Presence Of Mussels Research Articles

Baseline for the Northeast Atlantic (58-70°N) intertidal Mytilus species complex (Mytilus spp.).

Mussels (Mytilus spp.) are abundant in the North Atlantic, sessile, and sensitive to environmental change, and suitable as sentinels of environment and climate change of costal ecosystems. We aimed to determine the baseline for the Northeast Atlantic (58-70°N) Mytilus species complex, and to show the present distribution to surveys conducted 60 years ago. Baseline was obtained by investigating a total of 509 stations in the intertidal zone, in four regions comprising the environmental gradient from head of fjord to coast, and distributed over the latitudinal gradient from 58 to 70°N. The baseline shows a range in continuous abundance of mussels from 12% to 36%, patchy abundance from 26% to 57% and no or very limited mussel abundance from 26% to 46% between the four regions. The presence of mussels in the southeast and west region was visualized to previous surveys conducted 60 years ago. The data points to similar past and present presence of mussels in both regions, yet past major mussel fields in the inner section of region southeast was not detected in this study. The baseline of Mytilus spp. in the Northeast Atlantic (58-70°N) is now available for future reference. The baseline, plotted to surveys conducted 60 years ago, points to awareness of the population situated in the southeast section of the investigated region. Continued monitoring and modeling are needed to clarify drivers of temporal and spatial variation in the mussel populations along the Northeastern Atlantic coast.

Molecular methods confirm the first report of the non-indigenous Perna viridis Linnaeus, 1758 (Mytilida, Mytilidae) in southern Brazil

The mussel Perna viridis, commonly known as Green Mussel, is native from the Indo-Pacific region and has been introduced in various countries around the globe. In Brazil, the species has already been recorded in Rio de Janeiro and Ceará states. With the aim of assessing the presence of mussels in the southern region of the country, 14 individuals were collected in the Paranaguá Estuarine Complex, Paraná. The mussels were found attached at a depth of 2 m on the artificial structure of Ponta do Poço Marina. The DNA was extracted using a commercial kit, the COI gene was amplified through PCR using the primers dgL-CO-1490 and dgHCO-2198, sequenced by the Sanger method, and the species was identified through the BOLD Systems. The phylogenetic tree was built on the software MEGA 11 using 28 sequences from three Perna species. Therefore, the present study confirms the occurrence of P. viridis in Brazil through molecular identification for the first time and adds a second Brazilian state where it has been recorded. The Brazilian coastline provides optimal environmental conditions for the establishment and development of P. viridis. 

Species identity and diversity of filter‐feeding bivalves impact green and brown food webs

Abstract In freshwater ecosystems, consumers can play large roles in nutrient cycling by modifying nutrient availability for autotrophic and heterotrophic microbes. Nutrients released by consumers directly support green food webs based on primary production and brown food webs based on decomposition. While much research has focused on impacts of consumer driven nutrient dynamics on green food webs, less attention has been given to studying the effects of these dynamics on brown food webs. Freshwater mussels (Bivalvia: Unionidae) can dominate benthic biomass in aquatic systems as they often occur in dense aggregations that create biogeochemical hotspots that can control ecosystem structure and function through nutrient release. However, despite functional similarities as filter‐feeders, mussels exhibit variation in nutrient excretion and tissue stoichiometry due in part to their phylogenetic origin. Here, we conducted a mesocosm experiment to evaluate how communities of three phylogenetically distinct species of mussels individually and collectively influence components of green and brown food webs. We predicted that the presence of mussels would elicit a positive response in both brown and green food webs by providing nutrients and energy via excretion and biodeposition to autotrophic and heterotrophic microbes. We also predicted that bottom‐up provisioning of nutrients would vary among treatments as a result of stoichiometric differences of species combinations, and that increasing species richness would lead to greater ecosystem functioning through complementarity resulting from greater trait diversity. Our results show that mussels affect the functioning of green and brown food webs through altering nutrient availability for both autotrophic and heterotrophic microbes. These effects are likely to be driven by phylogenetic constraints on tissue nutrient stoichiometry and consequential excretion stoichiometry, which can have functional effects on ecosystem processes. Our study highlights the importance of measuring multiple functional responses across a gradient of diversity in ecologically similar consumers to gain a more holistic view of aquatic food webs.

Responses of native freshwater mussels to remediation to remove polychlorinated biphenyl‐contaminated sediments in the upper Hudson River

Abstract The Hudson River, New York, was contaminated with polychlorinated biphenyls (PCBs) from two manufacturing plants over a period of approximately 30 years, and PCBs are still present in sediment and biota today. The river provides habitat for a variety of plants and animals, including native freshwater mussels. A remediation programme, consisting of dredging followed by the placement of backfilled sediment and/or a subaqueous cap, was initiated in 2009 to remove PCB‐contaminated sediments, and managers were concerned about how remediation could affect the mussels. Quantitative surveys were conducted across nine reaches (pools) to estimate species composition, density, population size, population structure, and ecosystem services of mussel assemblages, pre‐ and post‐remediation. Surveys were stratified into remediated areas (targeted for dredging) and non‐remediated areas (not targeted for dredging). Pre‐remediation, the river contained a low diversity, and high, but variable, density of mussels that were strongly dominated by Elliptio complanata. The presence of few fresh dead mussels indicates low natural mortality. Frequent recruitment by many species, varied length classes, and high biomass also support robust assemblages that perform important ecosystem services, such as biofiltration. Remedial activity removed most of the mussels and the associated services that they perform: their density was reduced by 83% and their filtration capacity was reduced by 93%, relative to non‐remediated areas. Areas that were remediated were almost devoid of adult mussels, but the presence of small mussels indicates that natural recolonization is occurring. However, it is unknown whether these assemblages will persist. As mussels are generally long lived and slow growing, natural recovery is anticipated to be slow, in the order of decades.

Mussel Shells from Marine Aquaculture Act like Ecosystem Engineers: Legacy Effects on Benthic Communities

Ecosystem engineers are organisms that cause changes in the physical state of biotic and abiotic structures that modulate the availability of resources to other species, thus affecting biochemical cycles. Molluscs, especially bivalves such as mussels, are widespread in coastal environments and they are excellent ecosystem engineers because of the durability of their shells, which add complexity and heterogeneity to benthic environments. The presence of mussel farms favours the accumulation of shells in benthic environments and may influence surrounding bare sediments, with potential legacy effects on benthic communities. We studied the effects of the accumulation of mussel shells at finfish farms and mussel farms by experimentally comparing bare sediment and sediment with fragmented shells in terms of the abundance of the most relevant faunal groups, specifically polychaete families as well as physical–chemical variables in sediment water samples, specifically organic matter (OM), redox potential, and acid-volatile sulphides (AVS) NH4+ and PO43−. The experiment was replicated under two environmental conditions over a period of 35 days: eutrophic muddy sediments and oligotrophic sandy sediments. The OM and AVS values were significantly higher in the eutrophic sediment with mussel shells. Only NH4+ was positively affected by the mussel shells in the oligotrophic conditions. Differences between the two environments were observed, and the effect of the mussel shells on the polychaete assemblages was more significant in the oligotrophic conditions. Mussel shell accumulations affected the structure of benthic assemblages by modifying their heterogeneity and complexity, which suggests that the presence of mussel farms above bare sediment may affect ecosystem functioning. Aquaculture has potentially negative or positive effects that must be addressed on a large scale, considering the increased input of organic matter and also the simultaneous presence of mussel shell waste, both of which alter the surrounding environment. This is particularly important in oligotrophic sandy sediment.

Home sweet home: Comparison of epibiont assemblages associated with cultivated and wild sugar kelp (Saccharina latissima), co-cultivated blue mussels (Mytilus edulis) and farm infrastructure

Seaweed farming is expanding in Europe and may provide environmental benefits similar to those from natural kelp forests and shellfish farms, including habitat provisioning. Few studies have substantiated these claims however, and it remains uncertain whether seaweed farms will support similar biodiversity to kelp forests or provide valuable long-term habitat beyond the harvest season. We repeatedly surveyed an integrated sugar kelp (Saccharina latissima) and blue mussel (Mytilus edulis) farm in southwest UK to compare epibiont assemblages between cultivated kelps, to those from three nearby wild kelp populations, and to epibionts on farmed mussel lines and unseeded ‘bare’ lines. We found farmed kelps supported over 217 times the abundance of epibionts living on wild kelps at harvest time, however, taxonomic diversity per kelp was lower at the farm. Farmed kelp assemblages were dominated by amphipods, which were present on the wild kelps but in much lower numbers. Farmed kelp also supported distinct assemblages to cultivated mussels, which were similarly dominated by amphipods, but hosted higher relative abundances of crabs, echinoderms, worms and red algal biomass. The bare lines were heavily colonised by another pseudo-kelp, Saccorhiza polyschides, which supported similar epibiont assemblages to the seeded S. latissima lines. Our findings indicate that cultivating bivalves alongside seaweed can increase habitat provisioning at a seaweed farm and extend its permanence beyond typical seaweed cultivation periods as bivalves have longer, continuous farming periods. However, the presence of mussels will likely influence the epibiont assemblages on the farmed kelp, which are distinct from wild kelp populations.

A glimpse into the future: A suitable methodological approach for the detection and identification of micro-bioplastics in biota

In the frame of the circular economy, bioplastics are considered a good alternative to conventional plastic materials. Until recently, only a few studies have focused on the occurrence and impact of bio-microplastics (bio-MPs) in aquatic environments, and there is a lack of a methodological approach to measure their amount in marine compartments. This research aimed to identify and validate a method for bio-MPs extraction from biota. A chemical digestion protocol suitable for conventional MPs, using potassium hydroxide (KOH), was applied for the detection, in mussels, of MPs made with Mater-Bi (MBi) from socks used in mussel farming. This method was tested on virgin MBi (VMBi) and aged (AMBi) MPs, ranging from 200 to 1000 μm in presence and absence of mussel tissues.Samples were analysed in pre- and post-digestion steps to assess the recovery rate, potential visual and size changes and polymer alteration in different bio-MPs size ranges. Results showed that MBi seems to be affected by KOH under pre-production conditions (VMBi), whereas in the AMBi treatment, which represents the environmentally realistic condition, the presence of fouling due to deployment at sea preserves MBi from the action of the alkaline agent. This approach allowed the recovery of small MPs, generally difficult to extract from biota, in an optimal visual condition and without polymer alteration. Despite the fraction of organic material in the MBi, these results suggested the suitability of this method and provided the assessment of the KOH effects on MBi-MPs under different environmental conditions. Finally, validation tests proved that the KOH protocol represents a reliable approach for detecting bio-MPs in marine organisms.This study is an important starting point for assessing the impact of the bio-MPs on the marine environment and suggests future studies to improve these issues in order to fill the gaps in the field of bioplastics.

Assessing the potential for restoring freshwater mussels to urban streams

Abstract Field trials were conducted to assess the potential for stocking native unionid mussels in urban streams of the Chesapeake Bay catchment. Juvenile, hatchery‐raised mussels were placed in enclosures at five urban streams (two restored and three unrestored) and two nearby rural streams. Adult mussels were translocated to two restored urban streams. Mussel growth and survivorship were assessed at the stream sites and for individuals maintained at hatchery ponds. At all sites, water quality conditions were generally suitable for mussels with respect to temperature, pH, and dissolved oxygen. Food resources, as indicated by the quantity and quality of suspended and benthic particulate matter, were higher among rural sites and lower in unrestored urban streams. Positive growth rates were observed at all sites, among both juveniles (caged) and translocated adults. Mussel fatty acid profiles were generally similar among sites, except for docosahexaenoic acid (DHA), which was lower among stocked mussels relative to mussels maintained at the hatchery. Among the unrestored urban streams, the frequent occurrence of high discharge events resulted in burial and downstream loss of enclosures. At restored urban streams and rural streams, the washout effects were less severe. Apart from washout effects, mortality, as indicated by the presence of dead mussels, was low (<10%). Overall, rural and restored urban streams provided suitable conditions for stocking native mussels, whereas in unrestored urban streams, bed and bank instability during high discharge events resulted in a high attrition of mussels. Conservation efforts may be aided by the consideration of mussel habitat needs in the design of stream restoration projects. The inclusion of mussel stocking efforts in urban stream restoration projects has the potential to facilitate stream recovery, expand and bring greater attention to mussel conservation efforts, and garner public support for the preservation of stream health in urban areas.

Clearance of Escherichia coli by the freshwater mussel Lamellidens marginalis in laboratory conditions

ABSTRACT Scientists and environmentalists are searching for biological remedies to reduce E. coli concentrations in waterbodies to acceptable levels. The present research was conducted to investigate clearance of E. coli isolated from freshwater mussels (Lamellidens marginalis) in the Old Brahmaputra River, Mymensingh, Bangladesh by conspecific mussels from the same river in aquarium conditions. Mussels were acclimated, depurated and divided into three shell length (SL) groups. Small (38.28 ± 2.81 mm), medium (47.28 ± 1.52 mm) and large (55.89 ± 2.25 mm) mussels were assigned to aquaria designated as T2, T3 and T4 respectively whereas empty mussel shells were assigned to T1 as control in triplicate. After addition of pure E. coli suspensions, 3 mL water samples from each aquarium were collected at hourly intervals for 12 h for total E. coli count (TEC). Statistical analysis revealed that both time and treatments have significant effects (P < 0.05) on TEC. Presence of live mussels caused 1.41–1.63 log10 reduction of TEC after 12 h compared to the control. However, such differences were not consistent among the different SL groups. In conclusion, L. marginalis is capable of reducing E. coli concentrations although the efficacy is not consistently related with mussels’ shell lengths.

Pattern formation in marsh ecosystems modeled through the interaction of marsh vegetation, mussels and sediment

Spatial self-organization, a common feature of multi-species communities, can provide important insights into ecosystem structure and resilience. As environmental conditions gradually worsen (e.g., resource depletion, erosion intensified by storms, drought), some ecological systems collapse to an irreversible state once a tipping point is reached. Spatial patterning may be one way for them to cope with such changes. We use a mathematical model to describe self-organization of an eroding marsh shoreline based on three-way interactions between sediment volume and two ecosystem engineers – smooth cordgrass Spartina alterniflora and ribbed mussels Geukensia demissa. Our model indicates that scale-dependent interactions between multiple ecosystem engineers drive the self-organization of eroding marsh edges and regulate the spatial scale of shoreline morphology. Spatial self-organization of the marsh edge increases the system’s productivity, allows it to withstand erosion, and delays degradation that otherwise would occur in the absence of strong species interactions. Further, changes in wavelength and variance of the spatial patterns give insight into marsh recession. Finally, we find that the presence of mussels in the system modulates the spatial scale of the patterns, generates patterns with shorter wavelengths, and allows the system to tolerate a greater level of erosion. Although previous studies suggest that self-organization can emerge from local interactions and can result in increased ecosystem persistence and stability in various ecosystems, our findings extend these concepts to coastal salt marshes, emphasizing the importance of the ecosystem engineers, smooth cordgrass and ribbed mussels, and demonstrating the potential value of self-organization for ecosystem management and restoration.

A new genus and two new, rare freshwater mussel (Bivalvia: Unionidae) species endemic to Borneo are threatened by ongoing habitat destruction

Abstract Most of the Bornean endemic freshwater mussel (Unionida) species known to date have not been recorded by science for the past 50 years or more, owing to a lack of research effort and presumed population losses. This study assessed current patterns and recent changes in the diversity and distribution of freshwater mussels in north‐eastern Borneo. Physical surveys and interviews were conducted at 24 sites, and anecdotal evidence for current or historical presence of mussels was collected for a further 13 sites. Native species, i.e. Schepmania sp. and Khairuloconcha sahanae gen. &amp; sp. nov., were only found in one small stream of the Kinabatangan River basin within the Gomantong Forest Reserve, whereas the non‐native Sinanodonta cf. woodiana was common across the study area. Molecular phylogenetics (five genes) of the native taxa, including comparative material from West Kalimantan and Sarawak, revealed: (i) the presence of a new genus with two new, rare species: Khairuloconcha lunbawangorum sp. nov. in the Limbang River basin and K. sahanae in the Kinabatangan River basin; (ii) that Khairuloconcha and Ctenodesma form the Bornean endemic tribe Ctenodesmini trib. nov.; and (iii) that Schepmania represents another Bornean endemic tribe Schepmaniini trib. nov. Both Khairuloconcha gen. nov. species are known from a single stream each and are apparently restricted to forest stream habitats where they occur at very low densities. Schepmania appears to have a severely contracted range in the Kinabatangan and adjacent basins. We urgently call for full protection of the currently known sites of K. lunbawangorum and K. sahanae, and development of an action plan to save the Bornean freshwater mussel fauna.

Interactive effects of bitterling fish and mussel on the community structures of plankton and benthic macroinvertebrates

放养河蚌，提高水体透明度以促进沉水植物生长，是湖泊生态修复中的常用手段之一.而小型杂食性鱼类鳑鲏依赖河蚌繁殖，河蚌放养可能会促进鳑鲏种群的发展；而鳑鲏与河蚌交互作用对水生态系统的影响仍研究较少.于2018年11—12月通过原位受控实验，设置对照组、河蚌组、鳑鲏组和河蚌+鳑鲏组，研究了鳑鲏（大鳍鱊Acheilognathus macropterus）与河蚌（背角无齿蚌Sinanodonta woodiana）对水质、浮游生物和底栖生物的影响.结果表明：鳑鲏显著增加了上覆水总氮、总磷、悬浮质和叶绿素a（Chl.a）浓度；但并未显著影响无机悬浮质的浓度，说明鳑鲏对沉积物的扰动作用较弱.此外，鳑鲏显著增加了浮游植物生物量和蓝藻的比例.浮游动物总生物量并未受鳑鲏的影响，但显著增加了浮游动物的丰度，其中以轮虫为主.鳑鲏组的底栖动物总丰度（主要为水丝蚓）显著高于对照组，说明鳑鲏对水丝蚓的摄食压力较低.鳑鲏与河蚌交互作用对总磷、Chl.a、浮游植物和浮游动物丰度具有显著影响：具体表现为河蚌虽然抵消了部分鳑鲏对水质（如氮、磷和悬浮质浓度，以及Chl.a浓度和浮游植物生物量等）的负面影响，但其对浮游动物和水丝蚓生物量的影响不显著.在湖泊生态修复和管理中，需要关注和重视鳑鲏等此类小型杂食性鱼类对水生态系统可能产生的负面影响，通过物理（网簖等）或生物（放养肉食性鱼类）等方式将其控制在较低密度水平，从而降低这些鱼类对水质、浮游生物和底栖生物群落可能产生的负面影响，维持生态修复效果的长效与稳定运行.;In restoration of shallow eutrophic lakes based on recovery of submerged macrophytes, stocking of the filter-feeding mussels has been commonly used for improving water clarity, thereby enhancing the growth of submerged macrophytes. However, the small omnivorous bitterling fish has to rely on mussels for breeding. Thus, the increased abundance of mussels may enhance the population development of bitterling. Nevertheless, the effects of bitterling (Acheilognathus macropterus) and their host mussels (Sinanodonta woodiana) on the aquatic ecosystems are, so far, not well-studied. We conducted a mesocosm experiment to study the effects of bitterling, mussels, and their interactions on water quality and the community structures of phytoplankton, zooplankton and benthic macroinvertebrates, respectively. Our results showed that bitterling did not substantially affect the concentration of inorganic suspended solids (ISS) indicating weak effects on sediment resuspension. However, the concentrations of total nitrogen and total phosphorus were significantly enhanced by bitterling. Consequently, both the abundance and biomass of phytoplankton were enhanced in the bitterling-only mesocosms, and cyanobacteria dominated the phytoplankton community at the end of the experiment. However, rotifers dominated the zooplankton community leading to a higher abundance of zooplankton in the bitterling-only treatment, while the total biomass of zooplankton did not differ significantly between the control and bitterling-only treatments. Moreover, bitterling significantly increased the total abundance of benthic macroinvertebrates compared with the controls, while the biomass of macroinvertebrates was not pronouncedly affected. The presence of mussels significantly eliminated the negative effects induced by bitterling, such as reducing the concentrations of nutrients, suspended solids and chlorophyll-a and phytoplankton biomass. However, the biomass of zooplankton and benthic macroinvertebrates were not substantially affected by the presence of mussels. Our results suggest that bitterling alone can induce significantly negative effects on water quality though mussels can eliminate part of these impacts under our experimental bitterling-to-mussel biomass ratio. Therefore, in the restoration and management of shallow lakes, more attention should be paid on the effects of small omnivorous fish, like bitterling, on aquatic ecosystems. The biomass of these small omnivores should be controlled at a relatively low level by physical (e.g., trap net) or biological (e.g., stocking of effective piscivorous fish) methods to minimize the negative effects of the fish on lake ecosystems.

Effects of a native New Zealand freshwater mussel on zooplankton assemblages, including non-native Daphnia: a mesocosm experiment

Few studies have examined the effects of freshwater mussels on zooplankton in their native regions. We undertook an outdoor mesocosm-scale experiment to examine the effects of Echyridella menziesii, an endemic New Zealand mussel, on zooplankton composition. Experiments were undertaken in 125-L cylindrical drums that were randomly separated into the following three groups: seven control tanks with no mussels, seven treatment tanks with five mussels, and seven treatment tanks with 10 mussels each. Tanks were seeded with algae and zooplankton from a variety of small local water bodies, and monitored on Days 0, 5, 14 and 42. ANOSIM indicated that zooplankton composition among control and treatment tanks differed from Day 5 onward. Small, planktonic rotifers were commonly found to be most greatly affected by the presence of freshwater mussels. Benthic rotifers and larger crustacean zooplankton were typically unaffected or favoured when mussels were present. Overall, our results are consistent with removal of zooplankton by filtration, rather than competition for resources, being the primary driver of mussel influence on zooplankton community composition.

Fish vs. Aliens: predatory fish regulate populations of Limnoperna fortunei mitigating impacts on native macroinvertebrate communities

Limnoperna fortunei, an invasive mussel altering the structure of benthic communities, is preyed upon by several fish species in South America. To investigate the impact of predatory fish on populations of this mussel, and the effects of this top-down interaction on native macroinvertebrates, we performed an in situ experiment in the Uruguay River. By comparing benthic communities of artificial substrates colonised in treatments allowing or excluding fish access, it was demonstrated that fish significantly reduce colonisation by L. fortunei (i.e. its density, biomass and body size). In the absence of mussels (before settlement), fish preyed upon the native macroinvertebrate community inhabiting artificial substrates, reducing their densities compared to the fish exclusion treatment. However, it was found that in the presence of golden mussel (after settlement), the total density of benthic macroinvertebrates, densities of scrapers, and densities of dipterans and gastropods strongly decreased in fish exclusion treatments, suggesting a strong effect of L. fortunei in reducing the native fauna. By preying on L. fortunei, fish favoured the persistence of native macroinvertebrates. Further studies focused on predatory fish species and their efficiency in removing L. fortunei may contribute to advancing towards using native fish as mitigating agents.

Deep Lake Explorer: A web application for crowdsourcing the classification of benthic underwater video from the Laurentian Great Lakes

Underwater video is increasingly used to study aspects of the Great Lakes benthos including the abundance of round goby and dreissenid mussels. The introduction of these species has resulted in major ecological shifts in the Great Lakes, but the abundance and impacts of these species have heretofore been underassessed due to limitations of monitoring methods. Underwater video (UVID) can “sample” hard bottom sites where grab samplers cannot. Efficient use of UVID data requires affordable and accurate classification and analysis tools. Deep Lake Explorer (DLE) is a web application developed to support crowdsourced classification of UVID collected in the Great Lakes. Volunteers (i.e., the crowd) used DLE to classify 199 videos collected in the Niagara River, Lake Huron, and Lake Ontario for the presence of round gobies, dreissenid mussels, or aquatic vegetation, and for dominant substrate type. We compared DLE classification results to expert classification of the same videos to evaluate accuracy. DLE had the lowest agreement with expert classification for hard substrate (77%), and highest agreement for vegetation presence (90%), with intermediate agreement for round goby and mussel presence (89% and 79%, respectively). Video quality in the application, video processing, abundance of species of interest, volunteer experience, and task complexity may have affected accuracy. We provide recommendations for future crowdsourcing projects like DLE, which can increase timeliness and decrease costs for classification but may come with tradeoffs in accuracy and completeness.

Invasive species versus pollutants: Potential of Limnoperna fortunei to degrade glyphosate-based commercial formulations.

The intensive use of glyphosate in industrial agriculture may lead to freshwater contamination, encouraging studies of its toxic effect on non-target aquatic organisms. Glyphosate-based commercial formulations contain adjuvants, making them even more toxic than the active ingredient (a.i.) itself. The golden mussel Limnoperna fortunei is a freshwater invasive species which has been found to increase glyphosate dissipation in water and to accelerate eutrophication. The aim of this study is to evaluate the capability of L. fortunei to reduce the concentration of glyphosate in two commercial formulations, Roundup Max® and Glifosato Atanor®. Results were compared with the decay of the a.i. alone and in presence of mussels. Evasive response and toxicity tests were performed in a first set of trials to analyze the response of L. fortunei exposed to Roundup Max® and Glifosato Atanor®. Subsequently, we conducted a 21-day degradation experiment in 2.6-L microcosms applying the following treatments: 6mgL-1 of technical-grade glyphosate (G), Glifosato Atanor® (A), Roundup Max® (R), 20 mussels in dechlorinated tap water (M), and the combination of mussels and herbicide either in the technical-grade (MG) or formulated form (MA and MR) (all by triplicate). Samples were collected at days 0, 1, 7, 14 and 21. No significant differences in glyphosate decay were found between treatments with mussels (MG: 2.03±0.40mgL-1; MA: 1.60±0.32mgL-1; MR: 1.81±0.21mgL-1), between glyphosate as a.i. and the commercial formulations, and between the commercial formulations, suggesting that the adjuvants did not affect the degrading potential of L. fortunei. In addition to the acceleration of glyphosate dissipation in water, there was an increase in the concentration of dissolved nutrients in water (N-NH4+ and P-PO43-) even higher than that caused by the filtering activity of the mussels, probably resulting from stress or from the degradation of glyphosate and adjuvants. We believe that a larger bioavailability of these nutrients due to glyphosate metabolization mediated by mussels would accelerate eutrophication processes in natural water bodies. The approach used here, where L. fortunei was exposed to two commercial formulations actually used in agricultural practices, sheds light on the potential impact of glyphosate decay on water bodies invaded by this species.

Carbon and nitrogen recycling during cyanoHABs in dreissenid-invaded and non-invaded US midwestern lakes and reservoirs

Lakes and reservoirs play key roles in global carbon cycling, especially as a carbon sink. Enrichment of nutrients in lakes and reservoirs (eutrophication) and rising global temperatures favors the proliferation of bloom-forming cyanobacteria. Harmful blooms of cyanobacteria (cyanoHABs) alter carbon and nutrient cycling in freshwater ecosystems. Some evidence suggests the introduction or establishment of invasive mussel species (i.e., Dreissena spp.) also favor cyanoHAB formation through selective filter feeding, a process through which they may also impact biogeochemical processes including carbon cycling and sequestration. However, few studies have considered the combined effects of invasive mussels and cyanoHABs on carbon and nitrogen cycling in freshwater ecosystems. Here, we examined microbial community composition and biogeochemical attributes (including carbon and nitrogen stable isotopes) in eutrophic lakes, reservoirs, and rivers in western Ohio, eastern Indiana, and northern Kentucky during the cyanobacterial bloom period of the summer of 2015. Our samples include both sites impacted by invasive mussels and those where invasive mussels have not yet been observed. Based on 16S and 18S rRNA gene sequence analysis, we found that cyanobacterial and algal communities varied across sites and were most closely related to habitat (sediment or water column sample) and site, regardless of the presence of invasive mussels or other environmental factors. However, we did find evidence that invasive mussels may influence both carbon and nitrogen cycling. While the results are based on a single time point sampling, they highlight the interactions of multiple environmental stressors in aquatic ecosystems and the critical need for more temporally intensive studies of carbon and nutrient cycling in bloom- and mussel-impacted waters.

The Utilization of Native Freshwater Mussel &lt;i&gt;Pilsbryoconcha exilis&lt;/i&gt; as Biocontrol of Pathogenic Bacteria &lt;i&gt;Aeromonas hydrophila&lt;/i&gt; in Tilapia Aquaculture

This research aims to evaluate the capacity of freshwater mussel Pilsbryoconcha exilis as a biocontrol agent to prevent the transmission of Aeromonas hydrophila in tilapia cultivation. Briefly, 10 tilapia fish with average bodyweight 7,88±0,25 g were subjected to four treatments in the 8-liter aquarium with three replications in a randomized design trial. The treatments were M1 (one mussel for a two-liter of water), M2 (two mussels for a two-liter of water), and two control treatments without mussel ( M+ and M-). All treatments, except the M-, then challenged by adding A. hydrophila live culture to obtain a final density of 105 CFU mL-1 into the aquarium for 7 days duration. The final survival rate of fish, the water-total bacterial count, and the blood profile of animals were assessed. The research revealed that there is a significant impact from the presence of freshwater mussel on tilapia cultivation. Generally, the M2 treatment showed better results with a significant different (P&lt;0,05) according to the survival rate of fish (100±0,00%), water-total bacterial count (4,53±0,03 log CFU mL-1), and fish leucocytes (4,30±0,70x104 cell mm-3). Nonetheless, there was no different (P&gt;0,05) effect on fish erythrocytes among the treatments. Therefore, the feeding activity of freshwater mussel in the water column able to deplete pathogenic bacteria abundance and prevent pathogen transmission along with increasing the survival rate of fish.

Functional response and size-selective clearance of suspended matter by an invasive mussel

Filter feeding activities link suspension feeders with their environment and underpin their impact on aquatic ecosystems. Despite their ecological and economic impacts, the functional response and size-selective capture of suspended particulates have not been well documented for the golden mussel Limnoperna fortunei. Here we demonstrated that golden mussels had a type I functional response, with an attack rate a = 0.085 and negligible handling time (h). Clearance rate ranged between 72.6 ± 27.0 and 305.5 ± 105.9 mL ind.-1h−1 (Mean ± S.E.), depending on food concentrations, which exhibited an inverse relationship with clearance rate. Presence of golden mussels suppressed chlorophyll a concentration in experimental mesocosms, the extent of which was dependent on mussel abundance. Concentration of suspended particles in experimental mesocosms experienced a sharp initial decline across all size categories (≤1–>50 μm), though with increased final concentration of large particles (>25 μm), indicating packaging and egestion by golden mussels of fine particles (down to ≤1 μm). Capture efficiency of quantitatively-dominant suspended matter (≤1−50 μm) by golden mussels was inversely related to particle size. Animal abundance, particle size, and their interaction (abundance × particle size) determined the extent to which matter was removed from the water column. Presently L. fortunei occurs primarily in the southern end of the central route of South to North Water Diversion Project (China), but the species is spreading north; we anticipate that impacts associated with filtering of L. fortunei will correspond with local population abundance along this gradient.

Freshwater mussels increase survival of largemouth bass (Micropterus salmoides) in drying pools

AbstractBetween global climate change and anthropogenic water needs, freshwater systems are becoming more intermittent, stressing organisms adapted to perennial waters. Drought‐induced intermittency concentrates aquatic organisms into drying pools. These pools represent refugia from desiccation but apply other stressors, such as extreme temperatures and increased competition for dwindling resources. In the Southern United States, fishes and freshwater mussels are often concentrated together in drying pools during seasonal, summer droughts. This can result in increased competition for food among invertivorous fish, but also increased food abundance for these fish because mussels increase macroinvertebrate abundance. Further, since mussels require fish as hosts for their ectoparasitic larval phase, glochidia, competition with their host during this biologically active time is detrimental to mussels. We conducted an experiment to examine the effects of freshwater mussels on trophic resources and fish survival in drying pools. We stocked mesocosms with juvenile largemouth bass that were infected or uninfected with glochidia and tracked abiotic conditions, trophic resources and fish survival for 10 days. We found that fish survived longer in the presence of adult mussels, regardless of their infection status. We suspect that prey items supplemented by adult freshwater mussels increased the survival of fish. Thus, the presence of adult mussels and the resources that increase in their presence potentially mitigate stress to fish in “ecological crunch times.” By conserving mussels, fish populations might withstand droughts more easily.