Influence of the Amazon River plume on distributions of free-living and symbiotic cyanobacteria in the western tropical north Atlantic Ocean

被引:176
作者
Foster, R. A. [1 ]
Subramaniam, A.
Mahaffey, C.
Carpenter, E. J.
Capone, D. G.
Zehr, J. P.
机构
[1] Univ Calif Santa Cruz, Inst Marine Sci, Santa Cruz, CA 95064 USA
[2] Lamont Doherty Earth Observ, Palisades, NY 10964 USA
[3] Univ Hawaii, SOEST, Dept Oceanog, Honolulu, HI 96822 USA
[4] San Francisco State Univ, Romberg Tiburon Ctr, Tiburon, CA 94920 USA
[5] Univ So Calif, Wrigley Inst Marine Sci, Los Angeles, CA 90089 USA
[6] Univ So Calif, Dept Biol Sci, Los Angeles, CA 90089 USA
[7] Univ Calif Santa Cruz, Inst Marine Sci, Santa Cruz, CA 95064 USA
关键词
MEANDERING GUIANA CURRENT; MARINE NITROGEN-FIXATION; PHYTOPLANKTON BIOMASS; N-2; FIXATION; TRICHODESMIUM; IRON; DIAZOTROPHS; RICHELIA; PRODUCTIVITY; DISPERSAL;
D O I
10.4319/lo.2007.52.2.0517
中图分类号
Q [生物科学];
学科分类号
07 ; 0710 ; 09 ;
摘要
The vertical and horizontal distributions of seven diazotrophic populations in the western tropical north Atlantic (WTNA) Ocean were examined using a nifH DNA quantitative polymerase chain reaction (QPCR) approach. The nifH phylotype abundances were highest near the surface and decreased with depth, with the exception of the cyanobacterial symbiont Calothrix, which was not detected at any station. Richelia associated with the diatoms Rhizosolenia clevei and Hemiaulus hauckii were distributed within the freshwater lens of the Amazon plume. Abundances of H. hauckii-Richelia nifH genes dominated all depths in 6 of 10 vertical profiles and 10 of 20 surface samples. In addition, estimates of Richelia associated with H. hauckii increased northwest (8-12 degrees N, 56-54 degrees W) from the river mouth, where significantly (p < 0.001) higher abundances (> 10(5) copies L-1) were found in mesohaline waters (31-34.9). nifH copy abundance for surface populations of the H. hauckii-Richelia symbioses were positively correlated (r(2) = 0.59) with salinity. Three unicellular cyanobacterial groups and Trichodesmium had similar horizontal distributions, where the highest nifH copy estimates were at stations with salinity >= 35 and northeast (6-10 degrees N 50 degrees W) of the freshwater lens. The abundance of Trichodesmium spp. and unicellular Group B nifH gene copies co-varied (r(2) = 0.60). The QPCR study showed the dominance of H. hauckii-Richelia symbioses in the Amazon plume waters, implying that these associations had an ecological advantage over the other diazotrophs. Outside of the plume nutrients were below detection, abundances of free-living unicellular cyanobacterial phylotypes, including a novel group designated Group C, were abundant (> 10(5) copies L-1) and comparable to the abundances of Trichodesmium spp. Thus, there appeared to be a cascade of diazotrophic communities along gradients of salinity and nutrients in the WTNA.
引用
收藏
页码:517 / 532
页数:16
相关论文
共 53 条
  • [51] Zehr J P., 2001, Methods Marine Microbiology
  • [52] New perspectives on nitrogen-fixing microorganisms in tropical and subtropical oceans
    Zehr, JP
    Carpenter, EJ
    Villareal, TA
    [J]. TRENDS IN MICROBIOLOGY, 2000, 8 (02) : 68 - 73
  • [53] Unicellular cyanobacteria fix N2 in the subtropical North Pacific Ocean
    Zehr, JP
    Waterbury, JB
    Turner, PJ
    Montoya, JP
    Omoregie, E
    Steward, GF
    Hansen, A
    Karl, DM
    [J]. NATURE, 2001, 412 (6847) : 635 - 638