Bivalve Mytilus Edulis Research Articles

Sensitivity of the mussel Mytilus edulis to substrate‑borne vibration in relation to anthropogenically generated noise

© 2015 Inter-Research. Many anthropogenic activities in the oceans involve direct contact with the seabed (for example pile driving), creating radiating particle motion waves. However, the consequences of these waveforms to marine organisms are largely unknown and there is little information on the ability of invertebrates to detect vibration, or indeed the acoustic component of the signal. We quantified sensitivity of the marine bivalve Mytilus edulis to substrate-borne vibration by exposure to vibration under controlled conditions. Sinusoidal excitation by tonal signals at frequencies within the range 5 to 410 Hz was applied during the tests, using the 'staircase' method of threshold determination. Thresholds were related to mussel size and to seabed vibration data produced by anthropogenic activities. Clear behavioural changes were observed in response to the vibration stimulus. Thresholds ranged from 0.06 to 0.55 m s -2 (acceleration, root mean squared), with valve closure used as the behavioural indicator of reception and response. Thresholds were shown to be within the range of vibrations measured in the vicinity of anthropogenic operations such as pile driving and blasting. The responses show that vibration is likely to impact the overall fitness of both individuals and mussel beds of M. edulis due to disruption of natural valve periodicity, which may have ecosystem and commercial implications. The observed data provide a valuable first step to understanding the impacts of such vibration upon a key coastal and estuarine invertebrate which lives near industrial and construction activity, and illustrate that the role of seabed vibration should not be underestimated when assessing the impacts of noise pollution.

Immunotoxicity of heavy metals (silver, cadmium, mercury and lead) on marine bivalve Mytilus edulis: in vitro exposure of hemocytes

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Effects of Ocean Acidification on Toxicity of Heavy Metals in the Bivalve Mytilus edulis L

The anthropogenic release of carbon dioxide into the atmosphere leads to an increase in the CO2 partial pressure in the ocean, which may reach 950 μatm by the end of the 21st century. An experiment was performed to test the effects of increased sea water concentrations of CO2 combined with heavy metals on mortality rates, metallothionein, immune funtion, and uptake kinetics of the bivalve Mytilus edulis L. As a result, the mortality rates of Mytilus edulis L fluctuated with pH variety in all heavy metals (Cd, Pb, Cu) test seawater treatments compared to control group. It was demonstrated that in vivo Cd-, Pb-, or Cu pretreatment under acidifications can alleviate metallothionein by in vitro Cd, Pb, and Cu in soft tissues and suggested that acidification can aggravate heavy metals pollution and toxicity for marine organisms. Moreover, the fraction of eosinophilic cells increased over the 21 days period for Cd exposure, then decreased with 28 and 35 days incubation, the fraction of eosinophilic cells increased similar with Cd exposure and pH 8.2. The fraction of eosinophilic cells significantly increased from 32% to 53% of the hemocyte population over the 35-day period for Pb exposure and pH8.2, the fraction of eosinophilic cells increased from 35% to 58% of the hemocyte population over the 35-day period for Pb exposure and pH 6.2. Phagocytosis levels declined with increasing exposure time for Cd alone and phagocytosis levels declined with decreasing pH (from 8.2 to 6.2) with Cd exposure on 35 days. Mytilus edulis L in Pb with reduced pH (6.2) treatments also decreased their phagocytosis levels on 35 days. Further, phagocytosis decreased bigger than that of Pb with pH 8.2. At steady state equilibrium, CF of 109Cd was significantly higher at pH 6.2 and pH 7.7 than at pH 8.2, the accumulation of 203Pb was significantly higher at the lowest pH 6.2 level than at the two exposure levels (pH 7.7 and pH 8.2). Similarly, the lower the seawater pH 6.2, the more 63Cu was accumulated in the hemolymph of Mytilus edulis L. The results indicate that future reductions in pH caused by increased CO2 concentrations in the sea may have an impact on Mytilus edulis L combined with heavy metals pollution.

Differential concentration of Technetium-99 (99Tc) in common intertidal molluscs with different food habits

Concentration of 99Tc has been measured in fucoids and molluscs, sampled in a sheltered intertidal at the southwest coast of Norway from February to November 2006. The concentrations of 99Tc in molluscs differed significantly between species. The filtering bivalve Mytilus edulis had the lowest concentrations with averages of 2.3–5.9Bqkg−1d.w., while the herbivorous gastropods Littorinalittorina, Littorina obtusata and Patella vulgata had higher concentrations. P. vulgata and L. obtusata had the highest concentrations, 40–47 and 26–30Bqkg−1d.w., respectively. L. obtusata has a specialized habit of living, and prefers to feed on fucoids. P. vulgata can graze extensively on the fucoid Ascophyllum nodosum when available. Fucoids are known to have very high uptake of 99Tc, and this was also found in the present study. The high 99Tc-concentrations of L. obtusata and P. vulgata are most likely due to their habit of feeding on fucoids.

Identification of Reproduction-Specific Genes Associated with Maturation and Estrogen Exposure in a Marine Bivalve Mytilus edulis

BackgroundWhile it is established that vertebrate-like steroids, particularly estrogens (estradiol, estrone) and androgens (testosterone), are present in various tissues of molluscs, it is still unclear what role these play in reproductive endocrinology in such organisms. This is despite the significant commercial shellfishery interest in several bivalve species and their decline.Methodology/Principal FindingsUsing suppression subtraction hybridisation of mussel gonad samples at two stages (early and mature) of gametogenesis and (in parallel) following controlled laboratory estrogen exposure, we isolate several differentially regulated genes including testis-specific kinases, vitelline lysin and envelope sequences.ConclusionsThe differentially expressed mRNAs isolated provide evidence that mussels may be impacted by exogenous estrogen exposure.

Oxygen consumption, ammonia excretion, and filtration rate of the marine bivalve Mytilus edulis exposed to methamidophos and omethoate

In this study, the oxygen consumption, ammonia excretion, and filtration rate were monitored in Mytilus edulis in response to administration of the two pesticides, methamidophos and omethoate. Five sublethal concentrations (1, 10, 50, 100, and 200 µgL−1) were administered over 96 h. Oxygen consumption rates increased following administration of all concentrations of methamidophos for 96 h and to the lower concentrations of omethoate (1, 10, and 50 µg L−1) from 6 to 24 h. Over 24 h, oxygen consumption decreased significantly. Ammonia excretion rates were higher than the control after 36 h of exposure to methamidophos, while reduction was observed when M. edulis was exposed to omethoate. The O:N ratios increased when the animals were first exposed to these two pesticides and then decreased at all the concentrations. At the concentrations of 100 and 200 µgL−1, the O:N ratio was below 30 after 72 h. The filtration rate of M. edulis decreased with the increasing concentration of pesticide exposure.

Variability in cardiac activity of the bivalves Mytilus edulis and Modiolus modiolus

A noninvasive method was applied to study the heart rates of the White Sea bivalves Mytilus edulis and Modiolus modiolus in a long-term field experiment during the winter. No cardiac arrest and relatively high levels of cardiac activity (5.26 and 3.49 beats/min, respectively) were observed in both species. Oscillations of heart rate and signal amplitude with wavelengths of 3 to 6, 9 to 16, and 18 to 24 h were found. The oscillations of heart rate and cardiac signal amplitude occurred simultaneously and were connected with the tidal cycle only in the case of the short-term rhythms.

Climate change induced temperature effects: A physiological kinetic model for the incorporation of calcium and strontium in the bivalve Mytilus edulis

Climate change induced temperature effects: A physiological kinetic model for the incorporation of calcium and strontium in the bivalve Mytilus edulis

Application of particle image velocimetry to the study of suspension feeding in marine invertebrates

Planar (2 dimensional) particle image velocimetry (PIV) was compared against the established clearance rate method of estimating bulk flow through suspension-feeding organisms to evaluate PIV as a technique to estimate feeding activity. The study of ciliary pumps has relied on advances in technology, as it is difficult to access the pump without excessively disturbing the animal. We used PIV to examine feeding velocities in five species of suspension-feeding, benthic invertebrates including one ascidian (Styela clava) and four bivalves (Mytilus edulis, Crassostrea virginica, Argopecten irradians and Mercenaria mercenaria). In calibration experiments using pipes of varying diameters, we were able to resolve flow with >98.5% accuracy. We extended the pipe model to study water processing in the mussel M. edulis. Both velocity and bulk flow through the mussel changed in predictable ways in relation to clearance rate (P < 0.05). Application of PIV to the study of suspension feeding will further our understanding of the behavior and physiology of economically- and ecologically-important organisms.

Experimental determination of salinity, temperature, growth, and metabolic effects on shell isotope chemistry ofMytilus eduliscollected from Maine and Greenland

To study the effects of temperature, salinity, and life processes (growth rates, size, metabolic effects, and physiological/genetic effects) on newly precipitated bivalve carbonate, we quantified shell isotopic chemistry of adult and juvenile animals of the intertidal bivalveMytilus edulis(Blue mussel) collected alive from western Greenland and the central Gulf of Maine and cultured them under controlled conditions. Data for juvenile and adultM. edulisbivalves cultured in this study, and previously by Wanamaker et al. (2006), yielded statistically identical paleotemperature relationships. On the basis of these experiments we have developed a species‐specific paleotemperature equation for the bivalveM. edulis[T °C = 16.28 (±0.10) − 4.57 (±0.15) {δ18OcVPBD −δ18OwVSMOW} + 0.06 (±0.06) {δ18OcVPBD −δ18OwVSMOW}2; r2= 0.99; N = 323; p &lt; 0.0001]. Compared to the Kim and O'Neil (1997) inorganic calcite equation,M. edulisdeposits its shell in isotope equilibrium (δ18Ocalcite) with ambient water. Carbon isotopes (δ13Ccalcite) from sampled shells were substantially more negative than predicted values, indicating an uptake of metabolic carbon into shell carbonate, andδ13Ccalcitedisequilibrium increased with increasing salinity. Sampled shells ofM. edulisshowed no significant trends inδ18Ocalcitebased on size, cultured growth rates, or geographic collection location, suggesting that vital effects do not affectδ18OcalciteinM. edulis. The broad modern and paleogeographic distribution of this bivalve, its abundance during the Holocene, and the lack of an intraspecies physiologic isotope effect demonstrated here make it an ideal nearshore paleoceanographic proxy throughout much of the North Atlantic Ocean.

장봉도 갯벌의 쥐노래미(Hexagrammos otakii)와 조피볼락(Sebastes schiegeli)의 섭식생태

The comparative feeding ecology of greenling Hexagrammos otakii and Schlegel`s black rockfish Sebastes schlereli populations was investigated in the Jangbong tidal flat near Incheon, Korea. Monthly samples were taken using a modified otter trawl from November 1999 to January 2001. The stomach contents of 124 greenling and 115 Schlegel`s black rockfish were analyzed. The diet of H. otakii was dominated by the amphipods Gammaropsis iaponicus, Caprella scaura, Isaeopsis sp. and Monocorophium acherusicum, the shrimps Latreutes mucronatus and Alpheus japonicus, the mysid Neomysis orientalis and the bivalve Mytilus edulis. In contrast, S. schlegeli mainly fed on the mysids N. orientalis, N japonica, and N. awatschensis, the shrimps Exopalaemon carinicauda, A. japonicus and L. mucronatus, and the fish Pholis fangi and unidentified gobiids. A comparison of the frequency and abundance of food items showed that crustaceans (e.g. amphipods, mysids and shrimps) were important foods for both species. Their main dietary components, however differed which is probably due to differences in the spatial distribution of the two species and their prey items. In conclusion, greenling and Schlegel`s black rockfish, despite being sympatric on a tidal flat have distinct food habits and low dietary overlap (Schooner`s index: 0.1). These results indicate, to some extent, resource partitioning for the maximum utilization of available foods in the tidal flat.

Biomarkers of pollution effects in the bivalves Mytilus edulis and Macoma balthica collected from the southern coast of Finland (Baltic Sea)

ABSTRACT: Levels of selected biomarkers in 2 bivalve species, the hard-bottom filter-feeder Mytilusedulis and the infaunal deposit/suspension-feeder Macoma balthica were measured in 2 areas (Tvar-minne and Turku Archipelago) in the southern coast of Finland. The bivalves were collected for themeasurement of acetylcholinesterase (AChE), glutathione-S-transferase (GST) and catalase (CAT)activities, and for the determination of metallothionein (MT) content. The content of organochlorines(8 PCB congeners, DDE, DDD, DDT, HCH, HCB, dieldrin) and selected heavy metals (Cd, Cu, Hg,Zn) were measured in the soft tissues. In M. balthica collected from the Turku Archipelago region,biomarker gradients were observed in MT, GST and CAT, mostly coinciding with the tissue concen-trations of total PCBs, DDTs and selected metals. In M. edulis the biomarker responses were less con-sistent with regard to tissue pollutant concentrations. In the Tvarminne region no marked biomarkergradients were observed. The levels of all biomarkers varied significantly between the two species.The integrated biomarker response (IBR) index showed good accordance with the observed high tis-sue levels of organochlorines at the northern Airisto station in both species. This study is the first ofits kind performed in the coastal waters of Finland, and the results clearly demonstrate the usefulnessof the multibiomarker approach. Moreover, the use of 2 sessile species with markedly differing feed-ing modes and living habitats is considered a rational strategy for assessing the pollution status ofcoastal sea areas.KEY WORDS: Biomarkers · Baltic Sea · Bivalves ·

Effects of temperature on scope for growth and accumulation of Cd, Co, Cu and Pb by the marine bivalve Mytilus edulis

In many aquatic organisms including Mytilus edulis, the role of temperature on bioaccumulation of metals is still not clearly understood. In this study, uptake and accumulation of Cu, Co, Cd and Pb in mussels were investigated at different temperatures (6-26 degrees C). Results from exposure of isolated gills showed a positive relationship between temperature and metal uptake. But in whole organism experiments, only the accumulations of non-essential metals (Cd, Pb) showed a similar trend while the two essential metals Co and Cu were independent and inversely related to temperature, respectively. With exception of Cu, elimination process appeared to be independent of temperature. The study also showed that neither changes in scope for growth (SFG) of mussels nor chemical speciation could fully account for the observed temperature-effects. Overall, these results suggest that fundamentally (i.e. at epithelial membranes), temperature-effects on uptake are largely due to changes in solution chemistry and physical kinetics, which favours higher uptake at high temperature. But at whole organism level, complex physiological responses appears to mask the relationship, particularly for biologically essential metals like copper.

Comparative toxicity of alternative antifouling biocides on embryos and larvae of marine invertebrates

This study evaluates the impact of commonly used “booster” biocides (chlorothalonil, Sea-Nine 211, dichlofluanid, tolylfluanid and Irgarol 1051) on early developmental stages of marine invertebrates of commercial and ecological relevance. Toxicity tests were conducted with embryos and larvae of the bivalve Mytilus edulis, the sea-urchin Paracentrotus lividus and the ascidian Ciona intestinalis. Toxicity was quantified in terms of the EC 50 (median effective concentration) and EC 10 reducing embryogenesis success, larval growth and larval settlement by 50% and 10% respectively. The EC 10 and EC 50 for chlorothalonil ranged from 2 to 108 and from 25 to 159 nM; for Sea-Nine 211 values were 6–204 and 38–372 nM; for dichlofluanid effective concentrations were 95–830 and 244–4311 nM; tolylfluanid yielded values between 99–631 and 213–2839 nM; and Irgarol 1051 was the least toxic compound showing values from 3145 to > 25 600 and from 6076 to > 25 600 nM. Those biocides may be ranked in the following order from highest to lowest toxicity to embryos and larvae of M. edulis, P. lividus and C. intestinalis: chlorothalonil > Sea-Nine 211 > dichlofluanid = tolylfluanid > Irgarol 1051. The registered effective concentrations were compared to worst-case environmental concentrations reported in literature in order to evaluate the risk posed by these biocides to those invertebrate species. Our data support that chlorothalonil, Sea-Nine 211 and dichlofluanid predicted levels in marinas represent a threat to M. edulis, P. lividus, and C. intestinalis populations, whilst Irgarol 1051 showed no toxic effects on the biological responses tested here at worst-case environmental concentrations.

Effects of increased sea water concentrations of CO 2 on growth of the bivalve Mytilus edulis L.

It has been proposed that emission of anthropogenic carbon dioxide to the atmosphere will lead to increased concentrations of CO 2 in sea water corresponding to a decrease of pH of several tenths of pH units. An experiment was performed to test the effects of increased sea water concentrations of CO 2 on shell growth of the blue mussel Mytilus edulis. The experiment was performed in aquaria continuously flushed with sea water spiked with CO 2 to provide five different levels of pH between 6.7 and control sea water with a pH of 8.1. The shell length of the mussels was measured at the start and end of the 44 days experimental period. No mortality was observed during the first 23 days of the experiment. The growth increment in mm was much larger for small mussels than for large mussels, but relative growth profile as function of pH was more similar in the two size groups; observed differences may be random variation between samples. The experiments showed that CO 2 induced reduction of pH affects the growth of M. edulis negatively. There was a strong and statistically significant decrease in growth at the lowest pH values, with virtually no growth at pH = 6.7 and reduced growth at pH = 7.1. The effect seems to set in between pH 7.4 and 7.1; at mean pH levels 7.4 and 7.6 the growth increments were not significantly different from growth at normal pH 8.1.

WINTER FORAGING OF LONG-TAILED DUCKS (CLANGULA HYEMALIS) EXPLOITING DIFFERENT BENTHIC COMMUNITIES IN THE BALTIC SEA

We studied the feeding ecology of Long-tailed Ducks (Clangula hyemalis) in two different marine benthic habitats in the Baltic Sea to determine whether there were differences in diet choice, foraging selectivity, body condition, and bird abundance. Our results corroborate earlier suggestions that Long-tailed Ducks exhibit ecological plasticity in selecting winter habitat and food. The majority of Long-tailed Ducks occurred in hard-bottom habitats where they relied on the bivalve Mytilus edulis; however, some of the population wintered in less productive, soft-bottom habitats where they employed a prey-selective foraging strategy, in which they fed on less abundant, but energy rich, crustaceans. Both strategies were apparently viable, as dissected birds in both habitats were in good body condition and had substantial fat reserves.

Seasonal variability in biomarkers in the bivalves Mytilus edulis and Macoma balthica from the northern Baltic Sea

Metallothionein level (MT), and acetylcholinesterase (AChE), catalase (CAT) and glutathione- S-transferase (GST) enzyme activities in the bivalves Mytilus edulis and Macoma balthica were investigated for seasonal variations from an inshore and an offshore site in the northern Baltic Sea. All the biomarkers showed variability, following mostly a similar pattern at both sites. Relationships between biomarkers and environmental factors and protein concentration and weight of target tissues were examined. In M. edulis, GST activity was related to Secchi depth, while in M. balthica a correlation with near-bottom oxygen saturation was observed. AChE activity correlated with the weight of the foot tissue of M. balthica. In both species, an integrated biomarker index indicated a stressed condition during the spring/early summer period. Strong seasonal variability in temperature and a concentrated period of food availability in spring–both governing the reproductive cycle of the bivalves–probably explains most of the observed natural variability in biomarkers in this sea area.

Changes in water quality after addition of sea salts to fresh water: implications during toxicity testing

Sea salts (seven brands from six commercially-available sources) were dissolved in water to develop 30 g/l solutions, and selected water quality characteristics were then monitored for 96 h. One or more water quality characteristics changed significantly during the 96 h period in six of the reconstituted sea salts. Measured characteristics of sea water diluted to 30 g/l demonstrated no changes during the observation period. The sea salts from different sources also demonstrated differences in absolute concentrations of some characteristics measured. Application of the Biotic Ligand Model to predict copper toxicity to the bivalve Mytilus edulis in solutions of the salts tested yielded 96-h median-lethal concentrations that ranged from 2 to 13 μg/l. Since water quality affects toxicity of many environmental pollutants, the source of the sea salt and equilibration time should be considered when planning toxicity tests.

Complete sequences of the highly rearranged molluscan mitochondrial genomes of the Scaphopod Graptacme eborea and the bivalve Mytilus edulis.

We have determined the complete sequence of the mitochondrial genome of the scaphopod mollusk Graptacme eborea (14,492 nts) and completed the sequence of the mitochondrial genome of the bivalve mollusk Mytilus edulis (16,740 nts). (The name Graptacme eborea is a revision of the species formerly known as Dentalium eboreum.) G. eborea mtDNA contains the 37 genes that are typically found and has the genes divided about evenly between the two strands, but M. edulis contains an extra trnM and is missing atp8, and it has all genes on the same strand. Each has a highly rearranged gene order relative to each other and to all other studied mtDNAs. G. eborea mtDNA has almost no strand skew, but the coding strand of M. edulis mtDNA is very rich in G and T. This is reflected in differential codon usage patterns and even in amino acid compositions. G. eborea mtDNA has fewer noncoding nucleotides than any other mtDNA studied to date, with the largest noncoding region only 24 nt long. Phylogenetic analysis using 2,420 aligned amino acid positions of concatenated proteins weakly supports an association of the scaphopod with gastropods to the exclusion of Bivalvia, Cephalopoda, and Polyplacophora, but it is generally unable to convincingly resolve the relationships among major groups of the Lophotrochozoa, in contrast to the good resolution seen for several other major metazoan groups.

Marked load-bearing ability ofMytilussmooth muscle in both active and catch states as revealed by quick increases in load

The anterior byssal retractor muscle (ABRM) of the bivalve Mytilus edulis shows a prolonged tonic contraction, called the catch state. To investigate the catch mechanism, details of which still remain obscure, we studied the mechanical responses of ABRM fibres to quick increases in load applied during maximum active isometric force (P(0)) generation and during the catch state. The mechanical response consisted of three components: (1) initial extension of the series elastic component (SEC), (2) early isotonic fibre lengthening with decreasing velocity, and (3) late steady isotonic fibre lengthening. The ABRM fibres could bear extremely large loads up to 10-15P(0) for more than 30-60 s, while being lengthened extremely slowly. If, on the other hand, quick increases in load were applied during the early isometric force development, the ABRM fibres were lengthened rapidly ('give') under loads of 1.5-2P(0). These findings might possibly be explained by two independent systems acting in parallel with each other; one is the actomyosin system producing active shortening and active force generation, while the other is the load-bearing system responsible for the extremely marked load-bearing ability as well as the maintenance of the catch state.