Seasonal differences in mercury accumulation in Trichiurus lepturus (Cutlassfish) in relation to length and weight in a Northeast Brazilian estuary

• Published in: Environmental science and pollution research international 2009-06, Vol.16 (4), p.423-430
• Main Authors: Costa, Monica Ferreira, Barbosa, Scheyla C. T, Barletta, Mário, Dantas, David V, Kehrig, Helena A, Seixas, Tércia G, Malm, Olaf
• Format: Article
• Language: English
• Subjects: Animal tissues; Animals; Aquatic Pollution; Area 2.1 • Behavior of chemicals in water and their interactions with biota • research article; Atmospheric Protection/Air Quality Control/Air Pollution; Atomic absorption spectroscopy; Bioaccumulation; Bioavailability; Bioindicators; Biota; Body Size; Brackish; Brazil; Coastal waters; Conservation; Contamination; Crustaceans; Dry season; Earth and Environmental Science; Ecosystem; Ecotoxicology; Environment; Environmental Chemistry; Environmental Health; Estuaries; Fish; Fisheries; Food availability; Food chains; Food contamination; Food contamination & poisoning; Heavy metals; Indicator species; Industrial wastewater; Land use; Marine conservation; Marine ecology; Marine ecosystems; Marine fish; Marine mammals; Marine pollution; Mercury; Mercury - analysis; Mercury - metabolism; Mollusks; Muscle, Skeletal - chemistry; Muscle, Skeletal - metabolism; Oceans and Seas; Particulate matter; Perciformes - metabolism; Pollutants; Predators; Primary production; Public health; Rain; Rainfall; River flow; Rivers; Seasonal variations; Seasons; Shellfish; Spectral analysis; Spectrometry; Studies; Time Factors; Trichiurus lepturus; Tropical environment; Variance analysis; Waste Water Technology; Water flow; Water Management; Water Pollutants, Chemical - metabolism; Water Pollution Control; Water quality; Water quality standards; Weight
• ISSN: 0944-1344; 1614-7499
• DOI: 10.1007/s11356-009-0120-x

Background, aim, and scope At tropical latitudes, and especially on the semi-arid coasts of the Brazilian Northeast, the rainfall regime governs the water quality of estuaries due to the pronounced difference between the rainy and dry seasons. These changes may be responsible for seasonal changes in bioavailability of mercury (Hg) and other pollutants to the estuarine and coastal biota. Mercury bioaccumulates along estuarine-marine food chains usually result in higher concentrations in tissues of top predators and posing a risk to both marine mammals and humans alike. The Goiana River Estuary (7.5° S) is a typical estuary of the semi-arid tropical regions and supports traditional communities with fisheries (mollusks, fish, and crustacean). It is also responsible for an important part of the biological production of the adjacent coastal waters. Materials and methods Trichiurus lepturus (Actinopterygii: Perciformes) is a pscivorous marine straggler. Fish from this species (n = 104) were captured in a trapping barrier used by the local traditional population and using an otter trawl net along the main channel of the low estuary during two dry seasons (D1 = November, December 2005, January 2006; D2 = November, December 2006, January 2007) and the end of a rainy season (R = August, September, October 2006). Fish muscle samples were preserved cold and then freeze-dried prior to analysis of its total mercury (Hg-T) contents. Total mercury was determined by cold vapor atomic absorption spectrometry (CV-AAS) with sodium borohydride as a reducing agent. Results The studied individuals (n = 104) were sub-adult (30-70 cm, 71 ind.) and adult fish (>70 cm, 33 ind.). Weight (W) (204.1 ± 97.9 g, total biomass = 21,229.7 g) and total length (TL) (63.1 ± 10.1 cm, range 29.5-89.0 cm) presented a significant (p < 0.05) correlation. Two-way ANOVA (n = 81) showed that TL and W had significant differences (p < 0.05) among seasons, being higher in D1 than in D2 and R, respectively. Moreover, season vs. month interaction were detected for the variables length and weight. For the variable weight was detected significant difference for the factor month (p < 0.05). It suggests that the fish enter the estuary at the end of the rainy season and increase in length and weight during the time they spend in the estuary. Fish from this estuary are shown to be fit for human consumption (125.3 ± 61.9 μgHg-T kg⁻¹ w.wt.; n = 104). Fish mercury contents increased with size and weight. Correlatio