摘要

Underwater light environment and photosynthetic accessory pigments were investigated in Ariake Bay in order to understand how change of the pigments occurs in response to the tidal-induced changes in underwater light conditions. We hypothesize that phytoplankton increases photo-protective pigments and decreases light-harvesting pigments under higher light condition in the mixed layer caused by tidal cycle. Contribution rates of non-phytoplankton particles (a(nph)(400-700)) for light attenuation coefficient (K-d) was highest (32-85%), and those of phytoplankton particles (a(ph)(400-700)), dissolved organic matter (a(g)(400-700)) and water were 6-32, 6-21 and 5-23%, respectively. Mean K-d was higher during the spring tide (0.55 +/- 0.23 m(-1)) than the neap tide (0.44 +/- 0.16 m(-1)), and the Kd difference was caused by the substances resuspension due to the tidal current. In contrast, ratios of photo-protective pigments (diadinoxanthin and diatoxanthin) per chlorophyll a ((DD+DT)/Chl a) were higher during the neap tide (0.10 +/- 0.03 mg mg-Chl a(-1)) than the spring tide (0.08 +/- 0.03 mg mg-Chl a(-1)). And there was significant positive correlation between (DD+DT)/Chl a and mean relative PAR in the mixed layer ((I-mix) over bar). Moreover, there was significant negative correlation between ratios of light-harvesting pigments ( fucoxanthin) per Chl a (Fuco/Chl a) and (I-mix) over bar. These results suggested that phytoplankton in Ariake Bay increase photo-protective pigments and decrease light-harvesting pigments in the higher light condition of less turbid, shallower mixed layer during neap tide than spring tide.

  • 出版日期2010-12