Young Mussels Research Articles

The Effects of Natural Biofilms on the Reattachment of Young Adult Zebra Mussels to Artificial Substrata

This laboratory study examined the effects of natural biofilms on the reattachment of young adult zebra mussels, Dreissena polymorpha, in Petri dishes. Natural biofilms were developed in glass and polystyrene Petri dishes using water samples collected at various times of the year. Biofilms were developed over 1, 3, 8, and 14 d. Controls were clean glass and polystyrene Petri dishes. Zebra mussels collected from the field ( ⩽ 10 mm, ventral length) were placed in the dishes and their reattachment by byssal threads was recorded after 1 d. Zebra mussels reattached to the dish surface or the shells of other mussels in the dish, or remained unattached. The data indicate that reattachment to clean glass was greater than to clean polystyrene (p ⩽ 0.05, ANOVA), but there were no consistent differences between reattachment to filmed polystyrene and filmed glass dish surfaces. Zebra mussels in control and filmed glass dishes reattached in higher percentages to the dish surface compared to the shells of other mussels (p ⩽ 0.05, ANOVA). There was no difference in mussel of reattachment between the dish surface and the shells of other mussels in most control polystyrene dishes (p > 0.05, ANOVA), whereas in filmed polystyrene the percentage of reattachment to the dish surface was greater than to the shells of other mussels (p ⩽ 0.05, ANOVA). These results indicate that substratum wettability and the presence of biofilms on some types of substrata can be factors in the reattachment of young adult zebra mussels.

Response of Growth and Density of a Population of Geukensia demissa to Land-Derived Nitrogen Loading, in Waquoit Bay, Massachusetts

Nutrient enrichment is a widespread phenomenon affecting coastal waters, including salt marshes. As land-derived nitrogen loading in estuarine waters increases, chlorophyll concentrations in the water also increase. We hypothesized that such increases might increase growth of the food-limited population of Geukensia demissa, which is a dominant component of salt marshes. To test this, we conducted a regional scale experiment in three estuaries of Waquoit Bay, Massachusetts that receive different nitrogen loading rates. A stable isotope experiment on mussel tissues and on particulate organic matter (POM) showed that mussels within an estuary fed on POM characteristic of that estuary, demonstrating the direct linkage between POM and mussels within an estuary. In addition, we measured age-specific shell growth rates of mussel populations using two different methods: indirectly, shell growth of mussels indicated by internal shell-lines was measured by fitting the data to the von Bertalanffy equation, and directly, mussels were transplanted from one estuary to the other two, and their actual shell growth rates after 80 days were measured. Growth rates of mussels in the Waquoit Bay estuaries varied with age of the mussel, tidal elevation, and with mean concentration of chlorophyll in the water. Mussels grew best in the lower intertidal zone, at the marsh banks. Young mussels grew faster than older mussels. Growth rates increased in response to presumed greater food supply across the estuaries, only for younger mussels. The significant differences we found among the mussels from different estuaries indicate a response to higher concentrations of food particles available in estuaries subject to higher nitrogen loads.

Sexual maturity in young Dreissena polymorpha from Lake Como (N. Italy)

Summary The reproductive biology of the zebra mussel Dreissena polymorpha was studied during 1999 in a natural population living in Lake Como (N. Italy), with particular reference to the differences in behavior between young and adult mussels. Histological analysis of gonads was used to study the gametogenic cycles and to evaluate when the young reached sexual maturity. Signs of active gametogenesis were detected in ≥4 mm shell length mussels. Mature gametes and the first spawning events were observed in ≥5 mm males and in ≥6 mm females. The gonad feature of ≥7 mm mussels was similar to that of the adults. Size frequency distributions revealed that the new generation (0+) first spawned in the year following birth, but only after winter. The length of larval time seemed to vary greatly depending on the spawning period, in addition to the environmental conditions. The first settled mussels ≥500 μm in shell length were observed 3–4 months after the first depositions. Water temperature seemed to be the most important factor which regulated sexual phenomena of both young and adult mussels. Its role in the onset of the spawning events was confirmed, but it is important to point out that temperature is not enough to trigger reproduction since gamete release is impossible without sufficient energy, especially for young mussels.

A new record of the freshwater pearl musselMargaritifera margaritifera L. (Bivalvia, Unionoida) from the River Narcea (Asturias, north-western Spain)

1. A population of the freshwater pearl mussel Margaritifera margaritifera L. was found in the River Narcea in the province of Asturias (north-western Spain). Primary analysis of the population shows that it is well distributed along the river and is particularly abundant in shady river banks with a gravel substrate. 2. The length of living mussels ranges between a minimum of 22 mm and a maximum of 116 mm, with most in the size class between 65 mm and 70 mm. There is a good proportion of young mussels, although no fertile females were found in the course of the investigation. 3. Although there is no specific legislation in Spain for the protection of M. margaritifera, it has recently been proposed to include M. margaritifera in the Spanish List of Threatened Species as ‘vulnerable’. 4. Although the River Narcea seems to provide suitable conditions for the pearl mussel (water quality, available salmonid hosts, etc.), the main conservation measures must be directed at avoiding river fragmentation from dams, channelization and organic enrichment from individual farms or towns situated close to the river bank. Copyright © 2000 John Wiley & Sons, Ltd.

Sizes, densities and age structures of ScottishMargaritifera margaritifera (L.) populations

1. Populations of freshwater pearl mussels (Margaritifera margaritifera (L.)) were surveyed in 12 Scottish rivers (selected from those known to contain viable populations). Overall mussel densities in different rivers ranged from 0.27 to 30.01 m−2. Median densities ranged from 2.5 to 14.5 m−2 and a maximum of 398 mussels m−2 was observed in one river. 2. Total population estimates in different rivers ranged from 2000 to 0.9–3.7 million. One population is particularly dense, with an estimated 0.6–1.2 million mussels in a 4-km stretch of river. 3. Samples from nine populations were taken in order to provide mussel size/age data. Marked differences between size profiles and their corresponding age profiles were observed. It is difficult to interpret the former in terms of recruitment. 4. There were signs of recent recruitment in all of the populations investigated. Large numbers of young mussels (aged ≤20 years) were found in four rivers. The largest proportions at any particular site were 67/219 (30.6%) aged ≤10 years and 191/219 (87.2%) aged ≤20 years, both values being recorded in the same river. 5. The expected predominance of young mussels was not achieved in any population. Presumably, there is considerable underestimation of the youngest age classes owing to biased sampling techniques. However, several populations are thought to be recruiting at levels that are high enough to maintain viability. 6. One population (River F) is the best example of a ‘healthy’, moderately fished, recruiting population and its age profile could be used as a benchmark for future comparisons. 7. The results of this study emphasize the international importance of Scotland in terms of M. margaritifera conservation. However, the small numbers of juveniles found in some Scottish rivers indicates that many populations are vulnerable to decline and, therefore, their conservation status may be threatened in the long term. Copyright © 2000 John Wiley & Sons, Ltd.

In situ survival and growth of zebra mussels (Dreissena polymorpha) under chronic hypoxia in a stratified lake

Experiments and field surveys were conducted in Hargus Lake (Ohio, U.S.) to investigate the effect of lake stratification on the survival, growth and distribution of zebra mussels. During the lake stratification period, relatively stable temperature and dissolved oxygen (DO) gradients persisted across the water column, allowing us to examine the chronic effect of hypoxia on zebra mussels. Zebra mussels were incubated in cages and suspended at different depths in the water column at both pelagic (max. depth = 12 m) and littoral (max. depth = 3.5 m) sites from April 18 to September 28, 1994. No mussel survived to the end of the experiment in cages ≥ 5.5 m, whereas the highest survival rate (76%) occurred at 5 m depth where temperature and DO remained fairly stable for at least 3 months. The threshold oxygen level for survival was between 1.0–1.7 mg l-1 when water temperature was at about 17–18 °C. While zebra mussels′ survival rate was not affected under the sublethal hypoxic conditions, their growth was greatly retarded by poor water quality. The field survey showed that the zebra mussels and macrophytes had about the same distribution and their biomasses were positively related. The percentage of mussels in aggregates increased towards their maximum distribution depth. The maximum distribution depth of the naturally occurring zebra mussels was only 2.8 m, whereas the adult mussels could survive the entire stratification period when being artificially placed on the 3.5 m bottom, and young mussels could colonize the 3.5 m bottom if solid substrates were provided. We conclude that lack of substrate, rather than hypoxia, was the limiting factor of zebra mussel distribution above 5 m depth in Hargus Lake.

Immunochemical localisation of proliferating cells in mussel digestive gland tissue.

The distribution of proliferating cells in the digestive gland of the common marine mussel, Mytilus galloprovincialis Lmk, was investigated by means of immunochemical techniques employing PC10, a commercial monoclonal antibody to the proliferating cell nuclear antigen (PCNA). Immunoblot analysis of digestive gland whole homogenates revealed a single crossreactive band of 36-37 kDa, identical to the corresponding protein of rat liver and murine melanoma cells. A band of slightly higher electrophoretic mobility (34-35 kDa) was found in fish liver. In mussel digestive gland, the samples obtained from young specimens presented a more intense signal for PCNA than in those obtained from old mussels, suggesting that the digestive gland cells of young mussels exhibit a higher proliferative activity. In paraffin sections, PC10 specifically labelled nuclei of all cell types, but only a smaller number of cells lining the different digestive epithelia. PCNA expression was more intense in digestive cells than in basophilic cells. Hemocytes circulating along the interdiverticular spaces also presented immunoreactive nuclei. Electron microscopy revealed a specific and moderate PC10 labelling in nuclei. Thus, single gold particles appeared disseminated throughout the nuclei with accumulations of particles in the sites of DNA replication. Taken together, these data reveal that the capacity to proliferate resides within all cell types in the digestive diverticula and do not support the hypothesis of the existence of one stem cell in this epithelium. As opposed to the hepatopancreas of the crab, Carcinus maenas, where mitotic figures and PCNA immunoreactivity are only observed in the embryonic cells within the distal portions of the digestive diverticula, apparently there are not discrete regions of cell proliferation in the digestive gland of mussels.

Seasonal variation in growth and yield of the brown mussel Perna perna (L.) cultured in Ubatuba, Brazil

Seasonal variation in growth and yield of cultured brown mussels Perna perna was studied in Ubatuba, south-east Brazilian coastline. Young mussels were transplanted (seeded) into four groups of 16 polyethylene net tubes 2 m long, suspended from a wooden raft (18 m 2). The first group was set out in April (autumn), the next in July (winter), the next in October (spring) 1984 and the final group in January (summer) 1985. One net tube of each group was sampled monthly and biometric data were collected. Growth was initially faster for the spring group, but at the end of the culture period length and weight were not statistically different between groups. L ∞ and W ∞ were 73.9, 71.3, 72.7 and 73.8 mm and 26.3, 23.9, 25.7 and 25.7 g for the autumn, winter, spring and summer groups, respectively. Maximum yield was attained 9 months after seeding for groups of autumn, winter and spring (7.2, 5.2 and 6.3 kg×m −1, respectively) and after 10 months for the summer group (6.9 kg×m −1). The conclusion of this study is that, growth and yield were unaffected by the season of seeding at the study site and that it is not commercially worthwhile to farm mussels more than 9 months, due to yield decrease.

Growth and reproductive cycle of the zebra mussel in the River Rhine as studied in a river bypass.

In a Rhine River bypass built at a water pollution control station, the growth and reproductive cycle of the zebra mussel (Dreissena polymorpha) were studied over a period of nearly 3 years. The experimental setup offered the possibility to manipulate the temperature of the continuously passing river water and to calculate influences of temperature and food on the growth of individually marked mussels. Shell growth rates were a function of algal density (measured as chlorophyll a). This function followed saturation curves with temperature-dependent plateau levels, and saturation occurred at values above 40 μg/l chlorophyll a. The relationship between shell growth rate and temperature followed the courses of bell-shaped curves with algal-food-dependent heights. No clear correlations could be found between shell growth and other environmental factors such as dissolved organic matter, total organic content, seston, and turbidity. Two spawning periods per year characterized the reproductive cycle of the zebra mussels at the study site. The first one covered nearly 3 months (April to July) comprising several spawning events. The second shorter one occurred in August. Young mussels of the first spawning period settled at the end of May, and they were able to reproduce a few months later (end of August) when their shell length exceeded 9 mm. This first spawning period of the young-of-the-years coincided with the second spawning period of the older generations. Through the combined analysis of the results of both body weight determinations and shell growth experiments, it was possible to model mussel growth over a period of nearly 3 successive years, and to suggest the presence of an endogenous factor that might be involved in determining the start of the annual shell growth period.

Water Movements in a Lagoon and a Harbour as Constrained by Lead Isotopes in Mussels

Mussels, through their ability to concentrate metals from seawater (103 to 104 ) are generally used as bioindicators in many programmes of coastal survey (NOAA, French Mussel Watch). They have many advantages: they are widely distributed, easy to analyse and allowing weekly-integrated records. The previous studies generally used concentration variations in the mussels soft parts to determine anthropogenic impact, but concentrations alone do not allow us to constrain the metal origin(s). We use lead isotopes as tracers of human activities both on fleshes and shells (Labonne et al.). The comparison of the data with the various sources of lead already identified and geochemically characterized in the catchment allow us not only to determine the origins and proportions of natural and anthropogenic leads, but also trace water movements. The Thau lagoon is located in the South of France near Montpellier. This lagoon was chosen because of the various sources of both natural and anthropogenic inputs. The surrounding rocks are principally Jurassic limestones and Miocene marls (Petelet et al.). Along the lagoon coast we find the S~te harbour which presents a high density of industries: fertilisers and cement factories, boat workshops. An important highway crosses the watershed and several outputs of water treatment plants reach the lagoon (Monna et al.). Young mussels (Mytilus galloprovincialis) from the sea were introduced at several locations of the Thau lagoon: in the Sete harbour, in the lagoon centre, at the exutory of the main river feeding the lagoon and near a local city. Sampling was done in January 96, May 96 and July 96. The water movements inside the Harbour were also studied by the sampling of wild mussels directly in the channels (July 1996). Four locations were chosen: one close to a boat workshop in the main channel and three on a smaller channel near industrial piers.

Chlorination and mussel control in the cooling conduits of a tropical coastal power station

The rationale for the present study has been the continued problem of biofouling in the cooling conduits of Madras Atomic Power Station (Kalpakkam), in spite of intermittent chlorination used as a fouling control measure. A diver-assisted inspection of the tunnel proved that the green mussel, Perna viridis (L.) was the major component of the fouling community inside the cooling conduits. Maximum biomass value recorded was 211 kg/m 2, observed inside the forebay shaft at a depth of 22.5 m. The total biomass of fouling in the entire tunnel system was estimated to be 578 tonnes, of which the contribution by P.viridis alone was 411 tonnes. High-level chlorination, followed by continuous low-level chlorination brought large quantities of sessile biomass from the tunnel to travelling water screens (TWS). A total biomass of about 187 tonnes of fouling debris was collected from TWS during February 1988 to January 1990. Of these, P.viridis accounted for 164 tonnes. The sizefrequency distribution of P.viridis collected on the TWS clearly showed that the appearance of young mussels (0–2 cm shell length) was correlated with the breeding pattern of green mussels in the adjacent coastal waters. The present study showed that intermittent chlorination is an ineffective method for mussel control in the power station cooling conduits. Continuous high-level chlorination is useful for dislodging established mussel communities from intake tunnels.

Role of catastrophic disturbance in mediating Nucella-Mytilus interactions in the Alaskan rocky intertidal

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 138:125-133 (1996) - doi:10.3354/meps138125 Role of catastrophic disturbance in mediating Nucella-Mytilus interactions in the Alaskan rocky intertidal Carroll ML, Highsmith RC The mussel Mytilus trossulus is typically a dominant competitor and principal space-occupying species in the rocky mid-intertidal zone of south central Alaskan (USA). Its principal predator in the region is the whelk Nucella lima. We examined predator-prey interactions between M. trossulus and N. lima following a severe freeze which greatly reduced mussel abundance in the upper portion of their vertical range. N. lima in Kachemak Bay was locally abundant, but its spatial distribution was patchy, resulting in site-to-site variation in predation intensity. Following the freeze, mussel populations recovered to occupy 72% of primary space at a site where N. lima was rare. At sites where N. lima occurred in high densities (&GT100 m-2), mussel cover remained significantly lower. At the latter sites, up to 81% of mussel mortality was due to snail predation. In field trials, average densities of N. lima significantly reduced mussel cover within 2 wk. From published literature on Nucella sp. feeding rates and our data on in situ reductions in mussel beds, we estimate that N. lima can eliminate 60 to 90% of mussels at a given site in 1 season. In contrast to the general view that mussel recovery from disturbance is inevitable, our results indicate that local populations of young mussels were unable to increase space utilization because of intense N. lima predation. A stochastic, catastrophic disturbance event thus altered control of community structure by removing dense stands of large prey individuals that had grown to near-refuge size. This facilitated long-term N. lima control of what had been a mussel-dominated community by shifting the interaction toward smaller sized mussels that are susceptible to intense predation. Alaska . Community structure . Disturbance . Indirect effects . Rocky intertidal . Predation . Mytilus . Nucella Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 138. Publication date: July 25, 1996 Print ISSN:0171-8630; Online ISSN:1616-1599 Copyright © 1996 Inter-Research.

Distribution, Age Structure, and Movements of the Freshwater MusselElliptio complanata(Mollusca: Unionidae) in a Headwater Stream

ABSTRACT The distribution, age structure, and movements of the unionid mussel Elliptio complanata (Lightfoot) were studied in a first-order stream in Virginia, USA. Mean density of the mussel in this low-gradient, sand-bottomed stream was 2.5 individuals/m2 and biomass was 3.4 g dry mass/m2. About 87% of the population had a shell length of 6–9 cm, or age of 4–6 years. Only 11% of the population was less than four years old; the age of the oldest individuals encountered was only eight years. Distribution of the mussels was highly clumped, but no physical, chemical, or hydrologic factors examined were significantly correlated with mussel abundance. All young mussels (age < three years) were burrowed into the sediment, whereas older individuals occurred both below and at the sediment surface, depending on time of year. About 90% of the population was burrowed below the surface during the winter, but a high of 80% of the mussels moved to the surface in March and April, the time of peak reproductive activity. Tagged mussels moved an average of 2.9 m during one year. Although the direction of those movements was erratic, the overall movement of the population was a net 27 cm downstream, indicating no directed upstream movement to compensate for downstream displacement during storms.

Studies on the development of metamorphosis without parasitism in &lt;i&gt;anodontabigibba&lt;/i&gt; (heude)

1993年4、5月份观察到双峰无齿蚌Anodonta bigibba(Heude)母体排出的不是钩介幼虫, 而是幼蚌。幼蚌壳中具一呈似三角形、较厚的钩介幼虫外壳, 其腹缘顶端具壳钩。幼蚌在原钩介幼虫壳缘生长了1—4环新壳, 而且具育带纤毛的足、前后闭壳肌、管状鳃原基和肛门孔等。幼蚌在室内试养存活了39天, 显示已具独立生活能力。研究表明, 该蚌钩介幼虫在母体育儿囊中已经历并完成变态, 发育成幼蚌。这是我国首次发现的一种非寄生变态发育的珠蚌类, 对于研究我国珠蚌类的进化及与世界淡水贝类的亲缘关系有着重要价值。此外, 鉴于双峰无齿蚌与背角无齿蚌Anodonta woodiana(Lea)的成体壳形和发育生活史的不同, 应恢复Heude建立的双峰无齿蚌的种名。;Young mussels instead of glochidia were observed to be discharged by gravid individuals of Anodonla bigbba(Heude) in April and May of 1993. Among the shells of the young mussel，a stout，triangular shell of glochidium and its hooks at the far end of the ventral margin were in evidence. Loops of newly grown shell were found to be around the glochidial shell，and a ciliated foot，anterior and posterior abductors，gill rudiments，and anus could also be recognized. The young mussels were kept alive in laboratory for 39 days，indicating that they had the ability to live independantly. It is made clear by the study that the glochidia of this mussel species has undergone the metamorphosis inside the maternal marsupia. It is the first time to find in China a naiad species metamorphosing without parasitism，a significant fact for studying the evolution of Chinese unionid and its phylogenetic relationships with world freshwater mussels. Furthermore，in view of the differences of adult shell and life history between Anodonla bigbibba (Heude) and Anodonta woodiana (Lea)，the name of A·bigbbba given by Heude should be recovered.

Growth and population dynamics in mussels ( Mytilus edulis L.) cultured in the White Sea

Samples of mussels collected from net substrata suspended from production rafts in Chupa Inlet, the White Sea, were used to determine growth and population dynamics during 5 years. For comparison of growth, samples were also collected from tidal and subtidal mussel populations. Growth rate of cultured mussels was higher than that of benthic ones. Seasonal changes of growth rate were influenced mainly by sea-water temperature. By the first autumn after settlement, young mussels settled on the substrata could be divided into two main size groups. These groups could be distinguished until the 4th–5th year. The maximal mortality 1 in the cultured mussel population was observed during the 1st year after settlement and after the biomass reached more than 10 kg/m. Mussels of the main generation (settled in 1983) prevented spat settlement in the following years, until the 4th year when a considerable loss of large mussels occurred.

Endo- and Epibenthic Distribution of the Unionid Mollusc Elliptio complanata

18% of a population of Elliptio complanata was found living completely buried in the sediments of a Québec lake during mid-summer. This population was found to descend into the sandy sediment as winter approached, and emerged in the spring. More than 60% of the population was endobenthic during late autumn. Endobenthic mussels were significantly smaller than epibenthic mussels (50-60% of average length) and most mussels that were endobenthic during mid-summer were juveniles. Shell morphology did not vary significantly between epi- and endobenthic mussels. Failure to count endobenthic E. complanata in population surveys could result in severe underestimates of actual population densities. A sampling program based strictly on epibenthic mussels would underestimate the contribution of young mussels to the biomass and production of this population.

Biological control of the mussel in shellfish culture

Intermediate cultivation of scallops Pecten maximus and oysters Ostrea edulis in Mulroy Bay, Ireland, was subject to high mortalities due to the presence of small numbers of young mussels Mytilus edulis. The addition of dogwhelks Nucella lapillus which preyed on the mussels resulted in greatly increased survival.

Threats to the freshwater pearl mussel Margaritifera margaritifera L. in Central Europe

Data on threats affecting the life cycle of the endangered freshwater pearl mussel Margaritifera margaritifera L. are presented. There was no evidence to suggest that a change in density or age structure of host fish (brown trout) populations has contributed to the decline of mussels. The factor of greatest impact was pollution. Mortality of the adult stage exhibited a positive correlation with the concentration of nitrate in the water and, in particular, phosphate, calcium and BOD 5 were correlated with decreasing survival and establishment of juvenile mussels. As fertility (i.e. production of glochidia) is maintained even in sparse populations, and in polluted rivers, the populations should recover if the causes of decline are removed. Eutrophication should therefore be prevented. It might accelerate recovery of sparse populations if the numbers of young mussels released by the hosts were increased by introducing artificially infected fish.

Formation and disruption of aggregations of Mytilus edulis in the fouling community of San Francisco Bay, California

Successional dynamics of a fouling assemblage in San Francisco Bay were studied on a series of formica plates. Hydroids and barnacles were found to accelerate rates of succession to mussel dominance by fachtating recruitment of young mussels. Development of hydroid colonies along the borders of plates produced an edge effect that was reflected in the pattern of recruitment of mussels onto plates. The importance of edge-to-center ratios on plates of different sizes and shapes to rates of succession is discussed. Substantial annual and seasonal variation in recruitment was found to influence rates of succession to mussel dominance. Disrupbon of mussel dominance occurred when a mixed school of surfperch took up temporary residence. Predation on mussels by surfperch allowed other species to become established on plates, thereby promoting a more diverse assemblage, however disruption of mussel dominance by surfperch appears to be an unpredictable event, and local sites may be dominated for many years by a monoculture of mussels.

Zebra mussels and polystyrene

The growth of settled and metamorphosed larvae of the zebra mussel (Dreissena polymorpha) is clearly retarded when polystyrene plates are used as a substrate compared with the growth of those forms attached to PVC plates. Possibly, low molecular weight compounds are released into the aquatic environment by the polystyrene and these materials may have a strongly adverse effect upon the growth of young zebra mussels. There is no difference in colonization of young mussels between PVC and polystyrene plates if these plates are sufficiently overgrown with bacteria and algae.