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V Encuentro Sud Americano de Colisiones Inelásticas en la Materia
Chemical Characterization of Fish-Otoliths using Micro-PIXE
Stori, E. M. 1 , Dias, J. F. 1 , Favero, J. M. 2 , Dias, J. F. 2
1 Laboratório de Implantação Iônica – Instituto de Física, Universidade Federal do Rio Grande do Sul, Av. Bento
Gonçalves 9500, Porto Alegre, RS , Brasil
2 Instituto de Oceanografia – Universidade Estadual de São Paulo – São Paulo, SP, Brasil
email address corresponding author: elistori@gmail.com
Fishes contain a group of three pairs of
bone structures in their ear that are responsible
for hearing and equilibrium. These structures
grow in layers that look like rings if
sectioned (figure 1). [1]
of interest and its position in the otolith.
[5][6]
The knowledge of the trace elements
present in different rings would allow to establish
a relation between different places the
fish have lived and the stages of its life.
Figure 2 shows calcium maps of a juvenile
fish otolith, in which can be observed
the growth rings through the difference of
intensity of the calcium signal.
Figure 1. Sectioned otolith showing growth rings [2]
There are very well developed studies
that relate the rings in the otoliths with the
fishes’ age. While in adult’s otoliths the rings
may represent years of age, in juvenile fishes
and larvae the rings represent days. [1]
Moreover, the otoliths may give information
of fish migration pattern or their origin
by determining the trace elements contained
in them. [3][4]
The micro-PIXE technique (micro-
Particle Induced X-Ray Emission) is not
regularly used to determine trace elements in
otoliths. Its advantages include the nondestructive
character of the technique, and
the possibility of a spacial characterization of
the elements, enabling a more accurate analysis
of the relation between the trace element
(a)
(b)
Figure 2. Calcium maps of a juvenile fish otolith (a)
the entire otolith and (b) a more detailed map of the
central region of the otolith.
20 Valparaíso, Chile