But training has only been part of the M-31 prep… we need to plan for science too!
I’m leading a project on the bioenergetics of the giant barrel sponge, Xestospongia muta. Sponges are seriously ancient, in more ways than one. Sponges as a taxonomic group may have been the first animals on the planet, and fossil sponges dating from 635 Million years ago have been found. Work by Joe Pawlik's group at UNC Wilmington also suggests that individual sponges can be as old as 2000 years, making them true "redwoods of the reef." During our two-week mission, we will continuously monitor pumping activity, respiration rate, and feeding rate in a number of these organisms. These in situ (in the field) measurements of metabolic (body fuel burning) activity taken continuously over a relatively long period of time will help us understand the mechanisms driving the flow of energy through these organisms, as well as how natural fluctuations in the environment can impact this flow of energy. Specifically, we want to know how much energy goes into respiration, growth, and repair and replacement of cells. In a nutshell, we are trying to understand how these organisms allocate energy they receive from their food, and to better understand how global climate change may affect these ancient organisms. Sponges may provide a significant amount of energy to organisms higher up the food chain, and are essential recyclers of nutrients on the reef. In fact, all of the water on a reef passes through the body of a sponge every 24-48 hours! So, understanding how the environment impacts the flow of energy through sponges also gives us insight on how environmental change may impact the functioning of the entire reef.
During the mission, we will measure rate of oxygen uptake, i.e. the amount of oxygen removed by the sponge per unit time. Throughout the mission, two sponges at a time will each be equipped with a YSI water quality sonde, which will measure dissolved oxygen (as well as many other parameters) in the excurrent flow of the sponge (in the barrel of the sponge).