Comparative morphometric study of the invasive pearl oyster Pinctada radiata along the Tunisian coastline

Biologia (Impact Factor: 0.83). 04/2010; 65(2):294-300. DOI: 10.2478/s11756-010-0023-9


In order to study the relative growth of the pearl oyster Pinctada radiata in Tunisia, a total of 330 individuals of this species were collected from six sites along the Tunisian coastline. Quantitative
measurements of collected oysters were conducted for shell height, shell length, shell width, hinge length, height and width
of the nacreous part and wet weight. The size structure of the sampled populations was described and the relative growth between
different morphometric characteristics was estimated as allometric growth lines for the six P. radiata samples. It appeared that the majority of examined samples were dominated by large individuals that exceed a shell height
of 42 mm. The maximum size (100.5 mm), recorded in Bizerta lagoon, is bigger than that recorded elsewhere in particular in
the Red Sea. Size distribution analysis also showed that the majority of P. radiata samples were dominated by two or more size groups. Differences of allometric regression were found between the examined samples
for the tested relationships. Moreover, the Factorial Discriminant Analysis, coupled with Ascending Hierarchic Classification,
classified the sub-populations according to geographic locations.

Key wordsmorphometry-pearl oyster-
Pinctada radiata
-Tunisian coastline

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    • "This variation may be related to phenotypic plasticity (Kelly et al., 2012) and/or genetic variability (Benzie & Smith-Keune, 2006). Most morphogenetic investigations on the pearl oyster have focused on allopatric process, i.e. using samples from either end of a large geographic range with dissimilar environments with different ecological characteristics (Lind et al., 2007; Tlig-Zouari et al., 2010) to ensure the existence of a physical barrier and lack of a gene flow between the populations (Gopurenko & Hughes, 2002; Ward et al., 2006). As a result, sympatric differentiation of morphogenetic characterisics in P. radiata has rarely been reported, although it has been shown that morphological characteristics of P. radiata populations may differ without physical barriers (Rajaei et al., 2014). "
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    ABSTRACT: The pearl oyster, Pinctada radiata, shows great variation in shell morphology throughout its distribution. This variation can be related to phenotypic plasticity, genetic variability or a combination of both. Using geometric morphometric and microsatellite DNA analyses, two morphologically distinct populations of the pearl oyster were studied in the northern Persian Gulf, i.e. from the Lavan and Hendourabi Islands. Ten landmarks were selected to define the shape of the left shell. In addition, concentration of Zn, Mg, Fe, Cu, Pb, Cd, Mn and Cr of the soft tissues were measured using atomic absorption spectrometry. Six microsatellite loci were used to assess the population genetic structure of the pearl oyster. There were morphometric differences between the populations suggesting the existence of two morphotypes. There was a significant difference between the two populations in concentrations of Fe, Mg, Zn, Cd, Mn and Cr indicating that the specimens from the Lavan Island experience a more stressful environment than those from the Hendourabi Island. Analysis of molecular variance (AMOVA) indicated that the proportion of the genetic variation attributed to differences among populations of the pearl oyster was highly significant for both FST and RST (FST = 0.066, RST = 0.265, P < 0.001). Our findings showed that stressful conditions resulting from heavy metals may have a direct influence on the separation of the populations in Lavan and Hendourabi despite the lack of a physical barrier.
    Journal of the Marine Biological Association of the UK 11/2014; 95(03). DOI:10.1017/S0025315414001611 · 1.06 Impact Factor
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    • "). All measurements were done on the left valve (Huang and Okutani, 2003; Hwang et al., 2007; Tlig-Zouari et al., 2010). All morphological variables were transformed through dividing by the average (A) of SL, SH, and SW to remove the effects of size. "
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    ABSTRACT: Metapopulation characterization and discrimination of the pearl oyster Pinctada imbricata radiata in the northern part of the Persian Gulf is unknown. This study was conducted to examine differences in shell morphology of P. imbricata radiata from the Hendourabi and Lavan islands using principal component analysis (PCA) and elliptic Fourier analysis (EFA). Both EFA and PCA differentiated the shell form of the 2 populations significantly. PCA indicated that the pearl oysters from Hendourabi tended to be longer, while those from Lavan were wider and greater in thickness (width). Based on EFA, the specimens of Hendourabi Island were more fusiform than those from Lavan. In addition, the Lavan specimens were rounder than those from Hendourabi. The Lavan specimens had more diversity in form than those from Hendourabi. In conclusion, EFA and PCA approaches are clear-cut tools to identify and separate populations based on morphological characteristics, and EFA is a faster method compared with PCA in the discrimination of form in P. imbricata radiata.
    Turkish Journal of Zoology 10/2013; 37(1). DOI:10.3906/zoo-1207-9 · 0.63 Impact Factor
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    • "FDA method was used to show whether separation between the two shell forms occurs and CDA method was used to assess any differences within each shell form. The resulting multivariate analyses output identify the variables that contribute significantly to variation of shell shape within the sample sites and the discrimination between the tested samples is shown in the axis with high contribution of variables (Somers, 1986; Cadrin, 2000; Rabaoui et al., 2007; Tlig-Zouari et al., 2010b). Relationship significance was studied using the test of Monte-Carlo which is a test of permutation appropriately randomised allowing an exact and valid comparison compared to other tests (Blum et al., 1961; Dufour, 1981; Delgado, 1996). "
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    ABSTRACT: The morphometry of the limpet Patella ferruginea Gmelin, 1791 was described in four dense localities along the Northern Tunisian coastline, with use of univariate and multivariate analyses. Similarly to previous studies, the present study has confirmed the morphometric plasticity of the species. It also revealed the coexistence of the two shell forms rouxi and lamarcki in the same habitat, particularly in Zembra Island. Although it was only encountered within two localities (Kelibia and Zembra), the latter shell form was the less abundant in the study area. Multivariate analyses could highlight segregation between the four examined rouxi samples which can be matched to the geographic location of the sampling localities. Similarly, segregation between the samples was also found, on the basis of the shell form. Moreover, some intrasample heterogeneity was also detected in each shell form group. The coexistence of the two forms in the same locality seems to reflect that within a same biotope exist specific factors, e.g. the position on the substrate (slope) and the exposure of individuals (solar radiation), which are responsible for such morphological variation.
    Cahiers de Biologie Marine 01/2011; 52(3):269-278. · 0.80 Impact Factor
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