Multi-Biomarker Responses After Exposure to Pollution in the Mediterranean Mussels (Mytilus galloprovincialis L.) in the Aegean Coast of Turkey

Evaluation the Toxicity of Heavy Metal Mixtures in Anecic Earthworms (Aporrectodea giardi)

Using earthworms as bioindicators of heavy metal contamination in soils is a relevant tool for environmental risk monitoring. This study examines the combined effects of four distinct concentrations mixtures (M1, M2, M3 and M4) containing Cd, Cr, Cu, Ni, Fe and Mn on Aporrectodea giardi earthworms after 12 and 24 days (12 D/24 D) of exposure via the monitoring of certain biomarkers of stress including total protein content, glutathione (GSH), metallothionein (MT), catalase and lipoxygenase (LOX) activities. The results show a decrease in the total protein level for the M3 mixture after 24 D, whereas it increases for all other treatments regardless of exposure time. Glutathione and metallothionine levels increased for M2 and M3 and decreased for M1 and M4 after 12 D; they increased after 24 D for all the mixtures. Regarding enzyme activities, catalase activity was decreased for all the treatments unless for M3 (P > 0.05). However, LOX increased for M1, M2 and M4 except for M3 after 12 D, when inhibition of this biomarker was observed. LOX activity was inhibited for all the mixtures at the end of the treatment. All the mixtures generated oxidative stress in Aporrectodea giardi, which is minimized by increasing MT levels to remove the metal ions and triggering the antioxidant system, composed primarily of GSH and LOX to restore cellular homeostasis. These findings suggest that the species Aporrectodea giardi could be an excellent candidate for ecotoxicological risk assessment of soils contaminated by metal mixtures and it can be used in bioremediation for its fitness which allows it to tolerate high concentrations of metal mixtures.

Are iron ore microparticles toxic for the European clam Ruditapes decussatus? Response elements from biomarker activities and in silico modeling

Inevitably, high concentrations of iron, the most widely produced ore globally, can be found in aquatic environments. To assess the toxicity of iron on aquatic organisms, Ruditapes decussatus specimens were subjected to microparticles derived from two types of iron ore (hematite and magnetite) at four different concentrations (0.5, 1, 1.5, and 5 g/L). The findings revealed that both types of iron ore were absorbed by clams in a concentration-dependent manner. Biomarkers analysis demonstrated significant and organ-specific impacts on the health of the clams caused by these microparticles, which was further supported by computational analyses on bioavailability. Within seven days of exposure, changes were observed in the activities of several enzymes, including catalase, acetylcholinesterase, and glutathione S-transferases, as well as in the rate of lipid peroxidation in both the digestive gland and gills. This study provides an environmental perspective on the toxicological effects of iron ore microparticles.

First characterization of seasonal variations in biomarkers baseline in Patella sp. from Mediterranean ports (North Corsica, France)

In port areas the identification of contamination sources is necessary for an efficient management. Biomonitoring provides information on the environmental impact of the pollutants. It is often difficult to differentiate the natural variations of biomarkers from those induced by pollution. The present study aims to define a baseline level for biochemical biomarkers in limpet (Patella sp.) collected in four North-Corsica port areas. Reference data for five biomarkers (superoxide dismutase, glutathione S-transferase, laccase, pyruvate kinase and acetylcholinesterase) were described in a model, using length of the limpet shell, temperature and salinity. The measured biomarkers responses on potentially polluted sites usually fell within the range of the expected values for an unaffected site, suggesting that a main part of the variations is explained by environmental conditions. Not included in the model, biological factors (sex, development stage, etc.), annual variation or other physico-chemical parameter could explain the variations in the model.

Cellular Biomarkers in Mytilus galloprovincialis L. (Mediterranean Mussels) from Izmir Bay (Turkey)

In this study, cellular biomarkers and heavy metal concentration in the Mytilus galloprovincialis L. (Mediterranean mussels) collected from eight sites of Izmir Bay (Turkey) were determined to reveal water pollution for the first time in these stations. Results show that heavy metals (As, Cu, Hg, Zn, Cd, Sn, Pb) have been specified in mussels' tissues collected from all stations. According to GST, SOD, CAT activities, and TBARS contents, mussels in the outer bay have exposed more oxidative stress than the ones in the inner bay. Digestive gland tissues of them were showed more inhibition at AChE levels than gills. Also, abnormal nucleus rates and micronucleus frequencies (MN) were found to be higher in the inner bay than in the outer bay. This study showed that heavy metal pollution in different levels is an environmental issue on the Izmir Bay. Especially the coastal regions of the bay have been extremely affected by anthropogenic effects due to growing population.

First insight into the development of a new transcriptomic tool in French Corsica harbors

Coastal harbor areas are subjected to a myriad of contamination sources with largely unknown effects. Such complex chemical mixtures are difficult to monitor but transcriptomics is a promising approach for such biomonitoring. The present study was designed to verify the use of the Coastal Biosensor for Endocrine Disruption (C-BED) assay, previously developed to detect emerging contaminants and their effects on Mytilus edulis, on another mussel species, Mytilus galloprovincialis. Mussels were caged on St-Florent harbor (contaminated) and on Revellata Bay (reference) for three months. A classical multibiomarkers approach was coupled to the C-BED assay. The results of both approaches were analysed using the Integrated Biomarkers Responses (IBR) and compared to each other. Both approaches demonstrated a higher contamination and probable endocrine disruption of mussels in St-Florent, compared to the reference station. These results confirm that the C-BED assay provides an innovative method to expand our ability to detect emerging contaminants.

Differential tissue development compromising the growth rate and physiological performances of mussel

Differences in the food acquisition rates and in the energetic costs of metabolism seem to affect the growth rate variability of mussels. The aim of this study was to analyze if the physiological performances responsible for such growth rate variability are accompanied by structural differences at tissue or cellular level in the main organs involved in energy acquisition (gill) and processing (digestive gland). Fast growers had higher cilia density and metabolic efficiency in their gill, and well-developed digestive tissue with barely no connective tissue or atrophy. Slow-growing mussels displayed stress signs that impede the proper acquisition, digestion and absorption of food: low cilia density, low mitochondrial capacity and high antioxidant activity levels in the gills, and high atrophy of the digestive gland. The data herein explains the growth rate variability of mussels, demonstrating that morphological and functional differences exist between fast and slow growers.

Identification and characterization of the novel genes encoding glutathione S-transferases in Mytilus galloprovincialis

The superfamily of glutathione S-transferases (GST) plays an essential role in the xenobiotic metabolism, binding compounds to the glutathione, and is like a cell protector during the influence of various negative external factors. Nevertheless, there are very few works devoted to the investigation of these genes in marine invertebrates. Up to this time, only three classes of cytosolic GSTs for one of the leading commercial molluscs Mytilus galloprovincialis were described. We sequenced the whole transcriptome from the gill tissues and, using bioinformatic analysis, detected ten classes of glutathione S-transferases, which are expressed in the mussel M. galloprovincialis. For the first time, two subfamilies were described: mitochondrial GST (kappa class) and microsomal (MAPEG), as well as five classes of the family of cytosolic GSTs (mu, omega, rho, tau, theta). Omega and sigma GST classes might be rapidly regulated genes due to the lack of introns and this assumption was confirmed by the investigation of short-term hypoxia on M. galloprovincialis. Seven new classes of GST revealed a greater gene variety of this detoxifying enzyme in mussels than expected. The obtained nucleotide sequences are necessary for future investigations of GSTs expression in response to various external factors (pollution, oxygen starvation, infection, etc.).

Occurrence and distribution of fecal indicators and pathogenic bacteria in seawater and Perna perna mussel in the Gulf of Annaba (Southern Mediterranean)

The identification of fecal contamination in coastal marine ecosystems is one of the main requirements for evaluation of potential risks to human health. The objective of this study was to investigate the occurrence and distribution of fecal indicators and pathogenic bacteria in seawaters and mussels collected monthly during a period of 1 year from four different sites in Northeastern Algeria (sites S1 to S4), through biochemical and molecular analyses. Our research is the first to use molecular analysis to unambiguously identify the potentially pathogenic bacteria present in Algerian Perna perna mussels. The obtained results revealed that the levels of fecal indicator bacteria (FIB) from both P. perna and seawater samples largely exceeded the permissible limits at S2 and S3. This is mainly related to their location close to industrial and coastal activity zones, which contain a mixture of urban, agricultural, and industrial pollutants. Besides, P. perna collected from all sites were severalfold more contaminated by FIB than seawater samples, primarily during the warm season of the study period. Biochemical and molecular analyses showed that isolated bacteria from both seawater and mussels were mainly potentially pathogenic species such as E. coli, Salmonella spp., Staphylococcus spp., Klebsiella spp., Pseudomonas spp., and Proteus spp.

Effects of the Fragrance Galaxolide on the Biomarker Responses of the Clam Ruditapes philippinarum

The musk fragrance Galaxolide® (HHCB) is widely used in personal care and household products. Its large use leads to a continuous release of the compound into aquatic environments. Although some studies on the presence of HHCB in ecosystems and biota have been conducted, limited data about its effects on organism biomarkers are available. This study aimed at investigating both cellular and biochemical effects of HHCB in the clam Ruditapes philippinarum. Mussels were exposed for 7, 14 and 21 days to 100 ng/L and 500 ng/L of HHCB in seawater, and the effects on haemocyte parameters and antioxidant enzyme activities in the gills and digestive gland were evaluated. In addition, the neurotoxic potential of HHCB and its capacity to cause oxidative damage to proteins were assessed. Overall, our results demonstrated that exposure to HHCB was able to induce changes in biomarker responses of mussels, mainly at the cellular level.

Bacterial metagenome analysis of Mytilus galloprovincialis collected from Istanbul and Izmir coastal stations of Turkey

Mytilus galloprovincialis is a marine mollusk belonging to the Bivalvia class. It has been distributed largely in Turkish shores and worldwide aquatic environments. Besides being known as an environmental pollution indicator, it is highly consumed as a food and has a high economic value. Due to their nutritional mechanisms by filtering water, they are affected by pollution in seawater and mussels can host-microbial diversity of environmental origin as well as pathogenic bacteria. Therefore, in this study, bacterial species found in Mediterranean mussels collected from the coastal stations of Istanbul [Rumeli Kavagi (RK), Kucukcekmece (KC)], and Izmir [(Foca (MF), Urla (MU)] were investigated and compared with microbiological and metagenomic analyses. According to microbiological analysis results, 34 mussel-associated Enterobacteriaceae and Vibrionaceae family members were identified. As a result of the culture-independent metagenomic analysis, taxonomic groups for each station were identified and compared based on Operational Taxonomic Unit data. For all stations, the most abundant bacterial genera were the unclassified bacterial genera. The total number of mussel-related total richness identified in all groups was 4889 (RK = 1605; KC = 1930; MF = 1508; and MU = 1125). According to the metagenomic data obtained in this study, different relative amounts of Lachnospiraceae and Bacteroidetes taxa groups were reported for all stations. The pathogenic bacterial genera identified by metagenomic analyses which may be significant for the public health are Arcobacter, Clostridium, Aeromonas, Vibrio, Escherichia_Shigella, Klebsiella, Campylobacter, Helicobacter, Pseudomonas, Morganella, Serratia, Corynebacterium, Enterococcus, Staphylococcus, Yersinia, Mycoplasma, Brucellaceae_unclassified, Pantoea, and Proteus.

Acute toxicity of lead in fresh water bivalves Lamellidens jenkinsianus obesa and Parreysia (Parreysia) corrugata with evaluation of sublethal effects on acetylcholinesterase and catalase activity, lipid peroxidation, and behavior

The median lethal concentrations (LC₅₀) of Pb at 96 h were 8.84, 192.14, and 3.22 mg L^-1 for pre-reproductive and reproductive individuals of Lamellidens jenkinsianus obesa and reproductive individuals of Parreysia (Parreysia) corrugata, respectively. Thus, young L. j. obesa were much more sensitive to Pb than its adults, while P. (P.) corrugata was the most sensitive. However, all the three values were much higher than the Pb levels commonly found in natural waters, and indicative of the tolerance of these mollusks to acute, short-term Pb exposure. In contrary to these findings, acetylcholinesterase (AChE) and catalase (CAT) activities were affected and lipid peroxidation (LPO) elevated in young L. j. obesa and P. (P.) corrugata in 21-day sublethal toxicity tests at 26-68 ppb Pb concentrations, which might be considered environmentally realistic. Some behavioral patterns such as number of movement (Mov) and durations of foot mobilization together with siphon extensions (FSE) were reduced, and the durations of valves remaining completely closed without any extension of foot and siphons (VC) increased significantly at 25-69 ppb Pb as well. Thus, the study revealed significant interspecific differences as well as that between life stages of the same species, suggesting that apparently hardy species could be impacted by low Pb concentrations in their young stages. Further, a multi-biomarker approach involving biological effects, anti-oxidative enzyme activity and easy-to-measure behavioral elements could comprise a valuable tool in assessment of Pb-induced stress in freshwater bivalves.

A Multibiomarker Approach to Assess the Health State of Coastal Ecosystem Receiving Desalination Plants in Agadir Bay, Morocco

The present study aims to evaluate the initial health status of two stations receiving seawater desalination plants in Agadir Bay (Tifnit-Douira and Cap Ghir) and to assess their potential environmental impact on the marine ecosystem health. Six pairs of mussels (Mytilus galloprovincialis) were collected at six sampling sites on a monthly basis over two years. Each pair was homogenized to obtain the postmitochondrial fractions (S9). Toxicological effects were measured using a multibiomarker approach based on either acetylcholinesterase (AChE), glutathione S-transferase (GST), catalase (CAT), and malondialdehyde (MDA) rate. The results show a seasonal variation of the biomarkers: their activities increase in summer and decrease in spring and winter. High activities were recorded during summer in Cap Ghir (17.94 ± 0.88; 5.91 ± 052 nmol/min/mg of protein) for CAT and MDA, respectively. In Tifnit-Douira, low activities were recorded during winter for GST (3.74 ± 0.52 nmol/min/mg of protein) and during spring for the CAT (3.52 ± 0.45 nmol/min/mg of protein). The fluctuations in the activities of measured biomarkers could be attributed to different factors including the changes in environmental parameters, the influence of seasonal variation, and the contamination of the aquatic ecosystem. The data obtained in this study should be taken into account in the monitoring and management of the health of the ecosystems when the desalination plants are established.

Effect of sublethal gradient concentrations of nickel on postlarvae of Penaeus monodon, Perna viridis and Terapon jarbua: Enzyme activities and histopathological changes

The present study evaluates the enzyme activities and histopathological changes in the post larvae (PL) of shrimp (Penaeus monodon), green mussel (Perna viridis) and fingerlings of crescent perch (Terapon jarbua) exposed to sublethal gradient concentrations of Nickel (Ni). The median lethal concentration (LC₅₀) values were 2.49, 66.03 and 43.92 mg Ni L^-1 derived for the PL of shrimp, green mussel and fish fingerlings respectively. No Observed Effect Concentration (NOEC), Lowest Observed Effect Concentration (LOEC) and chronic values of the PL of shrimp were 46.5, 73.0 and 58.3 μg Ni L^-1 derived for the 21-d survival endpoint. The NOEC, LOEC and chronic values for the 30-d survival endpoint of the green mussels and fish fingerlings were 4.6, 6.32, 5.4 and 1.95, 2.6, 2.25 mg Ni L^-1 respectively. The isoforms of esterase, superoxide dismutase and malate dehydrogenase activities in the whole body tissues of test organisms were studied by native polyacrylamide gel electrophoresis after exposure to Ni. Histological examination of compound eye sections of shrimp revealed deformation, compression, fusion and detachement in the corneal cells from the corneal facet of the ommatidia indicating cellular anomalies due to Ni toxicity. Gill sections of the green mussel witnessed reduced haemolymph in sinuses of gill filaments, degenerative changes in interfilamentous junction and necrosis of frontal ciliated epithelial cells with vacuoles after exposure to Ni. Nickel affects the vision of shrimp and fish fingerlings, gills and byssus of green mussels.

Micronucleus Experiments with Bivalve Molluscs

The micronucleus (MN) test, as an index of accumulated DNA damage during the lifespan of cells, is the most applied assay in aquatic animals to assess the exposure to a complex mixture of genotoxic pollutants. An increase in MN frequency was reported on mussels exposed to the most common environmental pollutants under laboratory conditions, such as heavy metals, polycyclic aromatic hydrocarbons, and ionizing radiation. The test was applied in a large number of biomonitoring studies in different geographic areas to identify the exposure to different classes of pollutants with good discrimination power and to evaluate the recovery effects after accidental pollution events. A standardized MN assay protocol in hemocytes and gill cells for use in bivalve species, including scoring of different cell types, necrotic and apoptotic cells and nuclear anomalies, was established following the “cytome approach”. The mussel MNcytome (MUMNcyt) assay, using the proposed detailed criteria for the identification of cell types, is suitable for application in experimental studies under controlled conditions and in biomonitoring programs in aquatic environments.

Enzymatic and Histological Biomarkers in Ucides cordatus (Crustacea, Decapoda) in an Industrial Port on the North Coast of Brazil

The aim of this study was to evaluate enzymatic (glutathione-S-transferase and catalase) and histological (branchial lesions) biomarkers in Ucides cordatus (Crustacea, Decapoda) from an industrial port region on the north coast of Brazil. The crabs were collected in two distinct locations of the Brazilian coast: A1 = region under influence of port activities; and A2 = low-impacted area. We performed histological examination in the gills and glutathione-S-transferase (GST) and catalase activity in the hepatopancreas. The most frequent and severe histological lesions were found in A1, especially rupture of pilaster cells and lamellar collapse. Catalase activity did not show a pattern capable of differentiating the two analyzed areas. On the other hand, GST activity presented a more pronounced response in the crabs of the port area (p < 0.05), coinciding with the most frequent branchial lesions in these same organisms. These results suggest that the species is susceptible to environmental stress, once alterations at different organizational levels were verified.

Seasonal variations of multi-biomarker responses to metals and pesticides pollution in M. galloprovincialis and T. decussatus from Homa Lagoon, Eastern Aegean Sea

Biomarkers (CAT, SOD, GPx, and AChE) were investigated in hepatopancreas and soft tissues of mussels (Mytilus galloprovincialis) and clams (Tapes decussatus) in response to metal and pesticide pollutions in Homa Lagoon. Mussel and clam samples were seasonally collected in January, May, August and November 2015. According to the results, higher metal concentrations determined in the soft tissues of both species in January. Hepatopancreas was found to accumulate higher levels of metals than soft tissue. Metal deposition potential in clams were higher than mussels. Pesticide levels were below detection limits in clams. In mussels, only 4,4'-DDE was detected in soft tissues and hepatopancreas in November. Highest AChE, CAT, SOD and GPx activities in mussels were determined in January. On the other hand, maximum AChE and CAT activities in clams were found in November. Seasonal variations of metals and biomarker levels might be related to species-specific physiology and environmental conditions.

Integrated Biomarker Responses in Livers of the Pale Chub Zacco platypus for Risk Assessment of a Stream Contaminated by Wastewater Effluents

We evaluated the effects of wastewater effluents on pale chub (Zacco platypus) in a contaminated stream by integrating genotoxic, oxidative stress, histological, and physiological biomarkers. The metal pollution index indicated higher pollution loads at downstream sites (DS1 and DS2) compared with the upstream reference site. Significantly higher nuclear abnormality confirmed the existence of genotoxicity (p < 0.05) at downstream sites. Antioxidant activity (catalase and glutathione S-transferase) and lipid peroxidation levels in livers of Z. platypus were also significantly higher at the DS1 site (p < 0.05). The liver somatic index was also influenced, with abnormal histological alterations in the liver, possibly caused by heavy metal accumulation (Cd, Co, Cr, Mn, Ni, and Pb). The integrated biomarker response value was the highest at DS1 (13.74) followed by DS2 (1.94), indicating that wastewater effluents had the potential to cause adverse effects on Z. platypus inhabiting receiving stream.

Assessing the health status of farmed mussels (Mytilus galloprovincialis) through histological, microbiological and biomarker analyses

The Gulf of La Spezia (northern Tyrrhenian Sea, Italy) is a commercially important area both as a shipping port and for mussel farming. Recently, there has been increased concern over environmental disturbances caused by anthropogenic activities such as ship traffic and dredging and the effects they have on the health of farmed mussels. This paper reports the results of microbiological and histological analyses, as well as of measurement of several biomarkers which were performed to assess the health status of mussels (Mytilus galloprovincialis) from four rearing sites in the Gulf of La Spezia. Mussels were collected between October 2015 and September 2016 and histological analyses (including gonadal maturation stage), as well as the presence of pathogenic bacteria (Vibrio splendidus clade, V. aestuarianus and V. harveyi), viruses (Herpes virus and ostreid Herpes virus 1) and protozoa (Marteilia spp., in the summer season only) were carried out on a monthly basis. Conversely, biomarker responses in haemocyte/haemolymph (total haemocyte count, haemocyte diameter and volume, lysozyme and lactate dehydrogenase activities in cell-free haemolymph, and micronuclei frequency) and in gills and digestive gland (cortisol-like steroids and lipid peroxidation levels), were evaluated bimonthly. Microbiological data indicated that mussels contain a reservoir of potentially pathogenic bacteria, viruses and protozoa that in certain environmental conditions may cause a weakening of the immune system of animals leading to mortality episodes. The percentage of parasites detected in the mussels was generally low (9.6% for Steinhausia mytilovum, that is 17 samples out of 177 examined females; 3.4% for Proctoeces maculatus; 0.9% for Mytilicola intestinalis and 2% for ciliated protozoa), while symbiont loads were higher (31% for Eugymnanthea inquilina and Urastoma cyprinae). Interestingly, a previously undescribed haplosporidian was detected in a single mussel sample (0.2%) and was confirmed by in situ hybridization. Cells morphologically similar to Perkinsus sp. trophozoites were observed in 0.7% of the mussels analysed; however, infection with Perkinsus spp. could neither be confirmed by ISH nor by PCR. Different pathological aspects, such as host defence responses and regressive/progressive changes were detected in the gills, digestive glands, gonads and mantle. Only one single case of disseminated neoplasia (0.2%) was observed. As for the biomarker evaluation, the MANOVA analysis revealed the statistically significant effect that the variable "sampling site" had on the biological parameter measured, thus suggesting that the multibiomarker approach was able to differentiate the rearing sites.

Acute exposure to sunscreen containing titanium induces an adaptive response and oxidative stress in Mytillus galloprovincialis

The use of sunscreens to protect against ultraviolet radiation exposure progressively increases as result of a greater awareness of the people and the greater arrival of tourists. The components of these creams can end up in the waters affecting coastal species. Mediterranean mussels (Mytillus galloprovincialis) were subjected to an acute exposure of a sunscreen with TiO₂ in their composition during 24h. The low and medium concentrations used in the assays contained a concentration of TiO₂ in the range of values found in coastal waters of the Balearic Islands. Titanium and metallothionein concentrations were progressively increasing in gills with the sunscreen concentration in a dose-dependent manner. The activities of the antioxidant enzymes and the detoxification glutathione s-transferase evidenced a hormetic shape response with increased activities at lower sunscreen concentrations, a response that was abolished at the highest concentration. In accordance with these enzyme activities, the levels of malondialdehyde, as a marker of lipid peroxidation, were significantly elevated by the higher sunscreen concentrations. Acetylcholinesterase activity maintained control activities except for the highest sunscreen concentration, where a significant decrease was evidenced. In conclusion, the treatment of mussels with a sunscreen containing TiO₂ in the range of Balearic coastal waters induces an adaptive response that is overcome by the highest concentration. Follow-up biomonitoring studies are necessary to control the concentration of sunscreen compound in coastal waters such as titanium since they can induce oxidative stress to affected organisms.