Comparative Analysis of Subcellular Distribution of Heavy Metals in Organs of the Bivalve Mollusks <Emphasis Type="Italic">Crenomytilus grayanus</Emphasis> and <Emphasis Type="Italic">Modiolus modiolus</Emphasis> in a Continuously Polluted Environment

The distribution of Zn, Fe, Ni, Cu, Mn, Cd, and Pb in subcellular fractions, and of Cd, Zn, and Cu in cytoplasm proteins of the kidney and digestive gland of the mussels Crenomytilus grayanus and Modiolus modiolus, sampled from contaminated and conditionally clean areas, was studied. It was found that, in a contaminated environment, the organs of mussels were more highly enriched with metals. It was shown that essential trace elements were accumulated mostly in the cytosol of organs of both molluscan species from contaminated areas, whereas in the background areas the trace elements were associated mostly with membrane structures in Gray's mussel, C. grayanus, and with the cytosol in M. modiolus, the northern horse mussel. The lead was bound mostly to membrane structures in organs of both mussel species at all stations. The method of gel chromatography enabled us to isolate metallothionein-like proteins from the kidney of the northern horse mussel sampled in contaminated areas, whereas their concentration in the kidney of Gray's mussels was lower than the limiting error of the method. It is supposed that in the kidney of Gray's mussel the synthesis of metallothionein-like proteins was quenched by the integrated effect of the accumulated metals.     

The interaction between algal viruses and the mussel <Emphasis Type="Italic">Mytilus galloprovincialis</Emphasis> Lamarck, 1819 (Bivalvia: Mytilidae) in experiments

The utilization (possible assimilation and concentration in organs) of 99% of algal viruses from the water by the Black Sea mussel Mytilus galloprovincialis was confirmed experimentally. This index depends on the duration of the experiment, the complexity of the morphology of the virus, the age (size) of the mussels, and the presence of a nonindicatory microalga, which allows the experimental conditions to be close to natural and is conducive to the agglutination of viruses in pseudofeces and their enhanced utilization by mussels. It was found that some algal viruses concentrated by filter-feeding mussels return to the environment in the feces and are transported to the bottom (where they can be used by benthivores) or diffuse back into the pelagic zone. The results indicate that mussels have a role in the circulation of marine viruses, utilizing and transferring them from the pelagic to the benthic biotope.     

Blue mussel (<Emphasis Type="Italic">Mytilus edulis</Emphasis>) bouchot culture in Mont-St Michel Bay: potential mitigation effects on climate change and eutrophication

Purpose

Bivalve production is an important aquaculture activity worldwide, but few environmental assessments have focused on it. In particular, bivalves’ ability to extract nutrients from the environment by intensely filtering water and producing a shell must be considered in the environmental assessment.

Methods

LCA of blue mussel bouchot culture (grown out on wood pilings) in Mont Saint-Michel Bay (France) was performed to identify its impact hotspots. The chemical composition of mussel flesh and shell was analyzed to accurately identify potential positive effects on eutrophication and climate change. The fate of mussel shells after consumption was also considered.

Results and discussion

Its potential as a carbon-sink is influenced by assumptions made about the carbon sequestration in wooden bouchots and in the mussel shell. The fate of the shells which depends on management of discarded mussels and household waste plays also an important role. Its carbon-sink potential barely compensates the climate change impact induced by the use of fuel used for on-site transportation. The export of N and P in mussel flesh slightly decreases potential eutrophication. Environmental impacts of blue mussel culture are determined by the location of production and mussel yields, which are influenced by marine currents and the distance to on-shore technical base.

Conclusions

Bouchot mussel culture has low environmental impacts compared to livestock systems, but the overall environmental performances depend on farming practices and the amount of fuel used. Changes to the surrounding ecosystem induced by high mussel density must be considered in future LCA studies.

     

Effect of temperature on early development of the Pacific mussel <Emphasis Type="Italic">Mytilus trossulus</Emphasis> (Bivalvia: Mytilidae) in sea water polluted by copper ions

The effects of water temperatures of 7, 15 and 20°C and pollution of sea water by copper ions in concentrations of 0.005 and 0.01 mg/l on the early development of the Pacific mussel Mytilus trossulus were studied. It was shown that copper additives were most toxic at the initial stages of development, from fertilization up to the veliger stage. It was determined that larvae of the Pacific mussel were able to adapt to copper at a concentration of 0.005 mg/l. The copper toxicity increased to a greater extent with an increase in water temperature from its average value of 15°C, than with a temperature decrease.     

Encystment <Emphasis Type="Italic">in vitro</Emphasis> of the Cercariae <Emphasis Type="Italic">Himasthla elongata</Emphasis> (Trematoda: Echinostomatidae)

Trigger and toxic effects of Mytilus edulis (Bivalvia) hemolymph on encystment of cercariae Himasthla elongata obtained from infestated Littorina littorea (Prosobranchia) was evaluated as a result of 24-h experiments in vitro. The contact of H. elongata larvae with the whole hemolymph or mussel acellular plasma led to an intensive transformation of cercariae into metacercariae. In both tested media, the cercariae had to complete the encystment phase as fast as for 2 h, otherwise the risk of the larvae injury by humoral and cellular components of the mussel hemolymph would increase dramatically. The cercaria mortality after 24 h in the whole hemolymph was twice higher than in plasma (40% and 20%, respectively) and much higher than in the control medium (sea water). Both toxic and trigger effects of plasma was revealed to depend on its concentration, with the maximal larva mortality in the undiluted medium and with the highest number of successful transformations in the medium diluted more than 4 times. There is shown both the strong individual variability of toxicity of the individual mussel hemolymph for cercariae and the variability of the resistance to the toxic factors of the cercariae obtained from various L. littorea individuals. These experiments not only offer a method of the massive encystment of H. elongata cercariae, but also propose a perspective model for the study of the systemic defensive response of Bivalvia to invasion of multicellular parasite.     

Cadmium uptake,localization and detoxification in <Emphasis Type="Italic">Zea mays</Emphasis>

Cadmium uptake, translocation and localization in maize roots and shoots at the tissue and cellular level were investigated. Metal accumulation in plant organs as well as symptoms of Cd toxicity were closely correlated with an increase in Cd concentration applied (5 – 300 M). Most of the metal taken up was retained in roots, mainly inside the cells of endodermis, pericycle and central cylinder parenchyma. Accumulation of phytochelatins and related peptides also depended on Cd concentration in the nutrient solution.     

Dynamics of byssal thread production in <Emphasis Type="Italic">Crenomytilus grayanus</Emphasis> and <Emphasis Type="Italic">Modiolus modiolus</Emphasis> (Bivalvia) upon reattachment to substrate

It was established that the process of repeated attachment to a substrate in bivalve mollusks Crenomytilus grayanus (Grays mussel) and Modiolus modiolus (the northern horse mussel) involved several successive stages which took in vitro about one month at a water temperature of 19 ± 2°C. Comparison with Grays mussel revealed that the northern horse mussel had a higher rate of byssal thread production and a greater thread number by the end of the complete formation of the byssus complex. The observed differences are explained by the adaptation of mollusks to habitation in different biotopes.Original Russian Text Copyright © 2004 by Biologiya Morya, Selin, Vekhova.     

Toward using <Emphasis Type="Italic">Margaritifera falcata</Emphasis> as an indicator of base level nitrogen and carbon isotope ratios: insights from two California Coast Range rivers

Measurements of freshwater mussel tissue are potentially very useful for determining base-level isotopic values for food web studies in aquatic environments. As long-lived, filter-feeding organisms, mussels have the potential to spatially and temporally average the isotopic baseline signal. Following from earlier studies that focused on lake environments, this study investigates the stable carbon and nitrogen isotope ratios in tissue of the river dwelling freshwater mussel, Margaritifera falcata, in two extensively studied northern California coast range rivers, the South Fork Eel and Navarro. We highlight advantages and challenges for using riverine mussel isotopes as indicators of baselines. ¹³C of primary producers is known to vary with habitat along the South Fork Eel channel, but our measurements show no such variations, demonstrating that riverine mussels do preserve a spatially averaged measure of instream derived food sources. Mean ¹³C and ¹⁵N are shown to be markedly different in the two rivers, reflecting differences in food sources and possibly watershed land use. We also found that ¹⁵N of mussel tissue increased by approximately 2 with mussel age in both rivers. This suggests it is important to consider age and size effects when estimating baseline values from mussel tissues.     

Byssus production rate of the White Sea blue mussel <Emphasis Type="Italic">Mytilus edulis</Emphasis> (Linnaeus, 1758) in the presence of metabolites of some hydrobionts

The byssus production of the blue mussel Mytilus edulis L. was studied in the laboratory in the presence of the metabolites of the following animals: a predator (a starfish Asterias rubens L.) and several species competing with the mussel in White Sea fouling communities (a bivalve Hiatella arctica L. and a solitary ascidian Styela rustica L.). The byssus threads and attachment plaques produced by each mussel per day were counted. The number of byssus threads and plaques was smallest in pure sea water and in the presence of metabolites produced by conspecific individuals.     

Pattern of Selenium Distribution in TomatoLycopersicum esculentumMill

We studied the pattern of selenium accumulation inLycopersicum esculentumMill plants under conditions of selenium-enriched root and extraroot nutrition. Against the background of a general trend toward predominant selenium accumulation in the fruit skin, a higher level of accumulation of selenates (Se⁺⁶) than selenites (Se⁺⁴) was observed in the pulp. Application of Epin growth stimulant promoted selenium accumulation in the plants; its concentration in the pulp was comparable to the concentration after selenate application, while the level of the microelement accumulation in the fruit skin, leaves, and roots was 2.2, 2.4, and 1.4 times lower, respectively. Combined application of Epin and sodium selenate had virtually no effect on selenium accumulation in the pulp but increased the microelement content in the fruit skin and roots. Biological significance of the observed boundary effect of selenium as a manifestation of plant antioxidant protection is discussed.     

Effect of the excretory-secretory products of some marine invertebrates on byssus production of the blue mussel <Emphasis Type="Italic">Mytilus edulis</Emphasis> (Bivalvia: Mytilidae)

Under laboratory conditions, we investigated byssus production in the blue mussel Mytilus edulis, as affected by the excretory-secretory products (ESPs) of the mussel itself and some marine invertebrates: the predatory starfish Asterias rubens, and organisms competing with mussels in White Sea fouling communities—a bivalve Hiatella arctica, the solitary ascidians Styela rustica and Molgula citrine, and a sponge Halichondria panicea. The number of attachment disks produced by a mussel per day and the thickness of byssal threads were estimated. Excretory-secretory products of H. arctica and M. citrine had no effect on the number of attachment disks, while ESPs of S. rustica, H. panacea and A. rubens stimulated mussels to produce attachment plaques. The activity of the mussel was slightly increased at low levels of its own ESPs in seawater. The thickness of byssal threads decreased with an increase in the ESPs of mussels in seawater, but it increased in experiments with the ESPs of any other species tested.     

Long-Term Changes in Nutrients and Mussel Stocks Are Related to Numbers of Breeding Eiders Somateria mollissima at a Large Baltic Colony

Background

The Baltic/Wadden Sea eider Somateria mollissima flyway population is decreasing, and this trend is also reflected in the large eider colony at Christiansø situated in the Baltic Sea. This colony showed a 15-fold increase from 1925 until the mid-1990''s, followed by a rapid decline in recent years, although the causes of this trend remain unknown. Most birds from the colony winter in the Wadden Sea, from which environmental data and information on the size of the main diet, the mussel Mytilus edulis stock exists. We hypothesised that changes in nutrients and water temperature in the Wadden Sea had an effect on the ecosystem affecting the size of mussel stocks, the principal food item for eiders, thereby influencing the number of breeding eider in the Christiansø colony.

Methodology/Principal Finding

A positive relationship between the amount of fertilizer used by farmers and the concentration of phosphorus in the Wadden Sea (with a time lag of one year) allowed analysis of the predictions concerning effects of nutrients for the period 1925–2010. There was (1) increasing amounts of fertilizer used in agriculture and this increased the amount of nutrients in the marine environment thereby increasing the mussel stocks in the Wadden Sea. (2) The number of eiders at Christiansø increased when the amount of fertilizer increased. Finally (3) the number of eiders in the colony at Christiansø increased with the amount of mussel stocks in the Wadden Sea.

Conclusions/Significance

The trend in the number of eiders at Christiansø is representative for the entire flyway population, and since nutrient reduction in the marine environment occurs in most parts of Northwest Europe, we hypothesize that this environmental candidate parameter is involved in the overall regulation of the Baltic/Wadden Sea eider population during recent decades.     

Influence of the White Sea sponge <Emphasis Type="Italic">Halichondria panicea</Emphasis> (Pallas, 1766) on physiological state of the blue mussel <Emphasis Type="Italic">Mytilus edulis</Emphasis> (Linnaeus, 1758), as evaluated by heart rate characteristics

During laboratory testing it was shown that the presence of the White Sea sponge Halichondria panicea on the shell of the mussel Mytilus edulis negatively affects the functional state of the mollusk as expressed in the increased heart rate recovery time after functional test loads (a 50% water salinity drop for 1 hour). It was found that the degree of this negative influence rises with an increase both in the projective cover of mussel shells by the sponge and in the size/age parameters of mussels.     

Bacterial and archaeal communities inhabiting mussels,sediment and water in Indonesian anchialine lakes

Anchialine lakes are a globally rare and unique ecosystem consisting of saline lakes surrounded by land and isolated from the surrounding marine environment. These lakes host a unique flora and fauna including numerous endemic species. Relatively few studies have, however, studied the prokaryote communities present in these lakes and compared them with the surrounding ‘open water’ marine environment. In the present study, we used a 16S rRNA gene barcoded pyrosequencing approach to examine prokaryote (Bacteria and Archaea) composition in three distinct biotopes (sediment, water and the mussel Brachidontes sp.) inhabiting four habitats, namely, three marine lakes and the surrounding marine environment of Berau, Indonesia. Biotope and habitat proved significant predictors of variation in bacterial and archaeal composition and higher taxon abundance. Most bacterial sequences belonged to OTUs assigned to the Proteobacteria. Compared to sediment and water, mussels had relatively high abundances of the classes Mollicutes and Epsilonproteobacteria. Most archaeal sequences, in turn, belonged to OTUs assigned to the Crenarchaeota with the relative abundance of crenarchaeotes highest in mussel samples. For both Bacteria and Archaea, the main variation in composition was between water samples on the one hand and sediment and mussel samples on the other. Sediment and mussels also shared much more OTUs than either shared with water. Abundant bacterial OTUs in mussels were related to organisms previously obtained from corals, oysters and the deepsea mussel Bathymodiolus manusensis. Abundant archaeal OTUs in mussels, in contrast, were closely related to organisms previously obtained from sediment.     

Variation in the <Emphasis Type="Italic">COI</Emphasis> gene of the freshwater pearl mussel <Emphasis Type="Italic">Margaritifera margaritifera</Emphasis> from River Vuokkijoki

The freshwater pearl mussel Margaritifera margaritifera L. is one of the most endangered freshwater mussels in the world. Effective conservation of threatened species requires not only ecological, but also genetic information from the target species and populations. Since low genetic diversity can reduce the ability of a species to adapt to environmental changes, maintaining genetic diversity has been identified as one of the key elements in successful conservation programs. We examined genetic variation of the freshwater pearl mussel from the River Vuokkijoki, Karelia, Russia. We sequenced a fragment of the cytochrome c oxidase subunit I gene (COI) from 22 individuals and compared the data to 32 previously published COI sequences available in GenBank. We identified 10 different COI haplotypes in the sequenced samples, three of which had not been previously reported. Our results show that the River Vuokkijoki has high genetic diversity and suggest that the colonization of this northern freshwater pearl mussel population might have occurred from multiple and even distant refugia. Therefore, the freshwater pearl mussel population of the River Vuokkijoki is valuable for the conservation of the whole species.     

Cadmium bioaccumulation in Lamellidens marginalis and human health risk assessment: A case study in India

Abstract

Lamellidens marginalis is an easily available food with high nutritive value. The present study is based on the East Kolkata Wetlands (EKW), India that produces mussels, consumed by human. Thus, the study of heavy metal pollution in the wastewater and mussel, and its transport to human is considered to be need of the hour to assess the health risk to human. The present study focuses on the cadmium accumulation in the outer exposed organs and the internal organs of L. marginalis. The mussel, sediment, and water were collected from the field and analyzed in the laboratory. The environmental factors were analyzed in situ. The survey work was conducted among the consumers of mussel around the EKW to predict the effect of cadmium on human. The result showed that the cadmium concentration of water was relatively important for the bioaccumulation process in L. marginalis. People having low level of income and age above forty, living adjoining the EKW were at high risk of cadmium pollution. The hazard quotient value of the above group was highest among all the groups across age and income. A ‘biofilter’ technique was suggested to mitigate the biomagnification of cadmium at the EKW.     

The Effect of Metal Concentration in Bottom Sediments on the Accumulation of Metals by the Mytilids Crenomytilus grayanus and Modiolus kurilensis

The relationship between the concentration of Pb, Cu, Cd, Zn, and Ag in soft tissues of mytilids Crenomytilus grayanus and Modiolus kurilensis and in bottom deposits was studied to determine the potential and limitations in the use of these molluscs as bioindicators of contamination of coastal waters near Vladivostok (northwest of the Sea of Japan). It was found that the mussel C. grayanus began to accumulate Pb and Cu after certain threshold concentrations of these metals (60 and 150 g/g respectively) in fine fractions of sediments was reached. Accumulation of Pb and Cu by M. kurilensis also depended on the level of sediment contamination, but the higher initial metal content in tissues and the higher individual variability reduced the sensitivity of this species as a bioindicator. Accumulation of Cd and especially of Zn in mytilid tissues is adjusted by the organism, which restricts the opportunity of their use for tracking the anthropogenic input of bioavailable forms of these metals.     

The biogeochemical background and trace metal accumulation by brown algae of the genus <Emphasis Type="Italic">Fucus</Emphasis> in coastal waters of the Sea of Japan,the Sea of Okhotsk,and the White Sea

The ranges of background concentrations of Fe, Mn, Zn, Cu, and Cd in Fucus algae from the Sea of Japan, the Sea of Okhotsk, and the White Sea were determined. The lower background threshold of element concentration was calculated as Me₁₅–2MAD₁₅, the upper background threshold was determined as Me+2MAD. The upper background threshold of the metal contents in Fucus algae can be used as the maximum permissible regional concentration in assessing pollution levels of marine habitats. Comparison of the Me₁₅–2MAD₁₅ values showed that Fucus algae of the White Sea had increased Mn and decreased Cd concentrations compared to those in Pacific algae. The concentrations of Zn were higher in Fucus algae of the Sea of Japan than in macrophytes from the White Sea and the Sea of Okhotsk. The background concentration range of Fe in Fucus algae of the Sea of Japan was much narrower compared to that in their counterparts from the White Sea and the Sea of Okhotsk. The background metal concentrations in Fucus algae are specific to a sea region; their variations are connected not only with the trace element contents in abiotic components of the environment, but also with the functioning of coastal ecosystems.     

Toxic metals accumulation in <Emphasis Type="Italic">Trichoderma asperellum</Emphasis> and <Emphasis Type="Italic">T. harzianum</Emphasis>

Heavy metal contamination represents an important environmental issue due to the toxic effects of metals on different organisms. Filamentous fungi play an important impact in the bioremediation of heavy metal-contaminated wastewater and soil. The purpose of this investigation was to observe fungal uptake behavior toward heavy metal. For this aim Trichoderma asperellum TS141 and T. harzianum TS103 at growth period were screened for their tolerance and uptake capability of cadmium (Cd), lead (Pb) and nickel (Ni) at different concentrations (0, 25, 50, 100, and 200 mg/L) in PDB media (potato dextrose broth as a complex medium). Results showed that both fungi were able to survive at the maximum concentration of 200 mg/L of the heavy metals, and remove them. T. asperellum had a better uptake capacity for Cd compared to Pb and Ni in the highest metal concentration in media. Maximum removal efficiency of Pb (68.4%) at 100 mg/L and Ni (78%) at 200 mg/L was performed by T. asperellum. For Cd, the highest removal efficiency (82.1%) was recorded by T. harzianum at 200 mg/L Cd in aqueous solution. The uptake of Cd was highly dependent on pH of solution than Pb and Ni so that the optimal pH of Cd uptake was 9 for T. asperellum and 4 for T. harzianum. Also, optimal temperature was 35°C for Cd and Pb uptake in both fungi, whereas for Ni uptake was 30 and 35°C in T. harzianum and T. asperellum, respectively. We propose that T. asperellum TS141 and T. harzianum TS103 can be used as a bioremediation agent for metal remediation from wastewater and heavy metal-contaminated soils.     

Biogeochemical pathways of cadmium through an artificially contaminated intertidal mud flat system — a medium-scale enclosure experiment

Summary Two Bremerhaven caissons were used to investigate the interactions of cadmium (Cd) with sea water, particulate matter, sediments, suspended particular matter (SPM), and organisms in enclosed sea water-sediment systems, on the tidal mud flats of Jade Bay (FRG). One caisson was artificially contaminated by continuously injecting cadmium (as a chloride) so as to maintain a Cd concentration of 100 g/l in the inflowing water of each tidal cycle for 22 days. The other caisson was used as a control system. About 30% of the total Cd introduced into the caisson was transferred from the aqueous phase to the other phases during each tidal cycle. Cadmium appears to accumulate in elements of the system in the order SPM, organisms, sediments, water. SPM, initially low in Cd entering the system, rapidly accumulated Cd from solution after the first tidal cycle and the concentration continued to increase during the experiment. Particulate Cd transferred to the sediments results in the development of a Cd-rich layer that attained a depth of 4 cm over the course of the experiment. Among the biota, the blue mussel (Mytilus edulis) progressively accumulated the highest concentrations of Cd whereas other taxa, like polychaetes, accumulated less of the metal. Differnces in Cd accumulation appear to be due to the habitats of the different species and their ability to assimilate Cd from the dissolved and particulate phases. Together, the data indicate that in the contamination of tidal mud flats with aqueous cadmium most of the metal would remain available to the organisms in the aqueous phases and weakly bound to particulate matter. This would present the greatest environmental danger to filter feeders but not to animals living in the sediments.