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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 Hallegraeff
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.

Funding

Australian Research Council

History

Publication title

Proceedings of the 15th International Conference on Harmful Algae

Editors

HG Kim, B Reguera, GM Hallegraeff, CK Lee, MS Han, JK Choi

Pagination

231-234

ISBN

978-87-990827-4-2

Department/School

Institute for Marine and Antarctic Studies

Publisher

Maple Design

Place of publication

Busan, Korea

Event title

International Society for the Study of Harmful Algae

Event Venue

Changwon, Korea

Date of Event (Start Date)

2012-10-29

Date of Event (End Date)

2012-11-02

Rights statement

Copyright unknown

Repository Status

  • Restricted

Socio-economic Objectives

Fisheries - aquaculture not elsewhere classified

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