Trace metal (Cr, Ni, Cd and Pb) concentrations in teeth of commerson?s dolphins Cephalorhynchus commersonii.

IRIS CÁCERES-SÁEZ; SOLEDAD PEREZ-CATAN; NATALIA A. DELLABIANCA; CAROLINA LOCH; R. NATALIE P. GOODALL; H. LUIS CAPPOZZO

Valparaiso

Congreso; XVII Reunion de Trabajo de Especialistas en Mamiferos Acuaticos de America del Sur y 11° Congreso SOLAMAC; 2016

SOLAMAC y Universidad de Valparaiso

Calcified tissues such as teeth and bones are metabolically inert, preserving signals of environmental chemical variations. Moreover, temporal trends of trace elements and toxic metals can be measured in teeth. A preliminary study to investigate trace metal accumulation in teeth of the Commerson?s dolphin was conducted. Dry teeth (DW) were collected from bycaught Commerson?s dolphins from Tierra del Fuego, Argentina (RNP Goodall collection at Museo Acatushún). Total concentrations of Cr, Ni, Cd and Pb were determined by Graphite Furnace Atomic Absorption Spectrometry. Teeth were gathered from 42 specimens (9 females, 30 males and 3 of unknown sex) collected from 1975 to2011. Ages were estimated by counting growth layer groups (GLGs) in dentine. Ages ranged between 0 - 17 years. Statistical analyses were used to evaluate differences between sex and sexual maturity of individuals. Animals were grouped as mature and immature (>6 and ≤5 years old, respectively). We found high values of Pb concentration in a few male specimens of different ages. These values were not included in the statistical analysis. Chromium and Cd were not detectable, and were below the detection limit in 43% and 9.5% of the samples analyzed; respectively. The mean concentration of Cr was 0.13 µg gr-1 DW and for Cd was 0.61 µg gr-1 DW. Lead and Ni concentrations were the highest among the metals analyzed, and ranged from 0.11 to 4.1 µg gr-1 and 0.67 to 5.1 µg gr-1; respectively. Similar levels were found between sexes for these elements. Mature animals showed high mean concentrations in comparison to immature animals for Pb, Ni and Cd; however, this difference was not significant. An age-related accumulation trend needs to be confirmed in a larger samples. Teeth are the main target tissue for Pb accumulation, and the specific storage is explained by the close chemical behavior between Ca and Pb ions, which display a similar affinity for hard tissues. Trace element levels in animal teeth can help us understand patterns of individual exposure and overall environmental quality. This study adds new information on trace metal contents in calcified tissue of small cetaceans in the Southern Hemisphere.