Methylmercury bioaccumulation in stream food webs declines with increasing primary production

Environmental Science & Technology
By: , and 

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Abstract

Opposing hypotheses posit that increasing primary productivity should result in either greater or lesser contaminant accumulation in stream food webs. We conducted an experiment to evaluate primary productivity effects on MeHg accumulation in stream consumers. We varied light for 16 artificial streams creating a productivity gradient (oxygen production =0.048–0.71 mg O2 L–1 d–1) among streams. Two-level food webs were established consisting of phytoplankton/filter feeding clam, periphyton/grazing snail, and leaves/shredding amphipod (Hyalella azteca). Phytoplankton and periphyton biomass, along with MeHg removal from the water column, increased significantly with productivity, but MeHg concentrations in these primary producers declined. Methylmercury concentrations in clams and snails also declined with productivity, and consumer concentrations were strongly correlated with MeHg concentrations in primary producers. Heterotroph biomass on leaves, MeHg in leaves, and MeHg in Hyalella were unrelated to stream productivity. Our results support the hypothesis that contaminant bioaccumulation declines with stream primary production via the mechanism of bloom dilution (MeHg burden per cell decreases in algal blooms), extending patterns of contaminant accumulation documented in lakes to lotic systems.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Methylmercury bioaccumulation in stream food webs declines with increasing primary production
Series title Environmental Science & Technology
DOI 10.1021/acs.est.5b00911
Volume 49
Issue 13
Year Published 2015
Language English
Publisher American Chemical Society
Publisher location Easton, PA
Contributing office(s) Fort Collins Science Center, Contaminant Biology Program
Description 8 p.
First page 7762
Last page 7769
Online Only (Y/N) N
Additional Online Files (Y/N) N