Physiological responses of Sargasso Sea picoplankton to nanomolar nitrate perturbations |
| |
Authors: | Glover, Hilary E. Garside, Christopher Trees, Charles C. |
| |
Affiliation: | 1 Department of Natural and Social Sciences, University of Maine at Augusta, Maine 04330, USA 2 Bigelow Laboratory for Ocean Sciences, W. Boothbay Harbor, Maine 04575, USA 3 Center for Hydro-Optics and Remote Sensing, San Diego State University, San Diego, CA, 92120, USA |
| |
Abstract: | A study was conducted in July 1989 at three stations in thenorthern Sargasso Sea, where picoplankton (<1 µm)provided approximately half of the standing crop of chlorophyll.Temporal changes in the position of the nitracline at a singlelocation indicated that the vertical supply of nitrate was notat steady-state and phytoplankton distributionstracked the nitracline. Our main experimental objective wasto examine the short-term effects of ecologically significantnitrate perturbations (+20 and +100 nM) on the physiologyof <1 µm communities growing at low (nanomolar)ambient nitrate concentrations. A chemiluminescent nitrate methodwas used to measure the time course (up to 4 h) of nitratedisappearance at in situ irradiance, in parallel with measurementsof photosynthetic 14CO2 assimilation. Picoplankton growing at<60 nM nitrate rapidly responded to nanomolar nitratesupplements with luxury consumption and enhanced photosynthesisin proportion to their ambient nitrate environment. Light-saturatedSynechococcus populations from the most nitrate-depleted waters(13 nM) had doubled their cellular rate of photosynthesisafter 4 h, in response to a 20 nM nitrate pulse. |
| |
Keywords: | |
本文献已被 Oxford 等数据库收录! |
|