hallegraeff  3 , Kerstin Klemm  4 , Christopher J Bolch  3 , Sarah Ugalde  3   5 , Mark Van Asten  6   7 , Stephen Woodcock  1 , Matthew Tesoriero  1 , Shauna A Murray  1
Affiliations

An On-Farm Workflow for Predictive Management of Paralytic Shellfish Toxin-Producing Harmful Algal Blooms for the Aquaculture Industry

Rendy Ruvindy et al. Environ Sci Technol. .

Abstract

Paralytic shellfish toxins (PSTs) produced by marine dinoflagellates significantly impact shellfish industries worldwide. Early detection on-farm and with minimal training would allow additional time for management decisions to minimize economic losses. Here, we describe and test a standardized workflow based on the detection of sxtA4, an initial gene in the biosynthesis of PSTs. The workflow is simple and inexpensive and does not require a specialized laboratory. It consists of (1) water collection and filtration using a custom gravity sampler, (2) buffer selection for sample preservation and cell lysis for DNA, and (3) an assay based on a region of sxtA, DinoDtec lyophilized quantitative polymerase chain reaction (qPCR) assay. 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.

Keywords: alexandrium spp.; aquaculture industry; harmful algal blooms (HABs); molecular detection; on-farm workflow; paralytic shellfish toxins (PSTs); sxtA4 gene.

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Conflict of interest statement

The authors declare no competing financial interest.

Figures

Figure 1
Figure 1
Photo and technical diagram of the gravity-operated portable water sampler showing the following components: A. a first-stage prefilter with a 100 μm mesh; B. a 3 liter water chamber; and C. a second-stage filter with an 11 μm mesh designed to capture and retain HAB cells such as dinoflagellates and all measurements. The sampler is made from PVC piping with a midline ball valve/tap.
Figure 2
Figure 2
Standard curve of the DinoDtec assay using lysed cells of A. pacificum strain MMWA 83 as the template DNA, showing the quantification cycle (y-axis) versus the known cell number in log-scale (x-axis).
Figure 3
Figure 3
Copy number of sxtA4 L–1 in seawater and total concentration of PST in mussel tissue (mg kg–1) during the 2016 A. catenella bloom from Spring Bay Seafoods. The inset shows a portion of the same data from June to July 2016, with sxtA4 L–1 in seawater on a log-scale, highlighting that the qPCR assay detected significant sxtA4 copies prior to the detection of toxins in mussel tissue.
Figure 4
Figure 4
Dynamics of sxtA4 L–1 copies in seawater and the total concentration of PST in mussel tissue during the 2017 A. catenella bloom from Spring Bay Seafoods.
Figure 5
Figure 5
Sampling stations of the RV Southern Cross survey along the east coast of Tasmania, Australia, with the concentration of surface-sxtA4 copy L–1 detected at each site during the peak (26–28 August) of the A. catenella bloom in 2016.
See this image and copyright information in PMC

References

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