Influência de parâmetros de história natural (sexo, idade e maturidade sexual) nos padrões de acumulação de compostos organobromados do boto-cinza (Sotalia guianensis) da Baía de Sepetiba, Rio de Janeiro, Brasil

Abstract

Bioaccumulation of organobrominated compounds in marine mammals occurs mainly through diet and may be influenced by physiological factors inherent to gender, reproductive status and age. Therefore, the present study objective was to verify the influence of natural history parameters (gender, sexual maturity and age) on organobrominated compounds patterns, anthrogenic (PBDEs) and naturally-produced (MeO-BDEs), in Guiana dolphins (Sotalia guianensis) from Sepetiba Bay-RJ. This study was organized in two sections. In the first section, natural history parameters were determined in 109 Guiana dolphins and in the second section these parameters were confronted with organobrominated compounds concentrations found in 39 Guiana dolphins subcutaneous adipose tissue. Dolphins age varied from 0 to 20 years for females (N= 43; 7,8 ± 5,8) and 0 to 23 years for males (N= 66; 7 ± 4,8). Females reached sexual maturity at 6.5 years and males at 7.3 years. The length range in which males were sexually mature was from 183 to 188 cm and for females from 171 to 177 cm. Males reached asymptotic length with 190.7 cm and females with 187.8 cm. Gestation time for Guiana dolphins was estimated at 12 months, with a fetal growth rate of 9.08 cm/month. The average birth length was estimated at 96.15 cm. In Guiana dolphins subcutaneous adipose tissue, organobrominated compounds concentrations ranged from 12,4 to 758 ng.g-1 lipids (175,3±209,8) in females and from 97,8 to 739,2 ng.g-1 lipids (313,3±178,5) in males for anthropogenically-produced compounds (PBDEs). For the natural origin compounds (MeOBDEs) the concentrations ranged from 7,7 to 1364,2 ng.g-1 lipids (349,2±415,4) in females and from 101,6 to 854,7 ng.g-1 lipids (33,5±178,9) in males. Organobrominated compounds accumulation patterns, both anthropogenic and natural, were influenced by gender (p< 0.05) in Guiana dolphins using Sepetiba Bay, with differences between males and females contamination profiles being identified by discriminant analysis (p<0.05). Placental transfer of organobrominated compounds from mothers to the fetuses were identified and the highest transfer rates were observed for the compounds with the lowest number of bromine atoms. The results of the present study demonstrate that there is influence of life history patterns on the organobrominated compounds accumulation patterns in Guiana dolphins from Sepetiba Bay- RJ.