Black Mussel Research Articles

Growth and survival rates of different size classes of black mussel (Mytilus galloprovincialis Lamarck, 1819) at two culture systems in Dardanelles.

Growth and survival rates of different size classes of black mussel (Mytilus galloprovincialis Lamarck, 1819) at two culture systems in Dardanelles.

Antioxidants in the black mussel ( Mytilus galloprovincialis) as an indicator of black sea coastal pollution

The biologically active compounds, antioxidant activities, and free radical scavenging effects of black mussel dry matter ( Mytilus galloprovincialis)––(BMDM) were investigated. The extract from BMDM with absolute methanol (BMDMAMet) showed the strongest inhibition of lipid peroxidation as a function of its concentration, and was comparable to the antioxidant activity of butylated hydroxyanisole, at the same concentration of 0.2 mg/ml. The extract with 50%methanol/water (BMDM50%Met) had the weakest antioxidant activity, whereas other extracts such as 1.2 M HCl in 50%methanol/water (BMDM50%Met/HCl) exhibited an average inhibition of lipid peroxidation. BMDMAMet extract showed marked activities in free radical scavenging determined by β-carotene bleaching (β-carotene), nitric oxide (NO ) and 2,2 ′-azino-bis(3-ethylbenzothiazoline-6-sulfonate) radical cation (ABTS + ) methods. The antioxidant activities of BMDMAMet extract determined β-carotene, NO and ABTS + methods showed the highest correlation coefficients ( R 2) such as 0.998, 0.9976 and 0.6103, respectively, with the presence of total polyphenols. BMDM50%Met had lower antioxidant ability than BMDM50%Met/HCl in different scavenging methods, indicating that the major antioxidant components in these extracts must be derived from the polyphenols. Correlation between proteins and antioxidants was very low (0.0318 and 0.0433). The mussel extracts from polluted areas have shown by all using methods higher antioxidant activity than from the clean ones. The results presented in this report indicate that the antioxidant activities of mussel extracts could possibly be an additional index of pollution characterization.

Effect of genotypes of unspecific esterases and leucine aminopeptidase loci on the temporal dynamics of morphological variation in the black sea mussel Mytilus galloprovincialis Lam

In the Black Sea mussel Mytilus galloprovincialis Lam., the dependence of variation in 21 morphological characters of the shell on the genotype at the polymorphic loci encoding unspecific esterases and leucine aminopeptidase was estimated by means of ANOVA in 12 samples differing in age and belonging to different generations. The genotype at these loci was found to have no constant influence on the dynamics of variation in any morphological character. The effect of the parameters of polymorphism was ambiguous: a factor having a significant effect on a certain character in one sample might have no such effect (or produce an effect on a different character) in another sample. A directional change in the significant effect of genotypes during a certain period of generation's lifetime was revealed. The dependence of the effect of polymorphism at the studied loci on ecological conditions is discussed.

Oystercatchers use colour preference to achieve longer-term optimality.

The optimal diet model entails that foragers look beyond the individual prey encounter, to at least the level of intake rate across a bout of foraging, but optimization over a longer time remains controversial. In this paper, we show how oystercatchers increase their intake over the longer term using mussel colour as a cue. Wintering oystercatchers Haematopus ostralegus feed extensively on mussels Mytilus edulis in the estuaries of southern Britain. They show a marked preference for brown-shelled mussels over the commoner black-shelled morph, and we show that this enables them to maximize their rate of energy gain over a longer period than a single foraging bout. The brown and black mussels did not differ in ventral thickness and energy content, which are the main criteria for mussel selection and most important for short-term optimization. The brown mussels contained significantly less moisture, so by selecting them, oystercatchers could pack more mussel flesh into their limited oesophageal storage capacity. This enables them to increase their overall consumption during a feeding bout and increases their long-run energy gain rate, to an extent that is large enough to be significant for survival, especially during the short exposure of the mussel beds in winter.

Comparison of metal uptake rate and absorption efficiency in marine bivalves

Recent studies have quantified extensively metal assimilation efficiency from ingested food sources in aquatic invertebrates. Metal absorption efficiency (alpha) from the dissolved phase is analogous to metal assimilation efficiency, but it remains poorly defined and quantified. In this study, the alpha of four trace metals [Cd, Cr(VI), Se(IV), and Zn] was determined in three species of marine bivalves (green mussel [Perna viridis], black mussel [Septifer virgatus], and clam [Ruditapes philippinarum]). Individual bivalves were first measured for their clearance rates, followed by measurements of the metal influx rate, after which the metal alpha and the uptake rate constant (Ku) were then computed. Among the four metals considered, the highest Ku and alpha were found for Zn, followed by Cd > Cr(VI) > Se(IV). The Ku values were comparable between the two mussels but were 1.8- to 3.3-fold lower in the clams. Interspecific difference in metal Ku was strongly related to, but intraspecific difference in Ku was not affected by, the bivalve's clearance rate. Interspecific difference in metal alpha was smaller than the metal Ku and was independent of the clearance rate, whereas the intraspecific difference in metal alpha correlated with the individual variations of the clearance rate. Within each bivalve species, a significant negative correlation was found between the metal alpha and the clearance rate, implying that an individual pumping a greater amount of water was coupled to a lower alpha. Significant correlation between the alpha of four metals was also documented in all three species of bivalves. Thus, metal bioavailability from the aqueous phase was directly related to the physiological conditions of the animals. Both the aqueous chemistry and the physiology of the animals can be important in affecting metal bioavailability from the dissolved phase.

Depositional Role of Black Sea Mussels (Inferred from Experimental and Field Observations)

The influence of Black Sea mussels on sedimentary processes in the near-shore zone is considered. Using sedimentation traps, quantitative aspects of substance flux transformation by mollusks during the biogenic sedimentation of lithogenic material is studied. Mollusks increase ten to twenty times the vertical sedimentation rate of substance from suspension and change the flow direction from horizontal to vertical one. The substance flux produced during the filtration of Black Sea shelf waters by benthic organisms is two to five times higher than that provided by rivers of the entire discharge basin. The filtration of water by mollusks results in an intense geochemical transformation of substance in the suspension–sediment system. This is expressed in the removal of organic matter, calcium carbonate, and practically all microelements from suspension. Major components of the suspension, such as SiO2, TiO2, and Al2O3, as well as some microelements (Sr, Rb), are concentrated by mussels during the digestion process.

Prey preference and the consumption of sea urchins and juvenile abalone by captive rock lobsters (Jasus lalandii )

Recent studies on the diet of the South African rock lobster (Jasus lalandii) have shown an increase in the consumption of sea urchins in certain areas relative to earlier assessments. Concurrent ecological surveys have demonstrated the dependence of juvenile abalone on urchins for their survival, and a radical increase in the abundance of lobsters in the area that is the main abalone fishing ground. This paper describes laboratory experiments on the consumption of urchins by lobsters, and the preferences for different prey species. Small lobsters (<68 mm carapace length) ate no urchins. Larger lobsters ate urchins of all sizes, although small urchins were preferred. The consumption rate was easily sufficient for the lobsters to have caused the documented disappearance of urchins (and juvenile abalone) in the main abalone fishing area. Lobsters showed a strong preference for mussels over all other prey offered, and for juvenile abalone over urchins, although previous field observations and laboratory experiments have shown that urchins provide shelter for juvenile abalone. However, if black mussels were available in addition to sea urchins and juvenile abalone, consumption of sea urchins and juvenile abalone declined.

A new species of Dynoides (Crustacea: Isopoda: Sphaeromatidae) from the Cape d’Aguilar Marine Reserve, Hong Kong

A new species of sphaeromatid isopod, Dynoides daguilarensis n.sp., is described from intertidal black mussel (Septifer virgatus) beds in the Cape d'Aguilar Marine Reserve, Hong Kong. This species has been previously misidentified as D. serratisinus and D. dentisinus. It is characterized by a pleotelsonic apex with an open, sub-parallel slit, both edges of which are serrated from the bottom to the two sides of the apex; uropod endopods which are sub-apically notched externally; and a tubercle on the ventral side of the pleonal process. The composition of Dynoides and its relationships to Clianella are reviewed. A revised composition of Dynoides with a key to the species is provided.

Diet of the West Coast rock lobster Jasus lalandii : influence of lobster size, sex, capture depth, latitude and moult stage

Diets of male and female West Coast rock lobster Jasus lalandii in South Africa were compared across a large size range of 10–85 mm carapace length (CL). The diets of male rock lobsters were compared between two different depths, different seasons, across the moult cycle, and among eight sites along the South-Western Cape coast. There was no significant difference in diet between male and female rock lobsters for any of the size-classes examined. Male rock lobsters showed large differences in diet between small and large size-classes. The diet of small lobsters (<75mm CL) consisted of a wide range of species, which included, in order of importance, coralline algae, barnacles Notomegabalanus algicola, sponges and ribbed mussels Aulacomya ater. However, prey items rich in inorganic material were not dominant in their diet, as had been predicted. By contrast, large rock lobsters (>80mm CL) fed on few species, and fish and ribbed mussels were their most abundant prey items. There were some dietary differences between individuals captured at 20 m and those collected at 50 m, but these differences were less marked than between the two sampling sites (the Knol and Olifantsbos). There was seasonal variation in diet at the Dassen Island and Olifantsbos sites. Cannibalism was highest during the moulting periods. Gut fullness varied seasonally at Dassen Island, and was consistently high at Olifantsbos. However, the proportion of the population feeding showed marked seasonal trends at both sites, tracking the commercial catch per unit effort of rock lobster. Ribbed mussels were a ubiquitous and dominant component of the diet at the eight sites sampled. However, south of Dassen Island, black mussels Choromytilus meridionalis were scarce in the diet of rock lobster and sponges predominated. Gut fullness was lowest at the northernmost sites.

Physical processes contributing to harmful algal blooms in Saldanha Bay, South Africa

The study synthesises current understanding of the predominant physical processes responsible for the seasonality of harmful algal blooms, notably Alexandrium catenella and Dinophysis spp., in the nearshore environment of Saldanha Bay on the west coast of South Africa. Saldanha Bay is one of the few naturally sheltered areas on the South African coastline suitable for in situ shellfish farming and is the major site for the production of black mussel Mytilus galloprovincialis in South Africa. Mussel farming started there in 1985 and the present level of production is some 2 700 tons per annum. Since 1994, disruption of harvesting as a result of the presence of harmful algal species has been a regular late-summer phenomenon. Toxic blooms that are ultimately advected into the bay develop on the continental shelf to the north between 32°S and St Helena Bay, a region characterized by favourable conditions for dinoflagellate growth and circulation patterns that facilitate build-up of intense blooms during late summer. Offshore dinoflagellate populations are advected shorewards and polewards in response to relaxation of upwelling at the Namaqua cell to the north. Dinoflagellate blooms are advected south from the southern Namaqua shelf during upwelling relaxation. Under such conditions, the gyre south of Elands Bay moves offshore and a barotropic flow past Cape Columbine is established. Evidence suggests that the nearsurface component of the flow occurs as a sudden “flood” event. These dinoflagellate-containing shelf waters are in turn advected into Saldanha Bay when upwelling relaxes, when the density gradient between the bay and the shelf drives surface inflow and bottom water outflow. These flows are reversed with the resumption of upwelling over the shelf, resulting in intrusion and entrainment of bottom water and surface outflow. Entrainment dictates that the bay acts as a net importer of bottom water and net exporter of surface waters over a synoptic cycle. This system of exchange between Saldanha Bay and the shelf curtails the duration and severity of toxic episodes in the bay relative to the shelf.

Multivariate statistical approach to the temporal and spatial patterns of selected bioindicators observed in the North Sea during the years 1995?1997

A comprehensive database, containing biological and chemical information, collected in the framework of the bilateral interdisciplinary MARS project (”biological indicators of natural and man-made changes in marine and coastal waters”) during the years 1995–1997 in the coastal environment of the North Sea, was subjected to a multivariate statistical evaluation. The MARS project was designated to combine a variety of approaches and to develop a set of methods for the employment of biological indicators in pollution monitoring and environmental quality assessment. In total, nine ship cruises to four coastal sampling sites were conducted; 765 fish and 384 mussel samples were analysed for biological and chemical parameters. Additional information on the chemical background at the sampling sites was derived from sediment samples, collected at each of the four sampling sites. Based on the available chemical data in sediments and black mussel (Mytilus edulis) a pollution gradient between the selected sites, was established. The chemical body burden of flounder (Platichthys flesus) from these sites, though, did not reflect this gradient equally clear. In contrast, the biological information derived from measurements in fish samples displayed significant a regional as well as a temporal pattern. A multivariate bioindicator data matrix was evaluated employing a factor analysis model to identify relations between selected biological indicators, and to improve the understanding of a regional and temporal component in the parameter response. In a second approach, applying the k-means algorithm on the data matrix, two significantly different clusters of samples, characterised by the current health status of the fish, were extracted. Using this classification a temporal, and in the second order, a less pronounced spatial effect was evident. In particular, during July 1996, a clear sign of deteriorating environmental conditions was extracted from the biological data matrix.

Factors affecting trace element uptake in the black mussel Septifer virgatus

The variability of the influx rates of Cd, Cr(VI), Se(IV), and Zn in the black mussel Septifer virgatus from Hong Kong coastal waters was examined under different environmental and biological conditions using the radiotracer technique. The uptake of trace elements generally proceeded linearly over time and a short-term exposure (4 h) was therefore employed to measure the influx rate of trace elements. The uptake rates were directly proportional to the concentration of trace elements in the dissolved phase. The calculated uptake rate constant was 0.286, 0.085, 0.031, and 0.460 1 g -1 d -1 for Cd, Cr(VI), Se(IV), and Zn, respectively. Transport of Cd and Zn was primarily a facilitated process that was significantly inhibited by N-ethylmaleimide due to its specific binding with SH-containing ligands. Uptake rates of Cd and Zn were closely coupled, whereas no relationship of their uptake with Cr(VI) or Se(lV) uptake was found. Uptake of Cr(VI) and Se(lV) was decoupled, indicating that they were transported via different pathways into the mussels. The Ca channel was not involved in the transport of all trace elements. A decrease in salinity greatly enhanced the influx of all 4 trace elements. Changes in metal speciation and Ca concentration were not responsible for the underlying effects of salinity. The allometric scaling of Cr(VI) and Se(IV) uptake was comparable to the allometric scaling of the mussels' filtration rate, suggesting that gill surface area may determine their uptake rate. The uptake of Cr(VI) and Se(lV) may simply be predicted based on the measurements of the mussel's filtration rate. For Cd and Zn, the allometry of metal uptake may also be controlled by other processes such as SH-containing ligands available for metal binding.

Individual Variation and Seasonal Dynamics of Carotenoid Content in Gonads of Black Sea Mussels Mytilus galloprovincialis Cultivated in Collectors

Individual Variation and Seasonal Dynamics of Carotenoid Content in Gonads of Black Sea Mussels Mytilus galloprovincialis Cultivated in Collectors

The Relationship between Lipid Peroxidation and Antioxidant Activity in Tissues of Black Sea Mussels

The Relationship between Lipid Peroxidation and Antioxidant Activity in Tissues of Black Sea Mussels

Changes in Shellfish Species Composition and Mean Shell Size from a Late-Holocene Record of the West Coast of Southern Africa

This paper presents and discusses the results of a systematic analysis of the shellfish assemblage recovered from Pancho's Kitchen Midden, a site located in the western Cape coast of South Africa. Several hypotheses are considered in an attempt to explain the observed changes in shellfish frequencies and shell size. Changes in species composition in this particular sequence are mostly attributable to changes in collecting practices. Shellfish gathering was generally undertaken within the mid and low-intertidal zones throughout the Late Holocene, with slightly more frequent collections within the upper subtidal in the last 600 years. Changes in water turbidity, on the other hand, seem to explain most of the variability in the mean sizes of black mussels. Nevertheless, intense collection of large numbers of black mussels seems to have been an additional factor in bringing mussel sizes to a minimum around 3000bp. Subsequent recovery of mean mussel sizes appears to be the result of several factors: improvement in marine productivity and low water turbidity, greater access to large individuals inhabiting the low intertidal and upper subtidal, and/or relatively low levels of shellfish exploitation by people. Changes in sea surface temperature of the magnitude reported here do not appear related to changes in species composition and shell size. The comparison of this shellfish sequence with others from nearby sites, and analysed in a similar fashion, would be essential for the reconstruction of pre-Colonial shellfish-gathering practices at the western Cape.

Excavations at Mike Taylor's Midden: A Summary Report and Implications for a Re-Characterisation of Megamiddens

Despite considerable interest over the past twenty years, observations on the archaeology of the large shell midden known as Mike Taylor's Midden (MTM), near Eland's Bay on the South African west coast, have remained largely unpublished. This paper summarises excavations at MTM from the 1970s to the 1990s, and discusses interpretations of this and other large shell middens which appeared on the west coast between about 3000 and 2000 BP. It is argued that MTM displays much greater variability through time and space than previously suggested, and that large amounts of stone artefacts and bone remained 'invisible' to archaeologists because of the enormous quantities of marine shell refuse. Rather than functioning simply as a processing station for large quantities of black mussels, as previously suggested, MTM was also a camp site where stone knapping and animal food processing occurred. *Received August 1996, revised March 1997

Effect of distance from the polluting focus on relative concentrations of Bacteroides fragilis phages and coliphages in mussels.

Concentrations of fecal bacteria, somatic and F-specific coliphages, and phages infecting Bacteroides fragilis in naturally occurring black mussels (Mytilus edulis) were determined. Mussels were collected over a 7-month period at four sampling sites with different levels of fecal pollution. Concentrations of both fecal bacteria and bacteriophages in mussel meat paralleled the concentration of fecal bacteria in the overlying waters. Mussels bioaccumulated efficiently, although with different efficiencies, all of the microorganisms studied. Ratios comparing the levels of microorganisms in mussels were determined. These ratios changed in mussels collected at the different sites. They suggest that bacteriophages infecting B. fragilis and somatic coliphages have the lowest decay rates among the microorganisms studied, with the exception of Clostridium perfringens. On the contrary, concentrations of F-specific coliphages showed a greater rate of decay than the other bacteriophages at sites more distant from the focus of contamination. Additionally, levels of enteroviruses were studied in a number of samples, and in these samples, the B. fragilis bacteriophages clearly outnumbered the enteroviruses. The results of this study indicate that, under the environmental conditions studied, the fate of phages infecting B. fragilis released into the marine environment resembles that of human viruses more than any other microorganism examined.

A Dated Human Burial from the Namaqualand Coast: Observations on Culture, Biology and Diet

ABSTRACT -30° 50' A c. 2700 year-old burial of an approximately 40 year-old adult female with Khoisan morphological features was excavated at ~roenriviennond, ama aqua land. The remains revealed no signflcant skeletal abnormalities, although a profusion of wormian ossicles were observed in the cranial sutures, as well as heavy dental wear and osteophytosis in the lumbar vertebrae. Grave ofirings seem to have consisted of a single black mussel. Microfau-nal remains showing signs of acidic digestion were recov-ered from the thoracic and pelvic areas. 61ic and 615~ values obtainedfi-om the skeleton are interpreted as indi-cations of a mixed diet of marine and terrestrial origin. * Received July 1992, revised September 1992 Introduction During an initial archaeological survey undertaken in the area of Groenriviermond (Namaqualand) (30.50s; 17.35E) several dispersed open Later Stone Age (LSA) shell middens (Fig. 1) and Middle Stone Age artefact scatters were located.

Accumulation and depuration of petroleum hydrocarbons by black mussels. 1. Laboratory exposure trials

Laboratory experiments were conducted to measure the rates of accumulation and subsequent depuration of hydrocarbons by black mussels after exposure to various concentrations of water-soluble fractions of crude oil. The initial rate of uptake was related to the concentration in the water, but a maximum level of accumulation was found after long-term exposure. The rate of depuration was closely related to the time of exposure prior to depuration. The depuration profile consists of an initial rapid loss followed by a slower loss of the remaining hydrocarbons. Increased exposure time decreases the relative quantity of hydrocarbons lost in the initial rapid depuration. The results indicate that the use of mussels as petroleum hydrocarbon input "monitors" might have limitations.

Accumulation and depuration of petroleum hydrocarbons by black mussels. 2. Depuration of field-exposed mussels

Results of depuration studies of mussels collected from chronically polluted sites and those collected after a fuel oil spill tend to confirm laboratory-deduced indications that the rate of depuration decreases as the exposure time increases. Chronically polluted mussels lost their accumulated hydrocarbons with half-lives for depuration that varied between 25 and 45 days whereas, after the oil spill, mussels lost 90 per cent of their accumulated burden within two weeks with a depuration half-life of 3,5 days. These results indicate that information concerning the type of exposure could be obtained from depuration studies of mussels collected during monitoring programmes.