Progress 07/01/23 to 06/30/24
Outputs
Target Audience:We reach out to the Aquaponics community during the Aquaculture America 2024 meeting (San Antonio, Texas)and the Aquaponics 2023 meeting (Santa Fe, New Mexico). During that time, we exchanged information about the technical improvement of aquaponics systems and the production needs of farmers. We also interacted with the aquaponic farming community in Santa Fe, New Mexico, and attended their monthly meetings during the summer experiments.The mid-scale basil production was distributed between the local communities for free. Changes/Problems:We found a high incidence of bacterial infections and cannibalism in swordtail fish. This interferedwith the optimal production of fish.To solve this problem, we designed and established prophylactic treatments with peroxide and designed new fish hiding that will be tested shortly. What opportunities for training and professional development has the project provided?1 Master's students and four undergrads(2 from biology and two from engineering)were trained during this period. The master and two undergraduate students attended the National Aquaponics meeting. How have the results been disseminated to communities of interest?We maintain continuous communication with the Aquaponic community in Santa Fe and with the rest of the aquaponic farmers through the Aquaponics Association. What do you plan to do during the next reporting period to accomplish the goals?We aim to design and build, in collaboration with the engineering department, hiding sites for short-tailed fry to avoid cannibalism. We aim to develop the minnows culture described in aim two and elaborate on the financial analysis of every culture.
Impacts
What was accomplished under these goals?
Fish production in aquaponics is typically limited to common aquaculture species such as tilapia, catfish, and salmon. However, these species yield low outputs in small and mid-sized farms. Consequently, the fish component in aquaponics is primarily utilized as a source of nitrogenous compounds derived from fish waste. Our goal is to introduce new species of smaller fish (including ornamental, research, and recreational species) that can enhance the financial returns of these farms. AIM 1: Characterization of Reproductive Output of Green Swordtail (Xiphophorus helleri) in Small-Scale and Mid-Scale Basil Aquaponic Setups We conducted our experiments at Texas State University (fall 2023 and sprin 2024) and at a small to mid-sized farm at Santa Fe Community College from June to August 2024. Texas State University (Small Laboratory System) We have built four new aquaponics setups, each consisting of a 400-liter fish tank equipped with outlets adapted for small species, a sump pump, a biofilter, and a plant bed with 24 plants. These setups are located in the Biology Greenhouse at Texas State University. In our experiments, we developed co-cultures of basil and swordtail fish. We established optimal light conditions for basil production and analyzed the nutrient cycles in the plants and water, as well as the nitrogen contributions from the fish. We found that the nitrogen input from swordtails was insufficient to sustain our plant culture, necessitating the addition of fertilizer for adequate basil growth. Additionally, we encountered health issues that prevented the swordtails from reproducing. In response, we began developing peroxide treatments for the swordtails in the aquaponic systems. Our research indicated that two treatments per month of 200 ppm of hydrogen peroxide were adequate to prevent illness in the fish without significantly impacting basil growth. Santa Fe Community College (Small Farm) At this location, we co-cultured tilapia (26 kg/m²) and swordtails (0.1 kg/L) with 108 basil plants in two systems (one control and one treatment) over a 21-day period. The treatment involved a single exposure to 200 ppm of peroxide on day two of basil cultivation. Over the course of the experiment, we measured fish cortisol excretion, as well as water concentrations of NO2, NO3, and NH4. At the end of the experiment, we assessed plant and root growth and took samples for compositional analysis (N, P, K, Ca, Mg, S, Fe, Mn, B, Cu, Zn, Mo, Na, Al). This experiment was replicated three times over a three-month period. During this time, the fish biomass was sufficient to produce basil without the need for additional fertilizers. Although swordtails did not show any illness, their spawn was quickly cannibalized, indicating a need for better-designed hiding places for these species. Our preliminary data suggested that peroxide treatments rapidly affected the aquaponic systems, resulting in an increase in water ammonia from the fish within a few days after treatment, returning to baseline levels after 14 days. Cortisol levels in the water rose immediately after dosing but remained within typical aquaculture values. Only micronutrient levels, such as boron, manganese, and copper, were negatively impacted by the peroxide treatment. At the time of harvest, we recorded plant data including height, weight, root length, and leaf width. We also processed and analyzed root and leaf samples from each system for microbiome and chemical composition. Our preliminary data indicated that H2O2 treatments might affect plant production by causing stunted growth (a 5% reduction) while having a negligible impact on cortisol levels in the fish, indicating that the treatment did not induce significant stress.
Publications
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2023
Citation:
The Dynamics of Ammonia Excretion of Green Swordtails (Xiphophorus hellerii) in an Aquaponics Environment. William Ortiz, Alex Tran, Mar Huertas. Graduate Student Symposium. Texas State University. San Marcos, TX
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