Screening for negative effects of candidate ascidian antifoulant compounds on a target aquaculture species,Perna canaliculusGmelin

Abstract

The natural chemical compounds radicicol, polygodial and ubiquinone-10 (Q10) have previously been identified as inhibitors of metamorphosis in ascidian larvae. Accordingly, they have potential as a specific remedy for the costly problem of fouling ascidians in bivalve aquaculture. In this study, these compounds were screened for their effects on the physiological health of an aquaculture species, the green-lipped mussel, Perna canaliculus Gmelin, at or above the 99% effective dose (IC(99)) in ascidians. Three physiological biomarkers of mussel health were screened: growth (increases in shell height and wet weight), condition (condition index) and mitochondrial respirational function (Complex I-mediated respiration, Complex II-mediated respiration, maximum uncoupled respiration, leak respiration, respiratory control ratios and phosphorylation system control ratios). While polygodial and Q10 had no effect on mussel growth or the condition index, radicicol retarded growth and decreased the condition index. Mitochondrial respirational function was unaffected by radicicol and polygodial. Conversely, Q10 enhanced Complex I-mediated respiration, highlighting the fundamental role of this compound in the electron transport system. The present study suggests that polygodial and Q10 do not negatively affect the physiological health of P. canaliculus at the IC(99) in ascidians, while radicicol is toxic. Moreover, Q10 is of benefit in biomedical settings as a cellular antioxidant and therefore may also benefit P. canaliculus. Accordingly, polygodial and Q10 should be progressed to the next stage of testing where possible negative effects on bivalves will be further explored, followed by development of application techniques and testing in a laboratory and aquaculture setting.

Measurement of mitochondrial respiration in permeabilized fish gills

“…Permeabilization of tissues by detergents has been suggested as a more physiologically relevant approach as it leaves the physical structure of mitochondria and other organelles intact, and eliminates any centrifugation bias present in traditional isolation techniques (Saks et al, 1998;Picard et al, 2011). Indeed, a study performed on oyster gills used traditional methods requiring the mechanical shredding of gill tissues followed by permeabilization with detergents during the run (Cahill et al, 2013). However, including the permeabilization step during the measurement of mitochondrial function leaves the possibility of over-permeabilization during prolonged runs, and the mechanical separation of tissue fibres required to facilitate permeabilization can also be time consuming and challenging to sustain sample-to-sample consistency (Larsen et al, 2014).…”

Methods to prevent and treat biofouling in shellfish aquaculture

“…Several such treatment methods have been tested experimentally, including exposure to air (Darbyson et al 2009, Hillock andCostello 2014), freshwater (Forrest and Blakemore 2006b, Forrest and Blakemore 2006a, Denny 2008a, Denny 2008b, heat (Carver et al 2003, Guenther et al 2011, and organic acids and bases (Forrest 2007, LeBlanc et al 2007, Piola et al 2010, Rolheiser et al 2012). In addition, novel antifouling compounds are being tested against shellfish biofoulers (Cahill et al 2013a, Cahill et al 2013b. Many are recommended for use in the aquaculture industry (Fitridge et al 2012, NSPMMPI 2013), but industrial application has been met with varying success because the morphology, life history and biomass of biofouling organisms may mean that they react differently when exposed to the same treatment (LeBlanc et al 2007, Piola et al 2008, and because treatment costs are often greater than profit gains.…”