Combined effects of light intensity and NH 4 + -enrichment on growth, pigmentation, and photosynthetic performance of Ulva prolifera (Chlorophyta)

Ulva prolifera green-tide outbreaks and their environmental impact in the Yellow Sea, China

“…Apart from temperature and salinity, light intensity also affects the physiology of U. prolifera , including the growth, photosynthesis, reproduction, nutrient uptake, utilization, etc. [ 4 , 35 ]. Light promotes algae growth, but excessive light inversely inhibits their growth.…”

“…For the green-tide-forming species U. prolifera , suitable light intensity to drive its growth has been reported to vary from 18 to 175 μM photons m −2 s −1 [ 26 ]. Of course, such light intensity for growth also varies with changes in other environmental factors like nutrients, salinity and temperature [ 21 , 35 ]. Under ammonium-enrichment conditions, its maximum photosynthetic rate can reach 370 μM O 2 g FW −1 h −1 at the optimal light level of 120 μM photons m −2 s −1 [ 35 ].…”

“…Of course, such light intensity for growth also varies with changes in other environmental factors like nutrients, salinity and temperature [ 21 , 35 ]. Under ammonium-enrichment conditions, its maximum photosynthetic rate can reach 370 μM O 2 g FW −1 h −1 at the optimal light level of 120 μM photons m −2 s −1 [ 35 ]. The light intensity also affects the reproduction of U. prolifera by regulating the release or germination of spores and gametes.…”

High light might alleviate inhibitory effects of high temperature on growth and physiological parameters of Ulva prolifera

“…Some papers showed that there was no effect of temperature on the nitrate and phosphate uptake rates of Ulva lactuca (Han et al, ; Tremblay‐Gratton, Boussin, Tamigneaux, Vandenberg, & Le François, ), while the contrary result was also reported with lower uptake rates observed at higher temperature conditions (Fan et al, ). Besides, light intensity is another factor significantly effecting the growth, photosynthesis, biological metabolism and distribution of macroalgae (MacIntyre, Kana, & Geider, ; Singh & Singh, ; Takahashi & Murata, ; Xu et al, ). Compared to low light (LL) intensity (30 μmol m −2 s −1 ), the growth of U. prolifera was significantly enhanced by higher light intensity (130 μmol m −2 s −1 ), no matter at high N level or low N level (Xu et al, ).…”

“…Besides, light intensity is another factor significantly effecting the growth, photosynthesis, biological metabolism and distribution of macroalgae (MacIntyre, Kana, & Geider, ; Singh & Singh, ; Takahashi & Murata, ; Xu et al, ). Compared to low light (LL) intensity (30 μmol m −2 s −1 ), the growth of U. prolifera was significantly enhanced by higher light intensity (130 μmol m −2 s −1 ), no matter at high N level or low N level (Xu et al, ). When U. prolifera is exposed to LL intensity (<30 μmol m −2 s −1 ) due to continuous cloudy or rainy periods, the rate of photosynthetic oxygen evolution in the alga was decreased, resulting in reduced buoyancy and sinking, in turn affect the distribution of sunken alga (Lü & Qiao, ).…”