| Summary: | Stable isotope compositions of carbon and nitrogen (expressed as delta C-13 and delta N-15) from the European common cuttlefish (Sepia officinalis) were measured in order to evaluate the utility of using these natural tracers throughout the Northeast Atlantic Ocean and Mediterranean Sea (NEAO-MS). Mantle tissue was obtained from S. officinalis collected from 11 sampling locations spanning a wide geographical coverage in the NEAO-MS. Significant differences of both delta C-13 and delta N-15 values were found among S. officinalis samples relative to sampling location. delta C-13 values did not show any discernable spatial trends; however, a distinct pattern of lower delta N-15 values in the Mediterranean Sea relative to the NEAO existed. Mean delta N-15 values of S. officinalis in the Mediterranean Sea averaged 2.5 parts per thousand low than conspecifics collected in the NEAO and showed a decreasing eastward trend within the Mediterranean Sea with the lowest values in the most eastern sampling locations. Results sugge delta N-15 may serve as a useful natural tracer for studies on the population structure of S. officinalis as, well as other marine organisms throughout the NEAO-MS.
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