Regional patterns of δ 13C and δ 15N for European common cuttlefish (Sepia officinalis) throughout the Northeast Atlantic Ocean and Mediterranean Sea.

R J David Wells,Rui Rosa,Emily N Meese,Thomas Lacoue-Labarthe,Miguel Baptista,Ignacio Sobrino,Piero Addis,Giovanni Bearzi,Antonio V Sykes,Roger Villanueva,Jay R Rooker,Haritz Arrizabalaga,Persefoni Megalofonou,Igaratza Fraile

doi:10.1098/rsos.210345

Abstract

Stable isotope compositions of carbon and nitrogen (expressed as δ13C and δ15N) 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 δ13C and δ15N values were found among S. officinalis samples relative to sampling location. δ13C values did not show any discernable spatial trends; however, a distinct pattern of lower δ15N values in the Mediterranean Sea relative to the NEAO existed. Mean δ15N values of S. officinalis in the Mediterranean Sea averaged 2.5‰ lower 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 suggest δ15N 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.

Highlights

The European common cuttlefish, Sepia officinalis Linnaeus, 1758 is a coastal nektobenthic species ranging from the Shetland Islands through the Northeast Atlantic Ocean and Northwest Africa into the Mediterranean Sea [1]
(Sepia officinalis) were measured in order to evaluate the utility of using these natural tracers 2 throughout the Northeast Atlantic Ocean and Mediterranean Sea (NEAO-MS)
Subsamples of cuttlefish were paired with both (i) immediately freeze dried and (ii) ethanol-preserved specimens later freeze dried from Bay of Biscay–South (n = 20) and Gulf of Cadiz (n = 19) sample locations in order to assess if sample preservation techniques affected δ13C and δ15N

Summary

Introduction

The European common cuttlefish, Sepia officinalis Linnaeus, 1758 is a coastal nektobenthic species ranging from the Shetland Islands through the Northeast Atlantic Ocean and Northwest Africa into the Mediterranean Sea [1]. Sepia officinalis has a relatively short lifespan of 1–2 years, early sexual maturity and an extended spawning season laying eggs on the seafloor with direct benthic, large hatchlings [4,5] Given this species geographical distribution combined with limited dispersal, it has been a targeted model species to examine connectivity throughout the Northeast Atlantic Ocean and Mediterranean Sea (hereafter NEAO-MS) [6]. Depending upon the types of nutrients available to stimulate growth, δ15N values can be used to track energy flow in high-nutrient (nitrate) and low-nutrient (N2 fixation) ecosystems as well as new nitrogen (upwelled nitrate) versus regenerated nitrogen (ammonia, urea) Combining both δ13C and δ15N offers the potential to study the connectivity and population structure of species because longitudinal and latitudinal gradients exist throughout marine ecosystems [11,12], including the NEAO-MS [8,13]

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Conclusion