The Influence of Ecological Factors on the Contents of Nutritional Components and Minerals in Laver Based on Open Sea Culture System

Abstract

Laver is a popular food for its high nutritional value, which can change among culture areas and along with the progression of harvest. Neopyropia yezoensis and Neoporphyra haitanensis were cultured in succession in Taoluo and Muping, north China. The chemical composition of laver samples together with some ecological factors in the farms were investigated. From September to December, salinity increased while water temperature decreased in both areas. Dissolved inorganic nitrogen (DIN) and N:P decreased in Taoluo while increasing in Muping. Both N. yezoensis and N. haitanensis contained high levels of protein (26.90–41.38% DW) and low contents of fat (0.36–0.74% DW). High levels of minerals were detected in both species. The contents of protein, total amino acids, and total minerals in N. haitanensis increased significantly, while sugar content decreased significantly from September to December. The gray correlation analysis result implied that the typical ecological factors (DIN, dissolved inorganic phosphorus, N:P, pH, salinity, temperature, and transparency) have a great influence on accumulation of the crude nutrient, amino acid, fatty acid components, and mineral components in laver. The coefficient of variation analysis result also showed that environmental heterogeneity obviously enhanced differences in the contents of protein, amino acid, and trace elements in N. yezoensis. In addition, the principal component analysis result showed that the N. yezoensis strain ‘Huangyou No. 1’ had the highest comprehensive evaluation score in the four tested N. yezoensis strains, indicating that it has the best comprehensive quality and greatest exploitable value. We hope these findings will help to improve future laver breeding and farming.