Elements in Soft Tissues of the Young Mediterranean Mussel Mytilus galloprovincialis Lam. 1819 Collected in Sevastopol Bay (Crimea, Black Sea): Effects of Age, Sex, Location, and Principal Morphometric Parameters

Abstract

Although the mussel Mytilus galloprovincialis has been known for decades as an excellent bioindicator of trace element pollution in the marine environment, there is still no information on the effects of a suite of its principal morphometric parameters and age on trace element levels in soft tissues. In this work, using inductively coupled plasma mass spectrometry, we studied the contents of 72 elements in soft tissues of M. galloprovincialis aged 0.5–4, which were sampled at three stations within a relatively small water body, Sevastopol Bay. Significant effects of age and sampling location on the element contents and soft tissue dry-to-wet weight ratio were discovered. The effects of sex were not significant. It was presumed for the first time that the decrease in element content in the soft tissues of young mussels can be associated with the decrease in physiological needs for elevated contents of essential elements and intracellular water with age. Combinations of six principal morphometric parameters showed that a function of as few as three parameters (soft tissue dry weight, whole mollusk weight, and shell height, with by far the greatest contribution of the dry-to-total weight ratio) formed significant correlations with the contents of the largest possible number of elements (69–88% of the total number). For the first time, it was shown that linear discriminant analysis and canonical analysis of principal coordinates can be successfully used for tracing the exact origin of mussel samples within such a small water area. Canonical analysis of principal coordinates proved superior in the correct classification of the samples.

Rare Earth Elements in Shells of Black Sea Molluscs: Anomalies and Biogeochemical Implications

“…There exist special methods of multivariate analysis, such as linear discriminant analysis (LDA) and canonical analysis of principal coordinates (CAP), that are best suited for this purpose. These methods have been used for the accurate tracking of sampling locations of a number of molluscs [75,[123][124][125][126][127][128], and CAP proved to be superior, compared to LDA, in the correct classification of the locations [75]. In the present work, it is shown that mollusc species can also be successfully identified based on the REE contents in their shells.…”

“…In CAP, species identity was the group factor, and the number of permutations in the hypothesis testing was 999. The fundamentals for both multivariate ordination techniques are briefly outlined in the Supplementary Materials to [75]. For the agglomerative hierarchical cluster analysis (CLUSTER function), no standardization was applied, and the unweighted pair-group average was chosen as the clustering algorithm.…”

“…As this method seeks to maximize the dispersion along principal coordinates, it can discriminate between samples with sufficiently different element abundances. However, PCA demonstrates only moderate success in identifying separate groups of marine organisms based on a specific group criterion [73,75,[119][120][121][122], as also seen in Figure 3a. There exist special methods of multivariate analysis, such as linear discriminant analysis (LDA) and canonical analysis of principal coordinates (CAP), that are best suited for this purpose.…”

“…Principal component analysis applied to standardized element contents in tissues of Black Sea organisms usually associates principal component 1 with the overall element contamination in the environment [75,118,119]. As this method seeks to maximize the dispersion along principal coordinates, it can discriminate between samples with sufficiently different element abundances.…”

“…REE distribution was studied in marine biogenic carbonate skeletons of microbialites [53][54][55], corals [56][57][58][59][60][61] and foraminifera [62][63][64][65] in relation to their environment. There are a number of studies on the accumulation of REE in freshwater and marine molluscs in their natural habitat [4,[66][67][68][69][70][71][72][73][74][75][76][77][78][79][80][81] and on REE effects on molluscs exposed to these metals in laboratory conditions [82][83][84][85][86][87][88][89]. In some studies [68,78], it was found that the REE composition of shells of bivalves matched that of seawater, which implied the possibility of using shells as biomonitors of REE pollution in the marine environment.…”