Seasonal variations of growth in the red alga Chondrus crispus on the Atlantic French coasts. II. Relations with phosphorus concentration in seawater and internal phosphorylated fractions

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Abstract
Monthly measurements of the total phosphorus content in three parts of Chondrus crispus showed a gradient along the thallus with its seasonal variations. Parallel patterns of seasonal variations were observed between total phosphorus content in the growing parts of the alga (apex and middle) and dissolved inorganic phosphorus concentration in seawater. 32P-phosphorus absorbed in the alga was incorporated in organic compounds, of which 60% were water-soluble. Water-soluble phosphorylated compounds were those usually found in higher plants and other algae. With a low phosphorus content and a high specific radioactivity, the water-soluble inorganic fraction probably did not have a storage role. The water-soluble organic fraction presented the opposite characteristics; hence, it could be considered as a storage pool, together with the acid-insoluble fraction. As the seasonal pattern of the phosphorylated fractions was similar at the three parts of the alga, the phosphorus gradient along the thallus did not correspond to a qualitative or quantitative difference in storage compounds in these parts, but was still attributed to seasonal variations of phosphorus concentration in seawater and growth.