Publications: Peer-reviewed journal articles (by staff)

Evaluation of treatments to reduce the spread of a marine plant pest with aquaculture transfers

1 January, 2006
CITATION

Forrest BM, Blakemore KA 2006. Evaluation of treatments to reduce the spread of a marine plant pest with aquaculture transfers. Aquaculture 257(1-4): 333-345.

ABSTRACT

The role of aquaculture and other human activities in spreading non-indigenous marine organisms is well recognised. This paper assesses the feasibility of various 'environmentally friendly' treatments for key inter-regional transport vectors (equipment and seed-stock) within the New Zealand mussel farming industry, focusing on control of an internationally recognised seaweed pest, Undaria pinnatifida. The effects on Undaria of high pressure water blasting, natural air drying, and freshwater immersion at ambient (10 and 20 degrees C) and hot (35-55 degrees C) temperatures are described, and the tolerance of mussel seed-stock to the freshwater and hot water treatments is investigated. Water blasting was completely effective in removing Undaria gametophytes from shells at pressures : 2000 psi for 2 s. Undaria survived natural air drying for up to 2 days at ambient humidity (55-85% relative humidity; RH) and > 8 weeks at high humidity (> 95% RE). In freshwater, gametophytes survived immersion for 1-2 days, but plantlet mortality occurred within < 10 min. Undaria survival in hot water across the 35-55 degrees C ranae was tens Of Minutes to a few seconds. Using these findings as guidelines, these treatments would be relatively easily applied to sterilise equipment Such as farm floats and rope, with the preferred method selected based on cost, practicality and other constraints. Removing Undaria from mussel seed-stock is more problematical because of the importance of identifying treatment conditions that do not compromise mussel health. Mussels were not adversely affected when immersed in freshwater for a 2 day duration sufficient to ensure complete Undaria mortality. Hence, mussels could potentially be treated in freshwater at reasonable cost while being transported between aquaculture regions. However, to ensure an effective treatment the water would need to be exchanged during the transport phase in order to maintain salinities at <= 1 psu. Our findings also suggested that exposure to hot water at 55 degrees C for approximately 5 s would achieve complete Undaria mortality while maintaining a level of mussel survival comparable to untreated seed-stock. This method is likely to involve greater costs than freshwater immersion, and requires field validation to confirm both the efficacy against Undaria and to identify a method of implementation that ensures mussel survival is not compromised by the combined stresses of treatment and inter-regional transport.

 (c) 2006 Elsevier B.V. All rights reserved.