Concetta Tigano

Assessment of environmental stress in Parablennius sanguinolentus (Pallas, 1814) of the Sicilian Ionian coast.

The blenny Parablennius sanguinolentus was selected as a useful bioindicator of environmental pollution. Chemical parameters in water and sediments from three different sampling sites along the Sicilian Ionian coast were determined and metal concentrations in fish muscle were measured. DNA fragmentation and oxidation in erythrocytes and hepatocytes was determined by the Comet assay and HSP70 expression levels were evaluated in the liver. The results show an increased level of chromium in sediments and high polycyclic aromatic hydrocarbon (PAH) concentrations in water at one site. The bioaccumulation of metals in muscle tissue shows high concentrations of lead in some samples. A high percentage of DNA damage in blood and liver cells, as well as high hepatic levels of HSP70, were found in all the sites. The results demonstrate the usefulness of an integrated chemical and biological approach for the determination of environmental stress.

Morphological and genetic variation in four Italian populations of Lebias fasciata (Teleostei, Cyprinodontidae)

Abstract Morphological and genetic analyses in four Italian populations of Lebias fasciata were carried out in order to assess the level of differentiation among populations. Fourteen meristic and 23 morphometric characters, relative to the skull, vertebral column, and the rays of the dorsal and anal fins were examined. In addition, variations at seven gene loci were investigated by allozyme electrophoresis. Both morphological and genetic results showed a noteworthy differentiation among the four populations which reflects their high degree of isolation. Allozyme results indicated that genetic variation is consistent with geographical distribution of these populations, while morphological differentiation cannot be interpreted biogeographically. The lack of dispersion phases in the life cycle of L. fasciata and its limited potential for gene flow account for the genetic divergence among populations. The inconsistency between morphological and genetic results for the two Sicilian populations may account for appreciable environmental (non‐genetic) influences on the morphological characters examined, which may obscure any enzyme‐morphological relation.

Genetic divergence among and within four Italian populations of Aphanius fasciatus (Teleostei, Cyprinodontiformes)

Due to the natural fragmentation of its habitats, Aphanius fasciatus, a Cyprininodontid living in coastal brackish‐water habitats, is distributed discontinuously with considerable isolation of its populations, and characterized by a high degree of osteological and genetic differentiation among them. The genetic relationships in four different Italian populations were studied using the control region (D‐loop) mitochondrial DNA sequence and the polymorphisms generated by RAPD‐PCR. The results revealed a well‐defined genetic structuring, that was also confirmed by the high Gst and Fst values, and a close relationship between the populations of Ganzirri and Lesina, as well as the isolation of the other two Sicilian populations. Moreover, with respect to the mitochondrial DNA analyses, the total genetic variance was higher among populations, but lower in the case of the RAPD polymorphisms.

Body shape variation and colour change during growth in a protogynous fish

Protogynous sequential hermaphroditism is very common in marine fish. Despite a large number of studies on various aspects of sequential hermaphroditism in fish, the relationship between body shape and colour during growth in dichromatic species has not been assessed. Using geometric morphometrics, the present study explores the relationship between growth, body shape and colouration in Coris julis (L. 1758), a small protogynous labrid species with distinct colour phases. Results show that body shape change during growth is independent of change in colour phase, a result which can be explained by the biology of the species and by the social control of sex change. Also, during growth the body grows deeper and the head has a steeper profile. It is hypothesized that a deeper body and a steeper profile might have a function in agonistic interactions between terminal phase males and that the marked chromatic difference between colour phases allows the lack of strict interdependence of body shape and colour during growth.

Traditional and geometric morphometrics detect morphological variation of lower pharyngeal jaw inCoris julis(Teleostei, Labridae)

Abstract In the present study, variation in the morphology of the lower pharyngeal element between two Sicilian populations of the rainbow wrasse Coris julis has been explored by the means of traditional morphometrics for size and geometric morphometrics for shape. Despite close geographical distance and probable high genetic flow between the populations, statistically significant differences have been found both for size and shape. In fact, one population shows a larger lower pharyngeal element that has a larger central tooth. Compared to the other population, this population also has medially enlarged lower pharyngeal jaws with a more pronounced convexity of the medial-posterior margin. The results are discussed in the light of a possible more pronounced durophagy of this population.

Effect of natural confinement on the gill cell types and bony elements of Lebias fasciata (Teleostei, Cyprinodontidae): A morphological and immunohistochemical analysis

Abstract Histochemical and immunohistochemical techniques were used to investigate the effect of stress from heavy metals on the respiratory epithelia of the cyprinodont Lebias fasciata living in confined natural environments with different degrees of pollution (brackish swamps of Faro‐Ganzirri and Lesina). This effect was evaluated on cytokeratins and calcium‐binding proteins, with particular reference to the presence of neuronal nitric oxide synthase in the cells of the diffuse neuroendocrine system (DNS). A morphometric examination was also performed to identify possible cranio‐facial and vertebral anomalies; however, the results were negative for all specimens from the two environments. Regarding the presence of heavy metals, only slight differences were found between the two environments, except for the higher concentration of aluminum in the Lesina swamp. In the gills of individuals from the latter environment, the epithelium presented a morphologically and immunohistochemically modified structure, with a concomitant over‐production of mucus; this acts as a barrier to oxygen diffusion, causing strong hypoxia. Therefore, it is hypothesized that the high number of DNS cells and nerve fibers im‐munopositive to nNOS in the respiratory epithelium of Lebias fasciata specimens from lesina is a local reaction to hypoxia.

Pharyngeal and oral jaw differentiation in five populations of Lebias fasciata (Teleostei, Cyprinodontidae)

Abstract The degree of osteological differentiation of the pharyngeal and oral jaws in five populations of Lebias fasciata was studied. Fourteen morphometric and meristic osteological characters were examined. The results allowed us to differentiate the five populations of L. fasciata and particularly that of Manzonara, living in the Salso river and showing a more evident osteological differentiation. It is probable that the observed morphological differentiation among populations of L. fasciata could be a result of their isolation and that the characters examined could represent partially or totally fixed genetic adaptations.

Osteological and molecular analysis of three Sicilian populations of Aphanius fasciatus (Teleostei, Cyprinodontidae)

Abstract The study of three Sicilian populations of Aphanius fasciatus was carried out by examining the mitochondrial control region and the morphology of the bony elements of the skull and vertebral column. The osteological and molecular data obtained indicate a marked differentiation between the populations examined resulting from their isolation, even if the dendrograms of the two approaches are dissimilar. Molecular investigations show that populations are characterized by haplotypes that are well defined in relation to the limited gene flow; while the osteological investigation may account for appreciable environmental influences on the morphological characters.

Bioaccumulation of metals and biomarkers of environmental stress in Parablennius sanguinolentus (Pallas, 1814) sampled along the Italian coast

Heavy metal pollution is one of the greatest threats to the ecosystems because it degrades the habitat and is potentially toxic to wildlife and human populations. In the last few decades, bioaccumulation studies performed with a multimarker approach have been a valuable tool for the investigation of environmental and animal safety. We perform an analysis of a benthic teleost fish species - Parablennius sanguinolentus - sampled at several Italian coastal sites with different degrees of anthropogenic pressure. Our integrative analysis encompasses bioaccumulation of 10 metals, biomarkers of environmental stress (micronuclei and nuclear abnormalities) and neutral genetic variation (using sequences of the mtDNA control region). We find a clear and significant correlation of metal bioaccumulation with micronuclei and nuclear abnormalities, especially with undisputed genotoxic metals, such as Cd, Cr, Hg and Pb. Furthermore, the molecular genetic analysis revealed a decrease of genetic variability in the populations more subjected to anthropic pressure.

Comparative pattern of genetic structure in two Mediterranean killifishes Aphanius fasciatus and Aphanius iberus inferred from both mitochondrial and nuclear data

In this study, genetic variation was assessed in Aphanius fasciatus and Aphanius iberus characterized by similar ecological traits but with very different distribution ranges in the Mediterranean area. Five populations of A. iberus and five of A. fasciatus were analysed using five polymorphic microsatellite loci and partial mitochondrial control region (D-loop) sequences. Congruent results were found with both nuclear and mitochondrial molecular markers. The results showed that similar levels of genetic divergence, based on mitochondrial control region sequences, are present among populations of A. iberus and among populations of A. fasciatus despite the very different geographic distance existing among the examined populations of the two species (low geographic distance in A. iberus and high in A. fasciatus). A possible explanation could be that the populations of A. iberus were isolated for a longer time than the populations of A. fasciatus supporting the hypothesis that the split in the lineage leading to A. iberus is older than the split in the lineage leading to A. fasciatus. The possibility that the wide circum-Mediterranean distribution of A. fasciatus ensures the high connectivity of its populations, preventing, in some cases, local differentiation, however, cannot be ruled out.