Spatio-temporal variability of trace elements fingerprints in cockle (Cerastoderma edule) shells and its relevance for tracing geographic origin

Fernando Ricardo,Ricardo Calado,Luciana Génio,Tânia Pimentel

doi:10.1038/s41598-017-03381-w

Abstract

Understanding spatio-temporal variability of trace elements fingerprints (TEF) in bivalve shells is paramount to determine the discrimination power of this analytical approach and secure traceability along supply chains. Spatio-temporal variability of TEF was assessed in cockle (Cerastoderma edule) shells using inductively coupled plasma-mass spectrometry (ICP-MS). Four elemental ratios (Mg/Ca, Mn/Ca, Sr/Ca and Ba/Ca) were measured from the shells of specimens originating from eight different ecosystems along the Portuguese coast, as well as from four different areas, within one of them, over two consecutive years (2013 and 2014). TEF varied significantly in the shells of bivalves originating from the eight ecosystems surveyed in the present study. Linear discriminant function analyses assigned sampled cockles to each of the eight ecosystems with an average accuracy of 90%. Elemental ratios also displayed significant differences between the two consecutive years in the four areas monitored in the same ecosystem. Overall, while TEF displayed by cockle shells can be successfully used to trace their geographic origin, a periodical verification of TEF (>6 months and <1 year) is required to control for temporal variability whenever comparing specimens originating from the same area collected more than six months apart.

Highlights

The common cockle (Cerastoderma edule) is one of the most abundant bivalves in the estuaries and bays of the European Atlantic coastline[1,2,3] and supports several commercially important fisheries[2, 4]
The present study aimed to evaluate if Trace element fingerprints (TEF) of cockle shells from specimens captured in eight different ecosystems along the Portuguese Atlantic coastline (Fig. 1), where commercial fisheries targeting the live trade of this species occurs, can be used to successfully discriminate their geographic origin
Trace element fingerprints (TEF) of Cerastoderma edule shells differed among ecosystems, with the exception of Mira estuary (ME) and Ria de Alvor (RAl), with MANOVA analyses revealing strong significant differences when considered all trace elements together (Table 1)

Summary

Introduction

The common cockle (Cerastoderma edule) is one of the most abundant bivalves in the estuaries and bays of the European Atlantic coastline[1,2,3] and supports several commercially important fisheries[2, 4]. To protect consumers from potential risks, the European Union (EU) classifies the capture/production areas of bivalves according to the loads of E. coli present in the flesh and intra-valvular liquid of live specimens[12, 13] In this way, it is paramount in terms of seafood safety to know as accurately as possible the geographic origin of bivalves being traded for human consumption (e.g. adjacent areas, even in the same ecosystem, may display contrasting classifications for their capture/production). The present study aimed to evaluate if TEF of cockle shells from specimens captured in eight different ecosystems along the Portuguese Atlantic coastline (Fig. 1), where commercial fisheries targeting the live trade of this species occurs, can be used to successfully discriminate their geographic origin. The present study aimed to determine the temporal stability of TEF in cockle shells between two consecutive years (2013 and 2014) in areas within the same ecosystem (Fig. 1a) but displaying different classifications (according to European regulation (EC) No 1379/201318 for the capture/production of bivalves

Methods

Results

Conclusion