Total-Hg and organic-Hg in Cephalopholis fulva (Linnaeus, 1758) from inshore and offshore waters of NE Brazil

Ld Lacerda,Rc Campos,Ja Santos,Ra Gonçalves,R Salles

doi:10.1590/s1519-69842007000300014

Abstract

To investigate whether source proximity or bioavailability is the major factor controlling both Hg concentration and Hg speciation in marine fishes, total- and organic-Hg content in muscle and liver tissues from different populations of Cephalopholis fulva (piraúna) from inshore and offshore waters of the Brazilian northeastern coast were analyzed. Average total-Hg in muscle (104 ng x g(-1) w.w.) and liver (2,865 ng x g(-1) w.w.) tissues, as well as organic-Hg concentrations in muscle (169 ng x g(-1) w.w.) and liver (1,038 ng x g(-1) w.w.), were much higher in the offshore population of C. fulva than in the inshore ones. In the inshore population total-Hg and organic-Hg average concentrations in muscle tissue were similar and reached only 49 ng x g(-1) w.w., while in liver they reached 412 ng x g(-1) w.w. for total-Hg and 180 ng x g(-1) w.w., for organic-Hg. Concentrations of both Hg species in the two populations were higher in liver than in muscle. The average percentage contribution of organic-Hg to the total Hg content was higher in muscle (98-100%) than in liver (42-53%), but similar between the two populations. Total-Hg and organic-Hg concentrations in muscle and liver from the offshore population showed significant (P < 0.05) positive correlation with fish length. However, in the inshore population only the total-Hg and organic-Hg in muscle tissues correlate significantly with fish size. Although the coastal environments are enriched in total Hg relative to open waters, the significant higher Hg concentrations in the offshore population of C. fulva and the significant correlation found between organic-Hg in liver with fish size suggest higher bioavailability of Hg in offshore waters relative to inshore ones.

Highlights

Romeo et al (1999) evaluating Hg levels in muscle, gills and liver tissues in different fish species from the Mauritania coast, observed that Hg concentrations in the gills and muscle of the pelagic species are very low, whereas higher concentrations were found in the liver of benthic species
Higher Hg concentrations occurred in the liver compared to muscle tissues regardless of the area sampled
Less attention is given on the variability of Hg concentration and distribution in populations of a single species inhabiting different sites in a similar area, such as inshore and offshore waters of a given coast where, under the influence of similar Hg sources, Hg may be present with different bioavailability to fish uptake

Summary

Introduction

Higher Hg concentrations occurred in the liver compared to muscle tissues regardless of the area sampled. (2002; 2003) and Kehrig et al (2005) found organic-Hg percentages varying from 75 to 100% and 94 to 100%, in muscle tissue of tuna and other carnivorous fish species, respectively. Less attention is given on the variability of Hg concentration and distribution in populations of a single species inhabiting different sites in a similar area, such as inshore and offshore waters of a given coast where, under the influence of similar Hg sources, Hg may be present with different bioavailability to fish uptake.

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Conclusion