A multitracer approach to assess the spatial contamination pattern of hake (Merluccius merluccius) in the French Mediterranean

Abstract

Chemical contamination levels and stable isotope ratios provide integrated information about contaminant exposure, trophic position and also biological and environmental influences on marine organisms. By combining these approaches with otolith shape analyses, the aim of the present study was to document the spatial variability of Hg and PCB contamination of the European hake (Merluccius merluccius) in the French Mediterranean, hypothesizing that local contaminant sources, environmental conditions and biological specificities lead to site-specific contamination patterns. High Hg concentrations discriminated Corsica (average: 1.36 ± 0.80 μg g(-1) dm) from the Gulf of Lions (average values<0.5 μg g(-1) dm), where Rhône River input caused high PCB burdens. CB 153 average concentrations ranged between 4.00 ± 0.64 and 18.39 ± 12.38 ng g(-1) dm in the Gulf of Lions, whatever the sex of the individuals, whereas the highest values in Corsica were 6.75 ± 4.22 ng g(-1) dm. Otolith shape discriminated juveniles and adults, due to their different habitats. The use of combined ecotracers was revealed as a powerful tool to discriminate between fish populations at large and small spatial scale, and to enable understanding of the environmental and biological influences on contamination patterns.

Variability of PCB burden in 5 fish and sharks species of the French Mediterranean continental slope

“…Sex was also demonstrated to significantly affect PCB bioaccumulation. Lower bioaccumulation is commonly observed in females and is explained notably by the transfer of PCB to gonads during oogenesis and further excretion by spawning (Bodiguel et al, 2009;Cresson et al, 2015). In the present, no clear sexual pattern could be observed (Fig.…”

“…On the contrary, all CB 28 (3 Cl congener) concentrations were below detection limits, and CB 52 (4 Cl congener) was detected in H. dactylopterus only. Predominance of highly chlorinated compounds is consistently observed in Mediterranean marine fish Bodiguel et al, 2008;Storelli, 2008;Cresson et al, 2015) and is explained by the faster degradation of lowly-chlorinated compounds, whereas highlychlorinated compounds are hard to degrade and remain for a long time in the environment (Tolosa et al, 1995). Nevertheless, the predominance of congeners CB 153, 138 and 180 is a specificity of deep species, explained by the even higher resistance of these compounds to degradation processes, in environment or in biological tissues .…”

“…Individuals were measured (total length, to the nearest mm) prior to the dissection of two samples of muscle without skin. Dorsal muscle (~1g wet mass) was sampled for isotopic analyses, following international accepted procedures and previous laboratory experience (Pinnegar and Polunin, 1999;Cresson et al, 2014Cresson et al, , 2015. A whole filet (~ 15 g wet mass) was dedicated to PCB analyses since concentration in muscle is considered to reflect a more long-term exposure to contaminant than in liver or gonads .…”

“…PCBs burdens were determined following analytical procedures in accordance with standard NF ISO 10382 and XP X33-012 and previously described in Cresson et al (2015). A precisely weighed amount of the powdered muscle, 2 g dry mass, was extracted with acetone, pentane and iso-octane in acid medium with liquid-solid extraction ultrasonic extraction method.…”

Coupling biogeochemical tracers with fish growth reveals physiological and environmental controls on otolith chemistry

“…Furthermore, different tracers reflect different biological/ecological processes. Thus, it is desirable to simultaneously measure multiple biogeochemical tracers as well as the effects of growth or other physiological factors to allow for synergistic interactions to be explored and understood (Ethier et al 2010, Ramos and Gonz alez-Sol ıs 2012, Cresson et al 2015.…”