biofloc as a biosecurity tool against...

BIOFLOC AS A BIOSECURITY

TOOL AGAINST WSSV

Gabriel B. Santos Marcell B. de Carvalho

Technical Manager of Shrimp Breeding Program B.S. Oceanography & M.S. Aquaculture

Technical Account ManagerRidley Aquafeed - Australia

DEFINITION

OVERVIEW OF THE SYSTEM

How it works

Nitrogen waste and Microbial Protein

Microbial Communities

APPLICATION & MANAGEMENT

BIOSECURITY

EXAMPLES

CONCLUSION

SUMMARY

Aggregates formed by a complex interaction between particulate organic matter and

a large range of microorganisms, such as bacteria and phytoplankton, and grazers,

such as rotifers, ciliates and flagellates protozoa and copepods.

(Avnimelech, 2007; Ray et al., 2010; Emerenciano et al., 2013)

DEFINITION: BIOFLOCS

Biofloc under microscope view, from left to right, 10x, 40x, 40x.

Biosecurity

Strict environmental control

Isolation from contamination sources

Enhances prawn immune system

Farm Efficiency

Requires less land and water

Reuse of feed wastes

Allows higher densities, optimize

number of crops, increases productivity

Higher Quality

Enhances animal health and produces

stronger animals, increasing quality

after harvest

Environment

Zero or limited water exchange

Less effluent discharge

Less waste and better waste

management

DEFINITION: BIOFLOC TECHNOLOGY (BFT) SYSTEM

HOW IT WORKS?

TAN

[ NH3 + NH4+ ]Feces

Excretion

Feed waste

NO2

NO3

(Non toxic)

Feeds

C org

(C:N ratio)

Microbial

Biomass

C inorg

+

Oxygen

Nitrifying

Bacteria

Physical Substrate

Microorganisms in the system (bioflocs) – two major roles:

1. Uptake of nitrogen compounds generating “in situ” microbial protein and

maintaining water quality; and

2. Increasing culture feasibility by reducing FCR and a decrease of feed costs by

reducing protein demand

NITROGEN WASTE & MICROBIAL PROTEIN

Feeds

• Protein-rich

• Protein = 16% N

• N leaching and accumulation

Water Exchange

&

Nitrogen-rich Effluent

discharges


Discharge of effluents:

• Eutrophication of natural waters

• Ecological unbalance of the recipient environment

• Spread of diseases and contamination of wild

populations (permanent reservoirs)

Waste Management

• Environmental regulations

• Market trend for organic and ”green”

• Increase efficiency of feeds


BFT

70% less than

conventional system

BFT

• Recycling nitrogen into bacterial protein

• Establishment of microbial food chain (protein-rich)

• Transfer of N into prawn biomass

• Maintenance of N in non-toxic levels

• Less generation of waste


30% - 40% of prawn’s biomass is

obtained by biofloc consumption

in BFT system (Burford et al., 2004; Cardona et al., 2015)

Crude Protein Reference

43% McIntosh et al., 2000

12 - 42% Soares et al., 2004

26 - 41.9% Ju et al., 2008

31% Tacon et al., 2010

38.8 - 40.5% Kuhn et al., 2010

28 - 43% Maicá et al., 2012

• Reduce FCR

• Reduce feed demand

• Consequently increases efficiency


Microorganisms – three major groups:

1. Heterotrophic bacteria

2. Chemo-autotrophic bacteria

3. Photo-autotrophic microalgae

2.3. MICROBIAL COMMUNITIES

• Assimilate Ammonia into protein

• Consume organic carbon

• Very fast cell duplication

HETEROTROPHIC BACTERIA

• Form the Bioflocs

• Proteobacteria, Bacteroidetes,

Bacillus spp.

Imhoff cone showing

biofloc settled – Floc level

will increase with the

growth of heterotrophic

bacteria

Heterotrophic

bacteria Bacillus spp.

MICROBIAL COMMUNITIES

Molasses as carbon source applications, followed by drop of TAN levels.

Nitrogen assimilated as heterotrophic bacteria biomass. Da Silva et al., 2013.

• Assimilate Ammonia into protein

• Consume organic carbon

• Very fast cell duplication

HETEROTROPHIC BACTERIA

• Form the Bioflocs

• Proteobacteria, Bacteroidetes,

Bacillus spp.


Addition of Corg

• Nitrifying Bacteria

• Late establishment in the system

• Require to be attached for effective

nitrification

• Consume inorganic carbon (alkalinity)

• Probiotics and/or Inoculum

• Ammonia Oxidizer Bacteria (AOB)

• Nitrosomonas, Nitrosococcus, Nitrosospira

• Oxidize ammonia into nitrite (NO2)

• Nitrite Oxidizer Bacteria (NBO)

• Nitrobacter, Nitrococcus, Nitrospira

• Oxidize NO2 into nitrate (NO3) non toxic

CHEMO-AUTOTROPHIC BACTERIA


Nitrification process in biofloc system where nitrite

is being oxidized into nitrate. Da Silva et al., 2013.

PHOTO-AUTOTROPHIC MICROALGAE

• Light penetration

• Outdoor ponds and greenhouse

enclosed systems

• Daily fluctuations

• Diatoms

• Filamentous algae and blue-green

algae

• Management to balance

communities


Immature System

• Heterotrophic pathway 100% of N recycling

• Carbon addition necessary

• Increase in bioflocs (surface area)

• Protein source and immune system


Mature System

• Nitrification process established

• Chemo-autotrophic pathway – 65% of N recycling

• Heterotrophic pathway – 35% of N recycling

• Carbon provided by feeds (organic) and alkalinity (inorganic)

Outdoors and abundant light conditions

• Microalgae

• Can be beneficial if well managed

• Synergic balance among communities

APPLICATIONS

NURSERY PHASE

• High-biosecurity facilities to grow post-

larvae (0.3 – 3.0g)

• Very high stocking densities and

biomass (500 – 10.000 PL/m3)

• Management of nitrogenous wastes

• Improves immune system

• Stock grow out with more resistant

juveniles

High density nurseries provide safe environment for the most sensible life stage

after hatchery. When stocked in the farms, prawns are stronger and usually show

compensatory growth. In the image, a greenhouse enclosed nursey operating in

BFT system in southern Brazil.

APPLICATIONS

NURSERY PHASE

• USA, Mexico, Central America, Ecuador,

Brazil, Saudi Arabia, Southeast Asia –

mostly for L. vannamei

• Also successfully applied for F.

paulensis, F. brasiliensis, F. setiferus and

P. monodon

• P. monodon (88% survival at 1000

PLs/m3; 60% survival at 5000 PLs/m3)

• Basic initial cost: 15-25 USD/m2 *

Biofloc nursery for L. vannamei post larvae. Agua Blanca Seafood, Oaxaca,

Mexico

* Cost based on HPED liner, aeration system and greenhouse structure. Values will vary according to regional availability and market price.

APPLICATIONS

OUTDOORS GROW OUT

• Lined, smaller ponds

• Higher stocking density

• Higher aeration power

• Algae presence

• Biofloc Inoculum

• Biofloc system = higher animal health &

biosecurity

• Susceptible to environmental conditions

and sources of contamination (birds,

crabs, wind, etc)

Ecological interactions among the microbial community are more diverse in

biofloc system when in outdoors conditions, what requires a stronger

manipulation of the environment in order to set the functional roles of each

community in synergy. In the image, outdoor grow out pond operating in BFT

system in southern Brazil

APPLICATIONS

OUTDOORS GROW OUT

• Central and South America,

Southeast Asia

• In large industrial scale, mostly

L. vannamei


* Cost based on HPED liner and aeration system. Values will vary according to regional availability and market price.

Biofloc grow out ponds

of L. vannamei. Above,

Agua Blanca Seafood,

Oaxaca, Mexico; on the

right, Southern Brazil.

APPLICATIONS

INDOORS GROW OUT

• Higher stocking densities = less land and

smaller production units

• Higher initial investment

• Automatization

• Higher environmental control

• Barriers against contamination sources =

higher biosecurity

• Allows production in land and in seasonal

periods of low temperature

• Operation in sites previously affected by

WSSV

APPLICATIONS

INDOORS GROW OUT

• USA, Central and South America,

Saudi Arabia, Korea, China


* Cost based on HPED liner, aeration system and greenhouse structure. Values will vary according to regional availability and market price.

Indoors Biofloc prawn farming.

On the right, Marvesta Shrimp

Farms, Maryland, USA; below,

Fazenda Cultivamar, Southern

Brazil

APPLICATIONS

BROOD STOCK CULTURE

• Brood stock domestication

• Breeding Programs

• Avoid vertical contamination

• Generation of SPF lines

• Production of disease free PLs

• Culture under highest biosecurity levels

• Surveillance programs

• Artificial Insemination and individual validation

for new brood stock generation

Brood stock production facility operating in biofloc system in

Saudi Arabia

L. vannamei brood

stock reared in BFT in

site previously

affected by WSSV

outbreak

MANAGEMENT

Specialized management

• Qualified personnel

Dissolved Oxygen / Aeration

• High O2 demand: respiration and microbial processes

• Suspended solids

pH and Alkalinity

• Acidification; nitrification; buffer effect

Different kinds of aeration to keep biofloc in suspension and

oxygenate the water: above, paddle-wheels that provide

horizontal circulation; and on the left, microporous hoses that

generate vertical circulation cells

MANAGEMENT

Solids

• Excess: DO issues, gill fouling, sludge

• Scarcity: poor microbial process and

control of nitrogenous wastes

Imhoff cone showing

scarcity (left) and

excess (right) of floc.

Clarifiers for solid control

in BFT system in Saudi

Arabia

Sludge accumulated by solid excess

MANAGEMENT

Algae community

• Outdoors and greenhouses

• Balanced microbial community

• Filamentous species and blue-green algae

Filamentous algae bloomed in biofloc prawn culture Blue-green algae Nodularia spp. contamination of biofloc

pond (right) in southern Brazil.

MANAGEMENT

Feeding

• Adjusted feed rates; prawn and

microbial performance

• High quality feed = high quality floc

Nitrogen

• TAN / NO2 / NO3

• Constant and accurate monitoring

• Calculation of carbon applications

• Affects feeding management

Water quality monitoring by spectrophotometry 32% protein prawn feed produced in Brazil

BIOSECURITY

BIOFLOC & BIOSECURITY

Physical Barrier

• Minimum water exchange

• Rigorous water treatment

• Indoors culture


Biological Barrier

• SPF brood stock and larvae

• Beneficial bacteria (probiotic effect)

• Ecological competition

• Enhancement of immune system

BIOSECURITY

• Biofloc has bioactive compounds that contribute for a

healthy status of cultured prawns (Ju et al., 2008b)

• Expressions of certain hemocytes enzymes related to

immune system is enhanced in biofloc reared L.

vannamei (Jang et al., 2011)

• Bioflocs have positive effect in the immune response of

L. vannamei leading to higher resistance against IMNV

challenge (Ekasari et al., 2014)

• Immune system and antioxidants enhanced in L.

vannamei juveniles reared in biofloc (Xu & Pan, 2013)

• Prawns show resistance to Vibrio spp when reared in

BFT (Liu et al., 2017)

(Ju

et

al.,

2008b)

BIOSECURITY

Biofloc: higher degree of biosecurity

• Limited water exchange


• Physical barrier against pathogens

(indoors)

• Biological barrier against pathogens

• Enhances prawn immune system

Biosecurity Protocols

• Hygiene and sanitation

• Training of personnel

• Disinfection of facilities, materials, vehicles, staff

• Control and validation of raw materials

• Biosecurity zones and controlled movement

• Surveillance program

SPF & Tolerant lines

• Vertical contamination

• SPF larvae

• Head start for producer

• Brood stock domestication importance

• Tolerance against diseases

Water Treatment

• Need of sterile water

• Filter bags

• Sand, cartridge and carbon filters

• UV system

• Ozone system

EXAMPLES – LAGUNA, SC - SOUTHERN BRAZIL

• L. vannamei farming completely devastated by

WSSV outbreak in early 2000’s

• Contamination of natural water bodies and all

farms in the region

• Biofloc pilot installed in the epicentre of

outbreak

• Basic remodelling of the farm: smaller,

lined ponds, bird nets, crab fences, basic

biosecurity protocol, stocking of SPF PLs

Remodelling of WSSV contaminated ponds into biofloc operational units; implementation of basic biosecurity measures – bird nets, crab fences, vehicle

disinfection area. Laguna, SC - Brazil

EXAMPLES – LAGUNA, SC - SOUTHERN BRAZIL

CropsStock density

(pcs/m2)FCR Survival Yield (kg ha-1)

WSSV

occurrence

1 100 1.32 63% 6.36 NEGATIVE

2 118 1.25 75% 7.97 NEGATIVE

3 100 1.15 75% 6.75 NEGATIVE

Results of pilot crops in biofloc system operated in WSSV contaminated area in Laguna,

SC – Southern Brazil. Poersch et al., 2013 Panorama da Aquicultura Magazine

Panoramic view of the farm after remodelling to operate in Biofloc system.

• 3 successful crops regularly

monitored through PCR and

histopathological analysis – all

WSSV negative

EXAMPLES – SAUDI ARABIA

• First crop 2015: 15.000 t

• Second crop 2016: 17.500 t

• Target for 2017: 30.000 t

• Surveillance program: all WSSV negative

• P. indicus farming completely devastated by WSSV

outbreak in early 2010’s - Vertical contamination

• Introduction of SPF Tolerant L. vannamei

• Implementation of biosecurity protocols

• Biofloc system for the production of brood stock and

implementation of breeding program

•

L. vannamei prawn farms in Saudi Arabia – Rigorous biosecurity strategy and

biofloc-reared brood stock guarantee success in conventional system grow

out.

L. vannamei SPF

brood stock reared

in BFT system in

Saudi Arabia

CONCLUSION

S W

TO

• Higher Biosecurity

• Higher Productivity

• Less use of water and land

• Less environmental impact

• Higher investment

• Remodelling of existing units

• Require qualified

management

• Operate in areas affected

by WSSV outbreak

• Operate in seasonal

periods and continental

areas where conventional

system cannot

• Needs to be a part of a

rigorous biosecurity

strategy in order to thrive

• Risk of system crash if

not well managed

CONCLUSION

Disease outbreaks, particularly WSSS, typically cause major constraints to prawn

aquaculture. Industries in Australia and around the world must adapt their practices to

minimize and/or prevent the impact of these outbreaks. New technologies, such as

Biofloc and RAS, are available to assist in this challenge.

Although the initial investment is higher than other systems, best practices worldwide

have shown that BFT is suitable for industrial prawn aquaculture. It increases farm

efficiency, production, and enhances the immune-system of the prawns and on-farm

biosecurity. Such characteristics make BTF a powerful tool to produce in WSSV affect

areas, although it needs to be part of a much larger biosecurity strategy.

Transfer of technology, system remodeling, adaptations, and proper management must

be made to expand the scope of the commercial production in BTF to other species,

such as P. monodon. Transitioning to BTF will help improve prawn farming, which will

lead the aquaculture industry toward a higher level of sustainability and animal health.

Gabriel B. Santos

Technical Manager – Shrimp Breeding Program

B.S. Oceanography & M.S. Aquaculture

e-mail: [email protected]

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