Soft Tissues Of Mussels Research Articles

A nationwide survey of trace metals and Zn isotopic signatures in mussels (Mytilus edulis) and oysters (Crassostrea gigas) from the coast of South Korea

Thirteen trace metals and Zn isotopic signatures were investigated in mussels and oysters collected from the coast of South Korea to evaluate their bioavailability in bivalve mollusks. The average Cu, Zn, and Cd concentrations were 2.6–17.7 times higher in oysters than mussels, and high biota sediment accumulation factors (>30) were observed for these metals in oysters. Except for Pb in mussels, most metals had no correlation with total sediment concentrations. In oysters, Fe, V, Cu, Zn, Sn, and Pb concentrations were significantly correlated with sediments. The average values of δ66ZnIRMM3702 in mussels, oyster, and sediments were +0.09‰, +0.12‰, and −0.06‰, respectively. Soft tissues of mussels and oysters with high Zn concentrations tended to contain lighter Zn isotopes. The results indicate that oysters are a better biomonitoring organism for metal contamination than mussels and can be used in the monitoring and management of coastal environments and ecosystems.

Occurrence of Escherichia coli in mussels (Mytilus galloprovincialis) from farms in Boka Kotorska Bay, Southern Adriatic Sea

This study reports the occurrence of Escherichia coli in 243 mussel samples collected along the Boka Kotorska Bay (six harvesting areas), which is located in the Southern Adriatic Sea. Bivalve molluscs can concentrate contaminants from their water environment, so because of that, determination of E. coli levels is an important parameter for microbial pollution assessment in the investigated areas. The number of E. coli ranged between <18 MPN/100 g to 16 x 103 MPN/100 g of mussel soft tissues. In 243 bivalve mollusc samples, analysed during the period 2018-2019, 68.3% of them had low contamination levels, i.e. ≤ 230 MPN E. coli/100 g; 31.3% had between 230 and 4600 MPN E. coli/100 g, and 0.4% had > 4600 MPN E. coli/100 g. Statistical analysis of the number of E. coli in mussels established that the mussel farm vl. Duško Vlahović (M5) had the highest mean E. coli levels (949.00 ± 2541 MPN E. coli/100 g), while the lowest mean level was recorded in Boka mussels (M1) (149.20 ± 258.80 MPN E. coli/100 g). Boka Kotorska bay is classified as a Class B mussel production area because it has 32.9% of samples with E. coli MPN values between the 20-230 MPN/100g.

Effects of sizes and concentrations of different types of microplastics on bioaccumulation and lethality rate in the green mussel, Perna viridis

Microplastics (MPs) can be defined as small pieces of plastics that are less than five millimetres in diameter. MPs can be consumed and may be accumulated by filter-feeding organisms such as mussels. Therefore, this study aimed to determine the acute effects of different types, sizes and concentrations of artificially synthesized MPs on the mortality rate and MP accumulation of the green mussel Perna viridis. The samples were exposed to 66, 333, 666, and 1333 items/L of small MPs (<30 μm), medium MPs (30–300 μm), and large MPs (300–1000 μm) polystyrene (PS), polypropylene (PP), and polybutylene succinate (PBS) for 96 h. MPs accumulation in the soft tissue of mussels and mortality effects from MPs ingestion were assessed. There was no mortality observed in the control group. Small PP particles can lead to more mortality than PS and PBS particles of the same size. However, medium- and large PS caused a higher mortality percentage than the same size particles of PP and PBS. Large PS, PP, and PBS showed higher mortality potential than other sizes. MPs largely accumulated in the soft tissues rather than in gill tissues following the 96-hour exposure period. Increased accumulation of the three types of MPs was accompanied by an increase in the percentage of mussel mortality. The study highlights how particle size and type are key factors in plastic particulate toxicity.

An effective strategy for the monitoring of microplastics in complex aquatic matrices: Exploiting the potential of near infrared hyperspectral imaging (NIR-HSI)

Contamination by microplastics (MP) represents a critical environmental challenge with potential consequences at ecosystem, economic and societal levels. As the marine system is the final sink for MP, there is an urgent need to develop methods for the monitoring of synthetic particles in different marine compartments and sample matrices. Extensive evaluations are hindered by time and costs associated with to conventional MP spectroscopic analyses. The potential of near infrared hyperspectral imaging (NIR-HSI) has been recently evaluated. However, NIR-HSI has been poorly studied so far, limitedly to the detection of large particles (>300 μm), and its capability for direct characterization of MP in real marine matrices has not been considered yet. In the present study, a rapid near infrared hyperspectral imaging (NIR-HSI) method, coupled with a customised normalised difference image (NDI) strategy for data processing, is presented and used to detect MP down to 50 μm in environmental matrices. The proposed method is largely automated, without the need for extensive data processing, and enabled a successful identification of different polymers, both in surface water and mussel soft tissue samples, as well as on real field samples with environmentally occurring MP. NIR-HSI is applied directly on filters, without the need for particles pre-sorting or multiple sample purifications, avoiding time consuming procedures, airborne contaminations, particle degradation and loss. Thanks to the time and cost effectiveness, a large-scale implementation of this method would enable to extensively monitor the MP presence in natural environments for assessing the ecological risk related to MP contamination.

Acute copper accumulation in Mediterranean mussel and sea snail

In this study, the rate of copper accumulation in mussel (Mytilus galloprovincialis) and sea snail (Rapana venosa) organisms exposed to acutely different non-lethal copper concentrations was investigated for 5 days under laboratory conditions. All soft tissue concentrations were analyzed using an Inductively Coupled Plasma Optical Emission Spectrophotometer. At the end of accumulation, the rate of increase of copper level in mussel and snail soft tissues in different aquariums was found to be 19.19–36.93 and 2.37–7.41 times higher for mussel and snail soft tissues than before exposure, respectively. Differences in metal accumulation at the end of the experiment between species were not statistically significant (p > 0.05). In addition, bio-concentration factor and rates of accumulation values were calculated for both organisms. The corresponding bio-concentration factor values for mussels after exposure to 0.12, 0.36, and 0.60 mg L−1 copper were 406.00, 168.41, and 165.16, respectively, while the corresponding bio-concentration factor values for snails after exposure to 0.12, 0.36, and 0.60 mg L−1 copper were 276.29, 272.12, and 265.73, respectively. While accumulation rate values were 10.15, 12.26, and 20.12 for mussels exposed to 0.12, 0.36, and 0.60 mg L−1 copper, respectively, accumulation rate values were 6.85, 19.76, and 31.69 for snails exposed to 0.12, 0.36, and 0.60 mg L−1 copper, respectively.

Bioaccumulation of Lithium Isotopes in Mussel Soft Tissues and Implications for Coastal Environments

Bioaccumulation of Lithium Isotopes in Mussel Soft Tissues and Implications for Coastal Environments

Analysis of Manganese Bioaccumulated in Mediterranean Blue Mussel (Mytilus galloprovincialis) from the Bay of Mali Ston (Adriatic Sea, Croatia) during Diarrhetic Shellfish Poisoning Toxicity

Diarrhetic Shellfish Poisoning (DSP) toxicity was revealed in the Mediterranean blue mussel (Mytilus galloprovincialis) from the Bay of Mali Ston, in the south part of the Eastern Adriatic Sea, through the Croatian National Monitoring Programme in the period from January until June of 2011. A survey of DSP toxicity within the frame of regular controls carried out through the mouse bioassay (MBA, at the time the official method for DSP toxins) demonstrated that in some incidents, positive MBA, which manifested by the atypical symptomatology of the animals, dominated. Additional studies were done to explain the atypical results of the conducted biological tests at the time. In the current study, the bioaccumulated manganese concentration in the soft tissues of mussels was measured to investigate its influence on the MBA results. In both DSP negative and DSP positive samples, which were prepared for the analysis according to the modified US EPA 3052 method, the concentration of the bioaccumulated manganese was performed on the atomic absorption spectrometer using flame atomic absorption spectroscopy technique. The analysis revealed higher concentration of manganese in 87% of DSP positive samples and the expressed per wet weight ranged from 0.15 to 5.38 mg kg−1. The mean concentration of manganese for all DSP positive samples was 1.78 mg kg−1, while for DSP negative samples, it was 48% lower (0.93 mg kg−1). The highest concentration of manganese in DSP positive samples was measured in February 2011. Since the low concentrations of lipophilic biotoxins gymnodimines (GYMs) and spirolides (SPXs) were also detected in the analysed DSP positive samples in the parallel studies, the results obtained in this study suggest future investigations of the connection between the concentration of manganese and lipophilic biotoxins.

Higher bioavailability of Cu and Zn in the eastern part of Johore Causeway: Will the pattern remain the same beyond 2030?

The purpose of this paper is to discuss Cu and Zn concentrations in Perna viridis soft tissues from the western and eastern parts of Johore Singapore Causeway. The polluted eastern portion of the Causeway had greater levels of Cu and Zn in different areas of the soft tissues of mussels than the western part. This indicated the eastern section of the semi-enclosed Causeway had higher Cu and Zn bioavailability than the western part. With some reports of high metal levels in the eastern part of the Causeway from 2015 to 2018, it is predicted that there will be a plausible constant source of anthropogenic metal contamination in the eastern part of the Causeway beyond 2030 if anthropogenic activities are not effectively controlled.

Mercury in Marine Mussels from the St. Lawrence Estuary and Gulf (Canada): A Mussel Watch Survey Revisited after 40 Years

Various species of marine mussels have been used, in the last 50 years, as sentinel organisms for monitoring metal contamination along marine coasts. There are two main reasons for this: these mollusks concentrate metals in their soft tissue and they are geographically widespread. In practice, trace metal concentrations in mussel soft tissue reveal (after some correction for biotic effects) the contamination level of their surrounding environment. We present the results of a mercury (Hg) survey in Mytilus spp. collected in the summers of 2016, 2018, and 2019 at 51 stations distributed along the coasts of the Estuary and Gulf of St. Lawrence. Mercury concentrations ranged from 0.063 to 0.507 µg g−1 (dry weight, dw), with a grand mean of 0.173 ± 0.076 µg g−1 dw (±1 standard deviation), and a median of 0.156 µg g−1 dw for the 504 individuals analyzed. Mercury contents per individual mussel were significantly (p &lt; 0.01) related to shell length and dry tissue weight, with the smaller individuals having the highest Hg concentrations. To take into account these biotic effects, we normalized Hg concentrations of the mussel soft tissue for constant shell length (L) and soft tissue weight (TW) based on the log-log relationships between Hg content and L or TW. The normalized Hg contents of mussels varied from 10.9 to 66.6 ng per virtual individual of 35 mm length and 0.17 g dry weight. A similar normalization procedure applied to 1977–1979 data, yielded a very similar range: 12 to 64 ng. This observation suggests that the Hg bioavailable to marine mussels in the study area did not change over a span of 40 years. Regional Hg distribution patterns indicate a gradual decrease of Hg content in mussels downstream from freshwater discharges to the St. Lawrence Estuary and the Baie des Chaleurs, suggesting that rivers constitute a significant Hg source in these estuarine systems. Atmospheric Hg deposition and concentration in marine waters of the Atlantic Ocean are known to have decreased in the last decades. However, in coastal environments, the response to these changes does not seem to be rapid, probably because of the long residence time of Hg in soils before being exported to coastal areas.

The Accumulation of Al, As, Li, Mg, Mn, S, Si, Ti, and V in the Mussel Mytilus galloprovincialis from the Moroccan Mediterranean Coastal Areas: Trends Pertaining to Seasons and Levels

The accumulation levels of elements (Al, As, Li, Mg, Mn, S, Si, Ti, and V) in the soft tissue of mussels (Mytilus galloprovincialis), collected monthly in 2016, from Junuary to December, from sampling sites of the mussel farming facilities installed in the coastal areas of Al Hoceima, were investigated. The studied element levels were determined by using Inductively Coupled Plasma — Optical Emission Spectrometry (ICP-OES 720-ES). Descending order of the average element concentrations in soft tissue of M. galloprovincialis was S > Mg > Si> Al > Mn > Ti > As >V > Li. Element contents (Al, As, Mg, S and V) in tissue of mussels were significantly different (P < 0.05) between seasons, being highest in winter and lowest in summer. Strong correlations were observed between studied elements and chlorophyll a, indicating the importance of food for metal bioaccumulation in mussels in this period of the season. The observed strong correlations for metal levels in tissues of mussels can be explained by their common sources, which are associated with anthropogenic effects. The detected seasonal variations of investigated element concentrations in soft tissues of M. galloprovincialis could be attributed to physicochemical parameters such as temperature, salinity, dissolved oxygen, nutrients and food availability, as well as the biological status of the mussel. This study may provide basic information for detecting the current pollution status of investigated elements in Al Hoceima coasts from the Moroccan Mediterranean Sea using M. galloprovincialis as biological indicators.

The geometry of the toxicity of silver nanoparticles to freshwater mussels

The question about the influence of the geometry of silver nanoparticle (nAg) towards toxicity in aquatic organisms is largely unanswered. The purpose of this study was to examine if different geometries of nAg could initiate biophysical stress in the soft tissues of mussels. Freshwater Dreissenna bugensis mussels were exposed for 48 h at 15 °C to 10 and 50 μg/L of ionic Ag and to 3 forms of polyvinylpyrrolidone (PVP)-coated nAg of similar size: sphere, cube and prism. At the end of the exposure period, mussels were allowed to depurate overnight and the post-mitochondrial fraction of the soft tissues were analyzed for the levels of liquid crystals (LCs), changes in the activity and fractal dimensions of pyruvate kinase-lactate dehydrogenase (PK-LDH), F-actin and protein-ubiquitin (UB) levels. The data revealed that exposure to nAg forms lead to increased formation of LCs in increasing order of intensity: prismatic > cubic > spherical nAg. The activity in PK-LDH was decreased by all forms of nAg but not by ionic Ag+ (as with the following effects). Fractal kinetics of the PK-LDH system revealed that the nAg forms increased the spectral dimension (sD) in increasing order: spherical > cubic > prismatic nAg. A decrease in the fractal diffusion rate (fDR) with small changes in the fractal dimension (fD) was also obtained. The levels of F-actin and protein-UB were significantly affected for most forms of nAg and followed a pattern similar to LCs levels. In conclusion, the geometry of nAg could influence the formation of LCs, alter the fractal kinetics of the PK-LDH system, F-actin levels and protein damage in the soft tissues of freshwater mussels.

Influence of pH on Pb accumulation in the blue mussel, Mytilus edulis

Changes in seawater pH can alter the chemical speciation of waterborne chemical elements, affecting their bioavailability and, consequently, their bioaccumulation in marine organisms. Here, controlled environmental conditions and a 210Pb radiotracer were used to assess the effect of five distinct pH conditions (pHT ranging from 7.16 to 7.94) on the short-term (9 days) accumulation of Pb in the blue mussel, Mytilus edulis. After 9 days of exposure, higher levels of Pb were observed in the soft tissues of mussels maintained in the lower pH conditions, while Pb levels accumulated by mussel shells showed no difference across pH conditions. These results suggest that pH decreases such as those predicted by ocean acidification scenarios could enhance Pb contamination in marine organisms, with potential subsequent contamination and effect risks for human consumers.

The Use of Oxidative Stress Parameters of Bivalve Mollusks Dreissena polymorpha (Pallas, 1771) as Biomarkers for Ecotoxicological Assessment of Environment

The aim of this study was to investigate biomarkers of oxidative stress: сatalase (CAT), glutathione (GR), glutathione S-transferase (GST), low-molecular antioxidant—reduced glutathione (GSH) and lipid peroxide oxidation marker—malondialdehyde (MDA) and to measure heavy metal (НМ) concentrations in Dreissena polymorpha soft tissues at three different sampling sites in the Rybinsk reservoir (one of the largest in Europe) in order to assess exposure to anthropogenic pollution. The reservoir has a considerable source of pollution in its northern part due to a large industrial complex in Cherepovets. Mussels were collected at three sites which differ in the levels of anthropogenic load: more contaminated sites 1 (Cherepovets) and 2 (Koprino). Site 3 (Vesyegonsk) is relatively clean and is used as a control. In soft tissues of mussels from sites 1 and 2 significantly higher concentrations of HM (Pb, V, Cr, Ni, Cu, Mn, Zn, Cd) were detected than in mussels from site 3. Mussels from sites 1 and 2 subjected to long-term contamination from Cherepovets industry showed considerable CAT, MDA and GSH induction compared to mussels from relatively clean site 3. The correlation was found between elevated HM content and increased levels of CAT, MDA and GSH. The obtained data suggest that HM may contribute to the oxidative stress induction in mussel. MDA, CAT and GSH sensitivity in D. polymorpha demonstrated a possible use of these biomarkers in freshwater.

Paralytic shellfish toxin profiles in mussel, cockle and razor shell under post-bloom natural conditions: Evidence of higher biotransformation in razor shells and cockles

Concentrations of the paralytic shellfish toxins GTX6, C1+2, GTX5, C3+4, dcSTX, dcNEO and dcGTX2+3 were determined by LC-FLD in composite samples of whole soft tissues of mussels (Mytilus galloprovincialis), cockles (Cerastoderma edule) and razor shells (Solen marginatus) after exposure to a Gymnodinium catenatum bloom. Specimens were harvested weekly during three months under natural depuration conditions in the Mira branch of Aveiro lagoon, Portugal. Under the decline of G. catenatum cell densities, elimination or transformation of the uptake toxins associated with the ingestion of toxic cells differed among the surveyed species. Ratio between the toxins dcSTX plus dcGTX2+3 plus dcNEO and toxins GTX6 plus GTX5 plus C1+2 plus C3+4 was used to illustrate the biotransformation occurring in the bivalves. Enhancement of the ratios was observed for razor shells and cockles seven weeks after the peak of the algal bloom. Most likely it reflects more intense biotransformation in razor shells and cockles than in mussels. Conversion into toxins of higher toxicity may prolong the bivalve toxicity. These results show the complexity of toxin elimination in bivalves under post-bloom conditions and emphasize the pertinence of monitoring programs of bivalve toxicity in order to protect human health.

Mussel periostracum as a high-resolution archive of soft tissue δ13C records in coastal ecosystems

Stable carbon isotope ratios (δ13C) of mussel soft tissues have been widely used to characterize baseline δ13C isoscapes and identify carbon sources at the base of coastal food webs. Extending soft tissue δ13C records back in time, however, is extremely challenging due to very limited sample availability. Here, we test if the stable carbon isotopic composition of periostracum (the outermost organic layer of the shell) in the Mediterranean mussel (Mytilus galloprovincialis) can be used as an environmental archive, similar to soft tissue records. In general, spatial and seasonal variations of periostracum δ13C values are comparable to those of soft tissues, but apparently the latter are more time-averaged and smoothed. Irrespective of such offset, there is a significant linear correlation between mussel periostracum and soft tissue δ13C values (R2 = 0.608, p < 0.001). Moreover, high-resolution δ13C analysis of mussel periostracum indicates that it integrates much less time than soft tissue due to metabolically inert nature, consequently being able to record predictable events such as tidal changes and also unpredictable ephemeral events in coastal ecosystems. The present study demonstrates the potential of the periostracum as a viable alternative to the most widely used soft tissues in isotopic studies. Most promisingly, given ample collections over time scales up to hundreds of years and usually stored dry, this technique could be used to extend coastal organic carbon δ13C records back in time.

Sediment distribution coefficients (Kd) and bioaccumulation factors (BAF) in biota for natural radionuclides in eastern Black Sea coast of Turkey

Germanium (HPGe) detector was used to measure natural (226Ra, 232Th and 40K) radioactivity levels in sediment and seawater samples, and soft tissues of Mediterranean mussels (Mytilus galloprovincialis) of three different sizes, collected from twelve different stations along the coast of Giresun, Trabzon, Rize and Artvin provinces in Eastern Black Sea Region. The average activity concentrations of the sediment and seawater samples collected were 12.65 Bq kg−1 and 3.57 mBq L−1 for 226Ra, 14.25 Bq kg−1 and 4.01 mBq L−1 for 232Th and 294.8 Bq kg−1 and 317.8 mBq L−1 for 40K, respectively. The activity concentrations in soft tissues of three different sized mussel samples altered from 2.45 to 9.59 Bq kg−1 for 226Ra, 2.22–8.59 Bq kg−1 for 232Th and 251.9–382.1 Bq kg−1 for 40K. Moreover, sediment distribution coefficients (Kd) and bioaccumulation factors (BAFw and BAFs) in the mussel samples were calculated. While the bioaccumulation of 226Ra and 232Th from seawater to mussel was observed, the bioaccumulation 40K was observed from sediment to mussel. The ratio of the average concentration of radionuclides in large-sized mussels to that in water and sediment is greater as compared with smaller mussels. Although there were statistically differences (p < 0.05) among mussel sizes according to 232Th levels for activity concentrations, BAFw and BAFs values in soft tissues of the mussel samples, it wasn't observed difference according to 226Ra and 40K levels (p > 0.05).

Metal Bioaccumulation of Mytilaster lineatus (Gmelin, 1791) Collected From Sinop Coast in the Southern Black Sea

Objective: Metal bioaccumulation of the bivalve Mytilaster lineatus, based on different seasons and stations was investigated in Sinop Peninsula of the Black Sea. Soft tissues of mussels from Gazibey Rock and Içliman were taken during the spring and the summer of the year 2016 and were analyzed for Hg, Cd, Pb, Cu and Zn. Materials and Methods: The soft tissues of the mussels digested with Suprapur® HNO3 (nitric acid) using a Milestone Systems, Start D 260 microwave digestion system. The accuracy and precision of the method was verified by the simultaneous analysis of the certified reference materials NIST 2976 (mussel tissue) for the samples. The Inductively Coupled Plasma–Mass Spectrometer (ICP-MS), Agilent Technologies, 7700x was used for metal analyses. Results: Results showed that higher concentrations of almost all metals in Içliman than those in Gazibey Rock. However, no significant differences were detected between seasons except for both Cu and Zn. The metal amounts of M. lineatus ranged between 0.024-0.035, 0.054-0.072, 0.13-0.25, 0.64-0.85 and 6-20 mg kg-1 wet wt. for Hg, Cd, Pb, Cu and Zn, respectively. Conclusion: The measured metals in both sampling areas did not exceed the threshold set by the European Commission and Turkish Food Codex. The results of this study also confirmed the potential of M. lineatus to be used as bio-indicators of heavy metal pollution.

Exposure to a nanosilver-enabled consumer product results in similar accumulation and toxicity of silver nanoparticles in the marine mussel Mytilus galloprovincialis

The incorporation of silver nanoparticles (AgNPs) in commercial products is increasing rapidly. The consequent release of AgNPs into domestic and industrial wastewater raises environmental concerns due to their anti-microbial properties and toxicity to non-target aquatic organisms. The aim of the present study was to investigate the effects of nanArgen™ (Nanotek S.A.), a AgNP-enabled consumer product, in the marine bivalve Mytilus galloprovincialis. Two environmentally relevant concentrations of nanArgen™ (1 and 10 μg/L) were tested in vivo for 96 h, and Ag was quantified in mussel soft tissue and natural seawater (NSW). nanArgen™ suspensions were characterized via TEM, SEM, EDS, DLS, and UV–vis optical analysis. Several molecular and biochemical responses were investigated in exposed mussels: lysosomal membrane stability by Neutral Red Retention Time (NRRT) assay; micronucleus (MN) frequency in hemocytes; metallothionein (MT) protein content and gene expression (mt10 and mt20); catalase (CAT) and glutathione-S-transferase (GST) activities; malondialdehyde (MDA) accumulation in digestive glands; and efflux activity of ATP-binding cassette transport proteins (ABC) in gill biopsies. SEM, TEM and DLS analyses confirmed the presence of well-defined AgNPs in nanArgen™ which were roughly spherical with an average particle size of approx. 30 ± 10 nm. DLS analysis revealed the formation of AgNP aggregates in nanArgen™ suspension in NSW (Z-average of 547.80 ± 90.23 nm; PDI of 0.044). A significant concentration-dependent accumulation of Ag was found in mussels’ whole soft tissue in agreement with a concentration-dependent decrease in NRRT and an increase of MN frequency in hemocytes and GST activities in digestive glands. A significant increase in MDA levels and MT via both molecular and biochemical tests, were also observed but only at the highest nanArgen™ concentration (10 μg/L). No changes were observed in CAT activities. ABC efflux activities in gill biopsies showed a significant decrease (p < 0.05) only at the lowest concentration (1 μg/L). On such basis, nanArgen™ is shown to be able to induce toxicity and Ag accumulation in marine mussels similarly to AgNPs and in short-term exposure conditions at environmentally relevant concentrations. AgNP-enabled products, instead of pristine AgNPs, should be the focus of future ecotoxicity studies in order to address any risks associated to their widespread use, disposal and uncontrolled release into the aquatic environment for non target species.

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.

Use of whole mussels and mussel gills in metal pollution biomonitoring

The use of marine bivalves in metal pollution monitoring is undoubtedly one of the best tools to evaluate metal pollution in coastal areas worldwide. However, since bivalves integrate metal pollution from both the dissolved and the particulate phases, it cannot be assured that metal bioaccumulation in their tissues will predict the risk posed by metals to sensitive organisms such as invertebrate larvae or microalgae, which are known to be mainly affected by the free metal ion fraction. This study aims to test the usefulness of mussel gills–the primary exchange surfaces with dissolved metals–in reflecting dissolved metal bioavailability in the field. For that, we analyzed metal concentrations in environmental samples (whole soft tissues of mussels, mussel gills, sediment, and particulate and dissolved fractions in the water column) collected from 7 sampling sites during a multi-year investigative monitoring survey in the Ría de Vigo. The results showed a different pattern of Cu and Zn accumulation in gills compared to whole soft tissues, and these differences are attributable to the faster response of gills to changes in dissolved metal concentrations and to the regulation of essential metals at the whole body level. In the case of Pb, by contrast, concentrations in gills were very similar to those in the whole body. The use of mussel gills in metal pollution biomonitoring is a promising tool for the detection of changes in bioavailable metals in the environment, especially for essential metals such as Cu and Zn.