Lionfish sampling day 6-7: Graysby hunting

One of the four divers on this trip is a master' student at USF. His project is dealing with the diet of the predators on the reef and how they are impacted by the presence of lionfish. There are a few different ways to possibly answer this question. One way to analyze this data is the use of isotope analyses. The isotopes of nitrogen and carbon differ based on where their food is coming from.  If lionfish are having a significant impact on the native predators' ability to find food, the natives would shift their diet from their normal diet to different food. This shift would be present when the data is analyzed.

Graysby looking angry at the world

One of the resident preditors on the reef is a small grouper species called the graysby. For the master's project, we are spearing 1-2 graysby on each site. On each site, once Kara and I finish with our surveys for lionfish and other prediators, we spend the remainder of our time searching for a few graysby to shoot for the project. We swim around the reef & try to sneak up on them and spear them with a pole spear.

The student, Joe, will analyze their tissues for the nitrogen and carbon. Currently, each of the reefs we are visiting have at least a few lionfish living on them, and they have been there for the past few years.  In another few months the National Park will begin regularly visiting each site to remove the lionfish they find. On future trips, the divers will collect 1-2 more graysby. These will be after the lionfish have been removed from the area. If the lionfish were having an effect on the diet of the native predators, Joe's analyses should find a change in the isotopes. If lionfish are not affecting the diets of native predators, the isotope signatures will be the same both now and in a year.  Of course, we will not know the answer to this question for at least another year or more. It will be very interesting to find out what type of effect the lionfish have on the native predators.