Factors affecting Fe and Zn contents of mesozooplankton from the Costa Rica Dome.
Mineral limitation of mesozooplankton production is possible in waters with low trace metal availability. As a step toward estimating mesozooplankton Fe and Zn requirements under such conditions, we measured tissue concentrations of major and trace nutrient elements within size-fractioned zooplankton samples collected in and around the Costa Rica Upwelling Dome, a region where phytoplankton growth may be co-limited by Zn and Fe. The geometric mean C, N, P contents were 27, 5.6 and 0.21 mmol gdw-1, respectively. The values for Fe and Zn were 1230 and 498 nmol gdw-1, respectively, which are low compared with previous measurements. Migrant zooplankton caused C and P contents of the 2-5 mm fraction to increase at night relative to the day while the Fe and Zn contents decreased. Fe content increased with size while Zn content decreased with size. Fe content was strongly correlated to concentrations of two lithogenic tracers, Al and Ti. We estimate minimum Fe:C ratios in large migrant and resident mixed layer zooplankton to be 15 and 60 µmol mol-1, respectively. The ratio of Zn:C ranged from 11 µmol mol-1for the 0.2-0.5 mm size fraction to 33 µmol mol-1for the 2-5 mm size fraction.
Department of Ecology and Evolution , Stony Brook University , Stony Brook, NY 11789-5245 , USA.
Stephen B
SB
Baines
School of Marine and Atmospheric Sciences , Stony Brook University , Stony Brook, NY 11789-5000 , USA.
Xi
X
Chen
Bigelow Laboratory for Ocean Sciences, East Boothbay , ME 04544 , USA.
Benjamin S
BS
Twining
School of Marine and Atmospheric Sciences , Stony Brook University , Stony Brook, NY 11789-5000 , USA.
Nicholas S
NS
Fisher
Scripps Institution of Oceanography , University of California at San Diego , 9500 Gilman Dr., La Jolla, CA 92093-0227 , USA.
Michael R
MR
Landry
lithogenic; mineral limitation; size fractions