Pressurized seawater as an antifouling treatment against the colonial tunicates Botrylloides violaceus and Botryllus schlosseri in mussel aquaculture

Collin Arens,Aaron Ramsay,Christine Paetzold,Jeff Davidson

doi:10.3391/ai.2011.6.4.12

Collin Arens, Aaron Ramsay + Show 2 more

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https://doi.org/10.3391/ai.2011.6.4.12

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Journal: Aquatic Invasions	Publication Date: Dec 1, 2011
Citations: 35	License type: cc-by

Affiliation: University of Prince Edward Island

Abstract

The development of effective mitigation techniques against Botryllus schlosseri and Botrylloides violaceus colonizing blue mussel aquaculture operations has not been well studied. The objectives of our research were to determine the efficacy of using pressurized seawater in the mitigation of colonial tunicate fouling and to identify optimal treatment timing and frequencies in reducing tunicate biomass. Treatment trials using high- (~700 psi) and low-pressure (~40 psi) seawater spraying were conducted in St. Peters Bay and Savage Harbour, PEI, from May to November 2009. The use of high-pressure seawater was an effective anti-fouling measure for these species, causing significant reductions in tunicate biomass. In contrast, low-pressure seawater had no discernable effect. The timing of treatment was found to be the most important factor affecting efficacy, with reductions in tunicate biomass increasing in magnitude the closer the treatment occurred to harvest. Treatment frequency did not affect tunicate biomass. In addition, fewer treatments also resulted in less nuisance mussel spat fouling the mussel socks. Colonial tunicate fouling did not affect adult mussel growth and productivity, and no evidence of smothering or crop loss was observed.

Highlights

The spread of non-indigenous tunicates has had ecological and economic impacts world-wide as these species become dominant in marine biofouling communities (Lambert and Lambert 1998; Carver et al 2003; Coutts and Forrest 2005; Gittenberger 2009)
Peters Bay, high-pressure washing significantly reduced Botryllus schlosseri biomass in most treatment groups compared to the control, with the greatest reduction (84%) occurring in treatment group 10 (Table 3; Figure 2A)
Botryllus schlosseri biomass was similar between treatment groups 5 and 17, both of which were treated in October, though group 5 was treated five times and 17 only once

Summary

Introduction

The spread of non-indigenous tunicates has had ecological and economic impacts world-wide as these species become dominant in marine biofouling communities (Lambert and Lambert 1998; Carver et al 2003; Coutts and Forrest 2005; Gittenberger 2009). A combination of factors including increased maintenance and processing costs, production losses resulting from interspecific competition for space and resources (Lesser et al 1992; Carver et al 2003), and crop loss associated with smothering and detachment threaten the viability of the industry in some areas (Boothroyd et al 2002; Ramsay et al 2008a; Locke et al 2009a) This has prompted research to develop mitigation strategies that reduce tunicate fouling. For anti-fouling measures to be practical, they must be costeffective, environmentally benign, and minimize product loss and negative impacts on shellfish production, without compromising food safety (Braithwaite and McEvoy 2005; Locke et al 2009a)

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