Biology and Aquaculture of Tilapia

José Fernando López-Olmeda, Francisco Javier Sánchez-Vázquez, Rodrigo Fortes-Silva, José Fernando López-Olmeda, Francisco Javier Sánchez-Vázquez, Rodrigo Fortes-Silva

• Editore: CRC Press
• Anno: 2021
• ISBN:
  9781000482430
• Edizione: 1
• Argomento: Ciencias biológicas
• Categoria: Conservación y Protección del Medio Ambiente

This book reviews up-to-date knowledge on the biology and aquaculture of tilapia, with special focus on the Nile tilapia ( Oreochromis niloticus ). Tilapia are a group of fish species that have become one of the most cultured worldwide, currently having a big economic impact on both developed and developing countries. The first 12 chapters of the present book cover different aspects of tilapia biology such as genetics, nutrition, osmoregulation, pathology, reproduction and development. Each chapter includes both basic knowledge and its application to tilapia culture. The last 3 chapters are devoted to cutting-edge techniques for the industry of tilapia aquaculture. Experts from both academia and research institutes provide their expertise on the present book.

CHAPTER 14

Biofloc Technology (BFT) in Tilapia Culture

Maurício Gustavo Coelho Emerenciano,¹* Kevin Fitzsimmons,² Artur Nishioka Rombenso,¹ Anselmo Miranda-Baeza,³ Gabriel Bernardes Martins,⁴ Rafael Lazzari,⁵ Yenitze Elizabeth Fimbres-Acedo⁶ and Sara Mello Pinho^7,8

*Corresponding author: [email protected]

¹ CSIRO Agriculture and Food, Livestock & Aquaculture Program, Bribie Island Research Centre, Woorim, QLD, Australia

² Department of Soil Water and Environmental Science, University of Arizona, Tucson, AZ, USA

³ Sonora State University (UES), Navojoa Unit, Navojoa, SO, Mexico

⁴ Federal University of Pampa, Uruguaiana, RS, Brazil

⁵ Animal Science and Biological Sciences Department, Federal University of Santa Maria (UFSM), Palmeira das Missões, RS, Brazil

⁶ The Northwestern Center for Biological Research (CIBNOR), La Paz, BCS, Mexico

⁷ São Paulo State University (UNESP), Aquaculture Center of Unesp (CAUNESP), Jaboticabal, SP, Brazil

⁸ Mathematical and Statistical Methods (Biometris), Wageningen University, Wageningen, The Netherlands

1. History and basic aspects of BFT

The biofloc technology (BFT) was proposed as an alternative to the conventional extensive and semi-extensive aquaculture production systems. In terms of expansion, conventional systems face serious challenges such as competition for land and water and environmental regulations related to discharge of effluents which contain excess organic matter, nitrogenous compounds and other toxic metabolites that might compromise the adjacent culture areas and boost the spread of disease (Browdy et al. 2012). Currently, BFT is used in the cultivation of commercial species such as penaeid shrimp and tilapia (Figure 1), and more recently, as a management tool during early cultivation during nursery phases. In recent times, as the aquaculture industry has faced diverse issues, in terms of diseases and reduced production yields, BFT was considered (and still is) the new “blue revolution” (Stokstad 2010). Such system originated in the 1970s for shrimp at the French Research Institute for Exploitation of the Sea (IFREMER), located in Tahiti, and in partnership with private companies from the U. S. (Emerenciano et al. 2013, Anjalee-Devi and Madhusoodana-Kurup 2015). At this time, BFT was called a “moulinette” system (Emerenciano et al. 2012) due to the vortex created as a result of constant water aeration and movement. It was later expanded to commercial shrimp farms in both Tahiti and the U.S.

Fig. 1. Biofloc technology (BFT) applied to tilapia culture in Mexico (left) and Israel (right). Source: Maurício G. C. Emerenciano and courtesy of Y. Avnimelech.

In the 1980s Steve Serfling, at his tilapia farms in Southern California and the Jordan River Valley, Jordan, developed an Organic Detrital Algal Soup System, (ODASS), which is called BFT today. At roughly the same time, researchers in Israel and China began experimenting with similar systems using heavy aeration and water motion to encourage vast production of bacterial and algae biomass to process fish or shrimp wastes in situ (Avnimelech 2015). In the 1990s, the Waddell Mariculture Center, in the United States of America, and at the Technion-Israel Institute of Technology initiated deep scientific studies and commercial pilot-scale trials. In the mid-2000s, the Texas A&M University (Corpus Christi campus, USA), and the Federal University of Rio Grande (FURG, Brazil), two major research centers in North and South America, respectively, began several studies that formed a baseline to the development of BFT technology. Thanks to the diverse research projects and training of human resources, various professionals have spread BFT knowledge, implemented and managed commercial farms regionally and also globally.

Since the early 2000s, there has been a significant increase in number of scientific publications on BFT worldwide. According to Scopus database, this number has increased from less than 20 in 2009 to more than 150 publications in 2018 (Scopus 2019). For Google Scholar, this number increased to more than 4,900 publications in March 2021 (Google Scholar 2021). The majority of such studies were carried out in Mexico, Brazil, USA, China, and India helping to spread and strengthen the technology, as well as boost the industry. The wide range of courses and lectures offered in both scientific and commercial events for the academia and farmers were also important factors for such progress.

But how does BFT work? Microorganisms play a key role in BFT systems (Martínez-Córdova et al. 2015). Similar to an activated sludge water treatment system, fecal and nitrogenous wastes are oxidized to small organic compounds, CO₂ and NO₃ which are then assimilated by bacteria and algae. The bacteria and algae tend to form flocs. These flocs (Figure 2) are maintained in the water column by limited or zero water exchange and vigorous water motion/aeration (Emerenciano et al. 2013), making the floc available for consumption by detritivores like shrimp and tilapia. In addition, a high carbon to nitrogen ratio (C:N) is maintained since nitrogenous by-products can be easily taken up by heterotrophic bacteria (Avnimelech 1999). In the beginning of the culture cycles, these high ratio are required to guarantee optimum heterotrophic bacteria growth, while the chemoautotrophic bacterial community (i.e. nitrifying bacteria) stabilizes after approximately ~25–50 days (Avnimelech 2015). In addition, a minimum fish/shrimp biomass per cubic meter is required (>300 g/ m³) for a proper system to develop and the establishment of the bacteria population (Emerenciano et al. 2012). In the late stages, the nitrifying community might be responsible for 2/3rds of the ammonia assimilation (Emerenciano et al. 2017); thus, the addition of external carbon should be reduced or even eliminated, and alkalinity consumed by the microorganisms must be continuously replaced by different carbonates/bicarbonates sources (Furtado et al. 2015).

Fig. 2. Microbial aggregates from a biofloc technology (BFT) commercial production pond: diversity and abundance helping to maintain the water quality, nutrition and health of fish. Source: Maurício G. C. Emerenciano.

The water quality stability will depend on the dynamic interaction among communities of bacteria, microalgae, fungi, protozoans, nematodes, rotifers etc. that will occur naturally (Martínez-Côrdova et al. 2016), and suitable levels of various parameters such as dissolved oxygen, pH, alkalinity and suspended solids (Emerenciano et al. 2017). Besides the oxygen levels, excess of particulate organic matter and toxic nitrogen compounds (pH related) are the major concern in the BFT system. In this context, three pathways occur for the removal of ammonia nitrogen: at a lesser rate (i) photoautotrophic removal by algae, and at a higher rate (ii) heterotrophic bacterial conversion of ammonia nitrogen directly to microbial biomass; and (iii) chemoautotrophic bacterial conversion from ammonia to nitrate (Martínez-Côrdova et al. 2015).

In BFT, the nutrients are continuously recycled and reused in the culture medium as a result of the in situ microorganism production and the minimum or zero water exchange (Avnimelech 2015). The microbial aggregates (bioflocs) are a natural protein-lipi...