Persistent organic pollutants in river food webs: influence of trophic position and degree of heterotrophy

Abstract

Abstract:We investigated how the degree of autotrophy/heterotrophy and organism trophic position influenced the bioaccumulation of polychlorinated biphenyls (PCBs) in 10 benthic river food webs consisting of terrestrial detritus, periphyton, invertebrates, and age-0 brown trout (Salmo trutta) in southern Sweden. Concentrations of PCBs increased with trophic position, estimated from δ 15 N and δ 13 C, on a dry weight basis (ng·g -1 dry weight) but not on a lipid weight basis (ng·g -1 lipid). PCB biomagnification factors between the first and second trophic levels (invertebrates/ periphyton and invertebrates/detritus) ranged between 0.3 and 2.3 and between the second and third levels (trout/invertebrates) between 0.3 and 2.0 on a lipid weight basis. The mean proportion of carbon ultimately derived from terrestrial sources, α, was 0.82 ± 0.19 for invertebrates and 0.67 ± 0.28 for trout. Contrary to our hypothesis, PCB concentrations in trout were positively related to α (r 2 = 0.58-0.77, p < 0.05). As α and the periphyton density (g Cqm -2 ) in the rivers was positively related (r 2 = 0.88, p < 0.01), we propose that this relationship was due to an increased retention and exposure of PCBs to trout in rivers with low grazing pressure and high periphyton density.

Is PCBs concentration variability between and within freshwater fish species explained by their contamination pathways?

“…Moreover, we observed that sediments are historically more contaminated at GDL than at BRE, while fishes are more contaminated at BRE than at GDL and they specifically exploit more detrital carbon sources at BRE than at GDL. Furthermore, we showed that PCB concentration increases with the exploitation of detrital carbon sources, confirming the results obtained by Berglund et al (Berglund et al, 2005), who showed that individuals associated with the detrital pathway have higher PCB concentrations than those associated with the algae pathway. All these results confirmed that deposited sediment plays a central role in food-web contamination (Gewurtz et al, 2009), not only its contamination level, but also the ultimate carbon sources supporting the food web.…”

Influence of Trophic Position and Spatial Location on Polychlorinated Biphenyl (PCB) Bioaccumulation in a Stream Food Web

“…Unique Attributes of Bioaccumulation in Streams. Pathways of OCs into stream food webs are poorly understood (13). Marine and lake systems are often autotrophic, so studies have focused mainly on the water-phytoplankton-zooplankton pathway of OCs into pelagic food webs and the role of benthic invertebrates in moving contaminants from sediment to consumers (1,29,35).…”

Stable Isotope Tracing of Temporal and Spatial Variability in Organic Matter Sources to Freshwater Ecosystems

“…Kennedy et al 2005), contaminant transfer (e.g. Berglund et al 2005), and eutrophication (e.g. Debruyn & Rasmussen 2002).…”