Resolving Biofouling in Marine Aquaculture
by Parx Materials, the Netherlands
The Abalone is a mollusc notable not only for its resemblance to the human ear, earning it the nickname 'ear-shell,' but also for being one of the most expensive varieties of seafood in the world today. Especially valued in Southeast Asian cuisine, Abalone is known in Japan as the 'truffle of the sea.'
In a recent field trial conducted by an experienced and long established marine aquaculture farm, culture tanks were brought ashore to harvest abalone that was set out to grow six months before. During the six-month period, the delicacy grew to its full size in the plastic culture equipment set out in water. In total several hundreds of tanks were used for growing the shellfish.
Usually during this time, the plastic culture tanks can get covered with unwanted aquatic species that obstruct the flow of fresh water through the tanks, which is usually a common problem in marine aquaculture, but not this occasion.
For this trial a number of the tanks (about 100 pieces) were produced using Saniconcentrate™ from Parx Materials. Following six months in the ocean the tanks were still clean, and completely free of any fouling. The treated tanks also allowed the abalones to develop significantly better, growing larger than in the normal tanks. This increase in size means a higher yield of the valuable product and more profit for the aquaculture farm.
Sustainably Improving the Material
Saniconcentrate™ is a modified polymer concentrate that is added to plastics prior to the manufacturing process of the tanks. The concentrate contains the trace element zinc, a nutrient with 'utmost biological importance'. The incorporation of this trace element is achieved by use of a novel and patented method developed by an interdisciplinary team of scientists specialised in biomimicry, biochemistry, material science and polymerisation processes. Saniconcentrate™ is inspired by the defence mechanism in the human skin, where the trace element of zinc is vital for a healthy immune system protecting us against bacteria and viruses.
By incorporating this trace element, the materials mechanical/physical properties are improved, making the material surface resistant to the adhesion of fouling, bacteria and biofilm. An antifouling solution that does not leach out will not contaminate the oceans. Nothing of the technology is 'consumed' over the lifespan of the product, so the technology remains at full strength and does not fade away.
The technology is unique as there are no biocides or other toxic components involved. It only cleverly incorporates the biocompatible trace element like it is found in green vegetables such as broccoli and spinach or how it is present in your multi-vitamins.
Biofouling and shellfish fitness
Biofouling in marine aquaculture is one of the main barriers to efficient and sustainable production. The settlement and development of unwanted aquatic species on the surfaces of products and equipment can cause a variety of issues. The two main identified problems caused by biofouling are: the increased weight of culture equipment; making it more difficult and energy consuming to manage and clean, with the second being reductions of shellfish quality.
One of the most important impacts from biofouling in shellfish aquaculture is the reduction in shellfish quality. It can impact and reduce survival, growth, condition and weight. These aspects are typically attributed to direct competition for food and the obstruction of food, oxygen and other resources.
The direct economic costs of managing biofouling in the aquaculture industry are roughly estimated to be 5–10 percent of production costs. However, this percentage often varies considerably between aquaculture locations, species and companies and many of the indirect impacts are unclear. So the overall cost of biofouling in marine aquaculture is likely to be significantly higher.