Microalgal Preference and Feeding Density of Selected Microalgae Diets by Blue Swimming Crab Portunus pelagicus (Linnaeus, 1758).

Abstract

<b>Background and Objectives:</b> Blue swimming crab, <i>Portunus pelagicus</i> (Linnaeus, 1758) are economically important sources of soft-shell products for export demand. However, increasing over-exploitation and pollution towards the sea resources affected the production of the <i>P. pelagicus</i>. The study aimed to determine the microalgal preference and feeding density of the monospecific (<i>Nannochloropsis oculata</i>, <i>Chlorella vulgaris</i>, <i>Isochrysis galbana</i> and <i>Chaetoceros wighamii </i>) by individual <i>P. pelagicus </i>larvae. <b>Materials and Methods:</b> In the microalgal preference study, one polystyrene tray with 100 holes was set up in the experimental tank (200 L) to place the 50 mL centrifuges tube. For feeding density study, the survival rate, Specific Growth Rate (SGR), Body Weight (BW) and Larvae Stage Index (LSI) of each larvae stage were collected from Zoea 1 (Z<sub>1</sub>) till megalopa. <b>Results:</b> Results for mean microalgal preference of individual larvae preferred most <i>Chlorella vulgaris</i> during Zoea 1 and 2, the larvae consumed the highest of <i>Nannochloropsis</i> <i>oculata</i>. For Zoea 3 and 4, the highest preference is <i>Isochrysis galbana</i>. For feeding regime, Zoea 1, larvae fed rotifer, <i>Artemia</i> and <i>Chlorella vulgaris</i> (T<sub>3</sub>), was the highest survival rate, Zoea 2 was larvae fed rotifer, <i>Artemia</i> and <i>Nannochloropsis oculata</i> (T<sub>5</sub>) and both Zoea 3 and Zoea 4, larvae fed rotifer, <i>Artemia</i> and <i>Isochrysis galbana</i> (T<sub>4</sub>) was the highest survival rate. The highest SGR and LSI were obtained in T<sub>4</sub> cultured in 14 days. <b>Conclusion:</b> In conclusion, the microalgal preference and feeding density of the selected microalgae are different depending on each larvae stage.