Aquaculture

Aquaculture (AQ) is probably the fastest growing food-producing sector and it accounts for 50% of world’s fish food (www.FAO.org). Aquaculture takes place in coastal and inland areas and involves breeding, rearing, use of brood stock and fish harvesting. Aquaculture fulfils the need of the high demand for fish production, the value of biodiversity protection, sustainable use of sea resources, increase of efficiency and health benefit of sea-food diet. Aquatic environments impose a constant risk of exposure to disease-causing pathogens, and poor knowledge of background microbial diversity in aquatic farm leads to the emergence of possible environmental pollution and disease outbreaks.

The latter have wiped out entire populations in aquaculture farms, thus causing significant economic losses for aquaculture producers. A particular example is the human-pathogenic marine Norovirus, which is strongly correlated with water temperature, with concentrations increasing as waters warm seasonally. It can be concentrated in filter-feeding shellfish, molluscs, and especially oysters. Other examples are the WSSV (White-Spot Shrimp Virus) and Vibrio bacteria in bivalves, which pose a risk for the farmed species and human health. 

Although regulations and international oversight for the aquaculture sector are in place, the standard procedures for microorganism identification often require a clinical sample (i.e. animal flesh) and they take several days to deliver results. Recently developed methods involve the use of commercial flow cytometers. These are very bulky, expensive and do not offer sufficient sample representativeness. Plus,they require experienced operators within a laboratory environment and complex sample preparation procedures. Thus, they are not an optimum solution for in-line or in situ solution or field test.

The typical method of analysis is to use standard culture,  PCR or microscopy, all laboratory methods to quantify specific bacteria with sufficient reliability to meet regulations, but such methods provide only a few millilitres for each test and take between 1 and 12 days to get the results.