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Biofloc Technology

 

 

In 2009, the World Aquaculture Society published Biofloc Technology, a book by Dr. Yoram Avnimelech that reviewed the state-of-the-art and status of biofloc technology in aquaculture.  The first edition quickly sold out, so in consultation with Dr. Craig Browdy, manager of WAS publications, a corrected and expanded second edition has been published.

 

In the preface to the second edition Dr. Avnimelech says: I’m happy to add new chapters written by world experts that summarize new developments and reveal new insights into biofloc technology.  In the new chapters, we learn about:

 

• New developments in super-intensive biofloc shrimp farming from Andrew Ray

• Biofloc field trials in Asia from Nyan Taw

• The use of bioflocs in feed pellets from David Kuhn and Addison Lawrence

• The effects of bioflocs on the sexual development of shrimp broodstock from Mauricio Emerenciano and his coworkers

• The biotechnology behind bioflocs from Peter De Schryver and others at Ghent University in Belgium.

 

Both the scientist and the layman will find this book useful.  For the scientist, biofloc chemistry and water quality parameters are neatly detailed with scientific notation and backed up with extensive references and suggestions for additional research.  For the layman, each chapter begins with a brief preview of what’s going to be covered and ends with a summary of the important points, all of it supported with lots of examples.  The book’s 272 pages are loaded with tables, graphs, diagrams, pictures (black and white and color) and a glossary.

 

 

Excerpt

 

Currently there are not many super-intensive biofloc farms.  Although the technology is slowly being adopted by some companies, for the most part these systems are operated by research institutions.  The dominant reason for this is that cost of production needs to be lowered substantially to enhance profitability.

 

Some of the biological issues include poor growth rate, an inability to maintain adequate pH (likely due to high rates of microbial respiration and high CO2 concentrations) and bacterial infections.  Some of the mechanical issues include pump failures and oxygen supply system failures.  Research is ongoing to solve biological problems; mechanical problems will likely be solved with redundancy in important life support systems.

 

One way to enhance profitability and solve some of the other problems inherent in biofloc systems is to divert organic carbon accumulation on the pond bottom to periphyton on vertical substrates.  Periphyton, a complex mixture of algae, cyanobacteria, heterotrophic microbes and detritus, is quite similar to biofloc.  Without vertical substrates, suspended organic matter (dead algae, feces, feed residues) settles out the water column and accumulates on the pond bottom, where oxygen supply is meager and anaerobic conditions prevail.  Anaerobic metabolism of organic residues is appreciably slower than aerobic metabolism and its metabolites are often toxic.  This may be reversed, or modified, by placing either natural or synthetic vertical substrates (such as bamboo or plastic) in the pond that capture suspended organic matter before it settles on the pond bottom.  The organic matter attaches to the vertical substrates and is exposed to aerated water, where it degrades and contributes nutrients to the food web that the shrimp feed on.

 

In southern India, Mr. Suryakumar, a mechanical engineer and owner of Hitide Seafarms, has built an advanced biofloc farm that uses vertical substrates.  The farm has 24 hectares of growout ponds and 12 hectares of reservoirs.  Conventional plastic shade nets are used as vertical substrates.  The nets (20 meters long and a half a meter deep) are kept in position using empty drinking water bottles as floats and sand-filled bottles as anchors.  Placed downstream from paddlewheel aerators, an area of ample oxygen supply, the nets are maintained at a depth of 10 centimeters below the water surface and about 50 centimeters above the bottom.  Once in place, the nets are quickly covered with a layer of organic matter made up of detritus and periphyton.  These earthen-bottom ponds are operated at lower stocking densities than high-density biofloc ponds and represent a gradual transition from conventional extensive systems to intensive biofloc systems.  Ponds are stocked with 50 postlarvae (Penaeus monodon) per square meter.  Average shrimp weight at harvest is 42 grams with a feed conversion ratio of 2.

 

 

Chapter Titles

 

• Why Do We Need New Technologies for Aquaculture?

• Overview of Aquaculture Systems

• Microbial Processes and Communities Relevant to Aquaculture

• Biofloc Systems

• The Nitrogen Syndrome—Problem and Solutions

• Using Biofloc Technology to Control Inorganic Nitrogen Buildup

• Feeding with Bioflocs

• Ex-Situ Biofloc Technology (David D. Kuhn and Addison L. Lawrence)

• Optimizing Microbial Activity in Extensive Ponds

• Aeration and Aerator Deployment

• Pond Management

• Pond Construction

• Biofloc Technology for Super-Intensive Shrimp Culture (Andrew Ray)

• Biofloc Technology Effects on Fish and Shrimp Disease Control

• The Biology and Biotechnology Behind Bioflocs (Peter De Schryver, Nico Boon,

Willy Verstraete and Peter Bossier)

• Biofloc Technology Applied To Shrimp Broodstock (Mauricio Emerenciano, Gabriel

Gaxiola and Gerard Cuzon)

• Field Experience (written in cooperation with Dr. Nyan Taw)

• Biofloc Technology and Sustainable Aquaculture Development

• Final Notes and Requests

 

Information: Yoram Avnimelech (agyoram@tx.technion.ac.il, Department of Civil and Environmental Engineering, Technion, Israel Institute of Technology, Haifa 32000, Israel).

 

Information: The book sells for $50 (WAS members) and $70 (nonmembers) and can be purchased at the World Aquaculture Society’s Website (Item # 978-1-88807-21-9, https://www.was.org/shopping/shopexd.asp?ID=537).

 

Source: Biofloc Technology—A Practical Guide Book (Second Edition, 2012).  Yoram Avnimelech.  The World Aquaculture Society.  2009.

 

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