Biofouling and marine aquaculture: risks, management and control

Marine aquaculture is exposed to a diverse array of biofouling organisms, some of which can adversely impact both target culture species and farm infrastructure and result in significant production impacts and costs. In mussel... [ view full abstract ]

Marine aquaculture is exposed to a diverse array of biofouling organisms, some of which can adversely impact both target culture species and farm infrastructure and result in significant production impacts and costs. In mussel aquaculture, biofouling causes physical damage to stock, mechanical interference, biological competition and environmental modification. Biofouling control can be achieved through the avoidance of natural recruitment, physical removal and topical treatments. However, with the global expansion of marine aquaculture, additional innovative biofouling management strategies will be increasingly necessary. Key challenges include preventing ‘pollution’ of the surrounding marine environment through the unintentional spread of biofouling species, including Invasive Marine Species (IMS), due to farming methods. Mussel growers have traditionally attempted to minimise biofouling through strategies such as freshwater dips or water blasting, but these techniques do not always ensure biofouling mortality and can facilitate the spread of viable biofouling organisms, including IMS, to the wider environment. A range of ‘eco-friendly’ treatments exist, but their effect on widespread, common biofoulers is poorly known. Through experimental manipulations we found that treatment options involving heated seawater, acetic and citric acid, and combinations of both proved variably successful against a range of biofouling species, including some IMS. The hydroid Ectopleura crocea was highly susceptible to all treatments, whilst the ascidians Ciona intestinalis and Styela clava were moderately susceptible and relatively resistant, respectively. We identified treatments that cause high mortality of biofouling species but have minimal effects on mussel stock, providing some hope for growers in the battle against biofouling. However, such treatments may never be 100% effective. The Aquaculture industry is particularly vulnerable to IMS introductions and severe economic impacts have been documented, in some cases leading to the shutdown of aquaculture operations. There is a need for a critical assessment of the risks associated with biofouling management throughout the aquaculture industry. Future developments are likely to focus on the biosecurity risks posed by biofouling and effective mitigation via new technologies that effectively capture all biofouling debris.