We woke this morning and went to check the brittle star "condos" to see how many starfish liked their new homes. It appears as though half of them preferred not to remain in the dead sponges, while all of the brittle stars placed in the living sponges were still there. Preliminary results indicate that "not just any house will do" but we will continue the experiments for the next few days to see how many brittle stars choose to stay.

Joe and Monica came out to Conch Reef today to help with an experiment designed to determine if sponges are capable of changing their chemistry in response to grazing. This requires a little explanation - sponges are soft-bodied, attached to the ocean floor and are full of protein (nutritional value) but they are unable to escape from their predators. Because of these constraints, nature has provided some sponges with the ability to produce chemicals that are distasteful to their potential predators. Because "chemical-producing" sponges have to use energy to manufacture distasteful compounds, we propose that they would gain an "energetic benefit" if they could produce compounds only when they are needed, for example, while they are being eaten. It is this type of "induced defense" that Monica is attempting to investigate. To determine if this type of defense strategy is occurring in chemically defended sponges, the planned experiment is to take small samples at regular time intervals and send them to the surface where they will be "flash-frozen" and examined later to see if there is a change in the chemical composition over time.

We were all set to begin the experiment, but the current was too strong for us to complete the work. One of our tasks was to send a bag of small sponge samples to the surface with an inflatable buoy, but that would be like trying to fly a kite in high wind, so we decided to go out to one of the more remote worksites and conduct a survey of the area. Joe and Monica made a dive to see what sponges were present on the deep reef areas. We all decided that we should conduct the experiment when conditions are more favorable.

We came in for lunch this afternoon, grabbed a quick bite to eat and relaxed for a little while; I know, "How rough can it be to have to dive all day long?" Trust me, working in liquid all day is not the "stroll in the park" that you might imagine. As I mentioned earlier, the current was strong today, which is nice if you happen to be traveling in the same direction but doing so can lull you into a false sense of security - especially when its time to turn around and go the other way. The Aquarius crew prepared us for these contingencies, however, by outfitting the main travel routes with "excursion lines" that are attached to Aquarius and to specific points around the reef. When the current is strong, we can use these lines to pull ourselves back to Aquarius; the excursion lines are even fitted with indicators that tell us which direction to travel when the visibility is low. Pulling ourselves hand-over-hand through a strong current for a quarter of a mile is not nearly as bad as swimming the same distance with fins. Because our legs contain the largest muscles in the human body (and correspondingly require the most oxygen) we become tired much faster than if we use the smaller muscles of the arms and shoulders. One thing is certain…I'm really tired at the end of the day and rest is welcomed at any opportunity.

We ended the day scouting for areas in which the Giant Barrel Sponge is abundant. We are establishing sites to monitor their condition, reproduction, and life span, of what is the largest Caribbean reef sponge. In recent years, there have been reports of barrel sponges bleaching (losing color) throughout their entire range - sponges have bluegreen algae that live in their tissues. When they bleach, they generally fragment and fall apart, leaving only a ring on the ocean floor as evidence that something once occupied the space. We don't know why bleaching events occur, but we hope that gathering data on populations of these species over long time periods will help to solve some of the puzzling questions regarding their health and their contributions to the reef ecosystem.