introduction wfd

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Introduction During the early 2010, attracted by high shrimp selling prices, many producers in Thailand decided to use increased stocking densities in the search of higher production levels. Nevertheless, unusually high water temperatures (>32°C) and higher feeding rates resulted in increased organic matter levels in the ponds, with the emergence of a new pathological entity called “white feces disease”. The disease was first detected in Penaeus monodon cultivated in low salinity waters (3-5‰), but it was later spread throughout Thai’s entire shrimp production area, where currently 99% production corresponds to Litopenaeus vannamei. Disease scenario The disease occurs under different soil conditions, and it results in deteriorated water quality. Peak mortality rates are seen in the face of extremely low oxygen (<3.0 mg/L)/low alkalinity (<80 ppm) levels. Early disease indications appear in both control feed trays and at water surface, where abundant floating white feces are observed (Figure 1).

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Introduction

During the early 2010, attracted by high shrimp selling prices, many producers in Thailand decided to use increased stocking densities in the search of higher production levels. Nevertheless, unusually high water temperatures (>32C) and higher feeding rates resulted in increased organic matter levels in the ponds, with the emergence of a new pathological entity called white feces disease. The disease was first detected in Penaeus monodon cultivated in low salinity waters (3-5), but it was later spread throughout Thais entire shrimp production area, where currently 99% production corresponds to Litopenaeus vannamei.

Disease scenario

The disease occurs under different soil conditions, and it results in deteriorated water

quality. Peak mortality rates are seen in the face of extremely low oxygen (