title: Arsenic in stream waters is bioaccumulated but neither biomagnified through food webs nor biodispersed to land.
abstract: Human activities such as mining have contributed substantially to the increase of metals in aquatic environments worldwide. These metals are bioaccumulated by aquatic organisms and can be biomagnified along trophic webs. The dispersal of contaminants from water to land has been little investigated, even though most aquatic invertebrates in streams have aerial stages. We used field and laboratory approaches to investigate the effects of arsenic pollution on stream invertebrate assemblages, and its bioaccumulation, biomagnification and trophic transfer from aquatic to terrestrial environments by emergent insects. We conducted the study in an arsenic-impacted stream (40μgL-1As at the most polluted site) and a reference stream (0.3μgL-1As). Invertebrate abundance and richness were lowest at the most impacted site. Arsenic in biofilm and in invertebrates increased with the arsenic content in the water. The highest arsenic accumulators were bryophytes (1760μgg-1), followed by the biofilm (449μgg-1) and shredder invertebrates (313μgg-1); predators had the lowest arsenic concentration. Insects emerging from water and spiders along streambanks sampled from the reference and the impacted stream did not differ in their body arsenic concentrations. In the laboratory, the shredder Sericostoma vittatum had reduced feeding rates when exposed to water from the impacted stream in comparison with the reference stream (15.6 vs. 19.0mg leaves mg body mass-1day-1; p<0.05), but they grew faster in the polluted water (0.16±0.04% day-1vs. 0.05±0.01% day-1, p<0.05). S. vittatum exposed to contaminated stream water accumulated arsenic from food, not through contact with water. We concluded that although arsenic is bioaccumulated, mainly by food ingestion, it is not biomagnified through food webs and is not transported from the aquatic to terrestrial environment when insects leave the stream water.
authors.affiliation: Departament of Biological Sciences, Universidade Regional Integrada do Alto Uruguai e das Missões, 99709-910 Rio Grande do Sul, Brazil. Electronic address: luizuhepp@gmail.com.
authors.forename: Luiz U
authors.initials: LU
authors.lastname: Hepp
authors.affiliation: MARE - Marine and Environmental Sciences Centre, Department of Earth Sciences, University of Coimbra, 3001-517 Coimbra, Portugal.
authors.forename: João A M S
authors.initials: JA
authors.lastname: Pratas
authors.affiliation: MARE - Marine and Environmental Sciences Centre, Department of Life Sciences, University of Coimbra, 3001-401 Coimbra, Portugal.
authors.forename: Manuel A S
authors.initials: MA
authors.lastname: Graça
mesh_terms: D000818:Animals; D001151:Arsenic / Q000378:metabolism*; D044002:Bryophyta / Q000187:drug effects / Q000378:metabolism; D020387:Food Chain; D007313:Insecta / Q000187:drug effects / Q000378:metabolism; D007448:Invertebrates / Q000187:drug effects / Q000378:metabolism*; D008670:Metals / Q000494:pharmacology; D008906:Mining; D013112:Spiders / Q000187:drug effects / Q000378:metabolism; D014867:Water / Q000494:pharmacology; D014874:Water Pollutants, Chemical / Q000378:metabolism*
chemical_list: D008670:Metals; D014874:Water Pollutants, Chemical; D014867:Water; D001151:Arsenic
keywords: Arsenic contamination; Biomagnification; Isotopic approach; Macroinvertebrates; Water quality