Seasonal Variations of n-6: n-3 Ratios and Fatty Acid Compositions in Foot and Tissue of Chiton lamyi in a High Primary Productivity Area

Abstract

Problem statement: Fatty acid content and composition in mollusks is a function of their feeding diversity. Chabahar bay located in the northern part of Oman sea in Indian ocean provides high rates of primary productivity and a diverse food source for mollusks in this area. Identification of fatty acid compositions of Chiton lamyi and study their seasonal changes in the intertidal zone of Chabahar bay. Study the meat quality by n-6: n-3 ratios calculation throughout the year. Approach: Chiton lamyi species analyzed seasonally for its fatty acid compositions in foot and internal tissue separately by GC/MS chromatography. Temperature and nutrients measured monthly for evaluating their effects on investigated seasonal variations of fatty acids. Pearson analysis showed effects of measured environmental factors on studied fatty acids composition. n-6: n-3 ratio calculated seasonally in order to study meat quality. Results: Thirteen fatty acids identified in foot and internal tissue of Chiton lamyi. The major Saturated Fatty Acids (SFAs) were myristic, palmitic and stearic acids. The major Mono-Unsaturated Fatty Acids (MUFAs) were palmitoleic, oleic and 11-eicosenoic acids and Poly-Unsaturated Fatty Acids (PUFAs) were linoleic, eicosapentaenoic and arachidonic acids. Palmitic acid was the most abundant in this species. Fatty acid contents of foot and internal tissue of Chiton lamyi were similar but their seasonal variations were different. Pearson analysis showed correlation among palmitic and oleic acids with silicate; oleic acid with phosphate; Linoleic and arachidonic acids with nitrate in Chiton lamyi internal tissues, but no correlation observed in foot. Although temperature showed correlation with heptadecanoic and methyl-heptadecanoic acids in Chiton lamyi foot, no correlation found in internal tissues. Also, n-6: n-3 ratio calculations showed domination of n-3 fatty acid over n-6 only in spring. Conclusion: Fatty acid variations were not same at different organs and environmental factors could have opposite effects on them in this species. Also, n-6: n-3 ratio showed the lack of food loads throughout the year except in spring for this species. These findings can lead the best exploitation periods for such marine mollusks.