Quantitative image analysis of the gastro-intestinal tract of Penaeus vannamei on microscopy images for screening shrimp health.

Health assessment of aquatic species is fundamental to apply new prophylactic and therapeutic strategies to support and enlarge the aquaculture sector and the availability of high valuable animal proteins for human population. The primary aim of this project is to improve the understanding on anatomy and biological mechanisms on the gastro intestinal tract of Pacific White Shrimp by using image analysis of histological sections. Histology is the study of microscopic anatomy of cells and tissues by sectioning and staining, followed by examination under light and electron microscope. Traditional histological methodologies have some limitations and digitalized image analysis of histological sections is getting more and more popular thanks to its objectivity and reliability. Skretting Aquaculture Research Centre has proven this novel methodology to be effective in assessing the health status of fish, and also in evaluating the efficacy of new prophylactic approaches. On the first phase, different stages of the shrimp life cycle will be evaluated. The second phase will focus on the influence of feed and feeding regimes on the health status of shrimp.

Penaeid shrimp aquaculture is an important industry in Asia and Americas, and Pacific White Shrimp, Penaeus vannamei, is one of the most cultured species. The shrimp industry has always been affected by infectious diseases, mainly bacterial and viral etiologies. White Spot Syndrome (WSS) and more recently Early Mortality Syndrome (EMS) or Acute Hepatopancreatic Necrosis Syndrome (AHPNS) are responsible for significant economic losses and for the most costly epizootics. Nowadays the primary and most important means of health assessment and disease diagnosis is performed through histology. Image analysis of digitised histological sections provides a practical means for quantifiable assessment of structural and functional changes in tissues. Skretting Aquaculture Research Centre has proven this novel methodology to be effective in assessing the health status of fish, and also in evaluating the efficacy of new prophylactic approaches This PhD aims to improve the understanding of Penaeid shrimp histology and cell dynamics to assess the health status of the gastro-intestinal (GI) tract of P. vannamei by use of a (semi) quantitative histological analysis system for both light and electron microscopy. Therefore, a detailed description of the normal histological structure of the GI tract will be aimed. In the first phase, different moulting stages will be considered. In the second phase, the developed methodology will be applied to quantify the alterations induced by a stressful episode, such as defined starvation period. Additionally, when a re-feeding cycle follows a starvation period, reversible histological differences may be studied. Alternatively the effect of the diet on the tissue morphological structure will be evaluated by altering the dietary components and/or by using contaminated feed caused by inappropriate methods of feed storage. The third phase will focus on (semi)quantitative histological assessment for shrimp affected by WSS and AHPNS.