Copper induction of phosphorus deficiency inUlva fasciata(Ulvales, Chlorophyta)

Abstract The effects of Cu2+ on phosphorus (P) availability in Ulva fasciata Delile were studied by exposure to CuSO4 (0–100 µM) added in the nutrient-enriched artificial seawater media for 8 days. The growth rate decreased as medium Cu2+ contents increased, 50% growth inhibition was achieved at 9.8 µM Cu2+ (850 µg l−1). Tissue total Cu contents as well as cell wall–bound and intracellular Cu contents increased as medium Cu2+ contents increased. Normally, cell wall–bound Cu contents in Cu2+-treated thalli consisted of approximately 60% of total tissue Cu contents. When Cu2+ contents in the media were ≥ 50 µM, tissue P contents decreased in conjunction to tissue C : P and N : P molar ratio increased, but tissue C and N contents and tissue C : N molar ratio remained unchanged. Tissue soluble reactive phosphorus, soluble nonreactive phosphorus and total soluble phosphorus contents decreased, whereas Cu2+ contents in the medium were ≥ 50 µM. After 4 days of treatment, the inorganic oxyanion phosphate (Pi) upt...