What is Aquaponics?

photo-1Aquaponics is an ecosystem approach to food production. In one recirculating system, aquaponics maintains a school of fish, a variety of plants, and a healthy colony of beneficial bacteria. The bacteria are the real heroes here. They rapidly consume toxic ammonia waste produced by the fish and turn it into nitrates on which the plants can thrive.
It all boils down to the nitrogen cycle. The fish feed contains nitrogen in the form of protein, which is the primary source of energy for the fish. As part of their digestion and respiration, the fish excrete nitrogen as ammonia both directly from their gills and indirectly through their solid waste. This waste ammonia will rapidly accumulate in recirculating aquaculture systems, and is quite toxic to fish even at relatively low levels. For aquaculture, ammonia must either be flushed out of the system or consumed in a biofilter.
A biofilter is nothing more than an elaborate bacteria condominium. In the biofilter, there is a lot of substrate surface area for bacteria to call home. Two kinds of bacteria have been identified as the main beneficial actors in a biofilter: Nitrosomonas and Nitrobacter. In turn, these bacteria convert ammonia into nitrite and then nitrate. This is good for the fish because nitrate is far less toxic than ammonia. This is great for the plants because nitrate is great plant food.
After the bacteria in the biofilter have eaten up the ammonia and spat out nitrate, the plants uptake these chemicals and prevent them from building up. Thus, the plants effectively purify the water for the fish in the aquaculture system.
The plants get great fertilizer, the fish get pristine water, and the bacteria make it all happen.
Unlike aquaculture, aquaponics allows no effluent to leave the culture system for the environment to break down. Unlike hydroponics, aquaponics systems do not require the entire system’s water to be dumped down the drain every two weeks. With aquaponics, you can produce edible fish and plants, waste little water, and produce no external effluent.

Aquaponics at the University of Miami
At the University of Miami (UM) Experimental Hatchery, the main focus has been on raising marine pelagic finfish in semi-recirculating tank systems.
By leveraging the considerable aquaculture experience available in the faculty, staff and students at the hatchery, a successful aquaponics system has been started at the UM Experimental Hatchery to showcase the technologies relied upon in aquaponics systems. We are raising Tilapia in a completely recirculating aquaponics system, with no wastewater going down the drain.
For the hydroponic component of our aquaponic system, we are using a media bed filled with expanded clay and we are experimenting with a vertical tower system which allows greater production per square foot. We are currently growing two crops: basil and spearmint. If you have eaten the pesto at the restaurant SALT on campus since late in the fall semester of this year, there’s a good chance you’ve enjoyed the basil grown in our aquaponics system.
The Aquaponics program at the UM Experimental Hatchery continues to grow. Aquaponics is a great way to eliminate the waste effluent being produced at aquaculture facilities and hydroponic plant production facilities. We are engaging with a variety of commercial and educational facilities which are interested in developing aquaponics operations.

–Joshua Grubman, UM Rosenstiel School part-time lecturer

 

Oyster stuffing and other Thanksgiving traditions

When you think of Thanksgiving dinner does turkey and green bean casserole or oysters and shrimp cocktail come to mind? What you may not realize is that early celebrations to give thanks for a bountiful harvest included oysters and seafood among its traditional dishes. Today, oyster stuffing, shrimp cocktail, crab and even smoked fish dip still have a place alongside (or inside) the traditional turkey and green beans on many dinner tables.

If your Thanksgiving menu includes seafood this year, choose sustainably.  There are several free sustainable seafood guides that can become your personal shopping assistant. The most popular, Monterey Bay’s Seafood Watch Guide, is available as a smart phone app as is the Blue Ocean Institute’s FishPhone. Another reference guide is NOAA’s FishWatch Facts, which also provides information on the national standards that goes into sustainable seafood assessments.

What determines a fish’s sustainability is a complex formula that takes into account, among other things, current fish population levels and how effective management measures are in preventing overfishing and population declines. This assessment starts with good science.

Lucky for us, much of this good science is being done here at RSMAS. There are many RSMAS scientists working to collect the fishery population data and management that can be used to determine sustainability assessments.

If you want to learn more about how the science collection process works, check out the research being done by Dr. Jerry Ault and team in the Fisheries Ecosystem Modeling and Assessment Research (FEMAR) group and researchers studying fishery management, fish population dynamics and aquaculture.

What is your favorite Thanksgiving dish?

— Annie Reisewitz

Follow Annie on Twitter @annelore

Cobia Leave For Panama; Mahi Added to Line-up at UM Aquaculture

It’s hard to believe it’s already November. Time flies at the UM Experimental Hatchery (UMEH) when you’re busy making babies… fish babies, that is! The Aquaculture crew wrapped up this summer with an impressive total production of 100,000 cobia fingerlings. A large part of these fingerlings were shipped over to Open Blue Sea Farms in Panama to grow out in cages about seven-miles offshore. We are proud to say that two of our own students, Dan Farkus and Pat Dunaway, were also “shipped over” to Open Blue Sea Farms. They were recruited to work there incorporating UMEH hatchery technology that has been developed for cobia within Open Blue Sea Farm’s facilities. A big shout out to them for the first 25,000 cobia production run at Open Blue Sea Farms, definitely a success story to write home about!

Meanwhile, here at RSMAS we have added a new and very familiar species to our aquaculture lineup, the famous mahi-mahi (dolphin). This most recent addition brings us to five species at the hatchery: mahi-mahi, blackfin tuna, goggle-eyes, Florida pompano, and cobia. The mahi-mahi have been successfully spawning and the mahi fingerlings are growing day-by-day at the hatchery, a must see if you have not yet stopped by UMEH. Trials will be run on the mahi-mahi looking at metabolic rates and energy budgets for this species in relation to aquaculture feasibility. This will aid in the development of the technology to sustainably raise fish in captivity, such as mahi-mahi, to meet growing demands for seafood.

Cobias are also being extensively worked with for nutritional trials, which will continue through the winter. UMEH students and post-docs are replacing a percentage of the fishmeal that goes into cobia feed with soy meal replacement. This will help solve many problems that are inherent in Aquaculture such as environmental sustainability (heard of Fish In–Fish Out?) and improve economics when providing nutrition to the fish. The goggle-eyes, which is a well-known and expensive baitfish is also getting a very nice upgrade soon to a 30-ton brood stock tank. As of right now UMEH are the only ones working on bringing this coveted baitfish to the aquaculture industry.

This semester has brought in new eager personalities to the RSMAS Aquaculture facilities. Good thing too as we needed extra hands to help organize a tour at the Aquaculture facilities for the Society of Environmental Journalists 2011 Conference. UMEH hosted about 30 journalists from around the globe on a guided tour of UMEH facilities, including the research stations mentioned above before hunkering down in the seminar room for a conference with RSMAS Aquaculture Director – Dr. Daniel Benetti, as well as Lisa Krimsky – Florida Sea Grant Agent (Miami-Dade), and Mike Sutton – Director of the Center for the Future of Oceans (Monterey Bay Aquarium).

It’s been an exciting start to the Academic year at the UM Experimental Hatchery… we’re all looking forward for what more is to come… stay tuned!

— UM student Melissa Pelaez
Follow Melissa on Twitter @BlueAquaculture