Global versus local causes and health implications of high mercury concentrations in sharks from the east coast of South Africa

Effect of body length, trophic position and habitat use on mercury concentrations of sharks from contrasted ecosystems in the southwestern Indian Ocean

“…Le Bourg et al 2014;Lyons and Lowe 2013;Pethybridge et al 2010). Relationships between trophic position metrics and Hg concentrations at the levels of species (Cresson et al 2014;Pethybridge et al 2012), taxonomic groups (McKinney et al 2016;Pethybridge et al 2012) and communities (Atwell et al 1998;Campbell et al 2008;Lavoie et al 2010;Power et al 2002) show that feeding ecology of organisms dramatically influences Hg concentrations. Spatial variations of Hg concentrations in organisms (Hisamichi et al 2010;Jones et al 2013;Kojadinovic et al 2006;Sackett et al 2013) or correlations between depth of occurrence appears to be particularly important in driving Hg concentrations (Blum et al 2013;Chouvelon et al 2012;Choy et al 2009;Monteiro et al 1996), but the relative importance of environmental drivers on Hg concentrations in marine predators is still relatively poorly understood.…”

“…However, mercury (Hg) concentrations reported in sharks are frequently above the maximum values recommended for fish consumption (1 µg.g -1 wet weight; Escobar-Sánchez et al 2011;Hueter et al 1995;Kousteni et al 2006;McKinney et al 2016). Hg is toxic to organisms at low concentrations with known sublethal effects including reduced growth, impacts on reproduction (e.g.…”

“…Hg concentrations increase with size in various taxa such as cephalopods (e.g. Chouvelon et al 2011), predatory teleosts (Cresson et al 2014;Kojadinovic et al 2006;Sackett et al 2013) and elasmobranchs (Cresson et al 2014;Hueter et al 1995;McKinney et al 2016;Pethybridge et al 2010;Rumbold et al 2014). Differences in life-history traits may also influence Hg dynamics in elasmobranchs (e.g.…”

First histological examination of a neoplastic lesion from a free‐swimming white shark, Carcharodon carcharias L.

“…However, white sharks are likely to bioaccumulate and bioconcentrate pollutants as expected in top‐predatory fishes with high longevity, slow metabolism, lipid‐rich livers and high trophic position (Gelsleichter & Walker ; Mckinney et al . ), potentially increasing their susceptibility to high pollutant levels. Indeed, high levels of anthropogenic toxins and carcinogens have been reported from tissues of various shark species, including white sharks (Vas ; Mull et al .…”

“…For example, white sharks tagged at the Neptune Islands are considered pelagic sharks, mostly occurring on the continental shelf (Bruce, Stevens & Malcolm 2006) where pollutant concentrations are expected to be minimal compared to inshore areas. However, white sharks are likely to bioaccumulate and bioconcentrate pollutants as expected in top-predatory fishes with high longevity, slow metabolism, lipid-rich livers and high trophic position (Gelsleichter & Walker 2010;Mckinney et al 2016), potentially increasing their susceptibility to high pollutant levels. Indeed, high levels of anthropogenic toxins and carcinogens have been reported from tissues of various shark species, including white sharks (Vas 1991;Mull et al 2013;Gilbert et al 2015).…”