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Exploration of Phoslock® clay in mitigating Prymnesium parvum fish-killing algal blooms in aquaculture ponds


Seger, A and Body, A and Hallegraeff, G, Exploration of Phoslock clay in mitigating Prymnesium parvum fish-killing algal blooms in aquaculture ponds, Proceedings of the 15th International Conference on Harmful Algae, 29 October - 2 November 2012, Changwon, Korea, pp. 231-234. ISBN 978-87-990827-4-2 (2014) [Refereed Conference Paper]

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When 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.

Item Details

Item Type:Refereed Conference Paper
Keywords:clay, flocculation, algal blooms
Research Division:Biological Sciences
Research Group:Plant biology
Research Field:Phycology (incl. marine grasses)
Objective Division:Animal Production and Animal Primary Products
Objective Group:Fisheries - aquaculture
Objective Field:Fisheries - aquaculture not elsewhere classified
UTAS Author:Seger, A (Dr Andreas Seger)
UTAS Author:Hallegraeff, G (Professor Gustaaf Hallegraeff)
ID Code:96380
Year Published:2014
Funding Support:Australian Research Council (DP130102859)
Deposited By:IMAS Research and Education Centre
Deposited On:2014-11-03
Last Modified:2018-04-04
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