Hatha, A A M; Mujeeb Rahiman, K M; Deborah, Gnana Selvam(The ScientificWorld Journal, October 31, 2011)
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Abstract:
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 fromfeeder canal showed low oxygen levels (as low as 0.8mg/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 triggeringWSSV
infection in these traditional ponds
Description:
The ScientificWorld Journal
Volume 2012, Article ID 340830, 11 pages