Effects of temperature and irradiance on photosynthesis and growth of a green-tide-forming species (Ulva linza) in the Yellow Sea

Abstract

Samples of the massive drifting green alga, Ulva linza, were collected from the coastal waters of the Yellow Sea, southwest of Korea, in early July 2009, and cultured under laboratory conditions. The effects of various temperature (10-30°C) and irradiance levels (0-1,000 μmol photons m −2 s −1 ) on photosynthesis, growth, and tissue nutrient content of U. linza were investigated in laboratory for both individuals of the latestage vegetation (LSV) and the early-stage vegetation (ESV). After 1 h acclimation to various irradiance and temperature conditions, maximum gross photosynthetic rate of ESV was significantly higher than those of LSV. In the long-term (7-d) acclimation experiments to various irradiance and temperature levels, gross photosynthetic rates of ESV individuals were also significantly higher than those of LSV individuals. High photosynthetic rate of ESV individuals induced increase in mass of about 60% over the growth saturation irradiance (136 μmol photons m −2 s −1 ) and about 20% under low temperature conditions (10-15°C) during 7-d. The gross photosynthesis of LSV individuals was low when examined under temperature and irradiance conditions that were optimum for ESV growth. Consequently, freefloating U. linza exhibits cellular senescence beginning in early July in the Yellow Sea, and green tides formed by this species cannot be maintained beyond this time in the open sea. However, we expect that U. linza can proliferate quickly after settlement on new coastal habitats of the Yellow Sea because of the high tissue nitrogen utilization for photosynthesis in ESV, which is formed by germination of reproductive cells.

Re-evaluation of green tide-forming species in the Yellow Sea

“…(Choi et al 2010). The same phenomenon occurred in the southwest sea of Korea (the southeastern part of the YS) in 2009, and the green mats were senescent with reduced physiological activity (Kim et al 2011). The green tide reoccurred in the southwest sea of Korea in July 2011, and off the coasts of China (the western part of the YS), and this has become an annual event in the YS.…”

Genetic analyses of floating Ulva prolifera in the Yellow Sea suggest a unique ecotype

“…And the morphological characteristics displayed continuously through several generations cultured in the laboratory (Hiraoka et al, 2011). What is more, living conditions, such as the temperature range , irradiance (Kim et al, 2011), desiccation and salinity (Wei et al, 2010), are obviously different between the littoral attached and the floating populations in the Yellow Sea. Compared to the attached populations, the floating population was better adapted to the habitat on the sea surface (Hiraoka et al, 2011).…”

Tracking the Movement and Distribution of Green Tides on the Yellow Sea in 2015 Based on GOCI and Landsat Images

“…On the other hand, limited reproduction and sinking may be more common in the middle of the Yellow Sea because of the significantly lower amounts of nutrients (Wang et al, 2003). Kim et al (2011) reported that green algal mats observed in the southeastern Yellow Sea in 2009…”

“…Green tides appeared along the southwestern shore of Korea and around Jeju Island in Korea in 2008(Choi et al, 2010, 2009 (Kim et al, 2011), 2011 (Son et al, 2012;Son et al, 2015(MBC News, 2013. As for studies on floating green algae found in Korean waters, Choi et al (2010) identified green tide near Jeju Island during a field study in 2008.…”