Mercury concentrations in tidal marsh sparrows and their use as bioindicators in Delaware Bay, USA

Abstract

Mercury (Hg) contamination from industrial sources is pervasive throughout North America and is recognized by the US Environmental Protection Agency as a health hazard for wildlife and humans. Avian species are commonly used as bioindicators of Hg because they are sensitive to contaminants in the environment and are relatively easy to sample. However, it is important to select the appropriate avian species to use as a bioindicator, which should be directly related to the project objectives. In this study, we tested the utility of two tidal marsh sparrows, Seaside (Ammodramus maritimus) and Saltmarsh (Ammodramus caudacutus) sparrows, as bioindicator species of the extent of Hg contamination in tidal marshes along the Delaware Bay. To determine the possibility of using one or both of these species, we estimated sparrow blood Hg burden in five Delaware watersheds. We found no difference in Hg concentrations between species (F (1,133) < 0.01, P=0.99), but Saltmarsh Sparrows had limited sample size from each site and were, therefore, not appropriate for a Delaware Bay-wide Hg indicator. Seaside Sparrows, however, were abundant and relatively easy to sample in the five watersheds. Seaside Sparrow blood Hg levels ranged from 0.15 to 2.12 ppm, differed among drainages, and were greatest in two drainages distant from the Delaware Bay shoreline (F (4,95) =2.51, P=0.05). Based on a power analysis for Seaside Sparrow blood Hg, we estimated that 16 samples would be necessary to detect differences among sites. Based on these data, we propose that Seaside Sparrows may be used as a tidal marsh Hg bioindicator species given their habitat specificity, relative abundance, widespread distribution in marsh habitats, ease of sampling, and limited variation in blood Hg estimates within a sampling area. In Delaware Bay, Saltmarsh Sparrows may be too rare (making them difficult to sample) to be a viable tidal marsh Hg bioindicator.

Incorporation of Deepwater Horizon oil in a terrestrial bird

“…Adults and juveniles both feed on a variety of prey, including terrestrial as well as marine invertebrates (Post and Greenlaw 2006), thus exposing this species to a variety of contaminants through a number of potential routes. Consistent with this, the seaside sparrow was found to be a sensitive indicator species for mercury contamination in salt marshes (Warner et al 2010, Winder 2012.…”

Mercury in breeding saltmarsh sparrows (Ammodramus caudacutus caudacutus)

“…We believe Ammodramus species: Nelson's sparrow (A. nelsonii) (Winder and Emslie 2011) in northeastern Maine and Canada, SSTS from mid coast Maine south to New Jersey and seaside sparrow (A. maritimus) in Delaware and south (Warner et al 2010) make an appropriate bioindicator species in tidal marsh ecosystems. A suitable bioindicator should be easy to sample to address management issues, be widespread in the habitat in question, and occupy that habitat exclusively (Golden and Rattner 2003).…”

Mercury in Feathers and Blood of Gulls from the Southern Baltic Coast, Poland

“…Feathers, easy to collect in a non-invasive manner, are considered by many researchers to be good indicators of alimentary exposure and thus of environmental pollution with mercury (Burger 1993; Furness 1993; Ratcliffe et al 1996; Furness and Camphuysen 1997; Thompson et al 1998; Burger and Gochfeld 2004; Evers et al 2008). Studies on mercury concentrations in feathers are widespread (Cairns 1997; Monteiro et al 1999; Warner et al 2010) and enable evaluation and comparison of mercury pollution in different areas of the world. Feathers are also useful in terms of monitoring environments in which birds and other organisms (including humans) live, as mercury present therein is both physically and chemically stable.…”