Ligament, hinge, and shell cross-sections of the Atlantic surfclam (Spisula solidissima): Promising marine environmental archives in NE North America

Pierre Poitevin (1) , Julien Thébault (1) , Bernd R. Schoene (2, 3) , Aurelie Jolivet (4) , Pascal Lazure (5, 6) , Laurent Chauvaud (1)

1 LEMAR - Laboratoire des Sciences de l'Environnement Marin (LEMAR)
2 JGU - Johannes Gutenberg - Universität Mainz = Johannes Gutenberg University
3 Institute of Geosciences [Mainz]
4 TBM environnement
5 LOPS - Laboratoire d'Océanographie Physique et Spatiale
6 IFREMER - Institut Français de Recherche pour l'Exploitation de la Mer

The Atlantic surfclam (Spisula solidissima) is a commercially important species in North American waters, undergoing biological and ecological shifts. These are attributed, in part, to environmental modifications in its habitat and driven by climate change. Investigation of shell growth patterns, trace elements, and isotopic compositions require an examination of growth lines and increments preserved in biogenic carbonates. However, growth pattern analysis of S. solidissima is challenging due to multiple disturbance lines caused by environmental stress, erosion in umbonal shell regions, and constraints related to sample size and preparation techniques. The present study proposes an alternative method for describing chronology. First, we analyzed growth patterns using growth lines within the shell and hinge. To validate the assumption of annual periodicity of growth line formation, we analyzed the oxygen isotope composition of the outer shell layer of two specimens (46 degrees 54'20 '' N; 56 degrees 18'58 '' W). Maximum delta O-18(shell) values occurred at the exact same location as internal growth lines in both specimens, confirming that they are formed annually and that growth ceases during winter. Next, we used growth increment width data to build a standardized growth index (SGI) time-series (25-year chronology) for each of the three parts of the shell. Highly significant correlations were found between the three SGI chronologies (p \textless 0.001; 0.55 \textless tau \textless 0.68) of all specimens. Thus, ligament growth lines provide a new method of determining ontogenetic age and growth rate in S. solidissima. In a biogeographic approach, the shell growth performance of S. solidissima in Saint-Pierre and Miquelon was compared to those in other populations along its distribution range in order to place this population in a temporal and regional context.

Mots clés: bottom water temperature; clam; isotopes; ocean; age; oxygen; growth-rate; populations; bivalvia; ACL

Domaines: Biodiversité et Ecologie

Pierre Poitevin, Julien Thébault, Bernd R. Schoene, Aurelie Jolivet, Pascal Lazure, et al.. Ligament, hinge, and shell cross-sections of the Atlantic surfclam (Spisula solidissima): Promising marine environmental archives in NE North America. PLoS ONE, 2018, 13 (6), pp.e0199212. ⟨10.1371/journal.pone.0199212⟩. ⟨hal-02401178⟩