Enhanced bioaccumulation of mercury in deep-sea fauna from the Bay of Biscay (north-east Atlantic) in relation to trophic positions identified by analysis of carbon and nitrogen stable isotopes

Abstract

International audienceThe Bay of Biscay (north-east Atlantic) is an open marine ecosystem of particular concern in current European environmental policies. Indeed, it supports both a high biological diversity and numerous anthropogenic activities such as important fisheries. For the first time, stable isotope analyses (SIA) of carbon and nitrogen and analysis of total mercury (T-Hg) concentrations in the muscle (edible flesh) were performed on adult stages of a wide range of species (i.e., 120 species) from various taxa and various habitats of this ecosystem. Concentrations of this non-essential metal, toxic to all living organisms, ranged from 39 to 5074 ng.g-1 dry weight. Calculations of species' trophic positions (TPs) through SIA revealed a limited effect of TP in explaining Hg bioaccumulation by high trophic level consumers in particular. On the contrary, our results suggest an important role of habitat and/or feeding zone, which strongly influence muscle Hg bioaccumulation. Deep-sea fish species effectively presented the highest Hg concentrations. Possible interactions between biological factors (e.g., age of deep-sea organisms) and bioavailability of the metal in the deep-sea environment are discussed to explain such enhanced bioaccumulation of Hg by deep-sea fauna in the Bay of Biscay. This study also highlights a potential risk for human health when deep-sea fish are consumed frequently

Biomagnification of mercury through the food web of the Santos continental shelf, subtropical Brazil

“…A comparison between 2 flatfish showed that species feeding on fish, squid, and macrocrustaceans had higher Hg concentrations than did species feeding on amphipods and polychaetes (Payne & Taylor 2010). In contrast, and similar to our findings, an analysis of organisms across a wide depth range in the Bay of Biscay (30−600 m) showed that the pelagic fauna were less contaminated than the benthic and benthopelagic fauna (Chouvelon et al 2012b). Demersal fish of the Antarctic inner shelf were more contaminated than epipelagic fish (Bargagli et al 1998).…”

Seasonal Survey of Contaminants (Cd and Hg) and Micronutrients (Cu and Zn) in Edible Tissues of Cephalopods from Tunisia: Assessment of Risk and Nutritional Benefits

“…The highest concentration of Hg found in squid reflets their behavior of feeding mainly on fish and other cephalopod species (Pierce and others ; Coelho and others ). Such a pelagic diet would lead to higher Hg exposure and hence to higher Hg bioaccumulation in pelagic cephalopods, because their prey contains higher organic Hg loads than those of benthic species (Cossa and others ; Chouvelon and others ). The concentration of Hg in the edible parts of the cephalopod species under investigation were generally slightly lower than the levels reported by authors in other areas of the world (Bustamante and others ; Storelli and others ; Villanueva and Bustamante ; Lourenço and others ).…”

Mother–embryo isotope (δ15N, δ13C) fractionation and mercury (Hg) transfer in aplacental deep‐sea sharks

“…These results show that embryos of aplacental sharks tended to have similar or lower isotopic values when compared to their mothers. The exception, however, was δ 13 C values in liver of C. moluccensis embryos, which were generally higher than in their mothers, suggesting a change in the feeding area of the mothers after the maturation of the eggs because isotopic values in liver are considered shorter‐term, more recent indicators of diet than in muscle tissue (Domi et al , ; Chouvelon et al , ). Nevertheless, C:N in liver of C. moluccensis mothers are high (6·27 ± 0·91, n = 4), indicating insufficient lipid extraction.…”

“…of the eggs because isotopic values in liver are considered shorter-term, more recent indicators of diet than in muscle tissue (Domi et al, 2005;Chouvelon et al, 2012). Nevertheless, C:N in liver of C. moluccensis mothers are high (6⋅27 ± 0⋅91, n = 4), indicating insufficient lipid extraction.…”