Algae. 2000; 15(2): 81-88.

Effects of Inorganic Nutrients and Heavy Metals on Reproduction of the Green Alga, Ulva pertusa Kjellman

Jang-Kyun Kim, Tae Jun Han

Recent concern over marine pollution has developed great attention on likely alteration of ecosystems thereof. Considering that distributional ranges of seaweed species are governed by their success or failure of reproduction, intertidal green alga, Ulva pertusa, was studied to evaluate reproductive responses to environmental pollutants. Percent of sporulation and spore release of U. pertusa grown in the east seawater medium, optimal photon irrdiance west seawater at irradiances higher than 100μmol·m supper(-2)·s supper(-1). In the east seawater medium, optimal photon irradiance for reproduction was found to be at 100μmol·m supper(-2)·s supper(-1) whereas in the west seawater, that was 30μmol·m supper(-2)·s supper(-1). Total quantum requirements for sporulation and spore release were much lower in the east seawater than the west seawater, which suggests that reproduction may be influenced by water turbidity. When U. pertusa was exposed in batch cultures to various concentrations of nitrate and phosphate at 100μmol·m supper(-2)·s supper(-1) of white light, the rate of reproduction was markedly higher in nutrient-added conditions compared with controls with no nutrients. As nitrate concentration increased, the reproductive rate of U. pertusa increased in all cultures of phosphate concentrations indicating that nitrate but not phosphate plays an important role in reproductive process. When copper and lead in combination were added to U. pertusa, percent sporulation and spore release were solely dependent of copper concentration. Sporulation and spore release at 0.01 ppm of copper reached about 80% which was similar to that in control, but no sign of reproduction was found at 0.1 ppm of copper. It can therefore be speculated that reproduction is more sensitive to copper than growth in U. pertusa in view of the previous report that 0.1 ppm of copper was not inhibitive to growth.