An Investigation into Occasional White Spot Syndrome Virus Outbreak in Traditional Paddy Cum Prawn Fields in India

• Published in: TheScientificWorld 2012-01, Vol.2012 (2012), p.1-11
• Main Authors: Selvam, Deborah Gnana, Mujeeb Rahiman, K. M., Abdulla, Mohamed Hatha
• Format: Article
• Language: English
• Subjects: Acetes; Ammonia; Ammonia - metabolism; Animals; Aquaculture; Aquaculture - methods; Backwaters; Bacteria - classification; Bacteria - isolation & purification; Canals; Crustaceans; Disease Outbreaks; Dissolved oxygen; DNA, Viral - analysis; DNA, Viral - genetics; Epidemics; Farms; Fenneropenaeus indicus; Fish; Geologic Sediments - chemistry; Geologic Sediments - microbiology; Geologic Sediments - virology; Health aspects; Host-parasite relationships; Host-Pathogen Interactions; Hydrogen-Ion Concentration; Hypoxia; India; India - epidemiology; Macrobrachium rosenbergii; Nutrient loading; Outbreaks; Oxygen - metabolism; Parameters; Penaeidae - growth & development; Penaeidae - virology; Penaeus monodon; pH effects; Physiological aspects; Phytoplankton; Pollution load; Polymerase Chain Reaction; Ponds; Pseudograpsus intermedius; Residential areas; Scylla serrata; Seasons; Sesarma oceanica; Shellfish; Shrimps; Supersaturation; Temperature; Virus diseases; Virus research; Viruses; Water exchange; Water Microbiology; White spot syndrome; White spot syndrome virus 1 - genetics; White spot syndrome virus 1 - physiology; Zoological research
• ISSN: 2356-6140; 1537-744X; 1537-744X
• DOI: 10.1100/2012/340830

A yearlong (September 2009–August 2010) study was undertaken to find out possible reasons for occasional occurrence of White Spot Syndrome Virus (WSSV) outbreak in the traditional prawn farms adjoining Cochin backwaters. Physicochemical and bacteriological parameters of water and sediment from feeder canal and four shrimp farms were monitored on a fortnightly basis. The physicochemical parameters showed variation during the two production cycles and between the farms studied. Dissolved oxygen (DO) content of water from feeder canal showed low oxygen levels (as low as 0.8 mg/L) throughout the study period. There was no disease outbreak in the perennial ponds. Poor water exchange coupled with nutrient loading from adjacent houses resulted in phytoplankton bloom in shallow seasonal ponds which led to hypoxic conditions in early morning and supersaturation of DO in the afternoon besides considerably high alkaline pH. Ammonia levels were found to be very high in these ponds. WSSV outbreak was encountered twice during the study leading to mass mortalities in the seasonal ponds. The hypoxia and high ammonia content in water and abrupt fluctuations in temperature, salinity and pH might lead to considerable stress in the shrimps triggering WSSV infection in these traditional ponds.