Responses of phytoplankton to in-situ nutrient enrichment: Potential Influences on Species Dominance in a River

Publisher:
Wiley- VCH Verlag GMBH
Publication Type:
Journal Article
Citation:
International Review of Hydrobiology, 2001, 86 (3), pp. 283 - 296
Issue Date:
2001-01
Full metadata record
Files in This Item:
Filename Description Size
Thumbnail2004004414.pdf896.74 kB
Adobe PDF
The Hawkesbury River at Sackville, New South Wales, Australia is fresh and vigorously mixed by tidal movement. The location has frequent blooms of Microcystis aeruginosa, which have been recorded occurring throughout the year, including winter temperatures as low as 13 °C. Nutrient enrichment tests were performed in-situ on the natural phytoplankton population in 1997 and 1998 while Microcystis aeruginosa dominated (covering both summer and winter periods). These experiments compared population changes under the ambient nutrient regime with those after additions of ortho-phosphate, nitrate, ammonia and various combinations of these nutrients. Under ambient conditions, the Microcystis population was able to grow significantly (P < 0.05) while most non-cyanobacterial phytoplankton did not. Nutrient additions induced a variety of nutrient limitation responses that often varied between genera of major groups i.e. in the Chlorophyceae (Actinastrum sp. responded to phosphorus while Psephonema sp. responded to nitrogen). The possibility that shifts in population dominance from Chlorophyceae to the Cyanobacteria (M. aeruginosa) at Sackville are in response to competition for limiting nutrients is discussed
Please use this identifier to cite or link to this item: