HR: 0800h
AN: B21B-0884    [Abstracts]
TI: Magnetite in Black Sea Turtles (Chelonia agassizi)
AU: * Fuentes, A
EM: almafuentes70@hotmail.com
AF: Instituto de Geofisica UNAM, Laboratorio de Paleomagnetismo, Instituto de Geofisica, Universidad Nacional Autonoma de Mexico, Coyoacan, Mexico, 04510 Mexico
AU: Urrutia-Fucugauchi, J
EM: juf@geofisica.unam.mx
AF: Instituto de Geofisica UNAM, Laboratorio de Paleomagnetismo, Instituto de Geofisica, Universidad Nacional Autonoma de Mexico, Coyoacan, Mexico, 04510 Mexico
AU: Gardu¤o, V
AF: Instituto de Investigaciones Metalurgicas, Instituto de Investigaciones Metalurgicas, Universidad Michoacana de San Nicolas de Hildalgo, Ciudad Universitaria, Michoacan, Morelia, 58000 Mexico
AU: Sanchez, J
AF: Instituto de Investigaciones Quimico-Biologicas, Instituto de Investigaciones Quimico-Biologicas, Ciudad Universitaria, Universidad Michoacana de San Nicolas de Hidalgo, Micoacan, Morelia, 58260 Mexico
AU: Rizzi, A
AF: Universidad Ardito Desio, Departamento Microscopia Electronica, Universidad Ardito Desio, Milano, 4000 Italy
AB: Previous studies have reported experimental evidence for magnetoreception in marine turtles. In order to increase our knowledge about magnetoreception and biogenic mineralization, we have isolated magnetite particles from the brain of specimens of black sea turtles Chelonia agassizi. Our samples come from natural deceased organisms collected the reserve area of Colola Maruata in southern Mexico. The occurrence of magnetite particles in brain tissue of black sea turtles offers the opportunity for further studies to investigate possible function of ferrimagnetic material, its mineralogical composition, grain size, texture and its location and structural arrangement within the host tissue. After sample preparation and microscopic examination, we localized and identified the ultrafine unidimensional particles of magnetite by scanning electron microscope (SEM). Particles present grain sizes between 10.0 to 40.0Mm. Our study provides, for the first time, evidence for biogenic formation of this material in the black sea turtles. The ultrafine particles are apparently superparamagnetic. Preliminary results from rock magnetic measurements are also reported and correlated to the SEM observations. The black turtle story on the Michoacan coast is an example of formerly abundant resource which was utilized as a subsistence level by Nahuatl indigenous group for centuries, but which is collapsing because of intensive illegal commercial exploitation. The most important nesting and breeding grounds for the black sea turtle on any mainland shore are the eastern Pacific coastal areas of Maruata and Colola, in Michoacan. These beaches are characterized by important amounts of magnetic mineral (magnetites and titanomagnetites) mixed in their sediments.
DE: 1540 Rock and mineral magnetism
DE: 0400 Biogeosciences
SC: Biogeosciences [B]
MN: 2004 AGU Fall Meeting