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Exploration of Phoslock® clay in mitigating Prymnesium parvum fish-killing algal blooms in aquaculture ponds
conference contribution
posted on 2023-05-23, 09:29 authored by Andreas SegerAndreas Seger, Body, A, Gustaaf HallegraeffGustaaf HallegraeffWhen in 2009 a tropical Australian barramundi farm suffered from fish-killing Prymnesium parvum blooms, the farm manager decided to manipulate N:P nutrients by adding Phoslock® bentonite clay and adjusting pH through the addition of molasses. Phosphate levels were maintained at <0.03 mg/L, phytoplankton biomass and dissolved oxygen became more stable and Prymnesium disappeared from the system altogether. We conducted Prymnesium culture experiments under different N:P ratios to interpret field observations, while measuring toxins using the RTgill-Wl cell line assay. Methanol extracts of nitrogen deficient cells were the most toxic during stationary phase, followed by phosphorus deficient cells and with nutrient sufficient cultures least toxic (7, 20, 65% gill cell viability, respectively). Sonicated whole-cell cultures were more toxic after 4h (0-13% gill cell viability) but lost significant toxicity after 24h in the dark, suggesting toxin degradation. Phoslock® effectively removed 60-100% of water soluble toxicity of live Prymnesium and offers great potential as on-farm emergency response. We are currently refining clay type and dosage, including exploration of application of clays to other ichthyotoxic algae.
Funding
Australian Research Council
History
Publication title
Proceedings of the 15th International Conference on Harmful AlgaeEditors
HG Kim, B Reguera, GM Hallegraeff, CK Lee, MS Han, JK ChoiPagination
231-234ISBN
978-87-990827-4-2Department/School
Institute for Marine and Antarctic StudiesPublisher
Maple DesignPlace of publication
Busan, KoreaEvent title
International Society for the Study of Harmful AlgaeEvent Venue
Changwon, KoreaDate of Event (Start Date)
2012-10-29Date of Event (End Date)
2012-11-02Rights statement
Copyright unknownRepository Status
- Restricted