Landscape attributes, dissolved organic C, and metal bioaccumulation in aquatic macroinvertebrates (Arkansas River Basin, Colorado)

摘要

Relationships among landscape attributes, instream dissolved organic C (DOC) concentrations, and metal bioaccumulation in Arctopsyche grandis and Drunella doddsi were investigated in the Upper Arkansas River Basin, Colorado. A Geographic Information System (GIS) was used to calculate landscape attributes in 16 watersheds where DOC concentrations were measured from May to August 2001. Metal concentrations in Arctopsyche and Drunella were related to physicochemical characteristics measured in these streams and in the Arkansas River. Results of multiple linear regression showed that % forested area explained 47% and 59% of the variation in maximum and mean DOC concentrations, respectively. Maximum DOC was negatively associated with the concentration of Zn (R~2 = 0.25) and Cd (R~2 = 0.39) in Arctopsyche. DOC concentration did not describe metal concentrations in Drunella, which accumulated significantly more Zn, Cd, and Cu than Arctopsyche. The higher metal concentrations and the absence of a DOC effect on metal uptake in Drunella most likely resulted from dietary exposure to metal-enriched detritus and periphyton. Our results indicate that % forested area within a watershed can be used to describe DOC concentrations, which in turn influence metal bioaccumulation in Arctopsyche. To our knowledge, this study is the first to quantify the relationship between landscape attributes and DOC, and to demonstrate the influence of DOC on metal bioaccumulation in benthic macroinvertebrates in the field.