Young Mussels Research Articles

Population status and host fishes of the freshwater pearl mussel in the eastern part of the Onega Peninsula, Northern European Russia

Four populations of freshwater pearl mussel Margaritifera margaritifera were studied at lower sections of three river basins of the eastern part of the Onega Peninsula, Northern European Russia: the Bol’shaya Syarta, the Ust’-Yaren’ga and the Lopshen’ga (including Kamenny Stream). One of the populations from the Lopshen’ga River was discovered for the first time. Here we present preliminary data on the population status of M. margaritifera, its host fishes and glochidia infestation in the studied river basins. Living juvenile mussels and fishes infested by glochidia were recorded only in two waterbodies, i.e., the Bol’shaya Syarta and Ust’-Yaren’ga rivers. The pearl mussel population from the Bol’shaya Syarta River seems to represent the most prosperous among studied ones. The average density of visible mussels was small in the lower section of the river, but the proportion of young mussels was rather high (33.1 %) and intensity of glochidia infection reached 865 glochidia per fish. The highest average density was recorded in the pearl mussel population from the Kamenny Stream, Lopshen’ga River basin. However, only one juvenile mussel and none of host fishes infested by glochidia were recorded in this watercourse that may indicate the population aging and decrease of reproduction. Morphological analyses revealed significant differences between four studied populations of M. margaritifera towards the shell convexity index (SCI) and shell elongation index (SEI). In all studied basins, salmonid fishes were also infested by other parasites, mainly flatworms and their cysts. This factor may negatively impact the salmonid host fish populations that require monitoring of the current situation. The data obtained and future studies will allow to develop a system for protecting and monitoring of populations of a rare species such as the freshwater pearl mussel M. margaritifera.

Potential to produce brown mussel integrated to a net-cage fish farm in a Mediterranean bay

In this study, we investigated the potential exploitation of the brown mussel Perna perna (Linnaeus, 1758) in an aquaculture farm (Monastir Bay, Mediterranean Sea, Tunisia). The quality of seawater as well as performance indicators such as Condition Index, length, weight, growth and frequency distribution of the mussel were determined over an annual cycle; from July 2017 to August 2018. Interestingly, P. perna has an extended sexual cycle during the year with two main spawning periods, the first in spring and the second in autumn, when suspended matter and Chlorophyll a were at their maximum concentrations in seawater. Spat mussels and young mussels showed significant growth rates from 1 July 2017 to 31 October 2017. Adult mussels exhibited negative allometric growth and a modal size of 41 to 50 mm. Results showed that several potentially toxic microalgae species developed at low densities in this marine zone. By using Solid Phase Adsorption Toxins Tracker (SPATT); lipophilic toxins including Okadaic acid and yessotoxins were detected at low levels in seawater and may be involved in the positive LSTs (lipophilic shellfish toxins) mouse bioassays in P. perna during the autumn. No other toxins such as paralytic shellfish toxins or amnesic shellfish toxins nor pathogenic bacteria or viruses were detected in P. perna. Altogether, our results suggest that finfish farms in Monastir Bay could be suitable sites for farming P. perna.

Elements in Soft Tissues of the Young Mediterranean Mussel Mytilus galloprovincialis Lam. 1819 Collected in Sevastopol Bay (Crimea, Black Sea): Effects of Age, Sex, Location, and Principal Morphometric Parameters.

Although the mussel Mytilus galloprovincialis has been known for decades as an excellent bioindicator of trace element pollution in the marine environment, there is still no information on the effects of a suite of its principal morphometric parameters and age on trace element levels in soft tissues. In this work, using inductively coupled plasma mass spectrometry, we studied the contents of 72 elements in soft tissues of M. galloprovincialis aged 0.5-4, which were sampled at three stations within a relatively small water body, Sevastopol Bay. Significant effects of age and sampling location on the element contents and soft tissue dry-to-wet weight ratio were discovered. The effects of sex were not significant. It was presumed for the first time that the decrease in element content in the soft tissues of young mussels can be associated with the decrease in physiological needs for elevated contents of essential elements and intracellular water with age. Combinations of six principal morphometric parameters showed that a function of as few as three parameters (soft tissue dry weight, whole mollusk weight, and shell height, with by far the greatest contribution of the dry-to-total weight ratio) formed significant correlations with the contents of the largest possible number of elements (69-88% of the total number). For the first time, it was shown that linear discriminant analysis and canonical analysis of principal coordinates can be successfully used for tracing the exact origin of mussel samples within such a small water area. Canonical analysis of principal coordinates proved superior in the correct classification of the samples.

Limited population genetic variation but pronounced seascape genetic structuring in populations of the Mediterranean mussel (Mytilus galloprovincialis) from the eastern Adriatic Sea.

Population genetic analysis of variation at five neutral microsatellite loci for Mediterranean mussels (Mytilus galloprovincialis) from 18 sites along the eastern Adriatic Sea revealed little or no spatial variation. In contrast, seascape genetics analysis revealed a pronounced locus-specific gradient in allelic and genotypic frequencies across the study region. At a sixth locus, MGE7, the frequencies of two alleles, MGE7243 and MGE7249, were strongly associated, negatively and positively, respectively, with a single environmental variable - minimum salinity (minSAL). The frequency of the MGE7243/243 homozygous genotype was strongly negatively associated with minSAL, whereas the frequencies of the MGE7246/249 and the MGE7249/249 genotypes were strongly positively correlated with minSAL. Interpretation of these pronounced gradients is confounded by the fact that minSAL and another environmental variable, maximum sea surface temperature (maxSST), are highly correlated (R=-.911) and are therefore not necessarily acting independently. BLAST searches of the MGE7 locus against M. galloprovincialis whole genome shotgun sequence returned an alignment with contig mg10_S01094 (accession UYJE01010330.1) and 7 predicted M. galloprovincialis proteins VDI82194.1 - VDI82200.1. Conserved domain searches revealed a similar structure to the transcriptional regulator Msx2-interacting protein. The BLASTp search also returned significant alignments to Msx2-interacting proteins in Mytilus coruscus, Crassostrea virginica, and Haliotis rubra. The existence of the MGE7 gradient highlights the role that environmental variation may play in retarding gene flow among wild M. galloprovincialis populations, and also how the success of collection of young mussels (spat) from one site and their transfer to another site (the farm) may be influenced by a single factor such as minSAL or maxSST on a localized scale.

Combining genotypic and phenotypic variation in a geospatial framework to identify sources of mussels in northern New Zealand

The New Zealand green-lipped mussel aquaculture industry is largely dependent on the supply of young mussels that wash up on Ninety Mile Beach (so-called Kaitaia spat), which are collected and trucked to aquaculture farms. The locations of source populations of Kaitaia spat are unknown and this lack of knowledge represents a major problem because spat supply may be irregular. We combined genotypic (microsatellite) and phenotypic (shell geochemistry) data in a geospatial framework to determine if this new approach can help identify source populations of mussels collected from two spat-collecting and four non-spat-collecting sites further south. Genetic analyses resolved differentiated clusters (mostly three clusters), but no obvious source populations. Shell geochemistry analyses resolved six differentiated clusters, as did the combined genotypic and phenotypic data. Analyses revealed high levels of spatial and temporal variability in the geochemistry signal. Whilst we have not been able to identify the source site(s) of Kaitaia spat our analyses indicate that geospatial testing using combined genotypic and phenotypic data is a powerful approach. Next steps should employ analyses of single nucleotide polymorphism markers with shell geochemistry and in conjunction with high resolution physical oceanographic modelling to resolve the longstanding question of the origin of Kaitaia spat.

Promoting self‐facilitating feedback processes in coastal ecosystem engineers to increase restoration success: Testing engineering measures

Abstract Coastal ecosystem engineers often depend on self‐facilitating feedbacks to ameliorate environmental stress. This makes the restoration of such coastal ecosystem engineers difficult. We question if we can increase transplantation success in highly dynamic coastal areas by engineering measures that promote the development of self‐facilitating feedback processes. Intertidal blue mussels Mytilus edulis are a typical example of ecosystem engineers that are difficult to restore. A lack of self‐facilitating feedbacks at low densities limits establishment success when young mussels are transplanted on dynamic mudflats. In a large field experiment, we investigated the possibility of increasing transplantation success by stimulating the formation of an aggregated spatial configuration in mussels, thereby reducing hydrologically induced dislodgment and the risks of predation. For this, we applied engineering measures in the form of fences that trapped wave dislodged mussels. Mussel loss rates were significantly lower when mussels were placed between both artificial fences, and in high densities (4.2 kg/m2) compared with mussels placed in areas without fences and in low densities (2.1 kg/m2). The fences induced the formation of a banded pattern with high local mussel densities, which locally reduced predation. Synthesis and applications. Our results underline the importance of actively promoting the development of self‐facilitating processes, such as aggregation into patterns, in restoration projects of ecosystem engineers. In particular, the current study shows that engineering measures can help to initiate these kinds of self‐facilitating interactions, especially in highly dynamic areas.

Reduced infectivity inHimasthla elongata(Trematoda, Himasthlidae) cercariae with deviant photoreaction

Digenean larvae of hermaphroditic generation - cercariae - are known to be polymorphic at genetic and behavioural levels. Cercariae arise as a result of parthenogenetic reproduction of intramolluscan stages, and represent a clone if a snail was infected with a single miracidium. Here we investigated cercarial clones of Himasthla elongata - namely, the infectivity of cercariae with normal (negative) and deviant (positive) photoreaction. In our study, most H. elongata clones showed intraclonal variance in their response to light. The proportion of photopositive cercariae ranged between 0.2% and 60% in different H. elongata clones. Photopositive larvae demonstrated significantly reduced rates of encystment in Mytilus edulis haemolymph in vitro and in young mussels. We discuss the possible mechanisms behind intraclonal variations, such as non-specific genomic rearrangements.

Evaluation of reproduction for mussel Mytilus trossulus (Bivalvia: Mytilidae) in the Veselaya Bay (Tauiskaya Guba Bay, Okhotsk Sea)

Abundance, size composition, and terms of plankton stage were investigated for the larvae of pacific mussel in the Veselaya Bay (Okhotsk Sea) in two years with different oceanographic regime. The first larvae (density 8-30 ind./m³, shell length 75–150 μm) appeared in late June in the year with relatively high water temperature (2016) and in early July in the year with lowered temperature (2011), then their number had increased to 1750 ind./m³ in early August of 2016 and to 1320 ind./m³ in late August of 2011. Density and size composition of the spat and young mussels were examined in hanging collectors and nurseries. The growth rate change in dependence on shell length was noted. There is concluded that the hanging collectors are more effective for spat collection, while the nurseries are better for growing of littoral mussels.

By-catch in no-fed aquaculture: exploiting mussel seed persistently and extensively disturbs the accompanying assemblage

Abstract Although aquaculture sometimes lessens the negative effects of fishing by lowering the need to capture wild animals and plants, some aquaculture practices still require the exploitation of wild populations. A largely overlooked case is the use of wild populations to provide seed to sea farms. Mussel farming in Northwest Spain involve the capture of thousands of tons of young mussels (0.5–2 cm long) from the nearby rocky intertidal every year to supply floating rafts. Despite its volume, the impact of this activity on other sessile organisms remains unassessed. To fill this gap in our knowledge, we monthly monitored the sessile intertidal assemblage of five protected and six exploited sites during the closed season in 2016 following a nested sampling plan. Like the by-catch typical of other fisheries, harvesting young mussels for aquaculture was detrimental to the abundance and diversity of the associated sessile assemblage not directly targeted by this activity. Coverage and richness were also significantly lowered by the exploitation of mussel seed, and the community structure of protected and exploited sites was significantly different. These differences continued until the next open season, suggesting that the closed season was too short for the recovery of the associated non-target sessile assemblage. Given the size of the local mussel industry, the incomplete recovery along the closed season implies that mussel aquaculture must be putting a sustained pressure on a sizeable portion of the rocky intertidal of Northwest Spain.

FILTRATION ABILITY OF MUSSELS OF DIFFERENT PHENOTYPES OF ODESA DISTRICT OF THE BLACK SEA

Introduction. Мussel Mytilus galloprovincialis (Lamarсk, 1819) is an active filter feeder of seawater, it has an important role in the processes of biological self-purification of seawater. By the nature of distribution of the purple pigmentation in the outer prismatic layer of the mussel shell 3 phenotypic groups are distinguished: Fа – the pigment is absent, Fb – the pigment colours the whole shell, Fc – the pigment is located in form of radial strips alternating with non-pigmented zones.The purpose of the work is to study the filtration ability of various mussel phenotypes.Method. The mussels collected in April 2014 at the water temperature of 12°C served as the material. The research includes a two-week acclimation of the mussels in the natural sea water with an initial salinity. The experiments were carried out in the temperature range from 10°C to 30°C, with the temperature step being 2°C. In total 660 specimens of the mussels were processed and analysed.Results and conclusions. It was found that in the entire investigated temperature range of water part of filter feeder young mussels for all phenotypes of constituted: at 10°C –16-18 %; at 12°C – 48 %; at 18°C – 88 %, (reaching the optimum); at 20°C – 70-73 %, and at 24°C – 36-38 %. It was determined that at 10, 20 and 24°C, the proportion of adult filter feeder mussels decreased from phenotype Fа to Fb and Fc. At 16°C the filtration activity was characteristic of mussels of all phenotypes. At 18°C the maximum of filter feeder mussels was observed in phenotype Fа (98 %); and in each of phenotypes Fb and Fc – 91 %. It was found that at the maximum temperature of the water 30°C in young mollusks and adult mussels of all three phenotypes part of filter feeder individuals is nearly constant – from 3 to 5 %.

Experimental study of the ability of the sponge Halichondria panicea (Porifera: Demospongiae) to compete for a substrate in shallow-water fouling communities of the White Sea

The ability of the sponge Halichondria panicea to assimilate into the fouling communities of the blue mussel Mytilus edulis and the solitary ascidian Styela rustica has been studied in a field experiment, in which sponge fragments have been introduced artificially into epibenthic communities. The growth of H. panicea was suppressed greatly in the presence of young mussels; its survival rate averaged 40%. In the communities where S. rustica dominated, the survival rate of H. panicea reached 100%, but the growth rate was lower than in the control group (without competitor species). Despite the high natural growth rate and toxicity, the settlement success of H. panicea was low on the substrate occupied by another fouling species.

Activity of 1,3-β-D-Glucanases and Expression of CG-GLU1 in the Mussel Crenomytilus grayanus (Bivalvia) in Three Bays of the Sea of Japan

The level of the specific activity of digestive enzymes and expression of their corresponding glucanase genes (Cg-glu1) were studied in Gray's mussels, Crenomytilus grayanus, collected from the mussels' assemblages in different parts of Peter the Great Bay (northwestern part of the Sea of Japan). Both methods demonstrated similar independent results: there is variability in the contribution of phytoplankton to the nutrition of mussels in different parts of Peter the Great Bay. The highest level of the specific activity of 1,3-β-D-glucanases and expression of the glucanase genes were detected in the mussels from Amursky Bay: the differences were significantly increased (p<0.05) compared with the level of the specific activity of the digestive enzyme 1,3-β-D-glucanases in mussels from Vostok Bay and Ussuriisky Bay. In all three bays, young mussels consumed phytoplankton more actively than 20-year-old mussels.

Potential for production of ‘mini-mussels’ in Great Belt (Denmark) evaluated on basis of actual and modeled growth of young mussels Mytilus edulis

The present study is a first step towards evaluation of the potential for line-mussel production in the Great Belt region between the Kattegat and Baltic Sea, Denmark. We present experimental results for actual growth rates of juvenile/adult mussels Mytilus edulis in suspended net bags in terms of shell length and dry weight of soft parts during extended periods (27–80 days) in the productive season in the first 6 series of field experiments, including 4 sites in Great Belt and 2 sites in Limfjorden, Denmark. Data were correlated and interpreted in terms of specific growth rate (μ, % day−1) as a function of dry weight of soft parts (W, g) by a previously developed simple bioenergetic growth model μ = aW −0.34. Results were generally in good agreement with the model which assumes the prevailing average chlorophyll a concentration at field sites to essentially account for the nutrition. Our studies have shown that M. edulis can grow from settlement in spring to 30 mm in shell length in November. We therefore suggest line farming of 30 mm ‘mini-mussels’ during one growth season, recovering all equipment at the time of harvest and re-establishing it with a new population of settled mussel larvae at the beginning of the next season, thus protecting the equipment from the damaging weather of the Danish winter season. The growth behavior during the fall–winter season was recorded in an additional 7th series of mussel growth experiments on farm-ropes to show the disadvantage of this period.

Locomotor activity of the blue mussel Mytilus edulis L.

Locomotor activity of the blue mussels Mytilus edulis L. was investigated in the laboratory experiments. Movement speed of molluscs with shell length from 1 to 60 mm was analysed. Average values of motion measured during short-time intervals ranged from 8 to 12 mm/min and did not depend on the mussel size. Generally, movement of the mussels was uneven with periods of inactivity (breaks). Young mussels moved continuously with rare and short breaks. Frequency and duration of the breaks increased with mussel’s size. The rate of movement estimated for the period of experimental time changed according to the duration of breaks. Mussels with a shell length of 1–30 mm showed the maximal movement speed, while the motion activity of the bigger molluscs was significantly lower. The obtained results are discussed in view of behavioural changes in mussels during ontogenesis.

Ten years of experience in the rearing of young freshwater pearl mussels (Margaritifera margaritifera)

Abstract In rearing experiments performed between 1997 and 2007, captive‐bred juvenile mussels were harvested shortly after they had dropped off their host fish, and exposed to different types of cages and holding systems. Survival of juveniles ranged from 0 to 92% in the first 4 months, but the mean annual mortality was high in all trials and with all systems. In three trials with sheet cages and sediment boxes exposed to mussel rivers from an initial number of 1440 to 1660 only one to eight mussels reached 4 years of age. With the exception of mussels kept in spring water no relationship between growth and survival was observed. Low survival rates were obtained in sheet cages exposed to very oligotrophic and highly eutrophic brook stretches. Several natural sites that were lacking recruitment in the wild nevertheless showed good results in the cages. All holding systems showed irregular variations in survival rates. Pairs of sheet cages showed no correlation between the survival of mussels in the adjacent cages. In contrast, growth rates were correlated. No relationship could be found between the growth or survival in sheet cages at different sites and brooks and the corresponding data on water chemistry. The systems tested for rearing young mussels involving a minimal time and effort in the natural habitat were not successful due to the elevated mortality rates of juveniles. The rearing success of young pearl mussels in cages in the water flow of mussel rivers gives no information about the suitability of these sites for natural reproduction. Thus, to find potential natural habitats for Margaritifera, it is imperative to survey water quality, sediments and habitat structure. Copyright © 2010 John Wiley &amp; Sons, Ltd.

Density, Recruitment, and Shell Growth of Limnoperna fortunei (Mytilidae), an lnvasive Mussel in Tropical South America

ABSTRACT Limnoperna fortunei (Dunker, 1857) is an invasive freshwater bivalve native to rivers and streams of China and Southeast Asia. In 2001, it was discovered in Itaipú Reservoir, and its population has grown considerably since then. The aim of this study was to estimate density, recruitment, and individual growth of L. fortunei in a subtropical region from a field experiment using an artificial substrate. Samples were collected between December 2004 and December 2005 at Bela Vista Reservoir in Foz do Iguaçu, Brazil. Mussels were counted and measured to generate size-frequency and distribution data. Maximum and minimum densities (± standard deviation) were 204 ± 17 ind.100 cm−2 and 94 ± 22 ind.100 cm−1, respectively. Shell length ranged between 1 and 36 mm, and shell length frequency indicated presence of young mussels with variable densities throughout the period surveyed. The von Bertalanffy model fitted successfuHy in all cases explaining more than 96% of the variation in shell length. Measured growth parameters (k = 2.35 year−1, L∞ = 38 mm) were different from those estimated for populations of L. fortunei in a temperate region.

Modeling the influence of a young mussel bed on fine sediment dynamics on an intertidal flat in the Wadden Sea

Mussel beds are known to affect fine sediment dynamics and morphology on mudflat scale, a clear example of ecosystem engineering. Current research into possible ecological engineering applications of mussel beds makes quantitative modeling desirable. In this study a process-based model of the interaction between a young mussel bed and fine sediment was set up for use in the hydrodynamic and morphological model Delft3D-FLOW. The model encompasses the hydraulic roughness of the mussel bed, active capture of suspended sediment by filter feeding and changed bed properties due to biodeposited matter. The mussel bed implementation in Delft3D-FLOW was applied in a test case: a Wadden Sea intertidal mudflat model. It was concluded that a combination of active deposition via filtration and slow down of the flow due to increased roughness leads to high net deposition in the mussel bed. In addition, the ability of young mussels to quickly climb on top of deposited material results in rapid trapping of large amounts of fine sediment. In the wake of the mussel bed, deposition is also high because of reduced flow velocities. The effects of different existing mussel bed patterns were also evaluated. Patchiness and specifically striped patterns cause mussel beds to experience less sedimentation than uniformly covered beds of the same size and may therefore be favorable to mussels.

Variability of growth, health, and population turnover within mussel beds of Perna canaliculus in northern New Zealand

The growth and health of intertidal mussel (Perna canaliculus) populations were investigated along an exposed coastline at Ninety Mile Beach, northern New Zealand. A marked and recaptured experiment of young mussels (15–35 mm in shell length) over a year at three sites resulted in significant differences in recovery rates, shell growth, condition indices, age, and degree of shell parasitism. A high recovery rate of fast growing mussels coincided with a high condition index and low shell parasitism. Conversely, a low recovery rate of slow growing populations was associated with a low condition index and a high level of shell parasitism. Anomalous shell conditions included bored shells, wear and sloughing of periostracum, shell erosion, and nacre pits and bulges. Aging of adult mussels (70–80 mm) indicates that in areas of fast population turnover rates, mussels reach adulthood in only 1.1 years compared to the 2.5-year-old mussels found in low turnover areas. These differences are attributed to variations in environmental conditions (e.g., food availability, sediment load) throughout the study area, and highlight the importance of site-specific variability for intertidal populations.

Shell Form Variation of a Freshwater Mussel Velesunio ambiguus Philippi from the Ross River, Australia

Based on mussels collected from the Ross River, Australia, within 13 months, I studied the variation of their shell forms since the Ross River has changed from a flowing-water to a relatively still-water. At least four different shell forms were found including shells with characters of flowing-water species. Young mussels had distinctive “wings” at dorso-posterior part of the shells and in most cases, as the shells grew bigger, the wing development was less obvious. No significant differences were observed in obesity and relative height among mussels living in three different microhabitats (i.e. solid mud and plant litter, soft silt, soft silt and sand). The shells from Mt. Margaret Dam (a temporary dam) were thinner and their growth lines were easier to discriminate than those from the Ross River. Comparing with those living in temperate regions of Australia, the obesity and the relative height of mussels from the Ross River were smaller. Only few abnormal shells were found which usually appeared only as external deformations, such as: a light deflection on ventral margin and scars on the surface of shells. Seven age classes were found ranging between 6 and 12 years and it was estimated that the lifespan of the mussel in the Ross River was about 15 years.

Annual spawning of the hydrothermal vent mussel, Bathymodiolus azoricus, under controlled aquarium, conditions at atmospheric pressure

Dense macrofaunal communities of modioliform mussels are a major component of many hydrothermal vent and cold seep ecosystems. The hydrothermal vent mussel Bathymodiolus azoricus, that dominates hydrothermal vent communities near the Azores Triple Junction, can be maintained in aquaria at atmospheric pressure. Cages containing these mussels were placed over diffuse vent outlets and recovered at different times. Cages recovered in January 2003 contained mussels with ripe gonads while those recovered in July, August and November 2001 and in April 2003 did not. Mussels collected post-spawning in April 2003 spawned in the aquaria in January 2004. Young mussels recruited to the cages in April 2003. The data support a main single period of spawning and of juvenile recruitment for B. azoricus.