Civil War

Apostichopus japonicus is a commercially important species of sea cucumber found commonly in the shallow waters of south east Asia. In countries such as Japan and China, it is a popular food source and is both fished and farmed, having created a large aquaculture industry based around it. As is common in all types of farming and aquaculture industries, A. japonicas has had its fair share of disease outbreaks, thought to be aggravated in these regions by a substantial increase in the farming industry, which is increasing output and pollution.

Vibrio splendidus is a common pathogen of A. japonicas, causing skin ulceration syndrome, which is a major limitation in the farming of this species. Previous studies have looked into using various probiotics as a means of efficiently treating V. splendidus infections, and while they have proven effective at reducing the growth of V. splendidus, all of these tests have been carried out in vitro, and the efficiency at which they would perform in vivo is largely unknown.

(F. Yan, 2014) presents the results of the probiotic bacteria Paracoccus marcusii DB11 when used as a dietary supplement on the health of A. japonicus juveniles. The team exposed A. japonicus to DB11 via their feed at varying doses, and measured the levels and activities of 5 immune enzymes, the sea cucumbers growth rates, and the survival rate when infected with V. splendidus. They discovered that even the lowest dose of DB11 had positive effects on all factors measured, and growth rate increased with increasing doses of DB11, as did all immune enzyme activity. Additionally, at the highest dose of DB11 administered, there was 0% mortality when the juveniles were infected with V. splendidus, and only 15% mortality at the lowest dose, which could either suggest inhibition of the growth of V. splendidus, or inhibition of pathogenicity. These results are very promising when compared to a 40% mortality rate when the juveniles were left untreated, which undoubtedly has huge impacts on the aquaculture and farming of these organisms.

Using probiotics in aquaculture is a relatively new but very promising field, and while studies still seem to be in their infant stages (with most experiments being carried out in vitro), I think this paper provides a very useful insight into a real environmental use, which is potentially much less harmful and costly than the use of antibiotics and other previously tested methods to improve the health of organisms from aquaculture. I believe this paper gives some good indicators as to what to look for and how to conduct and efficiently apply these studies in the future, and could present an economically viable solution to many disease problems faced in aquaculture.

F. Yan, X. T. (2014). Growth performance, immune response, and disease resistance against Vibrio splendidus infection in juvenile sea cucumber Apostichopus japonicus fed a supplementary diet of the potential probiotic Paracoccus marcusii DB11. Aquaculture, 105-111.