The use of allelochemicals to counter ascidian fouling in aquaculture


***Tuesday, April 5, 2011***
Redfield Auditorium - 12:00 Noon
Patrick Cahill
University of Auckland, New Zealand: PhD Student

Ascidian fouling poses a significant threat to aquaculture on a global scale. Several species; including Ciona intestinalis, Didemnum vexillum and Styela clava; are widespread invaders which severely impact the culture of bivalves. A prime example is the Greenshell™ mussel culture industry in New Zealand which has periodically experienced significant decreases in productivity due to these pests. Despite a myriad of techniques being tested with the aim of controlling fouling ascidians, a long-term, cost-effective solution is yet to be found.  Our study exploits existing knowledge that a range of allelochemicals are capable of inhibiting metamorphosis in marine larvae. We aim to test these in seeking a high-tech remedy to counter ascidian fouling in the culture of bivalves. To date four compounds [polygodial (IC50: 97.2 hg ml-1, IC99: 712.8 hg ml-1), radicicol (IC50: 45.9 hg ml-1, IC99: 928.0 hg ml-1), muscimol (IC50: 21.0 hg ml-1, IC99: 39.3 mg ml-1), spermidine (IC50: 4.5 mg ml-1, IC99: 45.2 mg ml-1)] have been demonstrated to inhibit metamorphosis of C. savignyi larvae. Further to these findings, efforts will be made to quantify effects of the most potent contenders on the physiological health of post settlement Greenshell™ mussels, followed by the development of techniques for application in an aquaculture setting.