title: THE EFFECTS OF IRON AND COPPER AVAILABILITY ON THE COPPER STOICHIOMETRY OF MARINE PHYTOPLANKTON(1).
abstract: We studied the interactive effects of iron (Fe) and copper (Cu) availability on the growth rates, Cu quotas, and steady-state Cu-uptake rates (ρss Cu) of 12 phytoplankton (from four classes and two marine environments). A mixed-effect statistical model indicated that low Fe significantly decreased phytoplankton growth rates. In contrast, lowering Cu levels only decreased the growth rates of the oceanic phytoplankton. Under Fe/Cu sufficiency, the Cu quotas ranged from 0.36 to 3.8 μmol Cu · mol(-1) C. Copper levels in the growth medium had a significant positive effect on the Cu quotas, and this effect was dependent on the algal class. Under Fe/Cu sufficiency, the highest average Cu quotas were observed for the Bacillariophyceae, followed by the Cyanophyceae, Prymnesiophyceae, and lastly the Dinophyceae. Similar taxonomic trends were observed for the ρss Cu. Although the Cu:C ratios were not significantly higher in oceanic strains, there are five independent lines of evidence supporting a more important role of Cu in the physiology of the oceanic phytoplankton. The mixed-effect model indicated a significant Cu effect on the growth rates and ρss Cu of the oceanic strains, but not the coastal strains. In addition, lowering the Cu concentration in the media decreased the Cu quotas and ρss Cu of the oceanic strains to a greater extent (5.5- and 5.4-fold, respectively) than those of the coastals (3.8- and 4.7-fold, respectively). Iron limitation only had a significant effect on the Cu quotas of the oceanic strains, and this effect was dependent on Cu level and taxonomic class. Our results highlight a complex physiological interaction between Fe and Cu in marine phytoplankton.
authors.affiliation: Department of Earth and Ocean Sciences, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada Chemistry Department, Simon Fraser University, Vancouver, British Columbia, V6T 1Z4, Canada Tri-University Meson Facility (TRIUMF), Life Sciences Division, 4004 Wesbrook Mall, Vancouver, British Columbia V6T 2A3, Canada.
authors.forename: Jian
authors.initials: J
authors.lastname: Guo
authors.affiliation: Department of Earth and Ocean Sciences, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada Chemistry Department, Simon Fraser University, Vancouver, British Columbia, V6T 1Z4, Canada Tri-University Meson Facility (TRIUMF), Life Sciences Division, 4004 Wesbrook Mall, Vancouver, British Columbia V6T 2A3, Canada.
authors.forename: Suzanne
authors.initials: S
authors.lastname: Lapi
authors.affiliation: Department of Earth and Ocean Sciences, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada Chemistry Department, Simon Fraser University, Vancouver, British Columbia, V6T 1Z4, Canada Tri-University Meson Facility (TRIUMF), Life Sciences Division, 4004 Wesbrook Mall, Vancouver, British Columbia V6T 2A3, Canada.
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Ruth
authors.affiliation: Department of Earth and Ocean Sciences, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada Chemistry Department, Simon Fraser University, Vancouver, British Columbia, V6T 1Z4, Canada Tri-University Meson Facility (TRIUMF), Life Sciences Division, 4004 Wesbrook Mall, Vancouver, British Columbia V6T 2A3, Canada.
authors.forename: Maria T
authors.initials: MT
authors.lastname: Maldonado
keywords: Cu; Cyanophyceae; Dinophyceae; Fe; Prymnesiophyceae; colimitation; copper; iron; phytoplankton; quotas