Marine Ecology Progress Series | |
Dissolved N:P ratio changes in the eastern tropical North Atlantic: effect on phytoplankton growth and community structure | |
Jasmin M. S. Czerny1  Carolin R. Löscher1  Helena Hauss1  Ulf Riebesell1  | |
关键词: Phytoplankton; Nutrient limitation; Nitrogen and phosphorus stoichiometry; Diatoms; Diazotrophic cyanobacteria; Trichodesmium; Upwelling; | |
DOI : 10.3354/meps11600 | |
学科分类:海洋学与技术 | |
来源: Inter-Research | |
【 摘 要 】
ABSTRACT: Previous bioassays conducted in the oligotrophic Atlantic Ocean identified availability of inorganic nitrogen (N) as the proximate limiting nutrient control of primary production, but additionally displayed a synergistic growth effect of combined N and phosphorus (P) addition. To classify conditions of nutrient limitation of coastal phytoplankton in the tropical ocean, we performed an 11 d nutrient-enrichment experiment with a natural phytoplankton community from shelf waters off northwest Africa in shipboard mesocosms. We used pigment and gene fingerprinting in combination with flow cytometry for classification and quantification of the taxon-specific photoautotrophic response to differences in nutrient supply. The developing primary bloom was dominated by diatoms and was significantly higher in the treatments receiving initial N addition. The combined supply of N and P did not induce a further increase in phytoplankton abundance compared to high N addition alone. A secondary bloom during the course of the experiment again displayed higher primary producer standing stock in the N-fertilized treatments. Bacterial abundance correlated positively with phytoplankton biomass. Dominance of the photoautotrophic assemblage by N-limited diatoms in conjunction with a probable absence of any P-limited phytoplankton species prevented an additive effect of combined N and P addition on total phytoplankton biomass. Furthermore, after nutrient exhaustion, dinitrogen (N2)-fixing cyanobacteria succeeded the bloom-forming diatoms. Shelf waters in the tropical eastern Atlantic may thus support growth of diazotrophic cyanobacteria such as Trichodesmium sp. subsequent to upwelling pulses.
【 授权许可】
Unknown
【 预 览 】
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RO201912010136840ZK.pdf | 1632KB | download |