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An investigation into iron-stimulated phytoplankton productivity in epipelagic Lake Erie during thermal stratification using trace metal clean techniques

Authors :
Michael R. Twiss
Jean-Christian Auclair
Murray N Charlton
Source :
Canadian Journal of Fisheries and Aquatic Sciences. 57:86-95
Publication Year :
2000
Publisher :
Canadian Science Publishing, 2000.

Abstract

We tested the hypothesis that phytoplankton productivity in pelagic Lake Erie is limited by low Fe bioavailability during the period of thermal stratification. Iron enrichment (20 and 200 nM Fe) of water sampled from the eastern basin surface water (5 m depth) in July 1996 revealed a dramatic 180 and 30% increase in the standing crop of the picoplankton (0.2-2 µm) and nanoplankton (2-20 µm) size fractions, respectively. Light-saturated rates of photosynthesis for picoplankton increased 2.8 times that of the controls within 24 h. In contrast, simultaneous P and Fe enrichment experiments carried out in July 1997 and August 1998 with water samples from three pelagic stations revealed that P enrichment alone stimulated phytoplankton growth, although at several stations, phytoplankton yield was greater in combined P- and Fe-amended experiments relative to P-enriched treatments. Periodogram analysis of meteorological buoy wave height data and heat budgets calculated from thermal profiles in the eastern basin revealed important interyear differences in precruise conditioning of the epilimnion. Low-frequency, turbulent mixing events that characterized the 30-day precruise period in the years 1997 and 1998 relative to 1996 may have prevented Fe-stressed conditions in the phytoplankton community studied in 1997 and 1998.

Details

ISSN :
12057533 and 0706652X
Volume :
57
Database :
OpenAIRE
Journal :
Canadian Journal of Fisheries and Aquatic Sciences
Accession number :
edsair.doi...........40674da163b416ff192a1ad8533cefde
Full Text :
https://doi.org/10.1139/f99-189