Mission & Project Info | NOAA’s Aquarius Undersea Laboratory
Mission Blog

We completed field experiments on Wednesday as sea conditions has been worsening for a couple of days. We were able to complete most of the intended sampling on the ACRRE transplant corals including photos, branch extension, mucous samples, and photosynthetic efficiency measurements. There was a noticeable amount of tissue loss/disease on several of the staghorn coral transplants and one of the boulder coral transplants, as well as evidence of ongoing predation on these colonies by both snails and fireworms (the subject of our other mission experiments). The largest staghorn transplants, though, have grown to over a half meter in diameter in two years.

We successfully completed an experiment to quantify the feeding rate of corallivorous snails on different genotypes of staghorn coral prey. We were able to successfully execute the various steps in our planned fireworm experiment, but these experimental subjects were not as cooperative and did not feed as much as we had hoped in the time frame that we were working with. We were able to secure many samples of fireworms in many different feeding states (e.g., straight from the reef, after quarantine without food, after exposure to healthy and diseased staghorn coral prey) and corals with both disease-related tissue loss and predation-related tissue loss which will be subsequently analyzed histologically (i.e. to examine the microscopic-scale anatomy and cell structure). These histological studies should yield further insights regarding corallivore impacts on corals and the cellular processes of tissue loss affecting both transplanted and wild corals.

Observations from both the snail and fireworm experiments suggest that both corallivores may display what is called ‘injestive conditioning’ in their feeding behavior. This means that predators that have been exposed to a certain prey type in the past may prefer that prey type in the future. In the snail experiment, snails that we collected from Acropora spp. hosts fed much sooner and in greater quantity on the Acropora cervicornis prey presented in the experiment than snails that we collected from other host coral species. Similarly, the poor feeding behavior of the fireworms on A.cervicornis in our experiment is consistent with the hypothesis that these worms were collected from areas where they may not have been exposed to this prey type in the past. Additional quarantine time and longer planned feeding treatments would likely alleviate this challenge in future fireworm experiments.

As always, we offer our continued appreciation to the Aquarius Reef Base crew that always does their utmost to get done what we need, especially under difficult contingencies. Also to our various collaborators in this mission, especially the Coral Restoration Foundation, George Mason Univ, UNCW, and FKNMS.