An Epizootic of Vibriosis in Ecuadorian Pond‐Reared Penaeus vannamei Boone (Crustacea: Decapoda)

Abstract

A massive e p h t i c of vibriosis, named "sindroma gaviota" (or sea gull syndrome = SGS) by local shrimp fanners, began in November 1989 and continued through May 1990 in nursery and grow-out ponds in a number of shrimp farms located in the Gulf of Guaynquil near Cunyaquil, Ecuador. The level of cumulative mortalities ranged from slight in some ponds to more than 9O0h in others. Examination of affected shrimp, Penueus vunnumei Boone, led to the isolation of several closely related Vi6rio species. The predominant species were identified as VibriO puruhuenwlyricus, V. vulnifcus, and V. ulginolyficus using the API-NR system. Several of the strains exhibited a transient luminescence and some were positive for urease, an unusual trait for these species. Comparisons of the antimicrobial sensitivity patterns between farm and hatchery isolates from 1989-1990 and hatchery isolates from 1987-1989 indicate that the 1989-1990 pond isolates were not of hatchery origin. The epizootic coincided with the second year of a severe drought in Ecuador. Thus, the discharge of fresh water by the Guayas River was reduced and salinities and relative nutrient concentrations were elevated in the Gulf of Guaynquil. These environmental conditions were ideal for the increased growth of the causative vibrios in the estuarine waters and are believed to be factors that contributed to the 1989-1990 SGS epizootic.

Vibrio alginolyticus infection in the white shrimp Litopenaeus vannamei confirmed by polymerase chain reaction and 16S rDNA sequencing

“…V. alginolyticus isolated from moribund Penaeus monodon was reported to kill P. monodon and Maruspenaeus japonicus with an LD 50 of 1.13 × 10 5 and 2.46 × 10 5 CFU g -1 body weight, respectively (Lee et al 1996a,b Vibriosis in penaeid shrimp is generally recognized as a secondary infection influenced by factors such as stress, environmental failures and high numbers of potentially pathogenic bacteria in the enviromment (Mohney et al 1994, Lavilla-Pitogo et al 1998. Changes in environmental factors such as salinity, pH and ammonia are capable of altering the virulence of Vibrio harveyi and V. alginolyticus (Prayitno et al 1995, Liu & Chen 2004.…”

Toxic factors of Vibrio strains pathogenic to shrimp

“…culture (Lightner 1988, Brock & LeaMaster 1992, Mohney et al 1994. 'Syndrome 93' is a seasonal vibriosis caused by Vibrio penaeicida which affects juve-MATERIAL AND METHODS nile Litopenaeus stylirostn's (= Penaeus stylirostris) in grow-out ponds in New Caledonia.…”

Periodic occurrence of epithelial viral necrosis outbreaks in Penaeus vannamei in Ecuador

“…During 1997 production of pond-reared shrimp in Ecuador reached a record of 109 000 t (Melendez 1998). During recent years different diseases affecting shrimp production have been reported in Ecuador (Lightner et al 1992, Mohney et al 1994. The most important disease until 1998 has been Taura syndrome (TS), which has affected cultured shrimp near the Taura river, as described by Jimenez (1992).…”