GREEN WATER TECHNOLOGY FOR SHRIMP

FARMING: MODES OF ACTION

Eleonor A. Tendencia1, Marc Verdegem2

1 Southeast Asian Fisheries Development Center, Tigbauan, Iloilo, Philippines 2 Aquaculture and Fisheries Group, Wageningen University, NL

Philippines

• Luminous bacteria • White Spot Syndrome

Virus (WSSV) Restrains production

Survey of 174 shrimp farms and other

case-studies

77 farms monoculture – 97 polyculture (8 provinces)

47 variables related to:

● Pond site (history and description)

● Period of culture

● Pond preparation methods

● Water management

● Culture methods

● Inputs (feed and others)

● Biosecurity measures

Binary logistic regression; stepwise backward

WSSV risk factors

• Rainfall - Salinity fluctuation

• Low temperature: < 26-27oC - Stocking during the cold months

• Temperature fluctuation of 3-4oC in 10 hours (infection)

• Rapid pH fluctuation

• Sharing water with neighbours – same inlet and outlet

• Removing sludge and depositing on the dike

• Feeding with mollusc

• Higher stocking density

• Larger pond size

Survey of 174 shrimp farms and other case-studies

Survey of 174 shrimp farms and other

case-studies

WSSV protective factor

• temperature >28oC

• Percentage yellow vibrios >50%

• Feeding with phytoplankton

• High mangrove to pond area ratio

• On farms with mangroves in the receiving environment • WSSV infection did not result in disease outbreak; • Water quality in receiving environment with

mangroves better; • No difference in culture performance in ponds.

Interpretation of results

Sludge removal in itself improves culture environment, if disposed with no risk for re-contamination.

Feeding molluscs is a risk (filter feeders) WSSV carrier

Also case with polychaetes (Desrina et al. 2013)

Biosecurity measures were not effective (bird nets, crab fences, disinfection measures)

Sharing water sources between farms should be avoided.

Farming strategies practiced by farmers in the

Philippines Culture system Low-salinity culture, Crop rotation, Greenwater culture -Modified

greenwater culture Extensive shrimp farming milkfish/tilapia-shrimp

polyculture Biofloc systems Additives Disinfectants Antibiotics Probiotics Others Fry quality Biosecurity measures Minimum water exchange/closed

system

Seabass tilapia

tilapia shrimp

shrimp

5-15 ppt

1st crop: finfish

2nd crop: shrimp

Types of greenwater shrimp culture systems

a

b

Greenwater

Tilapia metabolic wastes provide nutrients stimulating phytoplankton production

Tilapia grazing dominated by green

algae (Chlorophyceae), Nannochloropsis sp. and Chlorella sp.

Add predator

Numerous pond organisms are carriers/vectors of WSSV

● Decapods

● Zooplankton

● Polychaetes

Carnivores reduce potential carriers

Duo culture tilapia – shrimp?

Size at stocking – predation & shrimp survival (Yuan et al.

2010)

Competition for available food:

● At high tilapia biomass reduced shrimp growth

● Feeding strategy:

● Only feed shrimp improved feed efficiency but lower shrimp production (Azaduzzaman et al.

2010)

● Feed fish and shrimp need for oxygen addition.

Separating fish and shrimp advantageous

Species used for co-culture with P. monodon

Evolution to different co-cultures

Comparison of the use and non-use of greenwater : cultured shrimp

Parameter GW Non-GW

DoC 160 133

Ind. wt (g) 38 25

Daily wt gain (g) 0.24 0.19

Survival (%) 93 69

FCR (-) 1.84+0.21 1.78+0.03

GW= cultured using greenwater technique Non_GW= cultured not using the greenwater technique DoC= days of culture ABW= average body weight DWG= daily weight gain SR= survival rate FCR=feed conversion ratio

Greenwater improves production levels

Improved water quality

Improved soil quality

Inhibition of pathogens

Boost shrimp immune response

Poor

environment

Susceptible

host

Virulent

pathogen

DISEASE

Higher % survival

Larger shrimp

Increased production

Improved water quality

Reference

Mugil cephalus secretes skin mucus containing heterothrophically nitrifying and oxygen tolerant denitrifying bacteria

Velusamy & Krishnani, 2013

NOB in coastal ponds are sufficiently diverse to continue exploring for bioremediation candidates.

Kithiravan et al., 2012

Sulfur oxidizing bacteria isolated from green fish slime maintain sulfide concentration within safe level

Kithiravan et al., 2010

Lower nutrient levels in green water ponds Tendencia et al., 2012. Tendencia et al., 2013

Presence of tilapia reduces phytoplankton blooms & enhances copepod presence, but reduced rotifers.

Sun et al.,2011

Soil Quality

Reference

Lower soil available sulfur in greenwater compared to non-greenwater ponds

Tendencia et al., 2013

Greenwater inhibits growth of pathogen

Reference

Sodium alginate extracts from brown seaweeds retards progression of WSSV

Immanuel et al. 2012

Shrimp fed with feed containing macro-algal metabolites control growth of V. alginolyticus & V. fischeri

Lipton et al., 2009; Selvin et al., 2012

Extracts of Gracilaria fischeri has anti V. harveyi activity

Kanjana et al., 2011

Shrimp fed with herbal and seaweed diets-enriched Artemia lowered V. parahaemolyticus load

Immanuel et al. 2004

Lower luminous bacterial count in greenwater compared to non-greenwater;

Tendencia et al., 2004; Tendencia et al., 2005; Tendencia et al., 2006; Tendencia et al., 2013

Shrimp immune response boost

Reference

Brown seaweeds extracts affect resistance to WSSV in P. monodon postlarvae

Immanuel et al., 2010

Extracts of Gracilaria fisheri had immunostimulant activity that could protect P. monodon against V. harveyi

Kanjana et al., 2011

Factors affecting efficiency of greenwater

Greenwater system research

●Fish (mollusc, algae) species

●Fish-shrimp biomass ratio

●Culture density

●Feeding strategies

Challenges

• Some farmers are reluctant to divide ponds into smaller units and allocate separate ponds for finfish and crustaceans

• Practice of the “proper” greenwater culture technique

• Is greenwater technique effective for extensive shrimp culture?

Foodweb ecology

● Nutrient cycling and turn over efficiencies?

● Community dynamics?

● Shrimp feeding

Questions?