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Differential mercury transfer in the aquatic food web of a double basined lake associated with selenium and habitat

Science of the Total Environment

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, , , , , and
DOI: 10.1016/j.scitotenv.2013.03.008

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Abstract

Food web trophodynamics of total mercury (THg) and selenium (Se) were assessed for the double-basined ultraoligotrophic system of Lake Moreno, Patagonia. Each basin has differing proportions of littoral and pelagic habitats, thereby providing an opportunity to assess the importance of habitat (e.g. food web structure or benthic MeHg production) in the transfer of Hg and Se to top trophic fish species. Pelagic plankton, analyzed in three size classes (10–53, 53–200, and > 200 μm), had very high [THg], exceeding 200 μg g− 1 dry weight (DW) in the smallest, and a low ratio of MeHg to THg (0.1 to 3%). In contrast, [THg] in littoral macroinvertebrates showed lower values (0.3 to 1.8 μg g− 1 DW). Juvenile and small fish species feeding upon plankton had higher [THg] (0.2 to 8 μg g− 1 muscle DW) compared to large piscivore fish species (0.1 to 1.6 μg g− 1 muscle DW). Selenium concentrations exhibited a much narrower variation range than THg in the food web, varying from 0.5 to 2.7 μg g− 1 DW. Molar Se:Hg ratios exceeded 1 for the majority of organisms in both basins, with most ratios exceeding 10. Using stable nitrogen isotopes as indicator of trophic level, no significant correlations were found with [THg], [Se] or Se:Hg. The apparent lack of biomagnification trends was attributed to elevated [THg] in plankton in the inorganic form mostly, as well as the possibility of consistent Se supply reducing the biomagnification in the food web of the organic portion of THg.

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Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Differential mercury transfer in the aquatic food web of a double basined lake associated with selenium and habitat
Series title:
Science of the Total Environment
DOI:
10.1016/j.scitotenv.2013.03.008
Volume
454-455
Year Published:
2013
Language:
English
Publisher:
Elsevier
Contributing office(s):
National Research Program - Western Branch
Description:
11 p.
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Science of the Total Environment
First page:
170
Last page:
180
Country:
Argentina;Chile
Other Geospatial:
Patagonia;Lake Moreno