Bioaccumulation of Lead and Arsenic in Gastropods Inhabiting Salt Marsh Ponds in Coastal Bay of Fundy, Canada

Abstract

The Cumberland Marsh Region (CMR), located on the coast of the Bay of Fundy, is a major feeding ground for waterfowl and contains significant coastal wetland systems. In this study, concentrations of lead (Pb) and arsenic (As) were assessed in the bottom sediments of various open water wetlands across the CMR, and gastropods were sampled from the same wetlands to assess bioaccumulation of these nonessential trace elements and the potential for transfer to higher trophic level species. It was predicted that gastropods would have higher concentrations of Pb and As from wetlands with higher concentrations of these elements in sediments. Although wetland sediments and gastropods had elevated Pb and As concentrations, in some cases above the Canadian Sediment Quality Guidelines for the protection of aquatic life, there were no significant correlations between sediment and gastropod trace element concentrations. Gastropod to sediment ratios of Pb and As concentrations were highest in the brackish wetlands, but overall, levels were not of toxicological concern. Wetland chemistries and gastropod physiologies are hypothesized to be driving factors in determining the level to which Pb and As will bioaccumulate and merit careful consideration when developing wetland management strategies.

A paleolimnological archive of metal sequestration and release in the Cumberland Basin Marshes, Atlantic Canada

“…Samples were dried in plastic boats at 60°C for 72 h in an open oven prior to sending samples for analysis. The elemental geochemistry of the sediment samples was measured by an Olympus X-50 portable X-ray fluorescence (pXRF) spectrometer, following methods outlined by Rouillon and Taylor (2016), Loder et al (2016), and Dunnington et al (2016). XRF spectrometry is a method that is increasingly used to provide high-resolution elemental geochemistry in lake sediments (Koinig et al 2003;Guyard et al 2007;Brunschön et al 2010;Kylander et al 2011;Rydberg 2014;Dunnington et al 2016;Gregory et al 2017).…”

“…Estuarine environments are important environments supporting both coastal and marine food webs, yet many have been modified by anthropogenic activity (Euliss et al 1999;Sharitz and Batzer 1999;Scott et al 2014;Mitsch and Gosselink 2015;Loder et al 2016). The ecological value of coastal wetlands within estuarine environments has long been recognized, and mitigating the effects of metal accumulation from natural and anthropogenic sources is a primary objective of many wetland managers (e.g., Englehardt 2013;Loder et al 2016).…”

“…The ecological value of coastal wetlands within estuarine environments has long been recognized, and mitigating the effects of metal accumulation from natural and anthropogenic sources is a primary objective of many wetland managers (e.g., Englehardt 2013;Loder et al 2016). In particular, the identification of metal sources, the potential for these metals to be sequestered or released into the environment, and management practices that mitigate further effects on wildlife are important areas of research.…”

“…Lead (Pb), arsenic (As), and mercury (Hg) are metals that bioaccumulate in various inorganic and organic forms, are toxic to waterfowl and marsh birds and, in the CMR, occur in lakebed sediments at levels that may exceed the Canadian interim sediment quality guidelines for the protection of aquatic life (Adler 1944; Canadian Council of Ministers for the Environment (CCME) 1999; Loder et al 2016). Although atmospheric deposition (Weiss et al 2002;Sullyman 2003;O'Driscoll et al 2005), lead shot (Schwab and Daury 1989), and till (Dummer et al 2015) have been recognized as possible sources of these elements in lakebed sediments in the CMR, their relative importance is unknown, and other unrecognized sources may exist.…”

“…Processes that sequester or release metals in lakebed sediments include sediment-water interface redox conditions (Davison 1993;Johnson 2008;Reiche et al 2011) and sediment resuspension (Kalnejais et al 2007;Terry 2011), but the degree to which these affect the availability of metals in the CMR is not known (Loder et al 2016). Finally, stratigraphic variability in metal concentration in lakebed sediments can have significant consequences for bioavailability and may influence habitat management practices.…”