Ahhh. The semester is over, it's almost Christmas. I figured it would be a good time to do another update seeing as how it has been two months since the last. The fish feeding study is finished now and the results are in. Duckweed grown in the same water as the fish who eat it = not so good. Maggots were almost comparable to the commercial feed which says a lot since we basically ran out of them for the last two weeks due to harvesting issues. If we could reliably harvest maggots I feel they have the potential to surpass the growth rate of commercial feed. (see graph to the right)

Back to the duckweed. The main issue we had with the duckweed is that nearly half the fish being fed it died. Needless to say, this is not the ideal situation when you are trying to raise fish to eat. Some thoughts: a green heron made it past our bird netting on more than one occasion and may have eaten some of the fish (See image below). If this is the case then why only duckweed fish? We also found some of the fish carcasses floating in the tanks, eliminating that idea somewhat unless the bird was pecking at the fish, killing them, and then not eating them. A possibility. Another hypothesis is that the duckweed was too large a bite for the tilapia fingerlings we were feeding. These were the ideas our research group came up with as part of their presentation of the project. (see their poster)

My personal thoughts have to do with nutrient cycling. The duckweed is grown in the same water the fish are grown in (separate tanks). Since the only inputs into the system are through the food the tilapia eat, my thoughts are that the duckweed is nutritionally deficient. Every time the the nutrients flow from the feed to the fish to the duckweed a little is lost to the plants and fish. I would like to do a comparison study of duckweed grown in the aquaponics water and duckweed grown in some other nutritionally rich water, perhaps pig waste.

Enough of the experiment, what else has been happening.

The bike shop is almost complete. Today I received the seeds ordered for planting the roof, now we just need to order the roof membrane. The building has a flat concrete roof that we are going to cover with six inches of soil. This will be an experimental garden to see what is salt, wind, and sun tolerant since there is plenty of each of those things twenty feet in the air next to the ocean. The nice thing is that IF I ever get anything to grow up there, there is no access besides an aluminum step ladder you have to carry over. This will make it very difficult for the fruits and veggies to grow legs and walk away as they currently do now.

The experimental living shadehouse seems to be working well thus far. The tufts of leaves and branches are almost comical on top the the trunk cuttings I put in the ground, kind of remind me of Truffula Trees from The Lorax by Dr. Seuss. Andrea and I made three twenty foot long by four foot wide raised beds with three trees each (See image at left). By next summer I expect them to have grown over the canopy enough to shade the cuttings and seedlings planted below. Currently we have carrots, cabbage, tomatoes, beans, other Moringa, and various fruit tree cuttings in the beds. Next I have to cut down the casuarina trees that will soon invade the grow beds with their roots. Damn invasives. . .

Hopefully I will get one more post out before break. I have to go take pictures so I can show you what I am talking about.