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PHYSIOLOGICAL ACCLIMATION OF MARINE-PHYTOPLANKTON TO DIFFERENT NITROGEN-SOURCES
被引:247
作者:
LEVASSEUR, M
THOMPSON, PA
HARRISON, PJ
机构:
[1] INST OCEAN SCI,SYDNEY V8L 4B2,BC,CANADA
[2] UNIV BRITISH COLUMBIA,DEPT OCEANOG,VANCOUVER V6T 1Z4,BC,CANADA
关键词:
AMMONIUM;
ENERGY;
NITRATE;
NITROGEN;
PHOTOSYNTHESIS;
PHYSIOLOGY;
PHYTOPLANKTON;
UREA;
D O I:
10.1111/j.0022-3646.1993.00587.x
中图分类号:
Q94 [植物学];
学科分类号:
071001 ;
摘要:
We examined the energetic dependency of the biochemical and physiological responses of Thalassiosira pseudonana Hasle and Heimdal, Chaetoceros gracilis Schutt, Dunaliella tertiolecta Butcher, and Gymnodinium sanguineum Hirasaka to NH4+, NO3-, and urea by growing them at subsaturating and saturating photon flux (PF). At subsaturating PF, when energy was limiting, NO3-- and NH4+-grown cells had similar growth rates and C and N quotas. Therefore, NO3--grown cells used up to 48% more energy than NH4+ -grown cells to assimilate carbon and nitrogen. Based on our measurements of pigments, chlorophyll-a-specific in vivo absorption cross-section, and fluorescence-chlorophyll a(-1), we suggest that NO3--grown cells do not compensate for the greater energy requirements of NO3- reduction by trapping more light energy. At saturating PF, when energy is not limiting, the utilization of NO3- compared to NH4+ resulted in lower growth rates and N quotas in Thalassiosira pseudonana and lower N quotas in Chaetoceros gracilis, suggesting enzymatic rather than energetic limitations to growth. The utilization of urea compared to NH4+ resulted in lower growth rates in Chaetoceros gracilis and Gymnodinium sanguineum (saturating PF) and in lower N quotas in all species tested at both subsaturating and saturating PF. The high C:N ratios observed in all urea-grown species suggest that nitrogen assimilation may be limited by urea uptake or deamination and that symptoms of N limitation in microalgae may be induced by the nature of the N source in addition to the N supply rate. Our results provide new evidence that the maximum growth rates of microalgae may be limited by enzymatic processes associated with the assimilation of NO3- or urea.
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页码:587 / 595
页数:9
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