title: Bioaccumulation Dynamics of Arsenate at the Base of Aquatic Food Webs.
abstract: Periphyton is an important food source at the base of freshwater ecosystems that tends to bioconcentrate trace elements making them trophically available. The potential for arsenic-a trace element of particular concern due to its widespread occurrence, toxicity, and carcinogenicity-to bioconcentrate in periphyton and thus be available to benthic grazers is less well characterized. To better understand arsenate bioaccumulation dynamics in lotic food webs, we used a radiotracer approach to characterize accumulation in periphyton and subsequent trophic transfer to benthic grazers. Periphyton bioconcentrated As between 3,200-9,700-fold (dry weight) over 8 days without reaching steady state, suggesting that periphyton is a major sink for arsenate. However, As-enriched periphyton as a food source for the mayfly Neocloeon triangulifer resulted in negligible As accumulation in a full lifecycle exposure. Additional studies estimate dietary assimilation efficiency in several primary consumers ranging from 22% in the mayfly N. triangulifer to 75% in the mayfly Isonychia sp. X-ray fluorescence mapping revealed that As was predominantly associated with iron oxides in periphyton. We speculate that As adsorption to Fe in periphyton may play a role in reducing dietary bioavailability. Together, these results suggest that trophic movement of As in lotic food webs is relatively low, though species differences in bioaccumulation patterns are important.
authors.forename: Adeline R
authors.initials: AR
authors.lastname: Lopez
authors.forename: Dean R
authors.initials: DR
authors.lastname: Hesterberg
authors.affiliation: Stroud Water Research Center , Avondale, Pennsylvania 19311, United States.
authors.forename: David H
authors.initials: DH
authors.lastname: Funk
authors.forename: David B
authors.initials: DB
authors.lastname: Buchwalter
mesh_terms: D000818:Animals; D001149:Arsenates; D017753:Ecosystem; D020387:Food Chain; D005618:Fresh Water; D007313:Insecta
chemical_list: D001149:Arsenates