Journal of Aquaculture Research & Development

Orange gills in Litopenaeus stylirostris : A new phenomenon in Caledonian shrimp ponds

International Conference on Aquaculture & Fisheries

July 20-22, 2015 Brisbane, Australia

Nelly Wabete1, Hugues Lemonnier1, Kiam Barri2, Dominique Pham1,Viviane Boulo1, Florence Royer1, Morgane Hubert1, Thierry Laugier1, Jean-Herv� Lignot4, Thomas Pierrot2, Bernard Blockmans3 and Nathalie Tostin3

ScientificTracks Abstracts-Workshop: J Aquac Res Development

Abstract:

Shrimp farming is an important economical sector in New Caledonia based on a non indigenous domesticated species, the Pacific Blue Shrimp Litopenaeus stylirostris. Animals with orange gills have been observed recently in grow-out ponds and up to 70% of the shrimp in one pond could be affected. This coloration impacts the quality product in the processing plant, leading to lessvalue shrimp for farmers. The phenomenon occurred when the average weight of shrimp is around 18g and after 80 days of rearing, concomitantly with a high feeding rate and an important phytoplanctonic biomass. Temporal fluctuations in gills coloration were also noticed. Individual observations allowed to conclude that gills coloration intensity varies according to the intermoult stages, from white in postmolt stage to a deep orange in premolt stage and disappeared after the molting . Orange gills percentage was greatly reduced in shrimp population by isolating them from the soil with floating cages in earthen impacted ponds. Histological, biochemical and scanning electron microscopy (SEM) studies have shown that heterogeneous iron layers were settled on the tissue surface and the iron concentration was tenfold higher in the orange gills than in white ones. Some bacterial colonisations have also been observed and are assumed to be involved in the iron precipitation processes which lead to these orange colorations. Very high concentrations in dissolved iron (till 70?M) were measured in the sediment pore water suggesting an environmental triggering of the phenomenon. All these results raise questions about the impact of orange gills on shrimp health, and in which conditions this phenomenon is promoted.

Biography :

Nelly Wabete is currently working in research Framework Department at Lagoons, Ecosystems and Sustainable Aquaculture in New Caledonia (LEAD NC), Ifremer. Mainly focused to study eco-physiological metabolism respiratory and nutrition in penaeid shrimp Litopenaeus stylirostris and application to shrimp farming in New Caledonia.