Gut microbes used to track the spread of invasive fish species.

A recent study has found clear differences  in the gut microbial communities of fish, providing a possible method for the monitoring of invasive species in river systems. The microbes present in the gut of invasive and non-invasive species of carp are very distinct, according to researchers from University of Illinois and the U.S. Geological Survey. The study, published recently in Nature’s ISME Journal analysed differences in these microbial communities using genetic sequencing.

The sequencing technique used was a technique called 16S pyrosequencing, which investigates a short gene called 16SrRNA. This gene does not change much over many generations so small changes can be used to differentiate between species of microbe. The technique is known as a “next generation” sequencing technique, meaning it sequences many fragments of DNA information at one time. This produces vast amounts of information very quickly, leading to a detailed picture of the gut microbial community in fish.

The invasive Asian Carp is an umbrella term for several non-native species that have come to dominate many areas in the Mississipi River basin in the United States. According to Wen Tso Liu, one of the authors of the study, “invasive species can be dangerous [because] they can eat the same food, and if the invasive species consumes more food, then the native species can be out-competed and their population will start to decline, leading to ecological disaster.”

The study found specific genetic markers unique to the invasive Asian Carp and others unique to the native Gizzard Shad. These markers can be found in fish faeces that is abundant in the water. According to Liu, targeting these markers could provide an easier and more precise method  for monitoring the spread of invasive species than other techniques in development.

The next step of the project is to carry out the same methodology in the Chicago River, home to around 50 different species of fish. The plan is to analyse the guts of all 50 fish species and find genetic markers for each. According to Liu this research should have further applications as well. “There is a lot more beyond just monitoring,” he says. “We will also learn more about the diversity of fish, their diets, how their diets are related to their gut microbiota and how they metabolize inside the gut.”

http://www.nature.com/ismej/journal/vaop/ncurrent/full/ismej2013181a.html