Lead in Marine Planktonic Organisms and Pelagic Food Webs

• Published in: Limnology and oceanography Vol. 35; no. 2; pp. 287 - 295
• Main Authors: Michaels, Anthony F., Flegal, A. Russell
• Format: Journal Article
• Language: English
• Published: Waco, TX American Society of Limnology and Oceanography 01-03-1990
• Subjects: Acantharia; Animal, plant and microbial ecology; Biological and medical sciences; Food webs; Fundamental and applied biological sciences. Psychology; Lead; Marine; Microbial ecology; Modeling; Oceans; Particulate matter; Phytoplankton; Plankton; Skeleton; Surface areas; Zooplankton; IS, Equatorial Pacific; Marine environment; Lead; Plankton; Biological accumulation
• ISSN: 0024-3590; 1939-5590
• DOI: 10.4319/lo.1990.35.2.0287

The bioaccumulation of lead in biological ecosystems traditionally has been interpreted in terms of the atomi ratio of Pb to Ca. In marine planktonic ecosystems, however, most of the particulate Ca is skeletal and its amount variable among taxa. The Pb in plankton can be partitioned between skeletal and nonskeletal components. In planktonic samples collected in the equatorial Pacific Ocean, <0.5% of the Pb was associated with $CaCO_3$ (primarily foraminiferan, coccolithophorid, and pteropod skeletons), while up to 54% of the Pb in these samples may have been associated with the $SrSO_4$ skeletons and protoplasm of Acantharia. Atomic ratios of Pb to Ca were highly variable, principally because of the varying amounts of $CaCO_3$ in the samples. Therefore, normalizing Pb concentrations to biomass rather than Ca is preferable for interpreting the bioactivity of Pb in planktonic food webs. We develop a simple model based on the ratio of surface area to volume of organisms to make predictions about the relative importance of organism size and food-web interactions in the transfer of Pb between trophic levels. For small orgnisms (<270-$\mu m$ spherical radius or the equivalent surface: volume ratio), Pb concentration is determined almost entirely by surface area. For larger organis, total body Pb will be a function of both the size of the prey and the distribution of Pb within tissues. The role of food-web interactions (e.g. grazing) in determinig the amount of Pb in plankton of different sizes will only be important for large plankton and nekton, where very little of it is adsorbed on the animal surface.