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.

Maggots, Tank Stands, Human Ecology

The semester is well underway at this point, to be specific it is a quarter completed. A week ago my intern Andrea and I went to work on our self harvesting maggot breeder. For the main chamber I used a mini fridge that Joseph and I sourced out of the local dump. The idea was to have the majority of the air exchange blocked by the seals on the fridge. The container has but a couple holes in it, one for the water to drain out, six for fly's to get in and lay eggs, and one with a pipe leading to the harvesting bucket. The image to the left shows the incubator minus the lid. This was the plan.

The reality has been that some of the information I read about the maggots ability to climb may have been incorrect. The ramp leading up to the collection hole should have been the easiest way for the little buggers to leave the unit but instead they chose to climb the vertical walls and pile up by the seal. This resulted in maggots getting out every time I opened the door. Not a god situation when you are trying to harvest them.

Plan B has been to switch over to five gallon buckets and a water drowning method for dealing with them after they crawl over the top lip and drop. The good news is that I haven't made anyone throw up this time so the process is improving! There may be a few more revisions of the system before it becomes fully functional. Students start feeding them to the little fish tomorrow.

Speaking of the little tilapia, I have had several days of research class so far and the students have been hard at work designing and constructing our experimental unit. We have twelve Brute totes inside of a pair of larger trough tanks as the basic design. Each tote has twenty fish in it and these will be the lucky fish chosen for the grand experiment. The image to the left is of the students and me putting the frame together to hold the tanks and walkway. The pair of tanks is designed to have water pumped into it from the main tilapia water system and it also gravity drains back into the regular system acting like any other tank in the system. Today we put a bird tent over the whole experiment due to the presence of a fish loving green heron that has appeared. I will post pictures when I get them off of Andrea's camera.

Along with the research class I am teaching I have been helping with the human ecology class that Remo is doing. Basically he wants the students to study the interaction between people and place. Since I am in charge or growing food here on the campus I have been getting the student hands on with all of our food systems so they can understand the difficulties of growing in this climate. Since the majority of our food is imported Remo and I feel that the students needed to understand why this is. I am done with that part of the class now as the students move on to other experiences like fishing with a local fisherman for a day, farming with a slash and burn farmer, and going to the mailboat to see our food arrive.

The two main activities I had the students work on were fish sampling and planting in the orchard. The first image is of the sampling process. Fifty fish are removed from one of the tanks and placed into a cooler with water. After they are all netted up they are removed one-by-one, weighed, measured, and returned to the original tank. This process is done once a month to track their growth and adjust feed rates accordingly.

The next image is of the hole the students dug in order to plant a new sugar apple out of the nursery. This is simply a hole in the ground about three feet in diameter and a foot and a half deep. Simple right? This was a two hour process involving six high schoolers, two pick axes, and five shovels. After the hole is prepped we placed three layers of cardboard in the bottom of the pit to help keep the nutrients from washing out of the soil. This was then covered with a sand, compost, wood shaving, and dirt mixture. The tree is set into this bed slightly recessed into the ground. This allows the water to pool near the tree instead of running away from it and also allows for a layer of mulch to be placed around the base of the tree. We used casuarina wood shavings as a mulch, six inches thick worth of it. Below is a picture of the finished tree planting.

The other student groups I had in the orchard propogated some eddible plants for all to enjoy in a couple of years. We used our waste milk containers cut in half as starting pots. This involved the students cutting through fifty containers with sour milk residue inside, filling it with potting soil that they had to sift the stones and sticks out of, and taking the clippings. A fun afternoon activity. Picture above is of the sifting process with the reclaimed containers below.

That's all for now, I think I have talked long enough.

Joshua

Thursday

Teacher Orientation
Phew! What a busy last couple of weeks it has been. Teacher orientation consisted of two weeks of regular work topped up with many hours of required classroom sitting. I did learn quite a bit or useful information like how ot respond to an emergency situation when you are four hours away from a hospital. The medical simulation was exhilarating and fun even though it would have been a very serious situation in real life. The simulation basically went something like this: Andy and I rode our bikes in to Deep Creek like we were usiong our free time to go get some icecream at V&H's. Once we got to town we ran into Chelsea who was running towards the school. She started out of breath so once we stabaized that situation we find out there was a swimming accident at the blue hole and thats why she was running. I stayed with her to calm her down since she was hysterical (she did a scarry good job at playing a hysterical student by the way). We had to borrow one of the short wave radios in town since our hand held wasnt working (real life problem not planned). Down at the blue hole David had jumped in and possibly broke his neck. Andy had to get him out of the water unconscious by himself. By the time I got there there were two vans and people form the Middle School and the Island School on the scene with some medical equipment. We had to get David on the backboard and get him strapped in. Very interesting stuff and enough to convince me no never go into the paramedic profession.

In the Facility
So the aquaponics system is starting to come around and work again even though the heat still hits the low 90's every day. I am beginning to theorize that the decline in production has more to do with cutting schedule and technique as well as plant age rotation. I have been working at getting the grow beds staggered in age so that some are young, medium, and old. This combined with regular cutting once a week has increased yields back to what they were prior. I am currentlygetting roughly 4-6 pounds of lettue per bed (24 sq ft)

I have aslo discovered that the root zone of the plants is infested with freshwater shrimp (amphipods) called Gammarus. They seem to be feeding on the detruiteus from the fish that makes its way into the beds as well as on the roots of my lettuce. I have also found many small tilapia in the grow beds when I clean them out, these will also eat the roots. Overall I have a problem with root growth that I still have not figured out a solution to.

On the Farm Lately
Not much time has been spent in the orchard and nursury lately. When my time gets short this is apparently where it comes out of. I guess permaculture and tree pruning is not as sexy as a technology rich aquaponics system. I did discover that I apparently have an excess of calcium (the soil is made of mostly calcium carbonate afterall) which is causing magnesium deficiencies and stunted growth in many of the plants. Unfortunately there is no easy solution to this dilema except more organic matter or I could try adding elemental sulfur. The only drawback to elemental sulfur is that microbes decompose it into sulfuric acid (good for lowering soil pH) but bad for any living plants or micobes already there. Compost it is then! I just need the biogas digester to come online so I can have a continuous supply of organic matter. . .

The students are here!!!! Yay!!!

Weekend Fun

So Saturday rolls around I had no idea what to do with myself on a half day of work. Thiago mentioned that after lunch he was going out to our aquaculture cage to feed the cobia.

Let me briefly describe the aquaculture cage: imagine an underwater mesh net in the shape of two cones joined at the wide bases to one another. This netting is held in place by a central spire that is anchored to the ocean floor in eighty five feet of water with the top twenty five feet below the surface. The central ring is roughly fifty feet in diameter. Inside there are five thousand cobia roughly five to eight pounds in size.

This is the offshore cage we were going out to feed the cobia at. Thiago also wanted to do some cleaning of the net since it is covered with algae that restricts water flow into and out of the cage. I haven'tdone nearly enough diving so I volunteered to help. Rob, Alyssa and I dive down after Thiago hooks up the feeding tube that pumps food from the boat into the cage. On our way down we noticed these large, slow, sleek looking fish cruising around the bottom of the cage. Oh, no worries, just four reef sharks six to eight feet long hanging out. We sat on the edge of the central ring and watched them cruizing around for five minutes or so. Such an amazing fish. Later in the dive after we cleaned a bit of the netting Rob and I found four sharks teeth laying on the top of the netting. I can't wait untill the bull sharks start coming around again. That will be fun to dive with.

Later Saturday I took my brothers Jeep out to Plum creek with Chelsea to show her how to compose some pictures with her DSLR. I posted some of the shots I took on my Flickr page. http://www.flickr.com/photos/joshua-island/ There are some amazing pictures of the sun, in my humble opinion.

New news with the aquaponics system. Catching Bahamian crickets is harder than I thought it would be. Veron devised a handfull of traps and just today we caught our first two. Now we have to make a home for them to breed in. I am also now looking at maggots as a protien source since it is much more readily available. I have some deliscious fish heads in a bucket making maggots for me. Yummy. The students are going to love working with me.

My First Post - Behind schedule already

12 August 2009 - Wednesday

So in all honesty I have been meaning to make this blog ever since I came down here to beautiful Eleuthera. Seeing as how it has now been a month and a half I figured I should post something. Here goes.

This week has been pretty full so far. We have a visiting group on campus from the wonderful town of Harlem, NY. There are about thirty eight students and four faculty staying on the Island School side of campus. It is pretty loud now compared to the almost deserted times during the summer.

My work for the week has been concentrated on preparing for the Island School students arrival at the end of the month. I am leading six or seven students in a research project involving the tilapia aquaponics system that I manage. We will be looking at the different growth rates of the fish depending on alternate local feeds. Specifically I am looking at duckweed, crickets, and cockroaches as a supplemental source of protein for the fish.

Today I set up two new duckweed tanks and plumbed them into the recirculating system that feeds the grow beds. This will hopefully secure a steady supply of duckweed to base our experiments on. I also set traps out tonight for crickets and cockroaches. I think I am going to call the cockroaches "Bahamian crickets" when the students get here so as to not freak them out about having to chop up cockroaches every morning as food. More to come later.