Shrimp water demands in a conventional versus a biofloc system. Slide by Esmeralda Chamorro.
By Esmeralda Chamorro Legarda, postdoctoral student at the Federal University of Santa Catarina (UFSC).
Shrimp cultivation in a traditional system needs a constant renewal of water to maintain the levels of compounds, which in high concentrations can generate toxicity affecting the animals’ growth, such as ammonia. This production system is still the most used given its low cost. Nonetheless, this system is more susceptible to the entry of diseases due to its contact with the environment and often depends on uncontrollable environmental factors.
Biofloc technology vs conventional shrimp farming
An alternative production model, the biofloc technology, is an innovative and sustainable tool that uses approximately only 0.16% of the amount of water used in the conventional system. However, it is necessary to remove the excess of organic matter, as sludge, from the system. Such sludge is saline and cannot be used as fertilizer in agriculture without prior treatment. The initial investment in infrastructure and the cost of management is high and for this reason, it is not being used to a greater extent in the shrimp industry.
Why integrate species with biofloc technology?
In biofloc technology, the microbiological processes serve as water quality controllers and as an additive in a feed. The excess of organic material can be removed in part by the bentonite fish, such as the mullet (https://doi.org/10.1016/j.aquaculture.2019.734308), and the excess of organic compounds dissolved in water, such as nitrogen and phosphorus, can be used as fertilizer for seaweeds, like Ulva fasciata (https://doi.org/10.1016/j.aquaculture.2020.736265). This diversification of species can generate new products from the recycling of surplus nutrients from shrimp farming. This integration is called integrated multitrophic aquaculture (IMTA).
What is the importance of the circular economy approach in aquaculture?
The circular economy system seeks to take advantage of resources to reduce, recycle and reuse what is discarded from the processes and gives it a second life, returning it to the market in a new form. In aquaculture, the concept of circular economy allows to manage the nutrient cycle to generate new products. For example, the seaweed that is produced with surplus nutrients from the cultivation of shrimp and mullet with biofloc technology can be used as a supplement for a marine fish (Seriola dorsalis), contributing to increase the docosahexanoic fatty acid (DHA), also known as omega 3 (https://doi.org/10.1016/j.aquaculture.2021.736414).
The circular economy approach in integrated multitrophic aquaculture (IMTA) helps us understand that each integrated component must have a purpose, either as a by-product or as a product.
What are we doing at the LCM – Marine Shrimp Laboratory of UFSC?
From experimental to commercial scale, and taking care of the integrated components in the IMTA biofloc system the UFSC is developing the following activities:
- Experimental scale: testing the best feeding rate for mullet. Ana Carolina Pereira develops this experiment in the framework of her master thesis.
- Pilot scale: 50,000-liter tank for shrimp cultivation and a 6,000-liter tank for mullet cultivation in biofloc.
- Commercial scale: testing the shrimp, mullet, and seaweed IMTA system in collaboration with a stakeholder.
- Integrated component: studying Ulva reproduction by sporulation. Afterward, the seaweed is cultivated in tanks fertilized with filtered biofloc water. Researchers Leila Hayashi and Fernando Z. Silva lead this activity.
Partners and financial resources
This work has been carried out thanks to the support and collaboration of the AquaVitae project, CAPES, CNPq, FAPESC, FAPEU, PPGAQI/UFSC, LCM/UFSC, Alltech, BRF, BlueEcoNet, Embrapa, GUABI, IFSC-Araquari, EPAGRI, LAPMAR, TANAC, USP, FURG, UABC, Conacyt, IIO.
Full recording of the webinar “Advances in IMTA & Biofloc. Research at UFSC” (17 Dec 20).