Location: Aquatic Animal Health Research
2023 Annual Report
Objectives
1. Develop, evaluate, and improve fish production systems for aquaponics.
Component 6: Problem Statement 6A
2. Develop, evaluate, and improve plant production systems for aquaponics.
Component 6: Problem Statement 6B
3. Develope environmentally and economically sustainable aquaponic systems.
Component 6: Problem Statement 6C
Approach
Auburn University faculty and their associated research team and ARS investigators will work collaboratively on both the aquatic animal and plant components in an effort to improve the yield and efficiencies of aquaponics production systems. Topics of interest to be explored include the optimization of: aquaculture system type, fish feeds, stocking densities, alternative aquatic species (e.g., high-value species such as pompano, red drum, cobia, marine shrimp, etc.), oxygenation strategies, animal and plant disease management, plant yields, improving nutrient and water use efficiencies, postharvest product quality, and salt tolerance.
Progress Report
ARS researchers in Auburn, Alabama, and Stuttgart, Arkansas, along with collaborators at the University of Arkansas at Pine Bluff, conducted a study to compare growth and mineral composition of sweet potato slips grown under commercial stocking conditions or in an aquaponic system receiving supplementation of black soldier fly larval frass produced from withered or expired fish food or fruits/vegetables. Trial data are currently being analyzed.
Burkholderia cenocepacia, a gram-negative complex bacterial species, is a serious opportunistic pathogen for immunosuppressed individuals. B. cenocepacia exists in diverse natural environments including fresh agricultural produce while the effective method for its surveillance is under development. ARS researchers collaborated in a study that identified unique genome loci among various B. cenocepacia related species. Specific primers were designed for quantitative PCR assays. Assay specificity was measured with 12 strains of closely related Burkholderia bacteria and demonstrated that the accuracy was 100% species specific. The method developed in this study could detect as low as 260 bacterial cells in one gram of agricultural produce, making it a promising technique for B. cenocepacia detection and epidemiological research on Burkholderia complex organisms from fresh vegetables.
Queen Conch (Aliger gigas) is among the most economically, socially, and culturally important fishery resources in the Caribbean. Its value as a fisheries commodity ranks second only to spiny lobster in the region. Overfishing of Queen Conch in the Caribbean has led to population decline. In 2019 the Naguabo Aquaculture Center (NAC) was established in Puerto Rico to support the production of Queen Conch for consumption and sustainability. The NAC hatchery system consists of a recirculating aquaculture system (RAS) that supports Queen Conch life stages from egg mass to the juvenile stage. In parallel, the system also contains an aquaponic system for the culture of sea vegetables and other shellfish species such as crabs and spiny lobsters. Since 2021, ARS researchers have been focused on developing biosecurity standards and establishing a bacterial monitoring system to improve the health and production of the Queen Conch, while preserving the performance of sea vegetables in the system. To do so, ARS researchers have collected bacterial samples from marine water, egg masses, larvae and juvenile Queen Conch and identified various pathogens by implementing a multifaceted approach including selective media, fatty acid methyl ester analysis (FAME), API (biochemical analysis), DNA extraction, PCR (polymerase chain reaction) and 16S rRNA sequencing. By understanding the bacterial community in this system, researchers hope to gain a better understanding of the optimal RAS/aquaponics conditions and make informed decisions to help promote the health, production, and biosecurity.
Various species of non-traditional plants have yet to be studied for their possible tolerance to salt. Traditional plants such as tomatoes, carrots, and basil have been studied and are known to exhibit salt tolerance. Plants tested for salt tolerance in this study included: arugula (Eruca vesicaria), anise (Pimpinella anisum), carrot (Daucus carota), dandelion (Taraxacum albidum), chicory (Cichorium intybus), common purslane (Portulaca oleracea), mint (Mentha spp.), sage (Salvia officinalis), basil (Ocimum basilicum), tomato (Solanum lycopersicum), sea purslane (Sesuvium verrucosum) and seashore paspalum (Paspalum vaginatum). The aim of this study was to discover new and alternative ways to grow non-traditional species in hydroponic systems. Plants were grown in these systems, supplemented with a hydroponic nutrient mix, and exposed to three different salt (NaCl) concentrations ranging from 0, 5,000, or 15,000 parts per million (ppm). Plant aboveground biomass and fresh root weights were taken 21 days after introducing plants to the hydroponic system. Results indicated that salinity at 15,000 ppm reduced biomass by more than half the volumes of those harvested at 5,000 ppm. Plants exposed to 5,000 ppm of salt had about a 25% decrease in biomass compared to the non-treated. Results from this study could potentially help expand new ways to grow alternative crops in aquaponics systems and increase productivity in various ways.
Accomplishments
1. Dietary inclusion of black soldier fly larvae frass enhanced production of channel catfish juveniles, stevia, and lavender in an aquaponic system. Aquaponics integrates aquaculture with hydroponics where waste produced by the fish can be utilized by the plants as nutrients. However, adding supplemental nutrients to enhance plant production is common. Frass, which is the manure of insects and the substrate used to culture them, can be used to enhance fish and plant production. Depending upon the culture substrate used to grow the insects, it may be possible to enhance both plant and fish growth with a dietary approach in an aquaponic system. ARS researchers in Auburn, Alabama, in collaboration with researchers at the University of Arkansas at Pine Bluff, and ARS researchers in Stuttgart, Arkansas, evaluated channel catfish juveniles which were fed diets with or without 10% black soldier fly larvae (BSFL) frass in an aquaponic system. Each system had two different plant bed types, floating raft and media and were used to grow stevia and lavender. Catfish grew significantly better when fed a diet containing 10% BSFL frass compared to fish fed a diet without frass. Further, intestinal histology showed reduced inflammation. The proximate composition of catfish was unaffected by diet, while both stevia and lavender had significantly more biomass when frass was added to the system, while plants grown in media beds were larger than plants grown in a floating raft subsystem. Frass significantly increased phosphorus in both stevia and lavender at week 8. Higher water calcium, magnesium, and nitrate levels may have allowed for higher growth rates as these nutrients are essential for proper plant health. The increase of fish growth was likely due to the upregulation of genes responsible for growth, mitigating intestinal inflammation, and enhancing diet intake. Thus, it appears that feeding catfish with BSFL frass and culturing stevia and lavender in media beds can improve overall productivity.
Review Publications
Romano, N., Webster, C.D., Sinha, A., Beck, B.H., Yamamoto, F. 2023. Dietary inclusions of black soldier fly (Hermetia illucens) larvae frass enhanced production of channel catfish (Ictalurus punctatus) juveniles, stevia (Stevia rebaudiana, and lavender (Lavaridula angustifolia) in an aquaponic system. Aquaculture. 575:739742.
Padeniya, U., Davis, D., Liles, M.R., Lafrentz, S.A., Lafrentz, B.R., Shoemaker, C.A., Beck, B.H., Wells, D.E., Bruce, T.J. 2023. Probiotics impact resistance to Streptococcus iniae in Nile tilapia (Oreochromis niloticus) reared in biofloc systems. Journal of Fish Diseases. 46:1137-1149. https://doi.org/10.1111/jfd.13833.
Liu, A., Phillips, K., Jia, J., Deng, P., Zhang, D., Chang, S., Lu, S. 2023. Development of a QPCR detection approach for pathogenic burkholderia cenocenpacia from fresh vegetables. Food Microbiology. 115:104333. https://doi.org/10.1016/j.fm.2023.104333.
Kelly, A.M., Renukdas, N., Barnett, L.M., Beck, B.H., Abdelrahman, H.A., Roy, L.A. 2023. The use of kaolin as a prophylactic treatment to prevent columnaris disease (Flavobacterium covae) in commercial baitfish and sportfish species. Veterinary Sciences. 10(7):441. https://doi.org/10.3390/vetsci10070441.
