Bioaccumulation and trophic transfer of mercury in striped bass (Morone saxatilis) and tautog (Tautoga onitis) from the Narragansett Bay (Rhode Island, USA)

Abstract

We examined the bioaccumulation and trophic transfer of mercury in two marine finfish species, striped bass (Morone saxatilis) and tautog (Tautoga onitis), collected from the Narragansett Bay (Rhode Island, USA). For each of these target fish, white muscle tissue was analyzed for total mercury (Hg) and results were evaluated relative to fish age, body size, and Hg content of preferred prey. Dietary and stable isotope analysis was also used to elucidate the effect of trophic processes on Hg concentrations in fish. The Hg content of muscle tissue was positively correlated with fish age and length for both species, although striped bass accumulated Hg faster than tautog. Accelerated Hg bioaccumulation in striped bass is consistent with its high trophic level (trophic level = 4.07) and Hg-enriched prey (forage fish and macrocrustaceans; mean Hg content = 0.03 mg Hg kg wet wt(-1)). In contrast, tautog maintain a lower trophic status (trophic level=3.51) and consume prey with lower Hg levels (mussels and crabs; mean Hg content = 0.02 mg Hg kg wet wt(-1)). Despite differences in Hg bioaccumulation between target fish, the mean Hg concentration of tautog exceeded levels in striped bass (0.24 and 0.16 mg Hg kg wet wt(-1), respectively) due to a disparity in age-at-catch between sampled groups (mean age of tautog and bass = 11.3 and 4.3 yr, respectively). Taking into account legal minimum catch lengths further revealed that 75.0% of legal-size striped bass (>70.2 cm TL; n = 4) and 44.8% of tautog (> 40.6 cm TL; n = 29) had Hg levels beyond the US EPA regulatory threshold of 0.3 mg Hg kg wet wt(-1). Moreover, Hg-length relationships suggest that each target fish meets this threshold near their minimum legal catch length. Our findings reiterate the value of species ecology to improve predictions of fish Hg and permit better management of human contamination by this important dietary source.

Environmental mercury in China: A review

“…Mercury levels in Chinese freshwater fish are lower than those reported for fish in Canada (0.047-1.82 mg kg À1 ) [89], the United States (0.02-0.92 mg kg À1 ) [90,91], and Brazil (0.23-2.70 mg kg À1 ) [92]. Various studies have confirmed that the Hg concentration in fish is decided mainly by trophic level and age [93][94][95][96][97] and is less strongly correlated to the environmental Hg concentration. This finding has also been confirmed by a study in Tibet in which Hg concentrations in fish were found to be much higher than those in most fish samples from areas with high environmental Hg concentrations [98].…”

Ontogenetic patterns in bluefish (Pomatomus saltatrix) feeding ecology and the effect on mercury biomagnification

“…4). Comparable Hg-length (or weight) trends have been reported for bluefish in the Long Island Sound and coastal New Jersey [18,19,54], as well as other estuarine and coastal fishes from the northwestern Atlantic [6,7,54,56]. The significant positive correlation between bluefish muscle Hg and length affirms that Hg biomagnifies in this tissue, and is likely attributable to the rapid uptake of the contaminant relative to its excretion from the body [21,57].…”

“…Isotope measurements of a subsample ($1 mg dry wt) of age 0 bluefish (muscle filet; n ¼ 20), age 1 þ bluefish (D 0 biopsy; n ¼ 20), and prey (whole body; n ¼ 20-85) were performed by the Boston University Stable Isotope Laboratory (Boston, MA, USA) [7]. Briefly, automated continuous-flow isotope ratio mass spectrometry was used to quantify isotopic signatures, and ratios of 15 C. The precision of the continuous-flow isotope ratio mass spectrometry method, as determined by the analysis of internal reference material (peptone and glycine), was 0.2% and 0.4% for nitrogen and carbon, respectively.…”

“…Nitrogen isotope signatures were used to estimate the trophic position of bluefish and prey, using the following equation modified from Piraino and Taylor [7]:…”

“…The blue mussel was selected as the reference primary consumer because it is phytoplanktivorous [41], and a concurrent investigation measured the d 15 N signature of blue mussels collected from the Narragansett Bay (d 15 N ¼ 10.62%; n ¼ 20) [7].…”