“Summer syndrome” in Litopenaeus stylirostris grow out ponds in New Caledonia: Zootechnical and environmental factors

Abstract

The "Summer Syndrome", a septicemic vibriosis caused by Vibrio nigripulchritudo, is responsible for one of the two main seasonal mortalities which affect shrimp aquaculture in New Caledonia. It was identified for the first time in December 1997 in an intensive shrimp farm (called farm DF) and has been enzootic ever since. The "Summer syndrome" affects shrimp during warm-season growout. Although the geographic area concerned is limited, it is a potential threat for the industry in that the disease could spread. Analysis of grow out data from 1991 to 2002 in this farm was carried out in order to characterize the disease and the environmental conditions in relation to mortality. Results of farm DF were compared to data from farms not affected by the disease (called farms HC). The "Summer syndrome" occurs during the warm season which is characterized by an increase in water temperature and sunny duration. This disease is characterized by simultaneously highest densities and weakest drying duration between crops in the farms studied. Between 1991 and 2002, the increase of feed input and nitrogen rate in feed has led to a significant increase of the growth rate over the years in farm DF. At the same time, water management has not changed and has induced an increase in environmental waste production. In consequence, an early eutrophication of water is observed, which is concomitant with the beginning of the mortality outbreaks. This could play a role by inducing directly or indirectly a stress for shrimp and/or a growth and/or virulence factors of the pathogen.

Dynamics of phytoplankton communities in eutrophying tropical shrimp ponds affected by vibriosis

“…The stocking date chosen for this field survey was particularly favourable to the occurrence of the diseases (Lemonnier et al, 2006). The ponds were managed by the farmer according to his usual techniques without advices from scientific team.…”

“…Whatever the disease, mortality appears in specific environmental conditions characterized by strong phytoplankton and bacterioplankton oscillations and abiotic parameters (pH, ammonia, etc.) close to stressful values (Lemonnier et al, 2006Lucas et al, 2010). Such conditions, which may occur in combination with another unknown triggering factor, weaken the host physiological status, parameters, increasing shrimp susceptibility to bacterial infections (Mugnier et al, 2013).…”

“…Known as "Summer Syndrome", this disease is currently restricted to one particular area of New Caledonia (St Vincent Bay). Regarding this epizooty, three risk factors were identified for shrimp mortality occurrence and strength: fast shrimp growth, early eutrophication of the pond ecosystem, and the presence of the HP Vn strain (Lemonnier et al, 2006). The second type of vibriosis is related to Vibrio penaeicida (Vp) and is known as "Syndrome 93" Goarant et al, 1999;Saulnier et al, 2000).…”

Historic emergence, impact and current status of shrimp pathogens in Asia

“…As previously stated, serious Vibrio infections are usually the result of mismanagement and they will not be discussed here further, except to mention that disease outbreaks caused by Vibrio penaecida (Ishimaru et al, 1995;Saulnier et al, 2000) and Vibrio nigripulcritudo (Goarant et al, 2006;Lemonnier et al, 2006) can be initiated by unmanageable weather conditions, and that infections with a new species Vibrio mediteraneanei (synonym = Vibrio shiloi = Vibrio shilonii) have recently been reported from diseased shrimp in Thailand (Longyant et al, 2008).…”

Exoskeletal deformities in Palaemonidae: Are they a threat to survival?

“…One might think, therefore, that their accelerated metabolism during that period would favour the emergence of deformities. Temperature could also be a factor affecting the availability or the toxicity of the factor responsible for the deformities (Dimmock et al, 2004;Lemonnier et al, 2006). This seasonality could also be explained by fluctuations in pollutant input: in Gironde, spring and summer are the seasons when pesticides or other micropollutants are discharged and carried into the estuary by rivers and runoff water.…”