Use of stable isotopes to estimate trophic ecology in Common Octopus (Octopus
vulgaris) from three sites off the Atlantic coast of Galicia (NW Spain)
Moreno R1, Rocha F2, Jover L3, Ruiz X1 & Sanpera C1
1 Dept Animal Biology. Fac. Biology. University of Barcelona. Diagonal 645. 08028
Barcelona, Spain
2 Dept Ecolgy and Animal Biology. Fac. Sciences. University of Vigo. Campus As
Lagoas Marcosende, 36310, Spain
3 Dept Public Health. Fac. Medicine. University of Barcelona. Casanova 143. 08036
Barcelona, Spain
During winter of 2005, 41 common octopus (Octopus vulgaris), 26 females and 15
males, were sampled at three fishing localities (Meira, Finisterre and Cedeira) off the
Atlantic coast off Galicia (NW Spain). We explored the potential use of stable isotope
analysis in octopus tissues to approach its trophic ecology, given the limitations found
to the study of feeding habits in this species, which is fished using bait. Some of their
life-history characteristics, predator habits and territorial behaviour make the octopus a
good candidate to explore its usefulness when looking for geographical differences in
local trophic webs. In the present study, stables isotopes of nitrogen ( 15N) and carbon (
13
C) were analysed in samples of lipid-free beak and mantle musculature. On the other
hand, we collected biometric data and determined reproductive status of these
individuals. Signatures of nitrogen were significantly lower in beaks than in mantle
tissue, whereas differences in carbon signatures between these tissues were much
smaller. A positive relationship between 15N and 13C was found in the muscle mantle as
well as in the beak; isotopes signatures between both tissues were also found to be
significantly correlated. Differences were found in both isotopes amongst sampling
localities. The interpretation of these differences is discussed in relation to the
oceanographic characteristics of Galician coast and in relations to the biological
parameters of octopuses.
The 5th International Conference on
Applications of Stable Isotope Techniques to Ecological Studies
Queens University Belfast, Northern Ireland
13-18 August 2006