Reed beds may facilitate transfer of tributyltin from aquatic to terrestrial ecosystems through insect vectors in the Archipelago Sea, SW Finland

Abstract

Due to their adsorptive behavior, organotin compounds (OTCs), such as tributyltin (TBT), are accumulated in aquatic sediments. They resist biodegradation and, despite a ban in 2008, are a potential source for future exposure. Sediment OTCs have mostly been measured from sites of known high concentrations such as ports, shipping lanes, and marine dredging waste sites. The possible flow of OTCs from marine to terrestrial ecosystems, however, has not been studied. In the present study, the authors assessed whether sediments in common reed beds (Phragmites australis) accumulate TBT and whether chironomid (Diptera: Chironomidae) communities developing in reed-bed sediments act as vectors in the transfer of TBT from aquatic to terrestrial ecosystems in the Airisto channel, Archipelago Sea. The authors also investigated whether distance from the only known source and depth and TBT concentration of the adjacent shipping lane affect reed-bed concentrations. Thirty-six sites along the Airisto channel were sampled at 2-km intervals with triplicate samples from reed beds and the adjacent shipping lane for sediment and seven reed-bed sites for chironomids, and these were analyzed with an solid phase extraction liquid chromatography tamdem mass spectrometry method. The closer to the source the sample site was, the higher the measured TBT concentrations were; and the deeper the shipping lane, the lower the concentration of TBT in reed-bed sediments. The chironomid TBT concentrations correlated with reed-bed sediment TBT concentrations and showed evidence of accumulation. Therefore, TBT may be transferred, through the food web, from aquatic to terrestrial ecosystems relatively close to a source through ecosystem boundaries, such as common reed beds, which are areas of high insect biomass production in the Archipelago Sea.

Sediment organic tin contamination promotes impoverishment of non-biting midge species communities in the Archipelago Sea, S-W Finland

“…We chose our sampling sites to lie on a unique and known TBT gradient, which begins at the repair ship yard mentioned above with additional sampling sites outside the range of effect (Lilley et al 2012, Fig. 1).…”

“…The equation for the trend line was used for the quantification of unknown samples. Additional information in Lilley et al (2012).…”

“…As a consequence, concentrations in sediments can still be relatively high, although organic tin compounds have been banned in the EU and countries belonging to the International Maritime Organisation since 2008 (IMO 2001). In the Archipelago Sea, in South-Western Finland, the mean measured sediment TBT concentration is 42 lg kg -1 and higher in the northern part (71 lg kg -1 Lilley et al 2012). In the vicinity of the largest individual source in Archipelago Sea, a repair ship yard, concentrations can be as high as 1443 lg kg -1 and relatively high concentrations have been measured from fishes living in the area (Airaksinen et al 2010).…”

“…We hypothesized that because of the multiple toxic effects of TBT on the metabolism of organisms (Antizar-Ladislao 2008) the species richness and abundance of chironomids decreases with an increase of sediment TBT concentration. The hypothesis is based on previous field studies (Sayer et al 2006) and laboratory tests, indicating a weakening of many life history parameters in Chironomus riparius (Vogt et al 2007b) and on the discovery of TBT in adult chironomids at the selected sampling sites in this study (Lilley et al 2012). However, being a study carried out in natural conditions, we also take into account environmental factors known to affect chironomid species distribution such as: sediment grain size and amount of organic material in sediment (LOI, Cartier et al 2010), soluble phosphorus in sediment (Brodersen and Anderson 2002;Luoto 2011) and sediment pH (Rees and Cwynar 2010).…”

“…They play a role in the detritus cycle (Hirabayashi and Wotton 1998) as well as being a component in aquatic and terrestrial food webs (Armitage 1995). Chironomids accumulate TBT during their juvenile period (Looser et al 2000;Lilley et al 2012) and TBT affects many of their life history traits (Hahn and Schulz 2002;Vogt et al 2007b;Vogt et al 2007a). Chironomids are an important food source for fish, birds and bats (Vaughan 1997) and TBT uptake via food may be an important accumulation route.…”