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BIOAVAILABILITY AND TROPHIC TRANSFER OF HUMIC-BOUND COPPER FROM BACTERIA TO ZOOPLANKTON
Citation:
Lores, E M. AND J. R. Pennock. BIOAVAILABILITY AND TROPHIC TRANSFER OF HUMIC-BOUND COPPER FROM BACTERIA TO ZOOPLANKTON. MARINE ECOLOGY PROGRESS SERIES 187:67-75, (1999).
Description:
The effect of humic acid (HA) on uptake and transfer of Cu by selected marine organisms from the microbial loop was determined. Bacteria grown to stationary phase in cultures with and without 15 ug Cu l -1 and with and without 10 mg Suwannee River Humic Acid (SRHA) l -1 were fed to Uronema sp. The Uronema were subsequently fed to Acartia tonsa under the same conditions to determine the effect of humic acid on the uptake and transfer of Cu from bacteria to copepods. In two experiments, the presence of 10 mg SRHA l -1 reduced Cu uptake in A. tonsa by 61 and 48% and significantly reduced the negative effects of Cu on reproductive success of A. tonsa. The percentage of the Cu residues in A. tonsa resulting from feeding was estimated by exposing A. tonsa to the same conditions with and without pre-exposed Uronema as food. The results indicate that approximately 40-50% of the Cu residue is due to feeding and that the proportion due to feeding is the same with or without SRHA. Thus, HA seems to affect Cu uptake in A. tonsa through binding of free Cu in the water at the same rate as through the food chain. This study demonstrates the importance of complexation of metals by organic matter and trophic transfer processes for organisms critical to estuarine food webs.