Effect of the Elemental Content of Shells of the Bivalve Mollusks (Mytilus galloprovincialis) from Saldanha Bay (South Africa) on Their Crystallographic Texture.

Pavel Nekhoroshkov,Tatiana Lychagina,Dmitry Nikolayev,Jacques Bezuidenhout,Inga Zinicovscaia,Alexey Pakhnevich,Nikita Yushin

doi:10.3390/biology10111093

Abstract

Simple SummaryThe aim was to study the question of whether the texture of mollusk shells changes with alteration in their elemental composition. Even though significant differences between concentrations of elements among the stations were found, the crystallographic textures of mussel shells from the studied bays showed insignificant dissimilarities. The observed differences in the maximum values in the pole figures fell within the range of variability identified for the genus Mytilus. Nevertheless, they appeared to correlate with the concentrations of Br, Mg, and Sr, which merits further investigation using larger sample sizes and higher variabilities of the ecological state of mussels.A both wild and farmed mussels in natural conditions, anthropogenic inputs are usually reflected in the increase of the content of specific elements. To determine the possible effect of the elemental patterns of farmed and wild mussels (Mytilus galloprovincialis) collected in the Saldanha Bay area (South Africa) on the crystallographic texture of the shells, the content of 20 elements in shells and 24 in the soft tissue of mussels was determined by neutron activation analysis. The crystallographic texture of mussel shells was analyzed using time-of-flight neutron diffraction. The wild mussels from open ocean site live in stressful natural conditions and contain higher amounts of the majority of determined elements in comparison with mussels farmed in closed water areas with anthropogenic loadings. The changes between the maximums of the same pole figures of the three samples are in the range of variability identified for the genus Mytilus. The content of Cl, Sr, and I was the highest in mussels from the open ocean site, which is reflected by the lowest mass/length ratio. The determined crystallographic textures of mussels are relatively stable as shown in the analyzed pole figures despite the concentrations of Na, Mg, Cl, Br, Sr, and I in shells, which significantly differ for wild and farmed mussels. The stability of the crystallographic texture that we observed suggests that it can be used as a reference model, where if a very different texture is determined, increased attention to the ecological situation should be paid.

Highlights

IntroductionMussel (including filum Mytilus), it tolerates changes of a wide range of environmental parameters (temperature, salinity, and pH)
It is worth to note that levels of such elements as Sc, Sb, I, Cs, and Th were found in shells close to those in soft tissues, which means that shells could be used as biomonitors for such elements
A pole figure of polycrystalline material is the projection of the normals to

Summary

Introduction

Mussel (including filum Mytilus), it tolerates changes of a wide range of environmental parameters (temperature, salinity, and pH). Some studies have focused on the analysis of micro or macroelements along transects of shells to describe the temporal trends connected with change of the environmental parameters and growth rates [1]. Several works are dedicated to the analysis of the interlinking of elements in soft tissues and shells of mussels used as bioindicators of water pollution [4,5]. In such studies, the number of determined elements is usually low (3–12 elements). They are hindered by the limits of detection of the techniques and lack of reference data about microelement concentrations

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