Hydrocarbons in size-fractionated plankton of the Mediterranean Sea (MERITE-HIPPOCAMPE campaign).

Aliphatic and polycyclic aromatic hydrocarbons (AHs and PAHs, respectively) were analyzed in the dissolved fraction (<0.7 µm) of surface water and in various particulate/planktonic size fractions (0.7-60, 60-200, 200-500 and 500-1000 µm) collected at the deep chlorophyll maximum, along a North-South transect in the Mediterranean Sea in spring 2019 (MERITE-HIPPOCAMPE campaign). Suspended particulate matter, biomass, total chlorophyll a, particulate organic carbon, C and N isotopic ratios, and lipid biomarkers were also determined to help characterizing the size-fractionated plankton and highlight the potential link with the content in AHs and PAHs in these size fractions. Æ©28AH concentrations ranged 18-489 ng L-1 for water, 3.9-72 µg g-1 dry weight (dw) for the size fraction 0.7-60 µm, and 3.4-55 µg g-1 dw for the fractions 60-200, 200-500 and 500-1000 µm. AH molecular profiles revealed that they were mainly of biogenic origin. Æ©14PAH concentrations were 0.9-16 ng L-1 for water, and Æ©27PAH concentrations were 53-220 ng g-1 dw for the fraction 0.7-60 µm and 35-255 ng g-1 dw for the three higher fractions, phenanthrene being the most abundant compound in planktonic compartment. Two processes were evidenced concerning the PAH patterns, the bioreduction, i.e., the decrease in concentrations from the small size fractions (0.7-60 and 60-200 µm) to the higher ones (200-500 µm and 500-1000 µm), and the biodilution, i.e., the decrease in concentrations in plankton at higher suspended matter or biomass, especially for the 0.7-60 and 60-200-µm size fractions. We estimated the biological pump fluxes of Æ©27PAHs below 100-m depth in the Western Mediterranean Sea at 15 ± 10 ng m-2 day-1, which is comparable to those previously reported in the South Pacific and Indian Ocean.

Microplastic-sorbed persistent organic pollutants in coastal Mediterranean Sea areas of Tunisia.

Microplastics (MPs) are emerging pollutants of global concern due to their pervasiveness, high sorption ability for persistent organic pollutants (POPs) and direct and indirect toxicity to marine organisms, ecosystems, as well as humans. As one of the major coastal interfaces, beaches are considered among the most affected ecosystems by MPs pollution. The morphological characteristics of MPs (pellets and fragments) collected from four beaches along the Tunisian coast and sorbed POPs, including polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs), were investigated in this study. The results showed that the MPs varied greatly in color, polymer composition and degradation degree. The color varied from colored to transparent and the most prevalent polymer identified using Raman spectroscopy was polyethylene. Scanning electron microscope (SEM) images exhibited various surface degradation features including cavities, cracks, attached diatom remains, etc. The concentrations of Σ12PCBs over all beaches ranged from 14 to 632 ng g-1 and 26 to 112 ng g-1 in the pellets and fragments, respectively, with a notable presence and dominance of highly-chlorinated PCBs such as CB-153 and -138. Among the OCPs, γ-HCH is the only compound detected with concentrations ranging from 0.4 to 9.7 ng g-1 and 0.7 to 4.2 ng g-1 in the pellets and fragments, respectively. Our findings indicate that MPs found on the Tunisian coast may pose a chemical risk to marine organisms as the concentrations of PCBs and γ-HCH in most of the analysed samples exceeded the sediment-quality guidelines (SQG), especially the effects range medium (ERM) and the probable effects level (PEL). As the first report of its kind, the information gathered in this study can serve as the baseline and starting point for future monitoring work for Tunisia and neighbouring countries, as well as for stakeholders and coastal managers in decision-making processes.

Contamination of planktonic food webs in the Mediterranean Sea: Setting the frame for the MERITE-HIPPOCAMPE oceanographic cruise (spring 2019).

This paper looks at experiential feedback and the technical and scientific challenges tied to the MERITE-HIPPOCAMPE cruise that took place in the Mediterranean Sea in spring 2019. This cruise proposes an innovative approach to investigate the accumulation and transfer of inorganic and organic contaminants within the planktonic food webs. We present detailed information on how the cruise worked, including 1) the cruise track and sampling stations, 2) the overall strategy, based mainly on the collection of plankton, suspended particles and water at the deep chlorophyll maximum, and the separation of these particles and planktonic organisms into various size fractions, as well as the collection of atmospheric deposition, 3) the operations performed and material used at each station, and 4) the sequence of operations and main parameters analysed. The paper also provides the main environmental conditions that were prevailing during the campaign. Lastly, we present the types of articles produced based on work completed by the cruise that are part of this special issue.

Heavy Metal Bioaccumulation and Oxidative Stress Profile in Brachidontes pharaonis (Bivalvia: Mytilidae) from the Tunisian Coast: Insight into Its Relevance as Bioindicator of Marine Pollution.

This study aims to verify the relevance of Brachidontes pharaonis to assess the ecotoxicological status of polluted sites. For this, the levels of some heavy metals (i.e. Zn, Cu, Pb, and Cd) and a battery of biomarkers including metallothionein (MT), malondialdehyde (MDA), reduced glutathione (GSH), glutathione peroxidase (GPx), superoxide dismutase (SOD), and catalase (CAT) were assessed in mussels collected from the harbor of Rades (North), and the harbor of Zarzis (South). Moreover, abiotic parameters including temperature, salinity, pH, and dissolved oxygen were assessed. Results from the ICP-OES showed that the southern population exhibited a higher metal pollution index with significantly higher Zn, Cu, and Pb concentrations. Moreover, the specimens from Zarzis displayed significantly higher levels of MDA, MT, GSH, GPx, SOD, and CAT reflecting higher levels of oxidative and chemical stress. These results emphasize the potential utility of B. pharaonis for the monitoring of heavily impacted sites.

Occurrence, origin and potential ecological risk of dissolved polycyclic aromatic hydrocarbons and organochlorines in surface waters of the Gulf of Gabès (Tunisia, Southern Mediterranean Sea).

We investigated the occurrence, origin, and potential ecological risk of dissolved polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyl (PCBs) and organochlorine pesticides (OCPs) in 27 surface water samples collected from a highly anthropized and industrialized area in the Gulf of Gabès (Tunisia, Southern Mediterranean Sea) in October-November 2017. The results demonstrated a wide range of concentrations (ng L-1) with the following decreasing order: Æ©16 PAHs (17.6-71.2) > Æ©20 PCBs (2.9-33.7) > Æ©6 DDTs (1.1-12.1) > Æ©4 HCHs (1.1-14.8). Selected diagnostic ratios indicated a mixture of both pyrolytic and petrogenic sources of PAHs, with a predominance of petrogenic sources. PCB compositions showed distinct contamination signatures for tetra- to hepta-chlorinated PCBs, characteristic of contamination by commercial (Aroclor) PCB mixtures. The dominant OCP congeners were γ-HCH, 2,4'-DDD and 2,4'-DDE, reflecting past use of Lindane and DDTs in the study area. Agricultural, industrial and domestic activities, as well as atmospheric transport are identified as potential sources of PAHs, PCBs and OCPs in surface waters of the Gulf of Gabès. Toxic equivalents (TEQs) suggested a low carcinogenic potential for PAHs in seawater samples (mean of 0.14 ng TEQ L-1). Evaluation of risk coefficients revealed low risk for PAHs and PCBs, and moderate to severe risk for OCPs.

Assessment of the heavy metal levels and biomarker responses in the smooth scallop Flexopecten glaber from a heavily urbanized Mediterranean lagoon (Bizerte lagoon).

Marine heavy metal pollution is a worldwide serious issue. Like almost all Mediterranean lagoons, the Bizerte lagoon is highly urbanized and suffers from intensive anthropogenic pressure. In the present study, we screened the metal contamination and biomarker responses in the smooth scallop Flexopecten glaber inhabiting this vulnerable ecosystem. To this end, the concentrations of six heavy metals (HM) (i.e., Cu, Pb, Zn, Cd, Hg, and Fe) and a panel of biochemical endpoints including malondialdehyde (MDA), metallothioneins (MT), reduced glutathione (GSH), glutathione peroxidase (GPx), superoxide dismutase (SOD), and catalase (CAT) were determined in the gills and digestive gland across seasons (warm and cold) and sites (S1 and S2). The distribution of almost all analyzed metals in F. glaber tissues varied significantly between sites, seasons, and organs. The highest levels were recorded at S2 during the warm period. Moreover, the digestive gland was found to accumulate greater concentrations of HM than the gills. Marked spatio-temporal variations were also observed for oxidative stress biomarkers, mainly in the gills, while the digestive gland seems to be rather sensitive to seasonal variability. Particularly, we noticed that among the used biomarkers, MT did not show significant variations in the two tested organs across seasons and sites. From the obtained results, F. glaber appears as a sensitive organism to anthropogenic metal contamination and can be proposed as a promising bioindicator species for marine pollution.

Effects of acute mercury exposure on fatty acid composition and oxidative stress biomarkers in Holothuria forskali body wall.

Mercury is one of the most harmful pollutant that threat marine biota. This study assessed the Hg impact on the fatty acid (FA) composition and the antioxidant statues in Holothuria forskali body wall tissue. Specimens were exposed to HgCl2 graded doses (40, 80 and 160 µg L-1) for 96 h. A decrease in linoleic, arachidonic and eicosapentaenoic acid levels and an increase of docosahexaenoic acid were mainly observed at the nominal tested dose. The exposure to the upper dose promoted oxidative stress with an increase of malondialdehyde, hydrogen peroxide, advanced oxidation protein product, glutathione and non-protein thiols levels. Moreover, a decrease in catalase and an increase in superoxide dismutase and glutathione peroxidase activities were observed. Yet, an increase of the metallothionein level was registered in all treated groups. This study confirmed the Hg toxicity on the redox statue of H. forskali and highlighted the usefulness of the FA composition as an early sensitive bioindicators.

Using environmental proteomics to assess pollutant response of Carcinus maenas along the Tunisian coast.

Biochemical responses to pollutants were studied at four Tunisia littoral sites using Carcinus maenas as a bioindicator. Proteomic analysis was used to assess the global impact of complex pollution mixtures, and to provide new biomarkers and basic insights into pollutant toxicity. Metal contents and metallothionein levels followed a gradient based on sampling sites: Bizerte ≫ Teboulba > Gargour~Mahres. Approximately 900 and 700 spots were resolved in digestive glands and gills, respectively. Gills from Bizerte animals had the maximum number of altered spots, mostly upregulated. In other locations, the number of altered spots in gills decreased in parallel to total metals in in the following order: Teboulba > Gargour > Mahres (mostly downregulated). Out of the 39 spots excised, ten proteins were identified in digestive glands and eight in gills. Digestive glands of Bizerte crabs had higher levels of ferritin, three vitellogenin forms and mannose-binding protein, while Gargour crabs had higher levels of four cryptocyanin forms. Gills of Bizerte crabs had higher levels of ferritin, three vitellogenins forms, lectin 4C, actin, and collagenolytic serine protease. Proteins with altered expression in crabs from Tunisia littoral are related to molting, oxidative stress and inflammation, innate immune response, and proteolysis.

Comparative study of the bioaccumulation and elimination of trace metals (Cd, Pb, Zn, Mn and Fe) in the digestive gland, gills and muscle of bivalve Pinna nobilis during a field transplant experiment.

The purpose of this study was to investigate the long-term bioaccumulation and elimination of Cd, Pb, Mn, Zn and Fe by Pinna nobilis tissues after their 90 day-transplantation period at Téboulba fishing harbor. During the transplantation period, the Cd, Pb, Mn, Zn and Fe concentrations in the different tissues of the mussels were measured before and after exposure period. Metal (Cd, Pb, Mn, Zn and Fe) accumulation in P. nobilis mussels varied depending on the analyzed tissue and the caging times. Notable differences in Cd, Pb, Mn, Zn and Fe accumulation patterns within the digestive gland, gills and muscle were found and may be due to the ability of each tissue to accumulate metals. During the depuration phase, the elimination of Cd, Pb, Mn, Zn and Fe depended on the target tissue and the metal speciation. Cd, Pb, Mn and Fe were eliminated rapidly from one organ and increased in other when compared to those of 90 day transplanted mussels. The increase of metal loads during the elimination phase is not clear and particularly what kind of processes is responsible for such response. However, it is reasonable to assume that metals increase is related to the existence of an accumulation/detoxification mechanism, which involves the transport of metals from an organ to another. The data obtained indicate that because of the significantly high quantities of Cd, Pb, Mn, Zn and Fe accumulated during the exposure phase, the transplanted mussels are suitable bioindicators for monitoring trace metals in marine ecosystem.

Proteomic analysis in caged Mediterranean crab (Carcinus maenas) and chemical contaminant exposure in Téboulba Harbour, Tunisia.

This study uses proteomics approach to assess the toxic effects of contaminants in the Mediterranean crab (Carcinus maenas) after transplantation into Téboulba fishing harbour. High levels of aliphatic and aromatic hydrocarbons were detected in sediments. Although their effects on vertebrates are well described, little is known about their early biological effects in marine invertebrates under realistic conditions. Protein expression profiles of crabs caged for 15, 30 and 60 days were compared to unexposed animals. Nineteen proteins with significant expression differences were identified by capLC-µESI-IT MS/MS and homology search on databases. Differentially expressed proteins were assigned to five different categories of biological function including: (1) chitin catabolism, (2) proteolysis, (3) exoskeleton biosynthesis, (4) protein folding and stress response, and (5) transport. The proteins showing major expression changes in C. maenas after different caging times may be considered as novel molecular biomarkers for effectively biomonitoring aquatic environment contamination.

Polychlorinated biphenyls (PCBs) and Polybrominated Diphenyl Ethers (PBDEs) in surface sediments from Monastir Bay (Tunisia, Central Mediterranean): occurrence, distribution and seasonal variations.

An assessment of PCB and PBDE contamination of surface sediments in Monastir Bay was carried out in two contrasted seasons of the year. Samples were collected from 5 sites and analyzed for the ∑7 marker PCBs (i.e. PCBs 28, 52, 101, 118, 138, 153 and 180) and ∑4 PBDE congeners (PBDEs 47, 99, 119 and 153) by GC/ECD. Concentrations of both PCBs and PBDEs showed seasonal variations. PCB concentrations were in the range of 3.1-9.3 ng g(-1) and 1.1-8.1 ng g(-1) in wet and dry season respectively, and sediments were considered moderately contaminated with PCBs. All PCBs analyzed were detected in surface sediments. PCB 153 and 52 congeners showed the highest relative abundance in both winter and summer. PBDE concentrations ranged from not detect to 0.1 ng g(-1), with only BDE-47 congener detected in sediments and only in winter. Analysis of spatial and seasonal variations indicated that PCB distribution is governed by hydrodynamics and temporal variability of inputs. While the PCB contamination appeared to be mainly land-based, PBDEs are suspected to originate from atmospheric deposition.

Biochemical responses and metals levels in Ruditapes decussatus after exposure to treated municipal effluents.

This study assessed the responses of biochemical biomarkers and metals levels in Ruditapes decussatus exposed to the increasing concentrations of treated municipal effluents (TME) discharged into the Tunisian coastal area. Clams were exposed to 0%, 1%, 3% and 10% for 7 and 14 day and the following biochemical responses were measured: (1) catalase activity and lipid peroxidation levels (TBARS) as oxidative stress biomarkers, (2) gluthathione S-transferase (GST) activity as a phase II conjugation enzyme; (3) cholinesterase activity (ChE) as biomarker of neurotoxicity, and (4) metallothioneins as a proteins highly induced by heavy metals. A significant uptake of Cu, Cd and Zn in digestive gland and serious biochemical alterations were observed. Thus, exposure of clams to croissant concentration of TME have the potential to increase the oxidative stress biomarkers (TBARS, CAT activity) and MT levels; and decrease ChE activity in both gills and digestive gland. Current experimental results suggest that CAT, GST, ChE activities and MT and TBARs levels in gills and digestive gland of clam R. decussatus are sensitive and suitable responses for assessing the effects of anthropogenic contaminants on the aquatic ecosystems, particularly effluent complex mixtures.

Distribution of trace metals, aliphatic hydrocarbons and polycyclic aromatic hydrocarbons in sediment cores from the Sicily Channel and the gulf of Tunis (south-western Mediterranean Sea).

Under the framework of the IAEA's Technical Co-operation project RAF7/004, international research cruises were carried out in 2004 to assess the distribution of radionuclides and micropollutants in the south-western Mediterranean Sea. Sediments samples had variable concentrations of total aliphatic hydrocarbons and polycyclic aromatic hydrocarbons ranging from 0.2 to 1.8 microg g(-1) and 26.9 to 364.4 ng g(-1), respectively, in the Sicily Channel and from 0.7 to 2.8 microg g(-1) and 14.7 to 618.1 ng g(-1), respectively, in the open sea of the Gulf of Tunis. Hydrocarbon concentrations changed with depth and were relatively high at 3 cm and 10 cm depths. The use of 'fingerprint' ratios of certain isomeric pairs of polycyclic aromatic hydrocarbons (PAH) and the proportion of 2-3 ring and 4-5 ring PAH concentrations showed that the main origins are characteristic of petroleum sources. The ranges of trace metal concentrations, expressed in microgg(-1), in the Sicily Channel and in the Gulf of Tunis, respectively, were: Hg 0.009-0.2 and 0.02-0.1; Pb 9.9-26.1 and 21.2-32.5; Cd 0.06-0.1 and 0.07-0.33; Fe 23.7-28.1 and 29.9-36.2p; Zn 83-99.5 and 83-104; Mn 309.2-752.5 and 651-814; Cu 17.1-18.5 and 33.5-51.3. Sediment metal abundances were in the order: Mn > Zn > Fe > Cu > Pb > Cd > Hg. The results showed significant differences (p < 0.001) for trace metal and hydrocarbon mean concentrations between the two cores. These concentrations are generally similar to the background levels from the Mediterranean Sea and could be affected by physico-chemical conditions and sedimentation rate as well as biodegradation.

A large scale survey of trace metal levels in coastal waters of the Western Mediterranean basin using caged mussels (Mytilus galloprovincialis).

A large scale study of trace metal contamination (Hg, Cd, Pb and Ni) by means of caged mussels Mytilus galloprovincialis was undertaken along the coastal waters of the Western Mediterranean Sea within the context of the MYTILOS project. Individual mussels from an homogeneous population (shell size 50 ± 5 mm) obtained from an aquaculture farm were consecutively caged and deployed at 123 sites located in the Alborán, North-Western, South-Western and Tyrrhenian sub-basins for 12 weeks (April-July) in 2004, 2005 and 2006. After cage recoveries, both the metal content in the whole mussel tissue and the allometric parameters were measured. Statistical analysis of the datasets showed significant differences in concentrations between sub-basins for some metals and mussel condition index (CI). Linear regression models coupled to the CI were revisited for the data adjustment of certain trace metals (Hg, Cd and Ni), and four level categories were statistically derived to facilitate interregional comparison. Seawater masses surrounding coastal areas impacted by run-off from land mineralised coasts and industrial activities displayed the highest concentration ranges (Hg: 0.15-0.31 mg kg(-1) dw; Cd: 1.97-2.11; Ni: 2.18-3.20 and Pb: 3.1-3.8), although the levels obtained in most of the sites fitted within moderate or low categories, and they could be considered as baseline concentrations. However, few sites considered little-influenced by human activities, at present, showed high concentrations of Cd, Ni and Pb, which constitute new areas of concern. Overall, the use of active biomonitoring (ABM) approach allowed to investigate trace metal contamination in order to support policy makers in establishing regional strategies (particularly, with regard to the European Marine Strategy Directive).

Distribution and partitioning of aliphatic hydrocarbons and polycyclic aromatic hydrocarbons between water, suspended particulate matter, and sediment in harbours of the West coastal of the Gulf of Tunis (Tunisia).

Harbours of La Goulette, Rades and Sidi Bou Said are considered as the principal largest and most important port in the Gulf of Tunis characterised by a direct influence of different activities (sailing, industry and fishing) to the Mediterranean Sea. Due to their social and economic impact, a comprehensive assessment of the spatial distribution and partitioning of 24 polycyclic aromatic hydrocarbons (PAHs) and 18 aliphatic hydrocarbons (AHs) in summer and in winter among overlying water, suspended particulate matter (SPM) and surface sediments is essential. Distribution of hydrophobic organic contaminants in abiotic compartments is important for describing their transfer and fate in aquatic ecosystems and to identify the potential danger due to mobilization of contaminants produced by managing of the same sediments. Total organic carbon (TOC) contents range between 4.3% and 6.5%, with an average value of 5.9% in summer, and between 2.3% and 9.6%, with an average value of 6.1% in winter. The average concentrations of ΣPAH in winter and in summer were respectively 703.1 ng L⁻¹ and 378.4 ng L⁻¹ in seawater, 4599.1 ng g⁻¹ and 3114 ng g⁻¹ in SPM, and 1507.6 ng g⁻¹ dw (dry weight) and 1294.6 ng g⁻¹ dw in surface sediment. For ΣAH the average concentrations in winter and in summer were respectively 701 ng L⁻¹ and 741.7 ng L⁻¹ in seawater, 6743.5 ng g⁻¹ and 6282.9 ng g⁻¹ in SPM, and 4971.3 ng g⁻¹ and 4588.1 ng g⁻¹ in surface sediment. Higher PAH and AH concentrations were observed in SPM than in surface sediment. SPM and water were dominated by PAH with low molecular weight, while for sediment low and high molecular weight PAHs were present. PAH and AH fingerprint ratios, such as pristane to phytane (Pr/Ph), phenanthrene to anthracene (Phe/An) and fluoranthene to pyrene (Fl/Py), suggest that hydrocarbons in all harbours may originate from both pyrolytic and petrogenic sources derived from discharge of untreated sewage and wastewater or from direct input by ship traffic in the area. The results showed significant difference (ANOVA, p < 0.05) for hydrocarbon mean concentrations between all harbours studied and between different matrixes.

Acute effects of chlorpyryphos-ethyl and secondary treated effluents on acetylcholinesterase and butyrylcholinesterase activities in Carcinus maenas.

The acute effects of commercial formulation of chlorpyrifos-ethyl (Dursban) and the secondary treated industrial/urban effluent (STIUE) exposure on acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) activities in hepatopancreas and gills of Mediterranean crab Carcinus maenas were investigated. After 2 d of exposure to chlorpyriphos-ethyl, the AChE activity was inhibited in both organs at concentrations of 3.12 and 7.82 microg/L, whereas the BuChE was inhibited only at higher concentration 7.82 microg/L of commercial preparation Dursban. The exposure of crabs to Dursban (3.12 microg/L) showed a significant decrement of AChE activity at 24 and 48 h, whereas the BuChE was inhibited only after 24 h and no inhibition for both enzymes was observed after 72 h. Moreover, a significant repression of AChE activity was observed in both organs of C. maenas exposed to 5% of STIUE. Our experiments indicated that the measurement of AChE activity in gills and hepatopancreas of C. maenas would be useful biomarker of organophosphorous (OP) and of neurotoxic effects of STIUE in Tunisia.

Biosorption of Cu(2+) and Zn(2+) from aqueous solutions by dried marine green macroalga Chaetomorpha linum.

The biosorption of the heavy metals Cu(2+) and Zn(2+) by dried marine green macroalga (Chaetomorpha linum) was investigated. The biosorption capacities of the dried alga for copper and zinc were studied at different solution pH values (2-6), different algal particle sizes (100-800microm) and different initial metal solution concentrations (0.5-10mM). An optimum pH value of 5 was found suitable for both metal ions biosorption for both metal ions. At the optimum particle size (100-315microm), biosorbent dosage (20g/l) and initial solution pH (pH 5), the dried alga produced maximum copper and zinc uptakes values (q(max)) of 1.46 and 1.97mmol/g respectively (according to the Langmuir model). The kinetic data obtained at different initial metal concentrations indicated that the biosorption rate was fast and most of the process was completed within 120min. This study illustrated an alternative technique for the management of unwanted biological materials using processed algal material. C. linum is one of the fast-growing marine algae in the lake of Tunis and could be utilized as a biosorbent for the treatment of Cu(2+) and Zn(2+) contaminated wastewater streams.