Aquatic Sciences Meeting, Albuquerque 2001

CS39 Trace Metal Limitation of Biogeochemistry

Date: Tuesday, February 13, 2001, Time: 11:15:00 AM

Location: Dona Ana

Wang, W, X, HKUST, Kowloon, Hong Kong POC, wwang@ust.hk

Dei, R, C, HKUST, Kowloon, Hong Kong POC, borobert@ust.hk

Xu, Y, , HKUST, Kowloon, Hong Kong POC, xuybo@ust.hk

CADMIUM UPTAKE AND TROPHIC TRANSFER IN MARINE PLANKTON UNDER DIFFERENT NUTRIENT REGIMES

We demonstrated that Cd accumulation in marine diatoms was dependent on the ambient nitrogen conditions and thus the physiological status of phytoplankton cells. Diatom cells inoculated under nitrogen limited conditions accumulated considerably less Cd than cells maintained under nitrogen enriched conditions. The intracellular partitioning of Cd in the diatoms was also positively related to the level of ambient N. Phosphate and silicate starvation did not affect Cd uptake in diatoms. The trophic transfer, quantified by measurement of the Cd assimilation efficiency (AE) from ingested diatoms in copepods, increased with an increase in the N quota of the diatom cells maintained in a semi-continuous culture. There was a linear relationship between the Cd AE and the Cd distribution in the cytoplasm of diatoms. The Cd regeneration rate in copepods was independent of the N status of ingested diatoms. Our study suggests that the cycling of Cd in marine planktonic food chains may be depressed under nitrogen limited conditions. Conversely, nitrogen enrichment leads to an increase in Cd uptake in phytoplankton cells and zooplankton, elevating the potential exposure of plankton to toxic metals.

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Aquatic Sciences Meeting, Albuquerque 2001

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