Mercury, Lead, Cadmium, Arsenic, Chromium and Selenium in Feathers of Shorebirds during Migrating through Delaware Bay, New Jersey: Comparing the 1990s and 2011/2012.

Joanna Burger,Nellie Tsipoura,Michael Gochfeld,Lawrence Niles,Amanda Dey,David Mizrahi

doi:10.3390/toxics3010063

Abstract

Understanding temporal changes in contaminant levels in coastal environments requires comparing levels of contaminants from the same species from different time periods, particularly if species are declining. Several species of shorebirds migrating through Delaware Bay have declined from the 1980s to the present. To evaluate some contaminants as cause for the declines, we examine levels of mercury, lead, cadmium, arsenic, chromium and selenium in feathers of red knot (Calidris canutus, N = 46 individuals), semipalmated sandpiper (Calidris pusilla, N = 70) and sanderling (Calidris alba, N = 32) migrating through Delaware Bay, New Jersey, USA, from 1991 to 1992 (N = 40), 1995 (N = 28), and 2011–2012 (N = 80) to determine if levels have changed. We found: (1) arsenic, chromium, and lead increased in red knot and decreased in semipalmated sandpiper; (2) cadmium decreased in semipalmated sandpipers; (3) mercury decreased in red knot and sanderlings; (4) selenium decreased in red knot and increased in semipalmated sandpipers. In 2011/2012 there were significant interspecific differences for arsenic, mercury and selenium. Except for selenium, the element levels were well below levels reported for feathers of other species. The levels in feathers in red knots, sanderling, and semipalmated sandpipers from Delaware Bay in 2011/2012 were well below levels in feathers that are associated with effect levels, except for selenium. Selenium levels ranged from 3.0 µg·g−1 dry weight to 5.8 µg·g−1 (semipalmated sandpiper), within the range known to cause adverse effects, suggesting the need for further examination of selenium levels in birds. The levels of all elements were well below those reported for other marine species, except for selenium, which was near levels suggesting possible toxic effects.

Highlights

With global change and increasing levels of industrial, commercial and agricultural contaminants it is important to track temporal trends and compare species, species of conservation concern, or those living or migrating through unique or sensitive habitats
We examined levels of mercury, cadmium, and lead because they are the major contaminants of concern in marine environments [18,19,20], arsenic, a concern for wildlife in marine and estuarine ecosystems [21], and chromium because it has posed a major environmental contamination problem from former industrial processes in northern New Jersey [22]
The temporal patterns differed, but more element levels increased in feathers of red knot, more decreased in semipalmated sandpipers

Summary

Introduction

With global change and increasing levels of industrial, commercial and agricultural contaminants it is important to track temporal trends and compare species, species of conservation concern, or those living or migrating through unique or sensitive habitats. In the 1990s, as many as 270,000 shorebirds were recorded in a single count, and estimates were made of more than 1 million shorebirds using the Bay during spring migration [1]. During the 2–3 week stop-over at Delaware Bay, shorebirds eat intensely and store fat to refuel for the last 4000+ mile leg of their journey to the Canadian Arctic and subarctic breeding grounds. Their migration through Delaware Bay in May coincides with the spawning of the horseshoe crabs (Limulus polyphemus) [2], whose eggs they consume in large quantities as they are easy to find, digest, and metabolize [3]. To successfully make the long migration and arrive in condition to lay eggs immediately upon arrival at the breeding grounds, the shorebirds need to nearly double their weight during May [4]

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