Put a structure in the ocean, and you attract a host of life wanting to settle on it. Aquaculture nets can become home to a host of sedentary species, like algae, molluscs, and hydroids. Unfortunately as these organisms accumulate, they can reduce water and oxygen flow through the net, decrease waste removal, increase the risk of disease to the farmed animals, and even physically damage the nets.
Aquaculturalists wishing to control such ‘biofouling’ have a few choices – physically remove the organisms, replace the nets, or use antifoulants to reduce the amount of biofouling occurring in the first place.
Copper is a naturally antimicrobial metal, and a common ingredient in biofouling paints that can be applied to nylon nets. Copper can even be used as part of the net-material itself. These copper alloy meshes also offer another advantages – reducing escapism or predation from holes that can develop in more traditional nylon-mesh settings. The downside to copper is that at high levels, it can be toxic to marine organisms, raising concerns about the use of copper alloy nets in the industry.
However, as Dr Ioanna Kalantzi (Hellenic Centre for Marine Research, Greece) and colleagues demonstrated in a recently published study, the effects of copper alloy nets may not be so different from copper-based antifouling paints...
This article was written for (and can be read in full at) The Fish Site.