Photosynthetic rate and biochemical composition of green algae Ulva flexuosa (Wulfen) J. Agardh as potential indicators of environmental stress in the intertidal zones

Abstract

Photosynthetic rate and biochemical composition total chlorophyll (TC), total soluble protein (TSP) and total soluble carbohydrates (TSC) were determined for Ulva flexuosa, a green marine algae collected from Nasese, Lami and Laucala Beach areas in Suva, Fiji Islands. Ulva flexuosa from Laucala Beach area had the highest photosynthetic rates, TC and TSP content, while algae from Nasese area had the highest amount of TSC. Algae from Lami area had the lowest amount of photosynthesis rate, TC, TSP and TSC. High photosynthetic rate and biochemical content were mainly due to the presence of high levels of nitrogen in the area. Algae thrived in Laucala Beach and Nasese area where nitrogen content was high. Low photosynthetic rate and biochemical composition were recorded in algae from the Lami area, which was apparently the most polluted area. It appeared that conditions in Lami area were intolerable to U. flexuosa. Algae collected from the three sites differed in the measured parameters with respect to the differences in the pH, temperature and nitrogen levels indicating that physiological responses of algae could be used as indicators to monitor the environmental quality of the intertidal zones.