Inorganic elements and calcium/phosphorus ratio in bones of Commerson?s dolphins (Cephalorhynchus c. commersonii) by X-ray dispersive analysis

CÁCERES-SÁEZ, I.; PEREZ-CATÁN, S.; DELLABIANCA, N. A.; AYALA, C.; ANDRADE GAMBOA, J.; GOODALL, R. N. P.; CAPPOZZO, H. L

Tampa, Florida

Conferencia; 19th Biennal Conference on the Biology of Marine Mammals; 2011

Society for Marine Mammalogy

Bone matrix durability can remain essentially unchanged for centuries after death. Museum collections have become an important source of information on species. The Commerson?s dolphin (Cephalorhynchus c. commersonii) is endemic to South America (40ºS-56ºS) and it is affected by incidental catch in Tierra del Fuego, Argentina (TdF). Major inorganic elements (Ca, P, Mg, Na, Fe) and crystalline-compound phases of bone were determined in Commerson?s dolphin. Specimens were provided by the Goodall Collection at the Museo Acatushún de Aves y Mamíferos Marinos Australes, TdF collected from 1975-2011. We studied 44 chevron bones including fairly recent prepared museum bones (PMB) and fresh bones (FB) from males (n=24), females (n=18) and unknown-sex (n=2). Ages available for 35 animals through GLG study ranged between 0-15 years. We explored the potential of utilizing an analytical and non-destructive technique, Scanning Electron Microscopy coupled to the X-Ray Spectroscopy. The proportion of elements was measured with a relative error of 0.05%. X-Ray powder diffraction was performed to identify the crystalline-compound phases. Measurements of Ca and Mg between PMB and FB were similar (t-test=1.88; P=0.07 and t-test=1.20; P=0.24); while significant differences for P (t-test=9.93; P<0.0001), Na (t-test=3.53; P=0.0001) and Fe (t-test=2.08; P=0.04) were detected. The Ca/P ratio showed no-significant differences between sexes for PMB (t-test=0.122; P=0.90) and FB (t-test=0.66; P=0.54), although differences for age-class (subadults <8, adults >8 GLGs) were observed for PMB (t-test=2.16; P=0.03). X-Ray-diffraction revealed that the calcium-phosphate phase was similar to hydroxyapatite, which constitutes the main inorganic phases of hard-tissue of vertebrates. This study is the first description of the major inorganic elements of Commerson?s dolphin bones through the use of SEM-EDS and this information could have relevance in nutritional or environmental condition research. A larger number of specimens should be assessed to confirm this trend