Physiological traits of free-floating green alga (Ulva linza) in response to temperature and irradiance

Abstract

Ulva linza were collected from the coastal water off the southwest of Korea in July 2009. Photosynthesis, growth and tissue nutrient contents of both the late stage vegetation (LSV) and the early stage vegetation (ESV) at various temperature and irradiance conditions were investigated in the laboratory. In the short-term (1 h) irradiance and temperature acclimation, the maximum gross photosynthetic rate (PBmax) and photosynthetic efficiency (a) of. ESV were higher than those of LSV. With respect to irradiance and temperature, gross photosynthetic rate of ESV was significantly higher than that of LSV in the long-term incubation (7 d). ESV showed the ca. 60% and 20% of weight increased over the growth saturation irradiance (136μmol photons m-2s-1) and under low temperature conditions (10-15℃). Nitrogen utilization efficiency of ESV was high

it means this alga proliferates quickly the weight. The production and respiration ratios of LSV were low over the ranges of optimum growth temperature and irradiance assumed. Therefore, the green tide species would be the onset cellular senescence in early July, and drift green mats cannot be prolonged any more this period.