Live Mussels Research Articles

Annual winter water level drawdowns limit shallow‐water mussel densities in small lakes

Abstract Regulated water level fluctuations alter the physical, chemical, and biological environments in lakes. However, few studies have measured the effects of repeated annual winter drawdowns on freshwater mussel populations (Bivalvia: Unionida), and it is unknown whether drawdowns permanently constrain mussel populations to deeper depths or are resilient to the annual disturbance. We quantified mussel densities during normal water levels and their mortality after the initiation of drawdown in lakes with annual winter (December–March) water level drawdown regimes that have existed for several decades. We used systematic quadrat sampling and visual snorkel surveys to estimate the number of live mussels at the surface and buried, and shell length in six drawdown and three control lakes at exposed (0.5‐m) and unexposed (1‐m) depths during winter drawdown. We also estimated mortality of mussels along the exposed lakebed for nine drawdown lakes. Study lakes were dominated by Elliptio complanata and Pyganodon cataracta. During normal water levels, mussel densities were much lower in drawdown lakes than control lakes at 0.5‐m depths. When mussels were present in drawdown lakes at 0.5‐m depths, they were often burrowed in the substrate and smaller than buried mussels in control lakes. At unexposed 1‐m depths, mussel densities were primarily explained by geographic region (western versus central Massachusetts), and found higher densities in drawdown lakes compared to control lakes. Mussel mortality after a single drawdown event in nine drawdown lakes was not correlated with drawdown magnitude or rate. Concordance of shell length‐frequency distributions between dead and buried living mussels in drawdown lakes suggests annual mortality of colonising individuals, which are typically small and presumably of young cohorts. Annual winter drawdowns still limit densities of E. complanata and P. cataracta in shallow‐water habitats in the following autumn (September–October) after 4–5 months of potential recovery, and hence constrain their distribution in lakes exposed to drawdowns. The development of sustainable water level management practices will be essential to minimise impacts to native mussel populations.

Reassessment of Freshwater Unionid Mussel Diversity and Abundance in the Walnut River Basin, Kansas

Species diversity of unionid mussels of the Walnut River Basin, Kansas was reassessed in 2017 and compared with surveys from 1979 and 2001. Our 1979 study surveyed 120 sites in the basin collecting 18 extant species. We resampled 87 of these sites in 2001, finding evidence of 8 extant species. In 2017 our survey of four sites collected 5 extant species. The most abundant species were Amblema plicata in 1979, A. plicata and Quadrula quadrula in 2001, and Quadrula pustulosa in 2017. The most abundant bivalve mollusk in 2017, comprising 36% of live mussels, was Tritogonia verrucosa. The non-unionid species Corbicula fluminea was absent from sample sites in the basin in 1979, comprised 51% of live individuals in 2001, and 24% of live individuals in 2017. Non-native Zebra mussels (Dreissena polymorpha) were found in the basin in 2017, but not in the earlier surveys. These results demonstrate that changes in mussel abundance and diversity have occurred since the 1979 survey, but do not suggest continual dramatic declines in mussels in the Walnut River Basin.

Examination of Bathymodiolus childressi nutritional sources, isotopic niches, and food-web linkages at two seeps in the US Atlantic margin using stable isotope analysis and mixing models

Chemosynthetic environments support distinct benthic communities capable of utilizing reduced chemical compounds for nutrition. Hundreds of methane seeps have been documented along the U.S. Atlantic margin (USAM), and detailed investigations at a few seeps have revealed distinct environments containing mussels, microbial mats, authigenic carbonates, and soft sediments. The dominant mussel, Bathymodiolus childressi, contains methanotrophic endosymbionts but is also capable of filter feeding, and stable isotope analysis (SIA) of mussel-shell periostracum suggests that these mussels are mixotrophic, assimilating multiple food resources. However, it is unknown whether mixotrophy is widespread or varies spatially and temporally. We used SIA (δ13C, δ15N, and δ34S) and an isotope mixing model (MixSIAR) to estimate resource contribution to B. childressi and characterize food webs at two seep sites (Baltimore Seep; 400 m and Norfolk Seep; 1500 m depths) along the USAM, and applied a linear mixed-effects model to explore the role of mussel population density and tissue type in influencing SIA variance. After controlling for location and temporal variation, isotopic variability was a function of proportion of live mussels present and tissue type. Isotopic differences were also spatially discrete, possibly reflecting variations in the underlying carbon source at the two sites. Low mussel δ13C values (∼−63‰) are consistent with a dependence on microbial methane. However, MixSIAR results revealed mixotrophy for mussels at both sites, implying a reliance on a mixture of methane and phytoplankton-derived particulate organic material. The mixing model results also reveal population density-driven patterns, suggesting that resource use is a function of live mussel abundance. Mussel isotopes differed by tissue type, with gill having the lowest δ15N values relative to muscle and mantle tissues. Based on mass balance equations, up to 79% of the dissolved inorganic carbon (DIC) of the pore fluids within the anaerobic oxidation of the methane zone is derived from methane and available to fuel upper slope deep-sea communities, such as fishes (Dysommina rugosa and Symphurus nebulosus), echinoderms (Odontaster robustus, Echinus wallisi, and Gracilechinus affinis), and shrimp, (Alvinocaris markensis). The presence of these seeps thereby increases the overall trophic and community diversity of the USAM continental slope. Given the presence of hundreds of seeps within the region, primary production at seeps may serve as an important, yet unquantified, energy source to the USAM deep-sea environment.

Lake Characteristics, Population Properties and Invasion History Determine Impact of Invasive Bivalves on Lake Nutrient Dynamics

Invasive species can have large impacts on ecosystems, including the cycling and distribution of nutrients. To determine the whole-ecosystem effects of invasive zebra mussels on lake nutrient dynamics, we sampled 10 invaded Minnesota lakes spanning a broad trophic status gradient. We conducted N and P excretion and biodeposition rate measurements and determined the C, N and P composition of dreissenid soft tissues and shell material in the study lakes. We also estimated the whole-lake biomass of live dreissenid mussels and their dead shell material, constructing comprehensive nutrient budgets for dreissenid populations in the study lakes. We used the results of our measurements and published data to estimate the contribution of dreissenids to P budgets in 24 additional lakes in Europe and North America. Results show that nutrient cycling rates and composition of soft tissues and shells vary with mussel size and lake trophic status. Zebra mussels made variable, but often large, contributions to cycling and storage of water column standing stocks of POC, PON and TP in the study and literature lakes. In some lakes, the effects of zebra mussels on P dynamics were also considerable in the context of estimated P external and internal loading, sediment sequestration and effects of other biota. We show that the impact of zebra mussels on whole-lake nutrient budgets depends on lake properties, dreissenid population characteristics and invasion history. This information can be used by ecosystem managers to prioritize invasion prevention efforts toward lakes likely to be most strongly impacted by zebra mussel invasions.

Physical Modelling of Blue Mussel Dropper Lines for the Development of Surrogates and Hydrodynamic Coefficients

In this work, laboratory tests with live bivalves as well as the conceptual design of additively manufactured surrogate models are presented. The overall task of this work is to develop a surrogate best fitting to the live mussels tested in accordance to the identified surface descriptor, i.e., the Abbott–Firestone Curve, and to the hydrodynamic behaviour by means of drag and inertia coefficients. To date, very few investigations have focused on loads from currents as well as waves. Therefore, tests with a towing carriage were carried out in a wave flume. A custom-made rack using mounting clamps was built to facilitate carriage-run tests with minimal delays. Blue mussels (Mytilus edulis) extracted from a site in Germany, which were kept in aerated seawater to ensure their survival for the test duration, were used. A set of preliminary results showed drag and inertia coefficients C D and C M ranging from 1.16–3.03 and 0.25 to 1.25. To derive geometrical models of the mussel dropper lines, 3-D point clouds were prepared by means of 3-D laser scanning to obtain a realistic surface model. Centered on the 3-D point cloud, a suitable descriptor for the mass distribution over the surface was identified and three 3-D printed surrogates of the blue mussel were developed for further testing. These were evaluated regarding their fit to the original 3-D point cloud of the live blue mussels via the chosen surface descriptor.

Experimental investigation of turbulent flow over live mussels

Unionids have been described as ecosystem engineers capable of affecting the local food web as well as the hydrodynamics, passively and actively. In this study, we perform particle image velocimetry measurements to characterize the flow around a live Amblema plicata using natural sediments as tracer particles under two specific flow rates and orientations i.e., facing upstream and downstream, to understand the interaction between the organism and flow surrounding it. The behavior of the mussel is also quantified under all the above experimental conditions using a hall-effect gape sensor that captures valve motion. The flow measurements show clear variations between the two orientations tested, with the presence of a low velocity region behind the mussel extending beyond the tested field of view for the upstream orientation. In contrast, the flow in the wake of the downstream orientation recovers very quickly to the incoming flow strength. The inspection of the vorticity contours around the mussel also highlights clear differences between orientations, with the structure of a shear layer under the upstream orientation changing to a region of concentrated vorticity near the siphons for the downstream cases. The variation of the net flux through the mussel along with the frequency of partial closures captured by the gape sensor measurements illustrate a potential added bioenergetic cost to the mussel feeding when facing downstream, especially at higher flow speeds.

After the Fall: Legacy Effects of Biogenic Structure on Wind-Generated Ecosystem Processes Following Mussel Bed Collapse

Blue mussels (Mytilus edulis) are ecosystem engineers with strong effects on species diversity and abundances. Mussel beds appear to be declining in the Gulf of Maine, apparently due to climate change and predation by the invasive green crab, Carcinus maenas. As mussels die, they create a legacy of large expanses of shell biogenic structure. In Maine, USA, we used bottom traps to examine effects of four bottom cover types (i.e., live mussels, whole shells, fragmented shells, bare sediment) and wind condition (i.e., days with high, intermediate, and low values) on flow-related ecosystem processes. Significant differences in transport of sediment, meiofauna, and macrofauna were found among cover types and days, with no significant interaction between the two factors. Wind condition had positive effects on transport. Shell hash, especially fragmented shells, had negative effects, possibly because it acted as bed armor to reduce wind-generated erosion and resuspension. Copepods had the greatest mobility and shortest turnover times (0.15 d), followed by nematodes (1.96 d) and the macrofauna dominant, Tubificoides benedeni (2.35 d). Shell legacy effects may play an important role in soft-bottom system responses to wind-generated ecosystem processes, particularly in collapsed mussel beds, with implications for recolonization, connectivity, and the creation and maintenance of spatial pattern.

Spoilage microbial community profiling by 16S rRNA amplicon sequencing of modified atmosphere packaged live mussels stored at 4oC

There is little information on the microbial communities associated with modified atmosphere (MA)-packaged live mussels. There is also a dearth of information on how pre-packaging depuration modifies the microbial communities and spoilage of live mussels. Amplicon sequencing was used to describe spoilage microbial succession in MA-packaged live mussels during storage at 4 °C. Proteobacteria, Cyanobacteria and Firmicutes were the three major phyla observed in the mussel meat and pouch water of undepurated and depurated mussels. Among these phyla, Cyanobacteria was more predominant on day 0 in mussel meat of undepurated and depurated mussels while Proteobacteria was predominant in commercially-depurated mussels. Synechococcus was apparently dominant on days 0–7 in the meat of undepurated mussels and days 0–10 in depurated mussels. Shewanella was dominant on day 0 in commercially-depurated mussels and dominant on day 15 in undepurated while Acidaminococcus was dominant in depurated mussels on day 15. Psychromonas was observed to be dominant in commercially-depurated mussels on day 7 and further shifted to Acinetobacter by day 10 and 15. In the pouch water, Acinetobacter was dominant throughout the storage days in undepurated mussels while Psychrobacter was predominant in both depurated and commercially-depurated mussels. This study demonstrated the impact of depuration on the microbiota and the spoilage mechanism of MA-packaged live mussels. Shewanella was easily removed through depuration. However, spoilage bacteria such as Acidaminococcus could not be easily removed although they are not important at the beginning but grew at the end. Pouch water contributed suitable biological medium for the growth of Acinetobacter and Psychrobacter and both enhanced the growth of spoilage bacteria such as Shewanella and Acidaminococcus.

Emersion survival manipulation in Greenshell™ mussels (Perna canaliculus): Implications for the extension of live mussels' shelf-life

Farmed adult Greenshell™ mussels were exposed to a range of conditions immediately after harvest to evaluate the effects on emersion survival and the implications for live transport. Two experiments were performed, coinciding with the mussel harvest season during summer and winter 2017. In the summer experiment, a wide range of conditions were tested to identify alternatives to be evaluated in more detail during the winter experiment. The postharvest experimental conditions selected included transient re-immersion at different temperatures, cold and heat-shock, tidal simulation, and packing with ice. These treatments aimed to either reduce postharvest stress and/or give the mussels a potentially beneficial physiological and behavioural advantage to help them cope with emersion. The mussels' responses in terms of gaping and survival differed between summer and winter, and among and within treatments. Sub-ambient temperature seawater exposure after harvest tended to improve the survival time of the mussels in both seasons, the effect being dependent on both temperature and duration of the exposure. Some of the differences observed could be explained by the conditions (in the wild and in the laboratory) to which the mussels were exposed before emersion and the different capability that each mussel has to cope with stress. However, the exact mechanisms driving these changes are not fully understood and require further investigation. This study, nevertheless, indicates that emersion survival (i.e. live mussel shelf-life) could be extended by re-immersion after harvest combined with a sub-lethal cold-shock followed by immersed recovery before transportation. If the commercial shelf-life of live product can be significantly extended, the implications for food quality and safety will also need to be evaluated. A similar approach could be applied in other shellfish such as other species of mussels as well as oysters or clams to improve shelf-life, considering their physiological capabilities and behaviour and how those are affected by environmental conditions in different seasons or regions.

Die‐offs of the endangered pearl mussel Margaritifera margaritifera during an extreme drought

Abstract Droughts may be responsible for important ecological impacts in freshwater ecosystems, including the death of rare species. This study assessed the mortality of the endangered pearl mussel Margaritifera margaritifera (Linnaeus, 1758) in the Mente, Rabaçal and Tuela rivers (north west of the Iberian Peninsula) during the extreme summer drought of 2017. Mortality occurred as a result of the low river flow, which led to mussel stranding near the banks and consumption (by predation or scavenging) by wild boar Sus scrofa (Linnaeus, 1758). Mortality differed across sites. The shell lengths of live mussels (measured before the drought) and dead mussels significantly differed in the Rabaçal River, but not in the Mente and Tuela rivers. Extreme droughts are predicted to increase in number and intensity in the future, and possible impacts on rare species such as M. margaritifera should be carefully monitored. Several M. margaritifera populations in Iberia (and elsewhere) may now be at increased risk, and measures should be implemented in order to mitigate the impacts of future extreme droughts.

Prospects for Biocontrol of Vibrio parahaemolyticus Contamination in Blue Mussels (Mytilus edulus)-A Year-Long Study.

Vibrio parahaemolyticus is an environmental organism normally found in subtropical estuarine environments which can cause seafood-related human infections. Clinical disease is associated with diagnostic presence of tdh and/or trh virulence genes and identification of these genes in our preliminary isolates from retail shellfish prompted a year-long surveillance of isolates from a temperate estuary in the north of England. The microbial and environmental analysis of 117 samples of mussels, seawater or sediment showed the presence of V. parahaemolyticus from mussels (100%) at all time-points throughout the year including the colder months although they were only recovered from 94.9% of seawater and 92.3% of sediment samples. Throughout the surveillance, 96 isolates were subjected to specific PCR for virulence genes and none tested positive for either. The common understanding that consuming poorly cooked mussels only represents a risk of infection during summer vacations therefore is challenged. Further investigations with V. parahaemolyticus using RAPD-PCR cluster analysis showed a genetically diverse population. There was no distinct clustering for “environmental” or “clinical” reference strains although a wide variability and heterogeneity agreed with other reports. Continued surveillance of isolates to allay public health risks are justified since geographical distribution and composition of V. parahaemolyticus varies with Future Ocean warming and the potential of environmental strains to acquire virulence genes from pathogenic isolates. The prospects for intervention by phage-mediated biocontrol to reduce or eradicate V. parahaemolyticus in mussels was also investigated. Bacteriophages isolated from enriched samples collected from the river Humber were assessed for their ability to inhibit the growth of V. parahaemolyticus strains in-vitro and in-vivo (with live mussels). V. parahaemolyticus were significantly reduced in-vitro, by an average of 1 log−2 log units and in-vivo, significant reduction of the organisms in mussels occurred in three replicate experimental tank set ups with a “phage cocktail” containing 12 different phages. Our perspective biocontrol study suggests that a cocktail of specific phages targeted against strains of V. parahaemolyticus provides good evidence in an experimental setting of the valuable potential of phage as a decontamination agent in natural or industrial mussel processing (343w).

What happens after mussels die? Biogenic legacy effects on community structure and ecosystem processes

Mussels are well-known ecosystem engineers in soft-bottom systems. Mytilus edulis beds have myriad effects on sediment, benthic organisms, and ecosystem processes such as hydrodynamic transport of sediment and animals. When mussels die, they may leave behind massive amounts of whole (empty) and fragmented shells. The legacy effects of this long-lasting biogenic material (i.e., shell hash) on benthic systems are poorly understood. We measured percent cover values of 4 bottom cover types, i.e., live mussels, whole shells, fragmented shells, and bare sediment, at the mussel bed in Carrying Place Cove, Harrington, Maine, USA, and examined their effects on sediment characteristics, community structure of macrofauna and meiofauna, and ecosystem processes of sediment flux and dispersal of postlarval macrofauna and meiofauna. We predicted that live mussels are the cover type with the greatest effects compared to bare sediment, followed by fragmented shells and then whole shells. We discovered mostly bare sediment, substantial cover of whole and fragmented shells, and almost no live mussels in what had in past years been a robust bed. We found significant univariate and multivariate differences in sediment and animals across cover types, especially for meiofauna. Fragmented shell material in particular may be an important driver in this system. Our results are the first to quantify the 4 mussel bed cover types and demonstrate their effects. Mussel beds in the Gulf of Maine have experienced severe declines in the past two decades, attributed primarily to climate change and the invasive green crab, Carcinus maenas. Our results may be useful in predicting the responses of soft-bottom systems as intact mussel beds die off, leaving large areas of bare sediment and shell hash.

Light and Scanning Electron Microscopic Studies of Unionicola tetrafurcatus (Acari: Unionicolidae) Infecting Four Freshwater Bivalve Species and Histopathological Effect On Its Hosts.

Water mites of the genus Unionicola are the most common symbionts of freshwater bivalves. During the current investigation, a total of 120 live freshwater mussels representing 5 species, Corbicula fluminea (Veneroida), Coelatura aegyptiaca (Unionoidea), Mutela rostrata, and Chambardia rubens (Mutelidae), were collected from 2 localities in Tura (Helwan Governorate) and El Kanater (Qaluobiya Governorate), Egypt. Only 3 of the 4 bivalve species listed are considered freshwater bivalves (members of Unionoidea). Corbicula fluminea belong to the family Cyrenidae within Veneroida. Collected mussels were dissected and examined for the presence of unionicolid mites. It was found that 30.83% (37/120) were infected with a single mite species, Unionicola tetrafurcatus (Unionicolidae). The highest prevalence was observed during the summer with 83.33% (25/30) whereas the least was observed in autumn, i.e., 33.33% (10/30). Mites were recovered from the gills, gonads, and visceral mass of mussel hosts. Gills of host mussels were the primary site of oviposition for Unionicola mites. Smaller bivalves in size had significantly greater numbers of mites than did larger ones in size. Numbers of mites per host species was variable and the highest prevalence level of 83.33% (25/30) was recorded in Cor. fluminea while the lowest one of 16.66% (5/30) was found in Ch. rubens. Morphological and morphometric characterizations of mites revealed some differences between the present species and other related Unionicola. Histopathological responses of host mussels to the eggs, larvae, and cuticular remnants of U. tetrafurcatus were also studied. Therefore, the present study demonstrated that freshwater bivalves have a new host and locality records for infection with U. tetrafurcatus. Future studies are recommended to include advanced molecular characteristics for these mites.

Single nucleotide polymorphisms in native South American Atlantic coast populations of smooth shelled mussels: hybridization with invasive European Mytilus galloprovincialis

BackgroundThroughout the world, harvesting of mussels Mytilus spp. is based on the exploitation of natural populations and aquaculture. Aquaculture activities include transfers of spat and live adult mussels between various geographic locations, which may result in large-scale changes in the world distribution of Mytilus taxa. Mytilus taxa are morphologically similar and difficult to distinguish. In spite of much research on taxonomy, evolution and geographic distribution, the native Mytilus taxa of the Southern Hemisphere are poorly understood. Recently, single nucleotide polymorphisms (SNPs) have been used to clarify the taxonomic status of populations of smooth shelled mussels from the Pacific coast of South America. In this paper, we used a set of SNPs to characterize, for the first time, populations of smooth shelled mussels Mytilus from the Atlantic coast of South America.ResultsMytilus spp. samples were collected from eastern South America. Six reference samples from the Northern Hemisphere were used: Mytilus edulis from USA and Northern Ireland, Mytilus trossulus from Canada, and Mytilus galloprovincialis from Spain and Italy. Two other reference samples from the Southern Hemisphere were included: M. galloprovincialis from New Zealand and Mytilus chilensis from Chile. Fifty-five SNPs were successfully genotyped, of which 51 were polymorphic. Population genetic analyses using the STRUCTURE program revealed the clustering of eight populations from Argentina (Mytilus platensis) and the clustering of the sample from Ushuaia with M. chilensis from Chile. All individuals in the Puerto Madryn (Argentina) sample were identified as M. platensis × M. galloprovincialis F2 (88.89%) hybrids, except one that was classified as Mediterranean M. galloprovincialis. No F1 hybrids were observed.ConclusionsWe demonstrate that M. platensis (or Mytilus edulis platensis) and M. chilensis are distinct native taxa in South America, which indicates that the evolutionary histories of Mytilus taxa along the Atlantic and Pacific coasts differ. M. platensis is endangered by hybridization with M. galloprovincialis that was introduced from Europe into the Puerto Madryn area in Argentina, presumably by accidental introduction via ship traffic. We confirm the occurrence of a native M. chilensis population in southern Argentina on the coast of Patagonia.

Evaluation of different media for cell proliferation in mantle tissue culture of the green mussel, Perna viridis (Linnaeus, 1758)

The aim of the present study was to establish a suitable culture system for tissue explants from the mantle of the green mussel, Perna viridis. The experiments were conducted using healthy, live green mussels in the size range of 75 to 110 g collected from Pulicat Lake, Tamil Nadu. Three different culture media namely M199, Leibovitz L-15 and sterile seawater were used to assess the most suitable medium for growth, proliferation and viability of mantle epithelial cells. The effect of the addition of two supplements viz., 10% foetal calf serum (FCS) and 0.1% yeast extract to the culture media was also evaluated. After carefully isolating the pallial layer from the mantle tissue, 1-2 mm2 size explants were successfully cultured in 12-well plates at 25°C for up to 14 days. Cultures were monitored under light and phase contrast objectives in an inverted microscope. Cell counts were made and cell size was measured for each treatment. Cells were observed to migrate from the periphery of the explant within 24 h after initiation of cultures. The liberated cells were mostly round and were either granulocytes or hyalinocytes. Fibroblast-like cells were also observed. Our results showed that proliferation of epithelial cells from mantle tissue was maximum in seawater medium (7.4x104 cells ml-1), followed by L-15 medium (2.55x104 cells ml-1). Average cell size in seawater medium was 10.72 μm and that in L-15 and M199 media was 8.56 and 6.39 μm, respectively. Adherent cells were also more prominent and higher in number in seawater medium. Supplementation of culture media with 10% FCS and 0.1% yeast extract improved both cell proliferation and cell size in all the three culture media. Four concentrations of 0.1% yeast extract (@ 50 μl, 75 μl, 100 μl, 150 μl ml-1 medium) were tested in the present study and best results were obtained with 100 μl ml-1, with respect to both cell counts and size.

Some Phoretic Associations of Macroinvertebrates on Transplanted Federally Endangered Freshwater Mussels

Abstract Benthic macroinvertebrates were washed from nearly 1000 federally endangered freshwater mussels that had been collected from Pennsylvania during a reintroduction project to 2 eastern Illinois streams. Most benthic macroinvertebrates collected were larvae of the Neophylax fuscus, but other caddisflies and segmented worms were also observed. No unoccupied caddisfly cases were observed on live mussels, leaving open the question as to the seasonal fate of these microhabitats after caddisflies pupate and emerge in the Autumn of each year. Unionid mussel shells might modify local-scale species diversity by influencing physical and hydrau lic properties of microhabitats.

Evaluation of spoilage potential and volatile metabolites production by Shewanella baltica isolated from modified atmosphere packaged live mussels

Under the current commercial practice, live mussels only have 10days' shelf-life. Observed spoilage indices reduce consumers' acceptance, palatability and shelf-life of modified atmosphere packaged (MAP) live mussels. The aims of this study are to isolate specific spoilage bacteria from modified atmosphere packaged live mussels, evaluate isolates for microbial spoilage indices using qualitative methods and volatile metabolites production. Forty-six hydrogen sulphide producing bacteria were isolated and evaluated for trimethylamine n-oxide (TMAO) reduction, proteolytic and lipolytic activities and hydrogen sulphide production. Twenty-eight isolates were obtained from pouch water and 18 from mussel meat. All the isolates could produce H2S on Iron agar at 25°C while 30/46 produced H2S at 4°C and tolerate 0–6% NaCl. Four (4/46) isolates could not hydrolyse mussel protein. Over 80% isolates reduced TMAO to TMA in 3days with the production of H2S. Results of this study shows hydrogen sulphide producing bacteria isolated from MAP live mussels produce microbial spoilage indices. Isolate with highest enzymatic activities and hydrogen sulphide production was identified as Shewanella baltica using 16S rRNA gene. Axenic culture of the isolate was inoculated into sterile mussel broth. Inoculated sample was further stored at 4°C for 10days for spoilage study. Volatile metabolites produced during storage were evaluated using headspace solid phase micro-extraction gas chromatography mass spectrometry (HS-SPME GC/MS). A total of 44 compounds were identified in the sample after 10days while 27 compounds were identified in inoculated mussel broth. Group of compounds identified are alcohols, aldehydes, phenol, furans, ketone, esters, organic acid, aromatic hydrocarbons, alkanes, nitrogen and sulphur containing compounds. Dimethyl trisulphide, methyl-phenol, 3,5-octadiene and thiohexene were unique to inoculated mussel broth. Understanding spoilage mechanism and attendant spoilage indices will help in designing effective mussel quality protocols and shelf-life extension.

Differential effects of adult mussels on the retention and fine-scale distribution of juvenile seed mussels and biofouling organisms in long-line aquaculture

AEI Aquaculture Environment Interactions Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections AEI 9:239-256 (2017) - DOI: https://doi.org/10.3354/aei00230 Differential effects of adult mussels on the retention and fine-scale distribution of juvenile seed mussels and biofouling organisms in long-line aquaculture Paul M. South1,2,*, Oliver Floerl1, Andrew G. Jeffs2 1Cawthron Institute, 98 Halifax Street East, Nelson 7010, New Zealand 2Institute of Marine Science, University of Auckland, Private bag 92019, Auckland, New Zealand *Corresponding author: paul.south@cawthron.org.nz ABSTRACT: The majority of juvenile seed mussels are lost in aquaculture production. Understanding the causes of the losses of seed mussels is critical to reducing uncertainties in mussel aquaculture production. One major cause of loss appears to be the secondary settlement behaviour of mussels, which is thought to be a behavioural process by which larger juveniles can safely recruit among adults. This implies that once a juvenile mussel has settled among adults, there is either some impetus to remain or other positive interactions that promote increased survival. In this study, 2 densities (5 and 20 per 45 cm experimental rope) of adult green-lipped mussels Perna canaliculus were deployed alongside juvenile seed mussels to test whether this enhanced the retention of the juveniles in a typical suspended culture. Adult shells were also deployed to ascertain whether any effects were due to the physical presence of the mussels or the influence of their biological functioning. The presence of adult mussels or shells did not increase the retention of juvenile P. canaliculus, but small-scale movements of juveniles were increased by the addition of 20 live adult mussels per experimental rope. However, the presence of adult mussels and mussel shells on experimental ropes greatly increased the abundance of biofouling organisms. While the addition of live adult mussels or shells failed to provide a simple tool for increasing retention of seed mussels on aquaculture lines, they offer new insights into the identity and ecology of key biofouling organisms that can be problematic in mussel aquaculture production. KEY WORDS: Mussel retention · Secondary settlement · Green-lipped mussel · Perna canaliculus · Mytilus galloprovincialis · Recruitment Full text in pdf format PreviousNextCite this article as: South PM, Floerl O, Jeffs AG (2017) Differential effects of adult mussels on the retention and fine-scale distribution of juvenile seed mussels and biofouling organisms in long-line aquaculture. Aquacult Environ Interact 9:239-256. https://doi.org/10.3354/aei00230 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in AEI Vol. 9. Online publication date: July 26, 2017 Print ISSN: 1869-215X; Online ISSN: 1869-7534 Copyright © 2017 Inter-Research.

Is attachment substrate a prerequisite for mussels to establish on soft-sediment substrate?

It is unknown whether the presence of hard substrate is a necessary prerequisite for the attachment and establishment of mussels, especially on soft-sediment habitats where hard substrates are scarce. Therefore, we examined the importance of natural attachment substrates in the form of mussel shell and adult conspecifics for the establishment of juvenile and adult green-lipped mussels (Perna canaliculus) on soft-sediment. In field experiments where shell material was added as substrate to soft-sediment it made no difference to the subsequent retention of adult mussels. Laboratory experiments showed that juvenile mussels preferentially sought out, and attached to adult mussels compared to remaining on unmodified soft-sediment. Furthermore, juvenile mussels attached to live adult mussels had higher survival in the presence of a common sea star predator compared to juveniles on unmodified soft-sediment or attached to mussel shell. The results suggest that establishment of mussel beds on soft-sediment requires only adult mussels, which receive sufficient anchorage through attachment to neighbouring adults and in so doing, providing a stable, complex substrate suitable for improving the survival of establishing juvenile mussels by protecting them from sea star predators.

Consequences of Dam Removal on Mussel Assemblages (Unionidae) in the Cuyahoga River

The primary objective of a new survey of the Cuyahoga River was to assess species richness and population abundance of various mussel species in the family Unionidae throughout the Middle Cuyahoga River and upper parts of the Lower Cuyahoga River. Historically, few records existed for this river between Lake Rockwell and the Cuyahoga Valley National Park, a region in which four dams have been removed in the past 12 years. Timed visual surveys were conducted during low flow conditions and by using tactile techniques in deeper water. Throughout the survey, only 37 live animals were located across the 18 Middle Cuyahoga River sites inspected, which included only Lampsilis siliquoidea, Pyganodon grandis and the state-endangered Ligumia nasuta. No live mussels were found between the Gorge and the Cuyahoga Valley National Park. That 434 shells and valves were collected, and all but two were classified as long dead, attests that mussels had been more abundant, and that at least nine of the ten species known to be present above Lake Rockwell had lived in the Middle Cuyahoga River. Remote sensing data and aerial photographs were used to characterize change in opening up the river, but benefits to water quality and stream flow subsequent to dam removal must be tempered with the apparent loss of an assemblage of mussels better adapted to lentic conditions.