Trace element accumulation in relation to trophic niches of shorebirds using intertidal mudflats

Abstract

International audienceThis study investigated the link between trace element concentrations and respective diets of two shorebird species present in the Pertuis Charentais, Atlantic coast of France: the Dunlin (Calidris alpina) and Redshank (Tringa totanus). Trace elements concentrations (Ag, As, Cd, Co, Cr, Cu, Fe, Hg, Mn, Ni, Pb, Se, Zn) were investigated in the liver, kidney, muscle and feathers of 28 dunlins and 15 redshanks accidentally dead during catches by mist net. Analyses of carbon and nitrogen stable isotope ratios were carried out in liver, muscle and feathers to determine whether differences in diet explained the variations in elemental levels. These results were compared to previous data obtained on two other shorebird species present on the same sites: the Black-tailed Godwit (Limosa limosa) and Red Knot (Calidris canutus). This study demonstrated that shorebirds of the Pertuis Charentais were characterized by differential trace element bioaccumulation. Arsenic and Se concentrations were elevated in red knots and dunlins, whereas redshanks displayed higher Cd concentrations in internal tissues. These trace element bioaccumulation discrepancies could mainly come from divergences of trophic habits between shorebirds. Species with the highest trophic position displayed the highest Hg concentrations in the liver, muscle and feathers demonstrating therefore the biomagnification potential of this metal, as opposed to Cd and Pb. The same trend was observed in muscle and feathers for Se and only in feathers for As. These data highlighted the need to study several tissues to obtain a full comprehension of trace element exposure and pathways especially for long-distance migrating species using various habitats and sites

Trace Element Concentrations in Relation to the Trophic Behaviour of Endangered Ivory Gulls (Pagophila eburnea) During Their Stay at a Breeding Site in Svalbard

“…Biomagnification of Se, however, has been reported by some authors (Lemly 1999;Muscatello and Janz 2009), whereas others reported no relationship with trophic position (Barceloux 1999;Campbell et al 2005;Lucia et al 2013). Results of the present study tend to indicate trophically decreasing Se concentrations along the ivory gull's food web.…”

“…from Barentsøya (Svalbard) in 2011,2012,2013,2014 nd: values below the detection limit Significant differences between years for each trace element and tissue distinctly are indicated by letters at the level α = 0.05 (Mann-Whitney U-test) Table 2 Concentrations (Mean ± SD, range; µg g -1 dw) of essential trace elements in tissues of the ivory gull (Pagophila eburnea) from Barentsøya, Svalbard, in 2011, 2012, 2013 nd: between 60% and 100% of the values were below the quantification limit, therefore, no means were calculated. When all values were below the quantification limit, "nd" was also indicated in range boxes Significant differences between years for each trace element and tissue distinctly are indicated by letters at the level α = 0.05 (Mann-Whitney U-test)…”

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

“…Sanderlings spend time foraging on the ocean beaches, semipalmated sandpipers sometimes forage on the salt marshes, and red knots mainly forage on the bay mudflats and beaches. Thus the differences in metal levels among species may indicate slightly different trophic levels, as has been found for shorebirds using mudflats along coastal France [ 36 , 37 ]. In the same species, trophic level could vary over two trophic levels indicating trophic plasticity [ 36 , 37 ].…”

“…Metal levels in feathers are available for dunlin ( Calidris alpina ), and redshank ( Tringa totanus ) [ 36 ], and red knots and black-tailed godwits ( Limosa limosa ) [ 37 ]. The feathers of red knots collected in 2011–2012 from Delaware Bay were either lower than (arsenic, cadmium, lead, mercury and selenium) or similar (chromium) to those collected in France [ 36 , 37 ]. Similarly, the levels in feathers of sanderling and semipalmated sandpiper were lower for all metals [ 35 ].…”

Trophic divergence of Lake Kivu cichlid fishes along a pelagic versus littoral habitat axis

“…Many of these changes along the littoral to pelagic axis in cichlids involve the size and shape of the preorbital region of the skull (Amaral & Johnston, 2012; Gerry et al., ; Parsons et al., 2011, 2015). Skeletal elements that include the opercular, orbital, and suspensorial bones commonly differ between littoral and pelagic fish (Bartels et al., 2012; Jones et al., 2013; Lucia et al., 2013; Muschick et al, 2012; Olsson & Eklöv, 2005). The heads of fishes are also densely packed with functional systems that contribute to feeding abilities in different environments.…”