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Regeneration, recycling, and trophic transfer of trace metals by microbial food‐web organisms in the pelagic surface waters of Lake Erie
Author(s) -
Twiss Michael R.,
Campbell Peter G. C.,
Auclair Jean-Christian
Publication year - 1996
Publication title -
limnology and oceanography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.7
H-Index - 197
eISSN - 1939-5590
pISSN - 0024-3590
DOI - 10.4319/lo.1996.41.7.1425
Subject(s) - picoplankton , pelagic zone , plankton , trophic level , food web , environmental chemistry , microbial food web , phytoplankton , surface water , water column , trace metal , environmental science , oceanography , ecology , biology , chemistry , nutrient , environmental engineering , metal , geology , organic chemistry
Rapid regeneration of 109 Cd and 65 Zn from their picoplankton prey into the dissolved phase by microzooplankton was observed in water sampled from the pelagic surface waters of Lake Erie (summer 1994 and 1995). Trace metals were added to grazing (lake water <210 µ m) and control (lake water <0.2 µ m) treatments in the form of radiolabeled Synechococcus. Picoplankton (0.2–3 µ m) were grazed heavily by consumers in the nanoplankton (3–20 µ m) and microplankton (20–210 µ m) size classes (collectively referred to as microzooplankton) as confirmed by dilution assays used to independently measure grazing activity. Most consumed trace metals were regenerated into the dissolved phase (<0.2 µ m), but some trophic transfer of 1 0 9 Cd and 65 Zn from radiolabeled prey into the nanoplankton and microplankton did occur: 65 Zn was transferred 2.5 times more efficiently into the microplankton and 2.9 times more efficiently into the nanoplankton than was 109 Cd. Recycling o:f regenerated 109 Cd back into plankton biomass was greater than that for 65 Zn. Grazing by microzooplankton influenced the molecular size distribution of regenerated trace metal in the dissolved phase (77±6% 109 Cd <5,000 MW; 8 ± 24% 65 Zn <5,000 MW). These results show that microzooplankton grazing tends to prolong the residence times of metals such as Cd and Zn in the pelagic surface waters of large lakes.