Bioaccumulation of polycyclic aromatic hydrocarbons in Solea solea from Bizerte and Ghar El Melh Lagoons (Tunisia) and human health risk assessment.

The present study objective was to assess polycyclic aromatic hydrocarbons in Bizerte and Ghar El Melh Lagoons Solea solea and to assess the potential risk to human health from its consumption. To reach these objectives twenty fish samples from each site were collected and 15 priority polycyclic aromatic hydrocarbons (PAHs) were analyzed in their muscles using high-performance liquid chromatography with a fluorescence detector. Total PAH sole concentrations from Bizerte and Ghar El Melh Lagoons were similar or lower to those recorded in other species from other regions across the world. In the studied fish species, the 2 and 3 ring PAHs are the dominated compounds that enter to the composition of PAHs which indicates that PAHs could be principally derived from a petrogenic origin for the both studied lagoons. The human health risk by sole consumption was evaluated and revealed to exhibit no hazard to the local population health concerning PAH intakes. The findings of this biomonitoring study will help in the implementation of sustainable environmental policies for effective water pollution control and the two investigated lagoons management.

Legacy and Emerging Brominated Flame Retardants in Bizerte Lagoon Murex (Hexaplex Trunculus): Levels and Human Health Risk Assessment.

Occurrence of traditional (PBDEs) and novel (HBB, PBEB, DBDPE) brominated flame retardants, as well as the natural compounds of MeO-PBDEs, were studied in a shellfish species (Hexaplex trunculus) sampled from Bizerte Lagoon. PBDE and MeO-PBDE mean concentrations in murex soft tissues were 187 and 264 ng g-1 lw respectively. The alternative flame retardants were not identified. The sum of PBDE and MeO-PBDE levels recorded in murex from the investigated aquatic ecosystem were comparable or a relatively lower than those reported for other organisms from other regions across the world. The amount of PBDE and MeO-PBDE concentrations from the Bizerte Lagoon recorded in murex were comparable or a relatively lower than those recorded from other areas across the world for other species. There is not a danger to the population health with regard to PBDE intakes associated with the consumption of murex in Bizerte city. We believe that this is the first study of the analysis of these pollutants in marine gastropod mollusks from Tunisian aquatic areas.

Monitoring and assessment of environmental disturbance on natural Gambusia affinis populations--histopathological analysis.

Physiological investigations are often used to assess the toxic effects of aquatic pollutants in fish and to establish criteria for water quality. In the present study, we tend to investigate the growth performance, skeletal abnormalities, and histological alterations noticed in three natural populations of the mosquitofish Gambusia affinis captured from three estuary sites. The analysis of growth performance demonstrated that the studied populations showed different growth patterns. Additionally, various types of skeletal deformities were observed, and the most commonly affected were the hemal and pre-hemal regions of fishes. For the histological study, gills, liver, and kidney tissues were selected for field monitoring. The major alterations observed in gill tissues were partial fusion of adjacent secondary lamellae, hypertrophy of epithelial cells, and disorganization of pillar cells in many areas of the secondary lamellae. In the liver, significant desquamation of tissues, congestion of the central hepatic vein, and hypertrophy of hepatocytes were noticed. For the kidney tissue, the frequencies of histological alterations showed a significant difference between the studied sites. Moreover, the histological aberrations consisted mainly in glomerule alteration and vacuolation of tubular epithelial cells. Taken together, these data support the hypothesis that the physiological alterations noticed in the present investigation are indicators of sensitivity towards environmental disturbance.

Structural and molecular analysis of pollution-linked deformities in a natural Aphanius fasciatus (Valenciennes, 1821) population from the Tunisian coast.

The Eastern coast of Tunisia hosts a mosaic of populations of the Mediterranean killifish A. fasciatus, an excellent monitoring species for the analysis of environmental impact in coastal Mediterranean areas. Among these populations, fish from the Sfax area, in the Gulf of Gabès, are known for presenting a high prevalence of different physiological alterations, including spinal deformation. Compared to a reference clean area, Luza, Sfax water and sediments are polluted with heavy metals (20 to 40 times more Cd, for example) and other compounds like PAHs (10 times higher levels). Histological analyses of deformed fish from this area showed an abnormal abundance of collagen fibers infiltrated in the spinal area, either as a physiological mechanism to alleviate the consequences of the deformation of the bones or as a secondary effect of the same pathological/toxicity mechanism inducing bone deformation. Deformed fish from Sfax showed elevated (4-5 fold) levels of transcripts from the collagen COL1A2 gene in bone tissue, compared to either non-deformed animals from the same location or normal animals from the reference Luza site. These results are consistent with an overexpression of collagen in the bone tissue, in agreement with the histological results. We propose that the deformation observed in the Sfax Aphanius population is a degenerative process occurring in adult animals and probably terminal, as it results in severe limitations on the fish capacity to swim, to catch food, and ultimately to survive.

First evidence of the utility of cephalopods for biomonitoring program in the field: case of Sepia officinalis south west of Mediterranean Sea (Gulf of Gabes, Tunisia).

This study was carried out to determine the concentration of selected heavy metals in common cuttlefish (Sepia officinalis) caught in the south west of Mediterranean Sea (Gulf of Gabes, Tunisia). To reach this objective, cuttlefish samples were collected from each area (Sfax and Djerba) situated along the Gulf of Gabes, and the concentrations of heavy metals (Cu, Zn, Pb, and Cd) were measured in the gills, gonads, digestive glands, and muscles. Sample preparation and quantification of the metals were accomplished via the wet digestion method and atomic absorption spectroscopy. The levels of heavy metals varied significantly among organs and sites. In fact, the population from Sfax (Gargour) shows the highest concentrations of copper, zinc, and lead compared to the population from Djerba. Globally, recorded metal concentrations were within the range or below the levels in similar species from other regions across the world. To our knowledge, this study is the first that interests to the bioaccumulation of metals in this cuttlefish species from the two investigated areas and to the evaluation of their levels in different tissues.

Biomarkers responses and polybrominated diphenyl ethers and their methoxylated analogs measured in Sparus aurata from the Lagoon of Bizerte, Tunisia.

This study aimed to the examination of the levels and effects of organobromine compounds (polybrominated diphenyl ethers: PBDEs and methoxylated brominated diphenyl ethers: MeO-PBDEs), in Sparus aurata native to the Lagoon of Bizerte. For that, different biomarkers of exposure (somatic indices, superoxide dismutase, and catalase activities) and effect (malondialdehyde level, histopathologic alterations, and DNA damage) as well as pollutant levels were measured in specimens collected from this impacted ecosystem and the Mediterranean Sea as a reference site. Bizerte Lagoon PBDE fish levels were higher than the Mediterranean Sea, whereas MeO-PBDEs were higher in the reference site. Fish from Bizerte Lagoon presented a higher hepatosomatic index, lower catalase and superoxide dismutase activity, higher level of malondialdehyde, and higher percentage of DNA tail in comparison to fish from the reference area. The histological study of the liver indicated substantial lesions in fish from the polluted site. The results showed strong positive correlations between the concentrations of the PBDE or MeO-PBDE and the MDA and DNA tail % levels and negative correlations for the activities of enzymes of SOD and CAT. Consequently, these findings could suggest a potential link between exposure to these pollutants and the observed biomarker responses in the Bizerte Lagoon seabream. Taken together, these results highlight the importance of biomarker selection and the selected sentinel fish species as useful tools for biomonitoring of aquatic pollution.

Influence of high temperature on cadmium-induced skeletal deformities in juvenile mosquitofish (Gambusia affinis).

The aim of this study was to assess the effect of high temperature on cadmium (Cd)-induced skeletal deformities in juvenile Mosquitofish, Gambusia affinis. For this purpose, 188 juveniles (1 day old) were equally divided into the control group, which was maintained in Cd-free water at 24 degrees C, and three treated groups exposed either to Cd (0.4 mg/l as Cd Cl(2)) at 24 degrees C, to high temperature (32 degrees C), or to Cd at 32 degrees C for 30 days. The results showed that Cd exposure at 24 degrees C significantly increased the Cd accumulation (P < 0.0001) in the whole tissues of juveniles as well as the incidence of skeletal deformities (P < 0.01) compared with control animals. Exposure to high temperature also led to a significant increase in the incidence of skeletal deformities (P < 0.01) with respect to the control group. Interestingly, our results showed that the combined exposure to Cd and high temperature led to a more significant increase in Cd accumulation and in the frequency of spinal deformities than exposure to Cd or high temperature alone. These results confirm that temperature increases Cd toxicity and needs to be taken into account for the accurate prediction and assessment of Cd-induced spinal deformities in fish.

Comparative study of the sensitivity to cadmium of two populations of Gambusia affinis from two different sites.

This study aims to demonstrate the influence of animals' origin on their sensitivity toward heavy metals. For this purpose, we compared LC(50) of cadmium in two populations of Gambusia affinis captured in two geographically isolated environments in the east of Tunisia; Oued El Gsil in the city of Monastir (S2) and Oued Chenini in the region of Gabes (S1). Although physicochemical parameters of the water (pH, dissolved oxygen and salinity) are similar in the two studied sites, cadmium concentrations in water, sediments and fish tissues from S1 are significantly higher (P < 0.01) than those from S2, 48-h and 96-h LC(50) of the (S1) population are significantly higher than those from S2. In the same way, the offspring of the polluted site (S1) population exhibit 48-h and 96-h LC(50) values much higher than those of the reference site (S2) population. These results show that the population of the Gabes region is more resistant to cadmium than that of the Monastir region and that this resistance could have a genetic basis. These results indicate the influence of the origin of animals that has to be taken into account not only in laboratory toxicity tests, but also in field ecotoxicological studies.

Distinctive accumulation patterns of heavy metals in Sardinella aurita (Clupeidae) and Mugil cephalus (Mugilidae) tissues.

The present study assessed the impact of metal pollution on two widely consumed types of wild fish Sardinella aurita and Mugil cephalus captured from the Gulf of Gabes (Tunisia) which is currently experiencing acute environmental problems. A study of the Cd, Cu, Zn, and Pb levels present in the studied site and vital in fish tissues (gills, liver, gonad, and muscle) was undertaken. As expected, muscle, liver, and gonad tissues contained the highest concentrations of all metals except for Zn. The metal levels showed a significant variation of accumulation between species with overall effects of the tested tissues. In addition, the results address the significant effects of the species/tissue interaction. Liver sections showed structural alterations consisting mainly of a significant desquamation of the tissue, a fibroblast proliferation, and a lipid droplet accumulation in both species. Additionally, the presence of skeletal abnormalities affecting the vertebral column was observed in the M. cephalus specimens. As a whole, our data provide the first evidence of distinctive metal accumulation patterns in vital fish tissues as well as the interspecific difference that can be correlated with the biological habits of the two selected models, S. aurita and M. cephalus, known respectively as pelagic and benthopelagic species.

Baseline assessment of heavy metals content and trophic position of the invasive blue swimming crab Portunus segnis (Forskål, 1775) in the Gulf of Gabès (Tunisia).

This study provides a baseline assessment of cadmium, copper, iron, manganese, lead, and zinc concentrations in muscles, gills, and exoskeleton of the Lessepsian blue swimming crab Portunus segnis captured in the Gulf of Gabès (Southern Mediterranean Sea, Tunisia) in November 2015. Furthermore, the species' trophic position is estimated using CN stable isotope analysis. The exoskeleton showed the lowest metal contents; in soft tissues, the essential Cu, Fe, and Zn and the non-essential Cd, Mn, and Pb showed the highest and lowest concentrations, respectively. The crab was characterized by a trophic position of 3.32, confirming its carnivorous trophic habits. Compared with literature data on invertebrate and fish species from the same area, Cd and Pb resulted remarkably low in the crab's soft tissues, while a food web-scale dilution effect was indicated. The need of a comprehensive assessment of the ecological impact of Portunus segnis in invaded Mediterranean waters is discussed.

Heavy metal levels in gonad and liver tissues-effects on the reproductive parameters of natural populations of Aphanius facsiatus.

The impact of heavy metal levels (Cd, Cu, and Zn) on the reproductive parameters in natural populations of the Mediterranean killifish Aphanius fasciatus was monitored in four sites of the Tunisian coast. Our study covered a period of the reproductive cycle, from April to November 2009. The significantly higher levels of Cd, Cu, and Zn in the liver and gonads for both sexes (p<0.05) were observed in the most polluted site (Sfax coast). During the reproductive cycle of A. fasciatus, an unbalanced sex ratio in favor to females was observed for all the studied populations. The progression of the hepato- (HSI), gonadosomatic (GSI), and K-factor revealed a spatio-temporal variation between populations during the sampling period. Estradiol-17ß amounts in the gonad tissues of females captured from the studied sites showed a significant difference, and the highest concentrations were noticed in the control site (Luza). Taking together, our data provide the first evidence of a physiologically stress and a disturbance of the reproductive status in natural populations of A. fasciatus.

Possible chemical causes of skeletal deformities in natural populations of Aphanius fasciatus collected from the Tunisian coast.

This study attempt to quantify and identify skeletal deformities in natural populations of Aphanius fasciatus collected from the Tunisian coast and tends to found a possible relationship between these anomalies and several types of pollutants presents in the environment. Fish were collected from one reference area (S1: coast of Luza) and three polluted areas (S2: industrialized coast of Sfax, S3: coast of Khniss and S4: Hamdoun'Oued). Various patterns of skeletal deformities were diagnosed using double staining technics, and the levels of heavy metals (Cd, Cu and Zn), various polycyclic aromatic hydrocarbons (PAHs) and estrogenic compounds were determined in water and sediment from different sites. Spatio-temporal variation of the spinal deformities frequencies in A. fasciatus show that high incidence of spinal anomalies has been recorded in population collected from S2 in comparison to three other ones. Morphological results indicated that skeletal deformities of adult A. fasciatus were grouped into 13 categories that described abnormalities on spines, vertebrae, arcs and mandibles. A total of 1025 abnormalities were quantified. The results of chemical analysis showed that the levels of heavy metals and PAHs were significantly higher in S2 than in S1, S3 and S4. High level of estrogenic activity was observed only in S4. A possible correlation between environmental exposures to a mixture of pollutants in coastal waters in S2 and spinal deformities in A. fasciatus was suggested.

Influence of cadmium exposure on growth and fecundity of freshwater mosquitofish Gambusia affinis: in situ and in vivo studies.

This study aims to investigate the effect of cadmium (Cd) exposure on growth and fecundity of mosquitofish Gambusia affinis. For this purpose, two natural populations of pregnant females of G. affinis captured from two sites were differently contaminated with Cd (S1 present Cd levels 5-fold higher than S2) and a sublethal exposure to 0.4 mg CdCl(2)/L (10% of LC(50)) during 56 days was conducted in vivo. The length-weight regression revealed a significant difference in the growth between these two populations. A significant difference in fecundity was also noted between the two populations. Indeed, the embryo numbers in pregnant females captured from S1 are significantly higher than those noted in pregnant females from S2 (21.17±5 and 7.97±2.12, respectively; p<0.05). Following Cd exposure, we noted a growth perturbation resulting in lower values of both indices BWG and SGR following 7 and 21 days (-5.21 and -1.18 for BWG, and -2.09 and -0.46 for SGR, respectively) and a recuperation of growing weight at 42 and 56 days (1.32 and 1.71 for BWG, and 0.45 and 0.54 for SGR, respectively). For CF index, we observed a significant difference (p<0.05) between control and Cd groups at 7 and 21 days of exposure, and at 21 and 56 days respectively for HSI and GSI indices. Furthermore, Cd contents in both tissues (liver and yolk sac) and fractions (cytosolic and membrane) are significantly different between groups during experimentation. In addition, the Cd contents noticed in the liver membrane fraction are significantly higher than those noted in the yolk sac tissue. The MTs levels revealed a significant difference between the control and Cd groups. In liver tissue, a significant difference was noted, in MTs levels, during the Cd exposure (7, 21, 42, and 56 days) while in the yolk sac tissue the difference was noted at 42 days of exposure. Taken together, these results imply the potential negative effect of Cd on physiological status of G. affinis as evidenced by decreasing growth and fecundity rate.