The Biochemical composition of sea weeds from the persian gulf and the effect of sea weed extract on the growth and biochemical composition of microalgae cultured as live food for penaeus indicus larvae

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Date
2011
Authors
Ghadikolaei, Kiuomars Rohani
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Abstract
The biochemical composition of three groups of seaweeds; green ( Ulva lactuca and Enthromorpha intestinalis ), brown (Sargassum illicifolium and Colpomenia sinuosa) and red (Hypnea valentiea and Gracilaria corticata) from the Persian Gulf and the effects of seaweed extracts (SWE) either as a supplement or as a substitute media t'o the f/2 medium on the growth and composition of two microalgae Isochrysis galbana and Chaetoceros muelleri cultured as live food for Penaeus indicus larvae were investigated. Results showed that seaweeds were relatively high in carbohydrate and ash, but low in lipid. Lipid content in green ( U. lactuca and E. intestinalis) seaweed was significantly higher than both the red and brown seaweed (P < 0.05). Protein content of red (G. corticata) and green (U. lactuca and E. intestinalis) seaweeds was notably higher than brown seaweed (P < 0.05). The green (U. lactuca) and red (H. valentiea) seaweeds. had the highest proportion of saturated fatty acids, while the brown (S. illicifolium and C. sinuosa) and red (G. corticata) seaweeds had the highest proportion of monounsaturated and polyunsaturated fatty acids, respectively. The mineral compositions 111 seaweeds were found 111 the sequence of K>Mg>Fe>Zn>Mn>Cu>Co. The study clearly showed that the two microalgae I. galbana and C. muelleri could be successfully cultured using the various SWE either as a supplement or as an he f/2 medium. Since no major changes were found in most of the measured growth parameters, proximate biochemical composition, important polyunsaturated fatty acids and minerals content following culture of the microalgae with SWE as an alternative media, particularly extracts of U lactuca, E. intestinalis and G. corticata, it was concluded that these SWE are able to provide the necessary nutrients for microalgae growth and could be used as a possible substitute to reduce microalgae production costs, at least two times lower than conventional f/2 medium, in establishing microalgal populations to use in aquaculture operations. The present study found that when P. indicus larvae were fed on microalgae I. Jtalbana and C. muelleri (exclusively or mixed) that had been cultured with SWE as a supplement media, they molted faster to mysis 2 (Mu) stage compared to the larvae fed on microalgae cultured with conventional f/2 media (control without any SWE). Maximum final total length, survival rate and specific growth rate were recorded for shrimp larvae fed on microalgae diets that included SWE as a supplement in the culture media compared to shrimp larvae fed the control diet. The overall growth performance clearly showed that P. indicus larvae were successfully reared using microalgae diets tested, and the shrimp larvae fed on mixed microalgae (1. galbana + C. muelleri) showed better larval growth, survival and d-evelopment than those that were fed on single microalgal diet. Furthermore, similar larval growth, survival and development were obtained when shrimp larvae were fed with microalgae cultured with SWE as a substitute media to f/2 medium. In conclusion, microalgae cultured with SWE could potentially be used as a low-cost alternative method in producing live food for the hatchery production of shrimp larvae.
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Keywords
Seaweed extract , Biochemical Composition , Microalgae cultured , Penaeus indicus
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