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Patterns of Vertical Migration in Freshwater Mussels (Bivalvia: Unionoida)
Journal of Freshwater Ecology
Abstract
The vertical migration patterns of eight freshwater mussel species were studied in outdoor enclosures. Individual experiments lasted from nine to 20 months, during which time mussels were observed three times per week. The mussels displayed two patterns of seasonal vertical migration; in both patterns populations of each species surfaced during spawning in spring and eventually reburied in autumn. These activities coincided with increasing spring water temperatures and decreasing autumn water temperatures, as well as increasing and decreasing durations of daylight. One group of species displayed a unimodal annual pattern, where most of the population surfaced in the spring and remained there until autumn. The second group displayed a bimodal pattern in which the population reburied itself after emerging in spring but then resurfaced and remained at the surface until autumn. We have not been able to associate this second emergence with any biological function. Patterns did not follow generic or subfamilial lines.
... and Pusch 2007; Cope et al. 2008). Numerous studies have documented the burrowing behavior of older juvenile and adult mussels (Lewis and Riebel 1984;Hull et al. 1998;Watters et al. 2001;Archambault et al. 2014;Block et al. 2013;Hazelton et al. 2014); they have been observed using their shell and foot to burrow into sediment. Though mussels generally are considered to be sessile, several studies have documented both vertical and horizontal movements (Kat 1982;Amyot and Downing 1991;Downing et al. 1993;Balfour and Smock 1995;Amyot and Downing 1997;Schwalb and Pusch 2007;Allen and Vaughn 2009). ...
... Horizontal movement of up to 15 cm/wk has been documented for Painter Mussels (Unio pictorum) and Duck Mussels (Anodonta anatina) in a river setting (Schwalb and Pusch 2007). Mussels may burrow completely or partially in sediment throughout the year, depending on water temperature (seasonal migration) and reproductive activity Downing 1991, 1997;Watters et al. 2001;Cope et al. 2008;Block et al. 2013). ...
... In the current study, the photoperiod was the standard 16:8 (light:dark) for all exposures (ASTM 2019a, 2019b). This photoperiod corresponds to a mid-April to mid-July time frame, when high densities of adult mussels have been reported at the sedimentwater interface (Amyot and Downing 1991;Balfour and Smock 1995;Amyot and Downing 1997;Watters et al. 2001). Juvenile mussels are thought to stay in the substrate for the first couple years of life. ...
... Dreissenids are epifaunal, are fully exposed to the water column, and attach to substrates by byssal threads. In contrast, unionids are infaunal, and burial position can vary with season (i.e., temperature change), reproductive activity, disturbance Downing 1997, 1998;Waller et al. 1999;Watters et al. 2001;Block et al. 2013), and in response to stressors (Gagnon et al. 2004;Archambault et al. 2014;. These behavioral and physiological differences could be exploited to selectively control zebra mussels, especially in unionid habitats. ...
... In the wild, unionid mussels tend to bury in response to decreasing water temperatures (i.e., late fall to early spring) and reduce movements and the frequency of valve opening (i.e., reduced filtration; Amyot and Downing 1997;Watters et al. 2001;Lurman et al. 2014aLurman et al. , 2014b. Burial and locomotor movements of unionids vary widely among species (Waller et al. 1999) and are often related to reproductive activities (Watters et al. 2001). ...
... In the wild, unionid mussels tend to bury in response to decreasing water temperatures (i.e., late fall to early spring) and reduce movements and the frequency of valve opening (i.e., reduced filtration; Amyot and Downing 1997;Watters et al. 2001;Lurman et al. 2014aLurman et al. , 2014b. Burial and locomotor movements of unionids vary widely among species (Waller et al. 1999) and are often related to reproductive activities (Watters et al. 2001). Coldwater application of CO 2 for dreissenid control corresponds to time periods when most unionid species are reproductively inactive and likely buried. ...
Zebra mussels (Dreissena polymorpha) have exacerbated the decline of native freshwater mussels (Order Unionida) in North America since their arrival in the 1980s. Options for controlling invasive mussels, particularly in unionid mussel habitats, are limited. Previously, carbon dioxide (CO2) showed selective toxicity for zebra mussels, relative to unionids, when applied in cool water (12 °C). We first determined 96‐h lethal concentrations of CO2 at 5 and 20 °C to zebra mussels and responses of juvenile plain pocketbook (Lampsilis cardium). Next, we compared the time to lethality for zebra mussels at 5, 12, and 20 °C during exposure to partial pressure of CO2 (PCO2) 110–120 atmospheres (atm; 1 atm = 101.325 kPa) and responses of juvenile plain pocketbook and fragile papershell (Leptodea fragilis). We found efficacious CO2 treatment regimens at each temperature that were minimally lethal to unionids. At 5 °C, plain pocketbook survived 96 h exposure to the highest PCO2 treatment (139 atm). At 20 °C, the 96 h LC10 (lethal concentration to 10% of animals) for plain pocketbook [173 atm PCO2, 95% confidence interval (CL) 147–198 atm] was higher than the LC99 for zebra mussels (118 atm PCO2, CL 109–127 atm). Lethal time to 99% mortality (LT99) of zebra mussels in 110 to 120 atm PCO2 ranged from 100 h at 20 °C to 300 h at 5 °C. Mean survival of both plain pocketbook and fragile papershell juveniles exceeded 85% in LT99 CO2 treatments at all temperatures. Short‐term infusion of 100 to 200 atm PCO2 at a range of water temperatures could reduce biofouling by zebra mussels with limited adverse effects on unionid mussels. This article is protected by copyright. All rights reserved.
... Although it would seem that freshwater bivalves would also have a need to contend with shifting sediment and periodic burial, work on their escape burrowing is practically non-existent. To be sure, attention has been given to vertical movement in freshwater bivalves relating to shell size, reproductive status, seasonal temperature variation, predation and desiccation avoidance [65][66][67][68][69][70], but not escape burrowing as defined here. ...
... Trueman [52] and Yeager et al. [72] deal with the mechanics of downward, non-escape burrowing, and find that in general it mirrors the downward burrowing mechanisms of marine bivalves. Horizontal, surface crawling is also commonly observed among modern unionoids [69,70,72] and has been attributed to avoiding environmental stresses such as low oxygen and inadequate food availability, and to enhancing reproductive success [68,69]. While these studies provide valuable information on unionoid motility, they do not address the issue of escape burrowing in these animals. ...
... Trueman [52] and Yeager et al. [72] deal with the mechanics of downward, non-escape burrowing, and find that in general it mirrors the downward burrowing mechanisms of marine bivalves. Horizontal, surface crawling is also commonly observed among modern unionoids [69,70,72] and has been attributed to avoiding environmental stresses such as low oxygen and inadequate food availability, and to enhancing reproductive success [68,69]. While these studies provide valuable information on unionoid motility, they do not address the issue of escape burrowing in these animals. ...
Many freshwater bivalves restore themselves to the sediment water interface after burial by upward escape burrowing. We studied the escape burrowing capacity of two modern unionoids, Elliptio complanata and Pyganodon cataracta and the invasive freshwater venerid Corbicula fluminea, in a controlled laboratory setting varying sediment grain size and burial depth. We found that the relatively streamlined E. complanata is a better escape burrower than the more obese P. cataracta. E. complanata is more likely to escape burial in both fine and coarse sand, and at faster rates than P. cataracta. However, successful escape from 10 cm burial, especially in fine sand, is unlikely for both unionoids. The comparatively small and obese C. fluminea outperforms both unionoids in terms of escape probability and escape time, especially when body size is taken into consideration. C. fluminea can escape burial depths many times its own size, while the two unionoids rarely escape from burial equivalent to the length of their shells. E. complanata, and particularly P. cataracta, are morphological paradigms for the extinct Devonian unionoid bivalve Archanodon catskillensis, common in riverine facies of the Devonian Catskill Delta Complex of the eastern United States. Our observations suggest that the escape burrowing capability of A. catskillensis was no better than that of P. cataracta. Archanodon catskillensis was likely unable to escape burial of more than a few centimeters of anastrophically deposited sediment. The long (up to 1 meter), vertical burrows that are associated with A. catskillensis, and interpreted to be its escape burrows, represent a response to episodic, small-scale sedimentation events due to patterns of repetitive hydrologic or weather-related phenomena. They are not a response to a single anastrophic event involving the influx of massive volumes of sediment.
... In the context of freshwater mussels, mussels temporarily emigrate when burrowing, which makes them unavailable for capture using tactile and visual searches. The Robust Design model also estimates return (γ′), but we had no reasonable evidence to suggest that this parameter would differ from temporary emigration because mussels are generally known to burrow in response to age, life history or environmental conditions (Amyot and Downing, 1997;Watters et al., 2001;Schwalb and Pusch, 2007;Meador et al., 2011). Similarly, we had no evidence to suggest that capture probability and recapture probability (c) would be influenced by tagging (Meador et al., 2011). ...
... Temporary emigration of freshwater mussels occurs when mussels burrow and become unavailable for capture using tactile and visual survey techniques. Burrowing may occur in response to age, reproductive behaviour, water temperature and increasing stream discharges (Amyot and Downing, 1991;Amyot and Downing, 1997;Watters et al., 2001;Schwalb and Pusch, 2007;Meador et al., 2011). Recent studies indicate that burrowing may also occur during exceptionally low flow periods to avoid emersion (Gough et al., 2012) and avoid increasing water temperatures (Allen and Vaughn, 2009). ...
... Incomplete detection of individuals can bias estimates of demographic parameters for mussels, thus changing perceptions of ecological factors influencing mussels (Villella et al., 2004;Peterson et al., 2011;Meador et al., 2011;Wisniewski et al., 2013). Small mussels are often times more difficult to collect than large mussels when using tactile or visual searches because they may be burrowed more frequently than larger mussels (Amyot and Downing, 1997;Watters et al., 2001;Schwalb and Pusch, 2007). However, the tactile and visual searches used in our study were effective for our study goals because the Robust Design estimates capture probability conditional upon mussels being available for capture at substrate surface. ...
Recurrent and prolonged droughts, coupled with increased water resource demand, threaten freshwater mussel populations through stream drying and water quality degradation. Augmentation of stream discharge was proposed as a short-term strategy to maintain adequate streamflows and water quality in reaches with important freshwater mussel populations during exceptionally low flow periods. We investigated the effects of water augmentation on seven freshwater mussel species in a small creek between 2011 and 2014. Using capture-mark-recapture methods, we monitored mussel populations in a control reach upstream of an augmentation outlet and two reaches immediately downstream of an augmentation outlet. Water quality measurements during our study indicated that augmentation improved water temperature and dissolved oxygen conditions during low flow periods. For all mussel species, apparent survival was positively related to minimum streamflows and declined precipitously as streamflows decreased. However, mean apparent survival between sampling occasions was high among all species but did not differ among treatment units, suggesting that flow augmentation rates in this study were insufficient for abating the effects of basin-wide reductions in streamflow. Temporary emigration differed among study reaches but did not support hypothesized relationships because it increased with stream stage and was highest in an augmented reach. This suggests that streamflows did not drop below thresholds, which invoked burrowing as a response to decreased streamflows. Streamflow augmentation may be a viable short-term mussel conservation strategy in small streams but will likely require higher augmentation volume capacity than evaluated during our study.
... It is well documented that freshwater mussels burrow into the substrate as a response to increasing temperature [48][49][50], and some mussels spend the majority of their lives burrowed [50,51]. There is a difference of only a few degrees between temperatures that are lethal to 50% of a mussel population and those that are lethal to only 5% of a population [25,30]. ...
... It is well documented that freshwater mussels burrow into the substrate as a response to increasing temperature [48][49][50], and some mussels spend the majority of their lives burrowed [50,51]. There is a difference of only a few degrees between temperatures that are lethal to 50% of a mussel population and those that are lethal to only 5% of a population [25,30]. ...
Freshwater mussels fulfill an important ecological role in aquatic ecosystems, but they currently face many threats, including thermal regime alteration. Thermal transformation of the aquatic environment is associated with climate change, land use alteration, and other pervasive anthropogenic global changes. To enhance our understanding of ecological thermal impacts, we combined extensive field measurements of temperature in the stream water column and substrate depths (5 and 15 cm) at sites where mussels occur, measures of abundance and species richness for mussels and fish, and thermal tolerance knowledge for mussels and fish to generate a comprehensive assessment of the potential threats mussels face as temperatures continue to rise as a result of global change. Mean summer (June–August 2010–2012) temperatures at mussel-occupied sites in the upper Tar River basin of North Carolina, USA, ranged from 16.2 to 34.7 °C. The mean temperature from the hottest 96 h at each site ranged from 23.5 to 31.5 °C. At 80% of sites, a period of moderate drought coincided with the hottest 96 h period. Temperature threshold exceedance durations indicated that chronic, combined chronic/acute, and acute freshwater mussel thermal tolerance thresholds (i.e., 28 °C, 30 °C, and 33 °C, respectively) based on laboratory exposures of glochidia (larvae) and juveniles were commonly exceeded. Water temperatures exceeded 28 °C for at least 24 h at 55% of sites and for at least 96 h at 35% of sites, and they exceeded 30 °C for at least 24 h at 15% of sites. We quantified a thermal buffering effect of the substrate that may be protective of mussels. There was a mean difference of 0.5 °C between the water column and the upper substrate (5 cm) and a mean difference of 0.9 °C between the water column and the lower substrate (15 cm). Maximum differences of up to 5.5 °C between the water column and the upper substrate and 11.5 °C between the water column and the lower substrate were observed. Our models estimating the relation between the water column and substrate temperatures more realistically characterize ambient temperature exposures and have widespread implications for mussel conservation and climate change risk assessment in similar streams. Freshwater mussels currently exist on the edge of their thermal limits, but their abundance and species richness cannot be explained by temperature patterns alone. Fish species richness was related to the thermal regime, indicating that species interactions may be an important driver of freshwater mussel responses to global change.
... Studies on seasonal vertical migration suggest that mussels burrow deeper in winter than in summer, and burrowing has been associated with day length, water temperature, reproductive timing, and flow velocity (Amyot & Downing, 1991, 1997Balfour & Smock, 1995;Lurman et al., 2014;Schwalb & Pusch, 2007;Watters et al., 2001;Zieritz et al., 2014). To the best of our knowledge, however, seasonal vertical migration of unionid mussels has never been studied in warmer subtropical rivers, such as those representative of central Texas drainages. ...
... Seasonal variation in association with changes in water temperature was detected as a significant driving factor for the variation of burrowing depth in the field, but shorter term experiments in the laboratory could not detect a significant effect of temperature. Previous studies have shown seasonal vertical migration, where mussels burrow deeper during colder months and re-emerge as water temperatures increase (Allen & Vaughn, 2009;Amyot & Downing, 1997;Balfour & Smock, 1995;Schwalb & Pusch, 2007;Watters et al., 2001;Zieritz et al., 2014). However, most of these studies were conducted in more temperate climates with cooler seasonal water temperatures than those found in rivers of central Texas that range between 9 C and 32 C for the lower Guadalupe River and 10 C and 29 C in the San Antonio River (Texas Commission on Environmental Quality, 2020). ...
1. Conservation efforts have increased in response to global mussel declines, and effective surveys are a crucial step in assessing and monitoring mussel populations and in determining their conservation status. The burrowing behaviour of mussels can affect their detectability, and a better understanding of these behaviours would help to improve survey design and guidelines.
2. The burrowing depth of mussels may differ between seasons, habitat conditions, species, and individuals, and little is known about the burrowing behaviour of mussels in subtropical rivers.
3. Burrowing depth variation was examined and compared at three sites in the San Marcos, Guadalupe, and San Antonio river drainages in central Texas. In addition, laboratory experiments were used to determine whether observed differences between field sites and seasons could be linked to differences in substrate type and water temperature and to examine differences between species.
4. Seasonal variation in burrowing depth was found at all field sites, and water temperature was a significant factor for explaining variation in burrowing depth, but there was no clear relationship between burrowing depth and temperature in shorter term laboratory experiments, where individual variation was high and burrowing behaviour seemed to be solely a function of time.
5. Mussels burrowed significantly deeper in finer substrate (sand vs. gravel) in both field and laboratory experiments. Few significant differences between species were found in the field, but no differences were found in the laboratory experiments.
6.The results suggest that surveys may need to follow different guidelines depending on local conditions, such as substrate and water temperature. Surveys will be less efficient and may fail to detect larger proportions of populations in colder water temperatures. In addition, a larger proportion of burrowed mussels can be expected at sites with finer substrate, such as sand. Under these conditions, visual searches will not suffice, as a large part of the population or specific species may be overlooked.
... There is no published evidence to date that kākahi completely bury in the sediments, though snorkelling is likely to find greater numbers that are buried than the bathyscope. Nevertheless, complete burial of kākahi should be examined to determine whether snorkelling provides accurate estimates of population numbers overall, and whether this varies seasonally (Amyot and Downing 1991;Watters et al. 2001). As mussels are commonly found to bury deeper into the sediment in winter months (Amyot and Downing 1991;Watters et al. 2001), for estimates of abundance to determine population density changes through time (years), observations should always be made at the same time of year. ...
... Nevertheless, complete burial of kākahi should be examined to determine whether snorkelling provides accurate estimates of population numbers overall, and whether this varies seasonally (Amyot and Downing 1991;Watters et al. 2001). As mussels are commonly found to bury deeper into the sediment in winter months (Amyot and Downing 1991;Watters et al. 2001), for estimates of abundance to determine population density changes through time (years), observations should always be made at the same time of year. The bathyscope method found more kākahi in 7.1% of the individual metres examined in Lake Rotorua, and 8.3% of those examined in Lake Rotoiti. ...
Kākahi (Echyridella spp.) are freshwater cultural keystone species in New Zealand; they represent a valuable mahinga kai (species used as a food) resource and have high cultural significance to Māori, particularly to the Te Arawa and Ngāti Tūwharetoa iwi (tribal groups). Population densities of kākahi are thought to have declined in many locations in New Zealand, and accurate assessment methods are thus required to monitor changes in populations. A bathyscope method is currently used by iwi to monitor kākahi populations in lakes Rotorua and Rotoiti. It is unclear, however, how accurate this method is for determining kākahi abundance changes compared to underwater methods such as snorkelling. Comparisons at seven sites in Lake Rotorua and three sites in Lake Rotoiti show that significantly fewer kākahi are observed using a bathyscope relative to snorkelling (p < 0.0001). On average, snorkelling estimated 2.1 times more kākahi than the bathyscope method in Lake Rotorua, and 2.5 times more in Lake Rotoiti. We conclude that under suitable conditions, snorkelling is generally more effective than surface visual assessments using a bathyscope. Nevertheless, the bathyscope method is inexpensive, safe and simple, ideal for use by iwi and community groups for long-term monitoring of kākahi populations.
... Biologists have devoted considerable effort to understanding species-specific habitat requirements in attempt to optimize conservation efforts Hoftyzer et al. 2008). Many studies have shown the importance of certain variables to mussel life history, including: substrate, temperature, flow, nutrients, dissolved oxygen, and calcium ( Lewis and Riebel 1984;Di Maio and Corkum 1997;McMahon and Bogan 2001;Watters et al. 2001;. However, the ability of some mussels to adapt to a wide range of these variables highlights the plasticity of this taxon (Haag and Rypell 2011) and can greatly influence project outcomes. ...
... Mussels generally need to be near the substrate surface or partially exposed throughout the growing season to obtain nutrients and fulfill life history needs, such as spawning ( Watters et al. 2001). However, mussels also need to be fully buried during other times of the year and to avoid threats (Amyot and Downing 1997). ...
The global decline of native freshwater mussels has accelerated conservation projects that preserve and restore populations, but the complex life histories among species challenges biologists in determining the most effective management strategies. This study details the conservation of plain pocketbook, a Tier I threatened mussel species in Nebraska that was artificially propagated and reintroduced into 13 sites from autumn 2016 to summer 2017. The objectives of this study were: 1) determine how handling influences mussels, and 2) evaluate mussel growth and survival following introductions. We conducted a laboratory experiment with age-2 plain pocketbook to assess the effects of handling on mussel growth and survival. We applied one of three handling rate treatments to experimental units for 12 weeks where mussels were handled up to 25 times. We compared end-of-study growth rates and survival among treatment and control group (i.e., no handling) mussels. Growth rates were unaffected by handling and no mortality occurred during the study, indicating plain pocketbook is tolerant of short-term repeated handling. We then conducted a mark-recapture study for introduced mussels to assess the relations of habitat, timing of introduction, and shell size to mussel growth and survival. We seasonally surveyed sites during 2017 and 2018 to collect habitat data and recapture tagged mussels. We used von Bertalanffy equations to model mussel growth among sites, introduction years, and streams. We used Cormack-Jolly-Seber models to estimate recapture and apparent survival rates of each site. We constructed cumulative daily survival curves and compared curves among sites, introduction years, and streams. We attributed growth differences to water temperatures relating to season of introduction. We determined mussels were at heightened risk for mortality during introduction and spring. We qualitatively linked these time periods to environmental stressors and used this information to identify suitable habitats for mussels and develop recommendations for further introductions. Handling is an anthropogenic stressor for mussels that can be moderated through proper research and techniques. Short-term monitoring studies can provide valuable insight on the population dynamics of introduced freshwater mussels. Implications from this study have the ability to collectively enhance the management of this imperiled taxon. Advisor: Mark A. Pegg
... Freshwater mussels are endobenthic and use their muscular foot and shell to burrow in the sediment (Allen and Vaughn 2009). Studies conducted by Amyot and Downing (1998) and Watters et al. (2001) documented the burrowing behavior of individual mussel species can vary with season and reproductive cycle, flow regime, substrate type and disturbance and parasite abundance, but also varies greatly among species. ...
... Predicting how deeply freshwater bivalves burrow is complicated. The depth unionids burrow to is influenced by factors such as the caliber of sediment, temperature, daylight hours, current velocity, sedimentation rate, shell thickness, response to parasites, and in some cases, the need to surface for spawning before burrowing again (Amyot & Downing, 1997;Balfour & Smock, 1995;Block et al., 2013;Hernández et al., 2021;Schwalb & Pusch, 2007;Watters et al., 2001). It is thereby difficult to attribute precise ethological interpretation to Lockeia, especially in equilibrichnion-like traces, which are typically attributed to behavioral reactions to hydrodynamic forces (e.g. ...
... Similarly, this intraspecies variability, along with the negative correlation between vertical movement and N-removal potentials, suggests that bioturbation by mussels has the potential to decrease anaerobic processes like denitrification by increasing O2 penetration and disrupting the oxic/anoxic sediment boundary layer (Fig. 1). Mussel burrowing behavior varies with species (Allen and Vaughn 2009), season, reproductive cycle (Watters et al. 2001), and substrate (Lewis andRiebel 1984, Sansom et al. 2022). Thus, there are multiple factors governing the activity of mussel burrowing behavior that may vary spatially and temporally in field settings and influence behavior in a mesocosm study. ...
... As federally protected species, varying brooding periods for H. altilis and H. australis could impact management decisions to better protect populations during reproductively active times. Elliptio pullata were only found gravid with EGG in May and June which corresponds to their characterization as a tachytictic species with a very short brooding period 24,48,49,50 . ...
Actively monitoring the timing, development, and reproductive patterns of endangered species is critical when managing for population recovery. Freshwater mussels are among the most imperiled organisms in the world, but information about early larval (glochidial) development and brooding periods is still lacking for many species. Previous studies have focused on the complex life history stage when female mussels are ready to parasitize host fish, but few studies have focused on the brooding period and timing of larval development. The protocol described here allows researchers to non-lethally evaluate the state of gravidity for female mussels. The results of this study show that this method does not affect a female mussel’s ability to stay gravid or become gravid again after sampling has been performed. The advantage of this method may permit its use on federally threatened or endangered species or other populations of high conservation concern. This protocol can be adapted for use on both preserved or live individuals and was tested on a variety of mussel species. The database provided is a repository for a breadth of information on timing of reproductive habits and will facilitate future freshwater mussel research, conservation, and recovery efforts.
... The most important abiotic factor that affects their digging speed is the substrate nature. The physical properties of the soft substrate, such as particle size, particle shape, and shear strength, affect their burrowing speed, so indicators such as the burrowing speed and burrowing time of the organisms in different substrates are often used to measure the degree of adaptation to the substrate [38,39]. ...
Simple Summary
Meretrix meretrix lives in substrates at a depth of 1–20 cm; the substrate has an influence on its growth, survival, living habits, and behavioral characteristics. In this study, we investigated the effects of different grain size substrates on substrate preference, burrowing ability, and behavior during the substrate selection process of M. meretrix. These results indicated that juvenile M. meretrix had a significant preference for and a stronger burrowing ability in fine sand. As the substrate grain size increased, the burrowing ability and preference of M. meretrix decreased, and these bivalves showed behavioral characteristics such as a prolonged selection time and an increased percentage of movement. In addition, by observing the substrate selection behavior of M. meretrix, we divided the selection process of the substrate by juvenile M. meretrix into four stages: preparation, selection, burrowing, and end stages.
Abstract
The substrate is the key environmental factor that affects the growth, survival, population and distribution of dwelling mollusks in mudflat settings. To clarify the effect of the substrate grain size on soft substrate preference, burrowing ability and behavior during the selection process of juvenile Meretrix meretrix, four different grain size substrates (coarse sand, medium sand, fine sand, and natural substrate) were set up for comparison. The results indicated that: (1) the burrowing ability of juvenile specimens in fine sand was the strongest; (2) the degree (from high to low) of the juvenile’s preference for the four substrates was in the order of fine sand > natural substrate > medium sand > coarse sand; and (3) the selection process of the substrate by the juveniles could be divided into four stages: preparation, selection, burrowing and end stages. These stages showed the behavioral characteristics of a longer selection time and higher percentage of movement in coarse sand. Therefore, our results demonstrated that sea areas or ponds with fine sand as the main component are more suitable for stock enhancement with M. meretrix. These results provide basic data for habitat selection and suitability evaluations for the aquaculture of M. meretrix.
... For the purposes of this study, we define 'locomotion' as solely horizontal unionid movements, excluding all vertical movements within the sediments and all movements of the posterior tip. Unionid burrowing and locomotion are affected by seasonality (Amyot & Downing, 1997;Watters, O'Dee & Chordas, 2001;Saarinen & Taskinen, 2003;Schwalb & Pusch, 2007;Allen & Vaughn, 2009;Block, Gerald & Levine, 2013;Lurman, Walter & Hoppeler, 2014a), and burrowing speed, locomotory speed and locomotory distance are known to increase with temperature (Schwalb & Pusch, 2007;Block et al., 2013;Lurman et al., 2014aLurman et al., , 2014b. Saarinen & Taskinen (2003) recorded crawling tracks on lake bottoms for several European unionid species and found that the distances covered were up to 1.9 ± 0.5 m for Anodonta anatina (Lopes-Lima et al., 2017;as A. piscinalis), 0.9 ± 0.3 m for Unio pictorum and 0.1 m for Pseudanodonta complanata. ...
Using time-lapse photography in a laboratory setting, we exposed Anodonta anatina and Unio pictorum for 4 h to algal (Chlorella vulgaris) concentrations ranging from 0.5 to 20.0 mg ash-free dry mass l−1 and to three different temperatures (11 ± 1, 15 ± 1 and 19 ± 1 °C). We analysed the proportion of mussels in locomotion, duration of locomotory activities, posterior tip movement and valve opening behaviour. The proportion of mussels in locomotion was significantly higher for A. anatina and for A. anatina was significantly lower at 11 °C. For both species, the proportion of mussels in locomotion, the duration of locomotion and movement of the posterior tip decreased with increasing algal concentration. The locomotory duration was significantly shorter in U. pictorum. In both species, valve opening peaked at intermediate algal concentrations, with the deviation from the peak being more prominent in A. anatina. Finally, we recorded a contrasting locomotory strategy for the two species (A. anatina crawled on the sediment surface, whereas U. pictorum moved through the sediment) and identified potential density dependence in behavioural adaptation.
... Burrowing is commonly used for protection against low temperature by benthic species. For example, mussels spend winters burrowed in the sediments and/or at greater depths compared to their summer distribution (Watters et al., 2001). Accordingly, our results suggest that more intensely burrowing individuals of S. woodiana perform better at colder sites at the invasion front. ...
Infaunal freshwater mussels are highly threatened and declining worldwide. One of the potential threats to mussels consists of biological invasions. We intended to investigate the habitat overlap and behavioural differences between native (Unio pictorum, Unio tumidus, Anodonta anatina, Anodonta cygnea) and invasive (Asian Sinanodonta woodiana) unionid bivalves to determine potential sources of competition. Furthermore, we investigated differences between S. woodiana from the established population in artificially heated waters and from the recent population in a natural thermal regime. We used pairwise choice tests on mud, medium, coarse and very coarse sand, mixture of medium and coarse sand, fine, medium and coarse gravel, and observed mussel locomotion and burrowing in preferred and non-preferred substrata. All species generally preferred fine-grained materials. The widest preference range was exhibited by S. woodiana (both populations), whereas A. cygnea was the most selective. The preferences of the cold-water population of S. woodiana were shifted towards coarser materials compared to conspecifics from the heated waters, and highly overlapped with the preferences of the native species. Anodonta cygnea most often moved horizontally and spent the shortest time deeply burrowed. Both Unio species were deeply burrowed for the largest amount of time and the horizontal locomotion of U. tumidus was the lowest among the test species. Sinanodonta woodiana, especially from the heated water population, exhibited relatively weak locomotion (compared to A. cygnea) and burrowing (compared to Unio spp. and A. anatina). Deep burrowing was more common on fine-grained materials. Our results suggest that the native mussels can be threatened by S. woodiana due to their overlapping habitat preferences, potentially hindering habitat separation. However, mobile native mussels may be capable of migrating and avoiding competition. Accumulating knowledge of the biology and ecology of freshwater mussels could contribute to the creation and improvement of conservation plans to protect these threatened animals.
... To prevent displacement and avoid unsuitable conditions, mussels can use their muscular foot to move horizontally across and vertically into the riverbed. Mussels vertically burrow and anchor themselves into the riverbed to maintain their position and prevent becoming dislodged downstream to unsuitable locations (Watters et al. 2001, Saarinen and Taskinen 2003, Schwalb and Pusch 2007. At higher discharges, mussels may burrow completely beneath the substrate to enhance resistance of displacement (Schwalb and Pusch 2007). ...
... Burrowing behaviour of adult Unionida mussels has been studied from many angles (e.g. Lewis & Riebel, 1984;Di Maio & Corkum, 1997;Watters et al., 2001;Saarinen & Taskinen, 2003;Taskinen & Saarinen, 2006;Allen & Vaughn, 2009). However, only a few studies have focused solely on the burrowing behaviour of juvenile Unionida (Yeager et al., 1994;Sparks & Strayer, 1998;Archambault et al., 2013Archambault et al., , 2014French & Ackerman, 2014;Kemble et al., 2020), and even fewer have examined the burrowing behaviour of margaritiferids (Bílý et al., 2020). ...
Juveniles of the endangered freshwater pearl mussel (FPM, Margaritifera margaritifera ) live burrowed in stream substrate for the first years of their life. Fine sediments block water exchange within substrate and may cause juvenile mortality and recruitment failure. To better understand the connection between success of juvenile FPM and substrate particle size, it would be important to understand behavioural responses of FPM to varying substrate sizes at this critical life stage. We placed newly detached FPM juveniles in a 7-mm layer of sieved sand sorted into five sizes (< 120, 120–200, 200–250, 250–500 and 500–650 µm) each with 10 replicate dishes, 10 juveniles per dish, with burrowing status monitored for 96 h. Mean dish-specific proportion burrowed (PB) was significantly affected by substrate size, increasing from 52% in the finest sand to 98% in the coarsest sand. Furthermore, the significant substrate × time interaction was observed due to dropped PB (30-34%) in finest sand at 2–4 h time points. Thus, results suggest a clear behavioural response by juvenile FPM to substrate size, with fine sediments triggering surfacing behaviour. Surfacing may indicate stress, can increase predation risk, and expose to drift and/or enable drift of juveniles.
... Females brood the fertilized eggs, and then glochidia, in the interbranchial chambers of their gills (marsupia) until the glochidia are mature (Kat 1984;Richard et al. 1991). The timing of spawning and brooding can vary by species and can be broadly categorized as either shortterm (tachytictic) or long-term (bradytictic) (Watters et al. 2001). In general, short-term brooders spawn in the late winter and early spring, with females brooding for a short period (2-8 weeks) after fertilization. ...
Freshwater unionid mussels are among the most imperiled fauna in North America, and their decline has been partially attributed to sediment from anthropogenic activities. However, there remains a debate regarding the role played by sediment in mussel declines due to a lack of field and laboratory evidence. If sediment is responsible for mussel declines, then a lack of information will likely impede efforts to mitigate species declines and protect remaining habitat. However, if the impacts of sediment are overstated, time and resources may be wasted on a threat that has little bearing on mussel declines or habitat loss. Given this knowledge gap, the purpose of this paper is to review the literature focused on the potential impact of suspended sediment and sedimentation on freshwater mussels. We focused our search on suspended sediment, expressed either as suspended sediment concentration (SSC) or total suspended solids (TSS), and sediment deposition and scour. We found increases in suspended solids could impact mussels by decreasing food availability, physically interfering with filter feeding and respiration, and impeding various aspects of the mussel–host relationship. We also found mussel–sediment thresholds, wherein certain concentrations of sediment caused significant declines in population performance, which could serve as reference points for ecological research and management. Specifically, we found clearance rates (a measure of feeding) were negatively impacted by TSS concentrations >8 mg/L, and respiratory stress occurred at ∼600 mg/L. Declines in fertilization success and glochidial (i.e., mussel larvae) development were observed at TSS values of 15 mg/L, and reproductive failure occurred at 20 mg/L. Impacts on host fish attachment and glochidial encystment occurred at TSS concentrations of 1250–5000 mg/L. Impacts on fish varied depending on the biological endpoint but typically occurred at TSS values ranging from 20 to 5000 mg/L. We also found mussels were sensitive to smothering and mortality occurred at depths as low as 0.6–2.5 cm of substrate. Finally, we found relative shear stress (RSS) values >1, which is a measure of substrate stability in response to scour and entrainment, resulted in significant declines in mussel biodiversity.
... Mussels can filter several liters of water per hour, with estimates dependent on species and body size (Naimo 1995;, and at large population or watershed scales, mussels can filter millions of cubic meters of water (i.e., billions of liters) per day (Newton et al. 2011;). Though mussels are generally considered sessile or sedentary, they migrate both horizontally and vertically in bed sediments (Balfour & Smock 1995;Amyot & Downing 1997;Watters et al. 2001). Research has confirmed that these movements lead to sediment mixing (i.e., bioturbation) and nutrient cycling . ...
Ecosystem services are generally defined as benefits that humans derive from nature, and though human reliance on nature is timeless, the scientific study of these services has become part of mainstream ecology only in the last two decades. From the mid-19th to the mid-20th Centuries, freshwater mussel populations in North America (Unionida) were valued and exploited for their material uses in the pearling and button-making industries. However, the depletion of mussel populations through exploitation, habitat destruction, and water quality degradation reduced their availability, utility, and visibility to human communities, leaving native mussels largely forgotten by most people. However, freshwater mussel populations and human populations are inextricably linked through their mutual dependence on water. Several modern studies have revealed that freshwater mussels perform a host of functions that are integral to maintaining surface water quality and keeping rivers and lakes properly functioning as ecosystems. These functions provide important ecosystem services related to maintaining water quality for human uses, but the capacity of mussels to contribute appropriately to ecosystem functioning and services is hampered because a majority of mussel populations are declining or imperiled. Furthermore, most aquatic species are not readily perceived by the public, and people may not realize their relevance in regulating waterways for human use and well-being. One area of ecosystem services research that has been underexplored is the role of native mussels in reducing aquatic pollution. Thus, I sought to advance the knowledge on ecosystem services of freshwater mussels from a contaminants perspective at both organismal and population scales, and I further explored human perceptions of floral and faunal influences on water quality.
First, I explored the feasibility of using existing data on mussel populations along with tissue concentrations of pollutants to estimate population-level pollutant sequestration as a potential ecosystem service. I investigated three scenarios that were selected based on my direct access to the rare resource of tissue contaminant data from mussels collected in the wild, and the availability of population estimates at these sites from the literature or from colleagues. These scenarios included Upper Mississippi River navigation pools, the Upper Neuse River watershed (North Carolina), and a polluted compared to a healthy mussel site in the Clinch River (Virginia and Tennessee). These scenarios represented a range of spatial scales, from wadeable streams to large river systems; contaminant datasets from metals to organic contaminants; mussel population sizes from tens of thousands to hundreds of millions; and population estimates based on data types that ranged from qualitative techniques (e.g., visual search of mussels) to robust, quantitative techniques (e.g., systematic sampling). Estimates of contaminant sequestration differed based on spatial scale, population size, and the kind of contaminant under consideration. We estimated that mussels in two navigation pools of the Upper Mississippi River sequestered approximately 15.6 tons of metals; mussels in the Upper Neuse River watershed sequestered between 2.4 and 5.8 billion ng of polycyclic aromatic hydrocarbons (PAHs); and Clinch River mussels at the polluted Pendleton Island site sequestered 24.2 billion ng of PAHs compared to 210 billion ng of PAHs sequestered by mussels at the healthier sites outside a mussel zone of decline – 10X greater capacity despite having much lower tissue concentrations. Estimating population-level sequestration by mussels using existing data varied in difficulty, from straightforward to highly conditional, based on the types of available population data. These efforts offer a proof-of-concept demonstration of the magnitude of pollution mussels are filtering out of the environment through their incidental exposure to contaminants. My findings suggest that contaminant sequestration may be interpreted as an ecosystem service, but mussels will only be able to remove contaminants so long as aquatic ecosystems are healthy enough to support their persistence.
After exploring population-level contaminant sequestration, I then addressed a central question in the discourse of contaminant related ecosystem services among mussel biologists: what happens to contaminants after mussels ingest them? Though there is scientific understanding that contaminants collect in soft tissue, as they do for humans and other exposed organisms, one area of research that has not been explored is the role of mussels in ecological partitioning of pollutants. I conducted 28-d laboratory experiments exposing mussels to environmentally relevant concentrations of Ni (0 to 100 µg/L) and Cd (0 to 2 µg/L) – two toxic heavy metals of both human and environmental health concern – to answer the following questions: what percentage of metals do mussels remove from water; how much is sequestered in soft tissue; how much is egested in biodeposits; how are filtration rates affected by metal exposure; and finally, how are these estimates affected by metal concentration or exposure duration? Mussels removed up to 36% of waterborne Ni and up to 77% of waterborne Cd and they sequestered metals in their soft tissue. Mussels also bound and bioconcentrated metals in egested biodeposits (e.g., feces). Ni concentrations in biodeposits were 2 to 7X higher than exposure concentrations, and Cd concentrations in biodeposits were 7 to 40X higher than Cd in the exposure water. These pollutant-processing functions fluctuated significantly within the environmentally relevant ranges of Ni and Cd concentrations over the course of 28-d exposures. Fluctuations in functional processing manifested differently for Ni and Cd. Mussels were more efficient at processing Ni at lower concentrations (i.e., when exposed to less pollution), while the duration of exposure was an important factor for Cd processing; these trends generally held for each metal even when mussels were exposed to both Ni and Cd. Moreover, this ability of mussels to influence the environmental fate and transport of metals was in turn affected by the metal concentrations to which they were exposed, suggesting that pollution may impede other beneficial ecosystem services that mussels provide. Ni exposure significantly reduced mussel filtration capacity at concentrations higher than 5 µg Ni/L. Filtration rates of mussels exposed to Cd were significantly reduced in the first two weeks of exposure compared to the last two weeks, but Cd concentration had no effect. Filtration rates of mussels under the stress of both metals were affected by metal concentration and exposure duration, suggesting an additive effect of the two pollutants. This work demonstrates the active role of mussels in environmental fate and transport of toxic heavy metals in aquatic ecosystems, and that pollution negatively affects freshwater mussel filtration and the ecosystem services they provide.
Finally, I engaged with local communities to investigate public perceptions of water quality’s mediating factors. Though aquatic species are integral to ecosystem functioning and maintenance of water quality, most are not readily perceivable by the public, and people may not realize the relevance of these ecosystem components in regulating healthy waterways for human use and well-being. It is imperative to capture how these resources are valued by communities because improved understanding of community values is a critical component of promoting effective watershed management. Social science research methods are increasingly employed to investigate public understanding and beliefs about conservation and natural resource issues. A first step in understanding the community valuation of ecosystem services related to water quality is investigating public perceptions of water quality’s mediating factors. Thus, I engaged 57 residents of central and eastern North Carolina in six focused small group discussions, using a series of photographs of plants and animals, including freshwater mussels, to examine communities’ beliefs about whether and how those flora and fauna relate to maintenance of water quality. Several prevailing themes emerged from the focus group discussions, including positive effects that flora and fauna have on water quality, dualistic “good and bad” or negative impacts, flora and fauna as indicators of water quality, and balance in nature. Participants also expressed uncertainty at times, and we identified a number of misconceptions about flora and fauna. Participants also offered some comments on impacts to water quality by humans, and the photographs sparked some commentary about connections to values or well-being related to waterways and water quality. Participants regularly relied on their prior experiences to explain their understanding of factors affecting water quality. Findings from these focus group discussions provide baseline understanding of public beliefs and knowledge of ecosystem functioning related to water quality. Participants identified several effects that flora and fauna have on water quality, including ecosystem functions that provide essential ecosystem services (e.g., regulating services, such as water purification through filtering and cleaning, and provision of habitat for aquatic species). These findings suggest an encouraging congruence of public beliefs with expert science, offering some common ground, similar language, and opportunities for connecting with communities on important issues that highlight or threaten ecosystem functioning and resulting ecosystem services that link environmental and human well-being.
**Available at: https://www.lib.ncsu.edu/resolver/1840.20/37311**
... The environmental determinants of spawning and brooding phenology are considered to be regulated by adequate flow, water quality (e.g., temperature), and food availability (Roe et al. 1997, Galbraith andVaughn 2009), but few studies have specifically tested these associations (but see Haggerty et al. 1995, Haggerty and Garner 2000, Watters et al. 2001, Galbraith and Vaughn 2009. For studies that have examined the environmental determinants of mussel reproduction most have taken place in the midwestern or southeastern United States. ...
Information on mussel reproductive life history, age, and growth is important for understanding evolutionary and ecological relationships and predicting how species will respond to conservation and management strategies intended to mitigate threats. In Texas, located within the southwestern United States, 11 species are pending review for listing under the Endangered Species Act, and information on mussel reproductive life history, age, and growth is lacking for most of these species. To address this knowledge gap, we examined life-history traits for 2 im-periled mussel species (Cyclonaias necki, Guadalupe Orb, and Fusconaia mitchelli, False Spike) and 1 common, widely-distributed species (C. pustulosa, Pimpleback) from a site in the lower Guadalupe River, located in Central Texas. The resulting information was then compared with existing life-history information for mussels. We observed peak sperm production between late January to early March and peak mean egg diameter from late winter to early summer in all 3 species. Brooding was observed in all species, usually between March and June, and brooding behavior and glochidia morphology were similar to those of congeners studied in other locations. Accumulated degree days was important in regulating the timing of gametogenesis and potentially the duration of brooding for all 3 species. Fecundity estimates for C. necki and F. mitchelli were much lower than the values reported for congeners in other locations. Fecundity was associated with both mussel age and shell length, although length was a better predictor than age. Trematode infestation rates were high (∼30%) in C. necki and C. pustulosa, and sex ratios were skewed toward males, which could mean that females are disproportionately affected. The age distribution and individual growth rate for C. necki and F. mitchelli closely mirror those of related congeners, although the maximum observed age for C. necki did not meet theoretical expectations based on the estimated growth rate for this species. It is unknown why fecundity is reduced for C. necki and F. mitchelli or why C. necki may have reduced longevity, but these differences could be the result of environmental change.
... As federally protected species, varying brooding periods for H. altilis and H. australis could impact management decisions to better protect populations during reproductively active times. Elliptio pullata were only found gravid with EGG in May and June which corresponds to their characterization as a tachytictic species with a very short brooding period 24,48,49,50 . ...
Actively monitoring the timing, development, and reproductive patterns of endangered species is critical when managing for population recovery. Freshwater mussels are among the most imperiled organisms in the world, but information about early larval (glochidial) development and brooding periods is still lacking for many species. Previous studies have focused on the complex life history stage when female mussels are ready to parasitize host fish, but few studies have focused on the brooding period and timing of larval development. The protocol described here allows researchers to non-lethally evaluate the state of gravidity for female mussels. The results of this study show that this method does not affect a female mussel’s ability to stay gravid or become gravid again after sampling has been performed. The advantage of this method may permit its use on federally threatened or endangered species or other populations of high conservation concern. This protocol can be adapted for use on both preserved or live individuals and was tested on a variety of mussel species. The database provided is a repository for a breadth of information on timing of reproductive habits and will facilitate future freshwater mussel research, conservation, and recovery efforts.
... The probability that a mussel is captured at the substrate surface is a function of its availability for detection and its detectability by a surveyor. Mussels generally exhibit seasonal (time) and species-specific reproductive behavior patterns of vertical migration in substrate that are influenced by environmental variables [70,72,73]. Particularly in the absence of excavating and sieving substrates, these patterns can strongly affect the probability of detection during a survey. ...
Our study objective was to compare the relative effectiveness and efficiency of quadrat and capture-mark-recapture (CMR) sampling designs for monitoring mussels. We collected data on a recently reintroduced population of federally endangered Epioblasma capsaeformis and two nonlisted, naturally occurring species—Actinonaias pectorosa and Medionidus conradicus—in the Upper Clinch River, Virginia, over two years using systematic quadrat and CMR sampling. Both sampling approaches produced similar estimates of abundance; however, precision of estimates varied between approaches, years, and among species, and further, quadrat sampling efficiency of mussels detectable on the substrate surface varied among species. CMR modeling revealed that capture probabilities for all three study species varied by time and were positively associated with shell length, that E. capsaeformis detection was influenced by sex, and that year-to-year apparent survival was high (>96%) for reintroduced E. capsaeformis. We recommend that monitoring projects use systematic quadrat sampling when the objective is to estimate and detect trends in abundance for species of moderate to high densities (>0.2/m²), whereas a CMR component should be incorporated when objectives include assessing reintroduced populations, obtaining reliable estimates of survival and recruitment, or producing unbiased population estimates for species of low to moderate densities (≤0.2/m²).
... In field conditions, native mussels can burrow well below the surface and remain buried for months. Decreasing water temperatures trigger burial (Amyot and Downing 1997; Watters et al. 2001), extended periods of valve closure (Lurman et al. 2014a, b), and lower metabolic rate in unionid mussels (Huebner 1982;Polhill and Dimock 1996;Lurman et al. 2014 a, b). These behaviors could reduce exposure to CO 2 and the potential toxicity of CO 2 to native mussels. ...
Abstract
Control technology for dreissenid mussels (Dreissena polymorpha and D. bugensis) currently relies heavily on chemical
molluscicides that can be both costly and ecologically harmful. There is a need for more environmentally neutral tools to
manage dreissenid mussels, particularly in cooler water. Carbon dioxide (CO2) has been shown to be lethal to several species
of invasive bivalves, including zebra mussels and Asian clams (Corbicula fluminea). We evaluated the effectiveness of
unpressurized infusion of CO2 for 24 to 96 h (100 000–300 000 μatm PCO2) at a water temperature of 12 °C on mortality,
byssal thread formation, and attachment of zebra mussels. The safety of elevated CO2 to a nontarget native freshwater mussel
(Fatmucket, Lampsilis siliquoidea) was also determined. Elevated PCO2 exposure induced narcotization and reduced
attachment of zebra mussels within 24 h. Mortality increased with exposure duration and PCO2. An estimated LT50 (lethal
time to produce 50% mortality) for fixed PCO2 ranged from 24 h at 275 000 μatm to ~ 96 h at 100 000 μatm. Exposure of
zebra mussels to CO2 for 96 h caused 80–100% mortality at all treatment levels. Fatmucket juveniles survived all PCO2
treatments but burial and byssal thread production were adversely affected during exposure. Our results demonstrate that CO2
is a viable option for management of zebra mussels in cool water and may have less adverse effect for native lampsiline
mussels than current-use molluscicides.
Key words: invasive species, dreissenid, unionid, elevated PCO2, toxicity, sublethal effects
... In field conditions, native mussels can burrow well below the surface and remain buried for months. Decreasing water temperatures trigger burial (Amyot and Downing 1997; Watters et al. 2001), extended periods of valve closure (Lurman et al. 2014a, b), and lower metabolic rate in unionid mussels (Huebner 1982;Polhill and Dimock 1996;Lurman et al. 2014 a, b). These behaviors could reduce exposure to CO 2 and the potential toxicity of CO 2 to native mussels. ...
Control technology for dreissenid mussels (Dreissena polymorpha and D. bugensis) currently relies heavily on chemical molluscicides that can be both costly and ecologically harmful. There is a need for more environmentally neutral tools to manage dreissenid mussels, particularly in cooler water. Carbon dioxide (CO 2 ) has been shown to be lethal to several species of invasive bivalves, including zebra mussels and Asian clams (Corbicula fluminea). We evaluated the effectiveness of unpressurized infusion of CO 2 for 24 to 96 h (100 000-300 000 μatm PCO 2 ) at a water temperature of 12 °C on mortality, byssal thread formation, and attachment of zebra mussels. The safety of elevated CO 2 to a nontarget native freshwater mussel (Fatmucket, Lampsilis siliquoidea) was also determined. Elevated PCO 2 exposure induced narcotization and reduced attachment of zebra mussels within 24 h. Mortality increased with exposure duration and PCO 2 . An estimated LT50 (lethal time to produce 50% mortality) for fixed PCO 2 ranged from 24 h at 275 000 μatm to ~ 96 h at 100 000 μatm. Exposure of zebra mussels to CO 2 for 96 h caused 80-100% mortality at all treatment levels. Fatmucket juveniles survived all PCO 2 treatments but burial and byssal thread production were adversely affected during exposure. Our results demonstrate that CO 2 is a viable option for management of zebra mussels in cool water and may have less adverse effect for native lampsiline mussels than current-use molluscicides.
... Except for L. bracteata, a high proportion of individuals became stranded regardless of dewatering rate, which is consistent with findings byGalbraith et al. (2015). Thus, a large proportion of mussel populations can become stranded and experience high levels of mortality downstream of hydropower dams or intense agricultural pumping areas, where water can recede quickly(Newton et al., 2015;Sethi, Selle, Doyle, Stanley, & Kitchel, 2004;Spooner, Xenopoulos, Schneider, & Woolnough, 2011).Although burrowing behaviour is thought to vary among species in the wild(Allen & Vaughn, 2009;Watters, O'Dee, & Chordas, 2001) and in response to drought conditions(Gough et al., 2012), our study showed little difference in burrowing behaviour among species, similar to another experimental study on dewatering by Galbraith et al. ...
• Freshwater organisms have developed different physiological, behavioural and life history strategies to cope with drying events. Although freshwater mussels (Unionidae) are endangered and drought and dewatering events pose a major threat, especially in the southern United States, little is known about their responses to such events and how physiology, behaviour and life history strategies may be linked.
• Our goal was to examine whether and how behavioural responses to dewatering and physiological tolerances to desiccation are linked in five species of freshwater mussels (Unionidae) within Texas, including two state‐threatened species (Cyclonaias petrina and Lampsilis bracteata) and one federally endangered species (Popenaias popeii), and to explore how differences in responses relate to life history strategies.
• We measured horizontal and vertical movements under three dewatering rates and assessed desiccation tolerance by examining survival after emersion at 30 and 40°C with laboratory experiments.
• Amblema plicata and C. petrina had the lowest horizontal movement rates and the highest desiccation tolerances, whereas L. bracteata and L. teres were less tolerant to desiccation, but more mobile. P. popeii were intermediate in its responses.
• Our results show that differences between species in their behavioural response to dewatering and physiological tolerance to desiccation tend to be associated with differences in life history strategies or may be explained by differences in adaptation to certain habitat conditions. We propose a life history strategy‐based framework for responses of mussels to drying events, which may be applicable to other taxa.
... Recent studies have documented that some adult unioniformes have the ability to move vertically. They bury themselves in order to reduce the risk of dislodgment due to eroding river currents at high discharge or to avoid severe cold during winter, and they emerge to the sediment surface during the reproductive periods, when water temperature rises or duration of daylight increases (Balfour and Smock 1995;Watters et al. 2001;Schwalb and Pusch 2007). Knoll et al. (2017) analyzed the escape capacity of two modern unioniform bivalves in relation to sediment grain size and depth of burial. ...
Environmental changes within a Neogene coastal dune system are recorded by endobenthic unioniform bivalves that lived in muddy or sandy interdune pond sediments. These bivalves were suspension-filter feeders that formed dense, almost monospecific communities in the wet-interdune deposits of the continental intervals of the Río Negro Formation (late Miocene-early Pliocene). Activity of unioniform bivalves appears to be related to sediment type; resting and locomotion traces dominate in the muddy heterolithic facies, whereas equilibrium/escape structures prevail in the sand-dominated heterolithic facies. These traces characterize two scenarios of the wet-interdune development. First, during high and/or relatively stable water levels, bivalves colonized the muddy bottom and produced resting and locomotion traces. When water level dropped due to desiccation, biogenic structures were impacted by the formation of mud cracks and subsequently covered by sand delivered by migrating dunes. Second, in spite of dune migration, some interdune areas remained wet or flooded and, in response to sediment aggradation, the bivalves produced equilibrium or escape structures, depending on the thickness of eolian sand cover. Only the integration of ichnologic and sedimentologic observations allows deciphering the evolution of the Neogene wet-interdune system in such a detail.
... This paucity of archaeological sites in the Windwards may be related to problems with si te preservation and visibility ( e.g. Crock and Petersen 2001;Da vis 1982;Delpuech 2004;Delpuech et al. 2001;Fitzpatrick 2012;Hofman and Hoogland 2015, in press;Litman 2001;Watters et al. 1992Watters et al. , 2001). The possibility of early contexts in the southern Lesser Antilles is, however, illustrated by a recent coring program, which has revealed anthropogenic fires and vegetation disturbance in nearly the entire southern portian of the archipelago, dating to more than 5500 years ago (Feller et al. 1992;Siegel et al. 2015aSiegel et al. , 2015b. ...
... Obtaining precise and unbiased estimates of mussel survival is challenging, even for translocated individuals. Mussels often burrow beneath the substrate surface when not actively feeding or reproducing, making them difficult to detect (Amyot and Downing 1998;Watters et al. 2001;Strayer and Smith 2003). Furthermore, an unequal proportion of the population is often sampled, such as larger individuals, those found in easy-to-sample areas, or those at or near the surface (Strayer and Smith 2003;Meador et al. 2011). ...
Translocation of freshwater mussels is a conservation tool used to reintroduce extirpated
populations or augment small populations. Few studies have evaluated the effectiveness of
translocations, mainly because estimating survival is challenging and time-consuming. We used a
mark-recapture approach to estimate survival of nearly 4,000 individually marked Clubshell
(Pleurobema clava) and Northern Riffleshell (Epioblasma rangiana) translocated to eight sites over a
five-year period into the Salt Fork and Middle Fork Vermilion rivers in central Illinois. Survival
differed among sites and between species; Clubshell were approximately five times more likely to
survive than Northern Riffleshell. Survival also increased in the fourth year following a release and
decreased following high-flow events. Translocating numerous individuals into multiple sites over a
period of years could spread the risk of catastrophic high-flow events and maximize the likelihood for
establishing self-sustaining populations.
... A singular focus on moderate bankfull events, the effective discharge (Wolman and Miller, 1960), however, neglects important changes occurring during base-flow periods that help determine the potential for geomorphic work (sediment erosion, deposition, and transport) to be accomplished during less frequent, high discharge events (Doyle, 2005;Doyle et al., 2005). Additionally, the annual, seasonal, monthly, and weekly durations of bankfull discharge events are short in comparison to base-flow periods, in which organisms have a larger effect on important geomorphic (e.g., feeding and spawning activities, burrowing; Watters et al., 2001;Moore et al., 2007;Johnson et al., 2011) and ecosystem processes (e.g., such as biogeochemical nutrient cycling; Atkinson and Vaughn, 2015;Atkinson et al., 2017), which can interact (Moore et al., 2007). Here we outline some examples of organisms that are important drivers of geomorphic processes and likely interact with these processes to have an impact on an essential ecosystem process, biogeochemical nutrient recycling. ...
Decades of interdisciplinary research show river form and function depends on interactions between the living and nonliving world, but a dominant paradigm underlying ecogeomorphic work consists of a top-down, unidirectional approach with abiotic forces driving biotic systems. Stream form and location within the stream network does dictate the habitat and resources available for organisms and overall community structure. Yet this traditional hierarchal framework on its own is inadequate in communicating information regarding the influence of biological systems on fluvial geomorphology that lead to changes in channel morphology, sediment cycling, and system-scale functions (e.g., sediment yield, biogeochemical nutrient cycling). Substantial evidence that organisms influence fluvial geomorphology exists, specifically the ability of aquatic vegetation and lotic animals to modify flow velocities and sediment deposition and transport — thus challenging the traditional hierarchal framework. Researchers recognize the need for ecogeomorphic frameworks that conceptualize feedbacks between organisms, sediment transport, and geomorphic structure. Furthermore, vital ecosystem processes such as biogeochemical nutrient cycling represent the conversations that are occurring between geomorphological and biological systems. Here we review and synthesize selected case studies highlighting the role organisms play in moderating geomorphic processes and likely interact with these processes to have an impact on an essential ecosystem process, biogeochemical nutrient recycling. We explore whether biophysical interactions can provide information essential to improving predictions of system-scale river functions, specifically sediment transport and biogeochemical cycling, and discuss tools used to study these interactions. We suggest that current conceptual frameworks should acknowledge that hydrologic, geomorphologic, and ecologic processes operate on different temporal scales, generating bidirectional feedback loops over space and time. Hydro- and geomorphologic processes, operating episodically during bankfull conditions, influence ecological processes (e.g., biogeochemical cycling) occurring over longer time periods during base-flow conditions. This ecological activity generates the antecedent conditions that influence the hydro- and geomorphologic processes occurring during the next high flow event, creating a bidirectional feedback. This feedback should enhance the resiliency of fluvial landforms and ecosystem processes, allowing physical and biological processes to pull and push against each other over time.
... The extent to which mussels influence physical roughness is dependent upon burrowing activity. Season (Amyot & Downing, 1997;Watters et al., 2001), reproductive cycle (Amyot & Downing, 1998), substrate (Lewis & Riebel, 1984), and species composition (Allen & Vaughn, 2009) all influence the frequency and extent to which mussels burrow. When alive or spent mussel shells protrude from the sediment, flow disruption will occur and affect near-bed hydrodynamics. ...
Freshwater mussels are important ecosystem
engineers, and recent studies have illustrated their
many ecological contributions, but little is known
about the interaction between mussels and their
surrounding flow environment at the organism scale.
In the present experimental campaign, we examine the
hydraulic interactions between mussels and openchannel
flow. We quantify how a mussel-covered bed
alters bed roughness and near-bed turbulent flow,
determine the filter behavior and capacity of live
Lampsilis siliquoidea, and design a model mussel to
simulate live mussel filtering to examine the impact of
the biologically mediated activity of filter feeding on
near-bed turbulent flow. In comparison to a gravel bed,
a mussel-covered bed increased shear velocity by 28%
and bed roughness by nearly 300%, and significantly
reduced near-bed flow velocity. The filter velocity in
L. siliquoidea varied within and between individuals,
and ranged from 0.4 to 20 cm/s. The excurrent flow of
the model mussel accurately simulated excurrent flow
observed in live mussels and, when subjected to
various boundary conditions, altered water velocity
and turbulent kinetic energy downstream. The ability
to describe and quantify these hydrodynamic interactions
provides new insight into how mussels modulate
near-bed flow and mixing processes, which can
contribute to future conservation efforts.
... Sperm release can be initiated by changes in temperature, and warm water often shortens the developmental times of glochidia. Other behaviors (valve movement, mantle flap activity, burrowing behavior) are also tied to temperature (Grier, 1926;Salánki et al., 1974;Watters et al., 2001). The behavior and survival after emersion across a range of air temperatures that are likely to be encountered during status surveys or relocations was conducted on three species of freshwater mussels. ...
Two native groups represent the freshwater bivalves of North America: the freshwater mussels (Unionoidea) and the pill, fingernail, and pea clams (Sphaeriidae). There are also two widely publicized invasive genera, Corbicula and Dreissena. These mollusks have interesting and important ecological interactions with their environments, not the least of which is their relationship to humans. The bias of this chapter is toward the freshwater mussels. They are the numerically dominant group, with 10 times more species, and considerably more data are available on them. This chapter covers general biology, including internal and external anatomy, physiology, and reproduction. General ecology is discussed, including life-cycles, age and growth, and biotic interactions. The role of freshwater biovalves as biomonitors is reviewed.
... 4; ranges shown as shaded regions in Fig. 4A). R C varies by season, species, and burrowing behavior, which introduce inherent uncertainty to this fixed parameter (Amyot and Downing 1997, Watters et al. 2001, Allen and Vaughn 2010. The model was sensitive to reductions in R C . ...
Freshwater fauna diversity and abundance have dramatically declined worldwide, concurrent with changes in streamflow and sediment loads in rivers. Cumulative effects and interdependencies of chronic co-varying environmental stressors can obscure causal linkages that may be controlling the population dynamics of longer lived freshwater fauna, such as mussels. To better understand changes in long-term mussel population density, we developed a dynamic, process-based interaction model that couples streamflow, suspended sediment, phytoplankton, and mussel abundance under the hypothesis that chronic exposure to increased suspended sediment and food limitation are the primary factors controlling native mussel population density in a midwestern USA agricultural river basin. We calibrated and validated the model with extensive survey data from multiple time periods and used it to evaluate changes in mussel abundance at a subbasin scale over decades. We evaluated sensitivity of simulated mussel densities across a range of mortality rates and initial population densities. In scenarios representing altered sediment concentrations, such as might occur with climate or landuse-induced changes in streamflow or sediment generation rates, mussel population density showed critical threshold responses to long-term changes in suspended sediment concentration. This model of mussel population density can be used to test hypotheses about limiting factors, identify priority locations for restoration activities, and evaluate the effects of climate- or landuse-change scenarios.
... Mussels have the ability to affect bed stability, sediment transport and their resistance to entrainment through their morphology (size and shape), flow alignment, burrowing activity and by living in clusters (Allen and Vaughn, 2011). Mussels interact with bed stability in two ways (i) they can destabilise the bed by burrowing into the sediment and (ii) they can resist bed instability by living deeply buried within the bed substrate (Watters et al., 2001;Allen and Vaughn, 2009). Field observations showed that freshwater pearl mussels are often found in tight clusters across a river reach, although in some river they can create a 'blanket' over the bed, which is commonly known as a 'mussel bed' (Strayer 2008). ...
Increased flood frequency and magnitude are predicted for Scotland, and the country contains several of the world's largest recruiting populations of freshwater pearl mussel (Margaritifera margaritifera). This study provides a unique flume experiment to measure the near-bed velocities required for freshwater pearl mussel entrainment and factors affecting their movement. It represents the first quantitative attempt at examining the precise water velocities at which freshwater pearl mussel become vulnerable to displacement during high flow events. Measurement of the near-bed velocities at which the mussels moved was undertaken using an indoor recirculating flume. The effect of the different parameters (bed substrate, mussel burial depth, mussel curvature, mussel alignment, shell curvature and the presence of a simulated foot) on entrainment velocity was tested in the flume and their significance was verified using Kruskal–Wallis and Mann Whitney tests. Bed substrate was found to have the biggest influence on mussel entrainment velocities with averages of 0.86 ms−1, 0.95 ms−1, 1.01 ms−1 and 1.42 ms−1 for sand, gravel, mixed bed and boulder beds respectively. Stepwise logistic regression showed that bed substrate, foot presence, mussel length, mussel burial depth and shell curvature were sufficient to explain mussel entrainment velocity. These findings provide valuable information for the modelling of freshwater pearl mussel dynamics in streams systems and assessing the vulnerability of endangered mussel populations to higher flows associated with climate change in Scotland. Copyright © 2015 John Wiley & Sons, Ltd.
... Sperm release can be initiated by changes in temperature, and warm water often shortens the developmental times of glochidia. Other behaviors (valve movement, mantle flap activity, burrowing behavior) are also tied to temperature [201,509,643] . The behavior and survival after emersion across a range of air temperatures that are likely to be encountered during status surveys or relocations was conducted on three species of freshwater mussels. ...
This chapter introduces general biology, morphology, ecology, physiology, life histories, evolution, and classification of bivalve molluscs found in freshwaters of North America. The freshwater bivalves of North America are represented by two native groups, the freshwater mussels (Unionoidea) and the pill, fingernail, and pea clams (Sphaeriidae), as well as two widely publicized invasive genera, Corbicula and Dreissena. The North American fauna of freshwater bivalves is the richest in the world, with about 350 species of mussels and clams, nine or so of which are exotic. The latter includes Asian clams and zebra mussels. Molluscs, are major deposit and suspension feeders within permanent lakes, streams, and large rivers, where they are often the largest invertebrates in body mass. Freshwater mussels are considered to be part of a guild of freshwater, sedentary filter feeders. These molluscs have interesting and important ecological interactions with their environments. Given the processes they perform and their high biomass in rivers where they are abundant, freshwater mussels have the potential to have strong effects by modifying the habitat and controlling the availability of resources to other organisms.
... There are likely multiple factors that affect the burrowing of these species. Elliptio complanata and other species have been shown to migrate vertically through the substrate in seasonal patterns (Amyot and Downing 1997;Watters 2001). The consistent reduction in the number of E. complanata found in September 2001 relative to the spring of that year follows the pattern found by Balfour and Smock (1995) in Virginia. ...
Authors:
Levine, Jay F
Bogan, Arthur E
Eads, Chris B
Russell, Periann P
Andersen, Elizabeth F
... The biomechanics of burrowing in bivalves have been well studied (e.g., Trueman 1983;Hull et al. 1998;Tallqvist 2001) and has been shown to be influenced by factors such as substrate grain size (Lewis and Reibel 1984;De La Huz et al. 2002;Candido and Romero 2007). Variation in burrowing behaviors in nature varies with season (Watters et al. 2001), flow (Da Maio and Corkum 1997), and disturbance (Lewis and Reibel 1984). To our knowledge, no study has empirically quantified the thermal influence on burrowing behavior and performance (i.e., latency and rate of burrowing) in freshwater mussels. ...
Background/Question/Methods
Temperature can greatly affect the biological processes in many organisms, especially in ectotheerms. Various processes in mussels’ life histories are at least partially affected by temperature, such as reproductive activities, release of larvae, and, potentially, burrowing. Mussels’ ability to burrow is important in their life histories and may be affected by ambient temperature. Our question was: how is the burrowing behavior of Potamilus alatus, a relatively common and abundant freshwater mussel, affected by changes in ambient temperature at which burrowing takes place. We studied the effects temperature has on success in, latency to and duration of burrowing. We collected Potamilus alatus (Pink Heelsplitters) from Kentucky Lake and subjected each of them to three temperature treatments (10, 20, and 30 ± 3°C) using a repeated measures design. Each treatment took place in a temperature regulated aquarium preceded by at least 24 hrs acclimation. The time it took for each mussel to begin to burrow (latency) and the duration of burrowing was recorded. The number of times mussels failed to burrow within a 3 hr time period was also recorded.
Results/Conclusions
The percent of mussels that failed to burrow was significantly higher at low (10C) temperatures than higher temperatures. We found no significant difference in the latency to burrowing or in burrowing duration. In most ectothermic animals, decreasing temperatures typically decrease the rates of physiologically processes underlying whole animal performance resulting in a large reduction in movement abilities. Interestingly, the finding that duration of burrowing was unaffected by temperature is contrary to other studies on different animals and this potential lack of temperature dependence on burrowing rates could be vital to survival during periods of changing ambient temperatures in nature. It is important to understand how burrowing may be affected by ambient temperature for the management of mussel populations. Choosing temperatures at which mussels are able to re-burrow will help ameliorate the effects of surveys. Anthropogenic changes to ambient temperatures through manipulation of rivers, such as by dams, and through climate alteration might affect mussel burrowing, which could in turn affect other aspects of their life history.
... For native mussels inhabiting rivers, movement behaviour might be particularly important for responding to disturbances that occur as a result of changing flow conditions and water levels. Some species of mussels may move seasonally into aggregations to enhance reproduction (Amyot & Downing, 1998;Watters, O'Dee & Chordas, 2001). Vertical movement or burrowing may help mussels escape predation, control zebra mussel infestation (Nichols & Wilcox, 1997;Burlakova, Karateyev & Padilla, 2000), avoid extreme temperatures and reduce dislodgement and transport to unsuitable conditions (Schwalb & Pusch, 2007). ...
Managers in the U pper M ississippi R iver ( UMR ) are using reductions in the R iver's water levels during summer to mimic historical water regimes and rehabilitate habitats for vegetation and other species. Concerns for the unintended effects of these actions on mussel populations threatened to halt these projects.
Our objective was to characterise the survival and movement of two mussel species in the UMR associated with a water level drawdown. During 2009 (no drawdown) and 2010 (0.3 m summer drawdown), we glued passive integrated transponder tags to 10 A mblema plicata and 10 L ampsilis cardium at each of 11 sites. Five sites were in shallow areas expected to be minimally affected by the drawdown (reference sites), and six sites were in shallow areas expected to be directly affected by the drawdown (treatment sites). About equal numbers of sites within both the reference and treatment areas had low and high slopes. Tagged mussels were randomly allocated across sites (within years).
Recovery of tagged mussels was >88% in 2009 and 2010. Mortality was similar and low (mean, c . 5% in both species) among reference sites but was variable and relatively high (means, c . 27% in L . cardium and c . 52% in A . plicata ) among treatment sites; variation in mortality among treatment sites appeared related to slope.
The study found evidence of drawdown associations with net horizontal movements in A . plicata but not L . cardium . Weekly horizontal movements in both species were significantly correlated with changes in water elevation. We observed significant slope associations related to the drawdown for mortality and net horizontal movement in A . plicata .
There were strong species‐specific differences in the effects of the drawdown on mortality, vertical movement and horizontal movement. These results suggest that A . plicata responded to the drawdown by vertical movement into the substratum, whereas L . cardium responded by horizontal movement to deeper water. No directionality of movement was observed in either species.
Collectively, these data suggest that drawdowns can influence the mortality, movement and behaviour of mussels in the UMR . However, more information on spatial and temporal distributions of mussels is needed to better understand the magnitude of these effects. Results from this study are being used by resource managers to better evaluate the effects of this management tool on native mussel assemblages.
... Sampling sites in tributaries were selected by scouting accessible areas and sites obtained from museum records (Ohio State University Museum of Biological Diversity 2011). Unionid mussels are known to burrow beneath the surface in winter months to avoid extreme cold (Watters et al. 2001) and sampling was started in July to ensure most mussels had emerged above the substrate surface. ...
Despite massive population declines in the open waters of Lake St. Clair due to invasive dreissenid mussels, the St. Clair River Delta has persisted as a refuge habitat for native unionid mussels. This study was conducted to determine how Dreissena-induced population declines might have impacted the genetic population structure of native unionid species. Nine variable microsatellite markers were used to assess the genetic population structure of the Fatmucket mussel (Lampsilis siliquoidea) across 18 sites (n = 341 individuals) within the delta and four of its tributaries. Results indicate that Fatmuckets within the various bays of the St. Clair Delta and tributaries show limited genetic differentiation by geographic distance but still represent a single population with evidence of recent gene flow, little differentiation among sampling sites, relatively high allelic richness at all sites, and little evidence supporting a recent genetic bottleneck. The Fatmucket is the most common species found in the delta and poor genetic health and connectivity of this species might have indicated a dire situation for less common and imperiled species found in the same habitats. Because this did not appear to be the case, little can be assumed about other mussel species.
Background
Freshwater mussels are important keystone and indicator species of aquatic ecosystems. Recent advances in sensor technology facilitate applications to individually track mussels and to record and monitor their behavior and physiology. These approaches require the attachment of sensor devices as “backpacks” to the outer shell surface. The interpretation of such data makes it necessary to understand the influence of these attachments on the horizontal and vertical movement behaviors of freshwater mussels. Over a series of mesocosm experiments, this study systematically investigated the effects of three size- and wiring-specific variants of artificially attached backpacks on the horizontal and vertical movement behavior of Anodonta anatina.
Results
Across all experiments, equipping mussels with backpacks did not result in a significant influence on horizontal movement for any of the backpack variants. In contrast to this finding, the big backpacks with a high ratio between backpack volume and mussel length resulted in a significantly negative effect on vertical movement, indicating a potential for adverse effects of such devices on mussels, especially in natural settings.
Conclusions
The findings of this study show that assessing the effects of attached devices on mussels requires a species-specific evaluation of potential impacts on the endpoints of interest. Especially for vertical movement patterns, selection of the smallest available devices appears mandatory.
Unionoids are in global decline, which may be associated with their complex life cycle. Their juveniles are unique because while hidden (burrowed deeply in bottom sediments) they undergo critical anatomical changes (also developing a characteristic juvenile shell sculpture). Currently, the juveniles’ period of life is believed to be both the least known and one of the most vulnerable—thus the possibility of obtaining any biological knowledge is essential for establishing conservation strategies and addressing functional or evolutionary questions. I propose two new methods for visualization of the burrowing behavior of unionoid juveniles within deposits that are cheap and easy: (1) laminated deposits of quartz–aragonite sand for time-stepped X-ray images of bivalve traces, and (2) silica gel serving as 'invisible sand' for direct observations and video recording of behavior within sediments. Both deposits in a pilot study were accepted by the juvenile unionoids—they were stable enough and penetrable, with no observable signs of harmful effects on animals’ behavior during trials. In both, juveniles were clearly visible, settled within the top 1 cm layer of deposits. Both methods are promising tools for future in situ within the deposits research on the biology of this much unexplored and vulnerable unionoids' life stage.
The freshwater pearl mussel Margaritifera margaritifera is an endangered bivalve which is usually regarded as sedentary, although individual movement has been observed both vertically and horizontally. Little is known about the causes and rates of mussel movement. The objective of this study was to test the effect of microhabitat characteristics on the horizontal movement distance and rates of freshwater pearl mussels. A total of 120 mussels (length range 40–59 mm) were marked individually with passive integrated transponder tags, placed in stream microhabitats differing in their sediment composition and monitored biweekly over a period of 10 weeks. Mussels situated in sand-dominated habitats had a significantly higher mean movement rate (3.2 ± 4.2 cm/day, mean ± SD) than mussels situated in gravel-dominated (1.9 ± 2.7 cm/day) or stone-dominated habitats (1.8 ± 3.2 cm/day). The direction of the movements appeared random; however, an emigration from sandy habitats was observed, probably to avoid dislodgment from these hydraulically unstable habitats. This study demonstrates that freshwater pearl mussels can actively emigrate from unsuitable microhabitats. Once suitable streams with respect to physical, chemical, and biological quality were identified, it is therefore only necessary to identify suitable mesohabitats (area of 10–30 m²) when reintroducing or relocating mussels.
Sediment depth preference was tested on 1-year-old freshwater pearl mussel juveniles. Mesh tubes allowing vertical migration with a possibility to leave hyporheic space, filled with 1–2-mm granulometry size substrate and populated with groups of juveniles, were placed in the natural river bed of the Teplá Vltava River, Czech Republic. The depth position of the juveniles was recorded after 1- and 2-month exposure during the summer and after 8 months including wintering. The juveniles showed a tendency not to stay on the sediment surface, but to penetrate into a very shallow depth, and to accumulate and stay 2–3 cm deep in the substrate in the summer period. No juvenile was found below 8 cm sediment depth, neither in the summer nor after wintering. In the experimental tubes, various survival rates (0–100%) were recorded in close relation to substrate oxygenation development at the tested sites. Oxygen decrease was accompanied by juveniles trying to escape the hyporheal.
• Freshwater mussels are a particularly imperilled group of aquatic organisms. To date, there is limited understanding of their dietary and nutritional subsidies, including those from both autochthonous (aquatic) and allochthonous (terrestrial) sources. The aim of this study was to evaluate the relative contributions of potential nutritional resources to mussel biomass using a Bayesian mixing model (MixSIAR) for (i) bulk suspended versus benthic organic matter (OM) pools, (ii) general autochthonous versus allochthonous OM sources and (iii) specific individual OM sources.
• Nutritional subsidies of five species of freshwater mussels were assessed using natural abundance stable isotopes (δ¹³C, δ¹⁵N, δ²H) and natural radiocarbon (Δ¹⁴C). The ranges for each of the four isotopes were similar across all species and sampling dates, and mussel δ¹³C and δ¹⁵N values were similar to those measured in previous studies. Despite relatively low variability in this study, species and temporal differences in mussel δ¹⁵N, δ²H and Δ¹⁴C values were generally significant (P < 0.05).
• Based on δ¹³C values alone, bulk suspended OM subsidised mussel biomass to a greater extent than bulk benthic OM (c. 60 and 40% respectively). Modelling of multiple isotopes indicated that while the collective allochthonous nutritional sources accounted for a significant part (c. 33%) of mussel biomass, autochthonous materials collectively subsidised mussel tissue at about twice this level (c. 67).
• Significant amounts of ¹⁴C‐depleted aged carbon were incorporated into freshwater mussel tissue (mean equivalent ¹⁴C age = 1325 ± 68 years BP). Potential nutritional sources were also mostly aged, including benthic algae (1226 ± 556 years BP), zooplankton (1682 years BP), terrestrial soil (10 588 ± 4330 years BP) and suspended particulate OM (1443 ± 57 years BP).
• No single potential individual nutritional OM source explained the multiple isotopic values of freshwater mussel tissue, indicating that these organisms have a multi‐source and potentially opportunistic diet. Benthic algae and phytoplankton were quantitatively the most important individual OM subsidies to freshwater mussel nutrition at our study site (27 and 19% respectively). Observed seasonal shifts in freshwater mussel isotopic values were minimal, suggesting (i) that mussels may not be seasonally limited by individual nutritional resources and/or (ii) the replacement times of C, N and H in freshwater mussel tissues make detection of temporal nutritional subsidy shifts – if they occur – difficult to discern.
The decline in freshwater mussels makes it imperative that more information be gathered on their population status, behavior, and habitat requirements. We examined vertical migration, aggregation, and reproductive potential of captive and field populations of Lampsilis siliquoidea. Both captive populations and a field population exhibited vertical migration. This movement was strongly correlated with day length, and somewhat less strongly correlated with water temperature. While captive mussels tended to orient their siphons into the current, no pattern of orientation was detected in the field population. The field population was significantly aggregated in the fall and winter. The spatial patterning of captive mussels was random in the fall and winter, but this result may have been an artifact of the small size of the artificial streams. Weather conditions prevented data collection in the spring and, therefore, no conclusions could be drawn about the relationship between aggregation and glochidia release. The average number of glochidia (parasitic larvae) produced by individuals across a limited size range was not correlated with any maternal or marsupial properties. These results are useful for implementing qualitative sampling methods under optimum conditions and for information on the reproductive potential of Lampsilis siliquoidea.
the goal of this study was to better understand population characteristics of Villosa iris (Lea) (Rainbow Shell) in the Spring River drainage in north-central Arkansas through documenting seasonal spatial patterns, movement behavior, population size, size-frequency distributions, sex ratios, and fecundity. We conducted monthly mark and recapture sampling between May and September 2007 (i.e., before, during, and after spawning) and documented the sex, size, fecundity, and spatial location of individual Rainbow Shell at 2 sites (SFSR1 and SR1). Population estimates were relatively high at both sites with 166 +/- 32 (SE) and 381 +/- 37 (SE) individuals at SFSR1 and SR1, respectively. Sex ratio was highly skewed toward males at SFSR1 with a ratio of 1.0:2.6, but only slightly skewed at SR1 with a ratio of 1.0: 1.3. Mean fecundity was 27,849 +/- 11,653 (SE) and 15,089 +/- 11,710 (SE) glochidia at SFSR1 and SR1, respectively. Spatially, statistically more males were found upstream of non-gravid females during the spawning period. Mean movement for all sampling events was 1.6 +/- 0.53 cm/day and 1.9 +/- 0.58 cm/day for SFSR1 and SR1, respectively. Home range was 29.3 +/- 27.7 cm(2) and 43.0 +/- 42.5 cm(2) for SFSR1 and SR1, respectively. From our study, we conclude that Rainbow Shell exhibits traits, such as male-skewed sex ratio and non-uniform distribution of males and females, that may influence fertilization rates of females.
Relocation of federally protected freshwater mussel (Unionidae) resources as a conservation strategy has occurred for more than 30 y to ameliorate site-specific threats associated with development activities or invasive species. In this study, we evaluated survival rates of resident and relocated Potamilus capax (Green, 1832) individuals and documented short-term (1 mo) and long-term (25 mo) horizontal movements. We observed P. capax survival rates >77% for all treatment groups and horizontal movement up to 120 m annually. While significant differences in movement behavior between treatment groups occurred during the early stages of the study, movement differences between resident and relocated treatment groups became nonsignificant as the study progressed. We concluded using survival as a success measure remains valuable, but requires further evaluation. However, we assert understanding movement behavior in the focus species remains critical to strategic development of monitoring strategies.
North American freshwater mussels are diverse and ecologically important, but are highly imperiled as a result of alterations to river habitat. The southern hickorynut (Obovaria jacksoniana) occurs in the southeastern United States and has recently been listed as threatened in Texas; however, minimal information exists on its habitat associations and behavior. Here we (1) describe, in detail, habitat conditions at two collection sites in the upper Neches River in east Texas and (2) present the results of a laboratory experiment on burrowing behavior in gravel and sand substrates. We collected a total of twelve live mussels at two sites in the upper Neches River. Mussels occurred in reaches with highly connected floodplain. Mussels occurred in shallow water (< 1.0 m) and substrate ranging from silt to gravel (10 mm diameter). In the burrowing experiment, horizontal movement was significantly greater in gravel compared to sand substrates. Vertical movement did not differ significantly between sand and gravel treatments. All movements occurred within the first 24 h. These results suggest that horizontal movements in southern hickorynuts can differ among substrates and horizontal and vertical movement can occur relatively quickly. Rapid horizontal and vertical movement may be important in avoiding displacement and mortality during unpredictable floods of regulated rivers. Moreover, sediment pollution has altered substrates which may influence burrowing behavior of this species.
Length, height and angle of the exposed part of mussel, Iridina spekei, above the bottom were examined on the sandy flat of Lake Tanganyika. The larger mussel protruded higher above the bottom, which seemed to be advantageous to scatter sperm or larvae father in order to increase chances of the fertilization or parasitism of larvae on fish. Immature mussels seemed to lie hidden to avoid predation by fish.
The different phases of the biological cycle of Anodonta cygnea L. living in lake Trasimeno (Central Italy) are described in the present paper. Researches have been carried out on histological sections of germinal tissues and gills of specimens of both sexes sacrificed every month and verified by following the course of the parasitic phase of life of glochidia on the fish of the lake. Moreover, the various species of fish heavily infested by glochidia have been identified and the glochidium infestation frequency has been determined. The structure of the glochidium shell has been studied with the scanning microscope for a better understanding of the mechanism of attachment to fish and to collect more information in order to compare the species of Anodonta from lake Trasimeno with those of other parts of Europe.
Although many environmental features have become altered during the course of the past century, the family Unionidae has been able to maintain itself in a very satisfactory manner. The ability of this group to survive is emphasized by the realization that it suffers from a double handicap: its members are almost sessile and, furthermore, they are inhabitants of the substratum. The lowermost layer of water, the only stratum which mussels can utilize, usually lacks more features which are necessary for the maintenance of living forms than any other portion of an aquatic habitat. Information on the life history of any animal is obtained by an assortment of methods. Some parts of it lend themselves to a statistical analysis so that results may be obtained. Other aspects can best be shown by charts or graphs. A large portion of a life history, which includes the study of ecological relationships, is gotten through a series of accurate observations. In this paper, simple mathematical computations have been necessary for various shell measurements, and in a few other instances. It is realized that the value of the results which are derived from direct observation depends upon the observer's ability to see and interpret natural phenomena accurately. The writer gratefully acknowledges the aid given him by his sons, Max and John Matteson, in connection with the field work required for this paper. Their aptness in water combined with their acute vision were almost indispensable. General discussion.-As one examines any stretch of water, either lentic or lotic, he soon becomes, aware that situations exist in which fresh-water mussels are plentiful while in others they are lacking. After carefully studying the living clam in its natural habitat, he finds that one can predict the presence or absence of these animals at a location accordirtg to the environmental conditions existing at that site. They respond so fastidiously to several of the more important features which compose their environment that deviation one way or another from the optimum by one or more of these items will determine the presence or absence of the population at a given position. Although there is some variation in the responsiveness of different species of clams to the individual environmental constituents, there is a striking uniformity of response by all clams in general to their surroundings. There are instances where general pollution of water has obliterated an entire population of clams from an area. For several successive years the author has studied the mussels in a small river near Urbana' Illinois. During the summer of 1951, a canning factory dumped refuse from its corn pack into a tributary of this stream. One month later an inventory of the same area studied before the contamination occurred showed only empty valves lying on the bottom. No living clams were found. Although some fish had been killed, many were still alive. The toxicity of the-polluting materials had been potent enough to kill the mussels without having a lethal effect on most of the higher organisms. As a family, the unionids have been able to perpetuate themselves in a 126
18% of a population of Elliptio complanata was found living completely buried in the sediments of a Québec lake during mid-summer. This population was found to descend into the sandy sediment as winter approached, and emerged in the spring. More than 60% of the population was endobenthic during late autumn. Endobenthic mussels were significantly smaller than epibenthic mussels (50-60% of average length) and most mussels that were endobenthic during mid-summer were juveniles. Shell morphology did not vary significantly between epi- and endobenthic mussels. Failure to count endobenthic E. complanata in population surveys could result in severe underestimates of actual population densities. A sampling program based strictly on epibenthic mussels would underestimate the contribution of young mussels to the biomass and production of this population.
Fish species congeneric with previously identified hosts, as well as exotic fishes (Xiphophorus variatus and Tilapia aurea) and the mosquitofish (Gambusia affinis), were exposed to glochidia of Villosa vanuxemi or V nebulosa to determine whether phylogenetically similar fishes can serve as hosts. Glochidia of V. vanuxemi metamorphosed on black (Cottus baileyi), mottled (C. bairdi) and slimy (C. cognatus) sculpins, and glochidia of V nebulosa metamorphosed on spotted (Micropterus punctulatus), largemouth (M. salmoides) and Suwannee (M. notius) basses and the mosquitofish. Exotic fishes were unsuitable hosts. A review of previous in vivo and in vitro studies suggests that chemical components of the blood serum in fishes, as yet unidentified, dictate host suitability to specific glochidia.
Many freshwater mussels of the family Unionidae form conglutinates, specialized packets of parasitic glochidia that often mimic host prey items. Conglutinates of the kidneyshell, Ptychobranchus fasciolaris, resemble either insect larvae or fish fry. These structures, examined with light and scanning electron microscopy, are composed of three acellular layers separated by fluid or mucoidal layers. Regions of the conglutinate that appear to mimic eyes are shown to be particularly thin areas that readily rupture and liberate glochidia. Thus, elaboration of mimicry characteristics, such as "eyes," is accompanied by functional differentiation of regions of the conglutinate.
Activity of Elliptio complanatus catawbensis (Lea) was automatically recorded with specimens undergoing a 23-hr 13-min entrainment schedule of variables such as light, temperature, and feeding. 1. The change to light or dark, under conditions simulating natural light, resulted in a doubling of the prior rate of opening of the valves. Increased light intensity did not increase the response. Results with specimens on 24-hour entrainment as well as on the shorter entrainment demonstrate a rhythmic response to the daily light cycle: Closures increased following the opening response to light-onset, but not following the opening response to the termination of the light period. The opening response to light-onset was of shorter duration than that to light-termination. Closures decreased towards the end of the dark period. 2. Water-change caused 89% of the closed clams to open within 1.5 hrs. This result with water-change was repeated with a limited supply of Amblema plicata plicata (Say). Vibrations alone, water-change without any vibrations, or simple removal and reintroduction of the original water, all caused most of the closed clams to open. Opening with light- or water-change or mechanical stimulation may relate to a feeding response in nature following introduction of organic debris. 3. A rapid series of brief closures, partial in some clams and complete in others, often occurred, especially at the beginning and termination of the open (active) period. Such stimuli as water-change, jarring, or rotation were twice as effective in causing the series of closures when applied to closed clams (two-thirds of the cases) as when applied to open clams (one-third of the cases). Open clams already exhibiting a rapid series of brief closures continued to do so after stimulation.
The gametogenic cycle, spawning and glochidial release periods, and age at sexual maturity were determined for four unionid species from the New River in Virginia and West Virginia: mucket, Actinonaias lieamentina; spike, Elliptio dilatata; purple wartyback Cyclonaias tuberculata; and pistolgrip, Tritogonia verrucosa. The mucket is a long-term brooder, spawning in mid-summer, brooding glochidia throughout fall and winter, and releasing them in spring. The spike, purple wartyback, and pistolgrip are short-term brooders. Spawning began in mid-March and continued into May for T. verrucosa, into June for C. tuberculata, and into July for E. dilatata. Glochidia were released upon maturation, beginning in mid-April and continuing through June for T. verrucosa, into August for E. dilatata, and extending from March through June for C. tuberculata. All four species are sexually mature at 4 to 6 years of age.
The distribution, age structure, and movements of the unionid mussel Elliptio complanata (Lightfoot) were studied in a first-order stream in Virginia, USA. Mean density of the mussel in this low-gradient, sand-bottomed stream was 2.5 individuals/m and biomass was 3.4 g dry mass/m. About 87% of the population had a shell length of 6–9 cm, or age of 4–6 years. Only 11% of the population was less than four years old; the age of the oldest individuals encountered was only eight years. Distribution of the mussels was highly clumped, but no physical, chemical, or hydrologic factors examined were significantly correlated with mussel abundance. All young mussels (age < three years) were burrowed into the sediment, whereas older individuals occurred both below and at the sediment surface, depending on time of year. About 90% of the population was burrowed below the surface during the winter, but a high of 80% of the mussels moved to the surface in March and April, the time of peak reproductive activity. Tagged mussels moved an average of 2.9 m during one year. Although the direction of those movements was erratic, the overall movement of the population was a net 27 cm downstream, indicating no directed upstream movement to compensate for downstream displacement during storms.
Summary The cycless musselsAnodonta cygnea andPseudanodonta complanata do not show any phototaxis. In the “Zweilichterversuch” (two-light-experiment) they react to the decrease of light intensity. If light is increasing, the mussels will not react; if put in the shade, they immediately do so. If the shadow is moved, the mussels even react when the intensity of light decreases much less, which demonstrates the importance of motion. From this it follows that the reception of motion may be considered as possible where there is light sensitiveness of the skin, and where the experiment connects motion with shading.
Largemouth Bass were infected with glochidia of the freshwater mussel Lampsilis cardium. Three fishes each were held at 4.5, 10, and 15.5°C; five fish were held at 21°C. By 64 days, metamorphosed juveniles were found in the 15.5 and 21°C trials but not in the 5.5 and 10°C trials, indicating that the lower threshold temperature for metamorphosis was between 10 and 15.5°C for the duration. In a second experiment, Largemouth Bass were infected with glochidia of L. cardium and held at 10°C. A sample of fishes was removed monthly and brought to 21°C. Numbers of glochidia that metamorphosed after being warmed were compared to the number that metamorphosed without warming. The percentage that metamorphosed after warming decreased linearly with time. At one month, 100% of the glochidia metamorphosed after warming. This decreased to 80% by two months, to 30% by four months and 3% by six months. Although this post-warming percentage decreased with time, the total percentage of metamorphosed juveniles (at all temperatures) was not correlated with time. Controls kept at 21°C required three weeks to reach peak metamorphosis, but test subjects subjected to 10°C required less than nine days to metamorphose once warmed. Many overwintering glochidia therefore complete a portion of their development on the host at winter temperatures, but stop short of excystment. Some glochidia metamorphosed without being warmed, but this phenomenon is not understood. This study confirms that glochidia may overwinter on hosts, with some glochidia persisting for more than six months before metamorphosing when warmer conditions return.
An analysis of about 4,500 hours of shell movement tracings of the freshwater mussel, Hyridella australis Lam., is presented. Nine series of experiments have been conducted, representing variations in light and temperature conditions. It has been found that, as well as shell movements, shell position or degree of openness must be considered. The shells may be closed (phase 1), completely open (phase 3), or stationary, intermediate between the two (phase 2), for the validity of which position mathematical proof has been found. The characteristics of each phase have been outlined. Temperature, within the range 17 to 27°C shows no well-definded influence on shell movements or the degree of openness. The influence of light, especially in regard to phase 2, is discussed. A diurnal light rhythm is associated with a diurnal feeding rhythm; under continuous illumination the shells tend to remain apart but in phase 2, darkness suppresses shell movements and feeding. The shell movements during ovulation are discussed.
Diurnal rhythms were found in the unionid clam Ligumia subrostrata for valve activity and oxygen consumption. Valve closures and valve gape were measured as indices of valve activity. Recordings were made after the animals were entrained to each of three photoperiods: 12 h light (L): 12 h dark (D), 16 L: 8 D, and 24 L. Statistically significant (P < 0.01) rhythms of activity were found in 12 L: 12 D and 16 L: 8 D photoperiods with high activity occurring during the dark phase. The onset of darkness was indicated as the entraining factor. No rhythm of valve activity was found in 24 L. Flow-through respirometry of individual clams was used to determine if oxygen consumption paralleled activity rhythms. Rhythms of oxygen consumption were present in all three photoperiods with a change in light rather than the onset of darkness as the entraining factor. The activity rhythm was exogneous, whereas the oxygen consumption rhythm was an endogenous rhythm. Overall levels of activity and oxygen consumption were highest in the 16 L: 8 D regimen and depressed in constant light.
Reproduction of Megalonaias nervosa (Rafinesque, 1820) has not been documented for over 20 y in much of the Cumberland River, where water temperatures have decreased and flow regimes have been greatly altered by hypolimnetic discharges from impoundments. Studies in other streams have implicated low temperatures or changes in discharge patterns as causative factors inhibiting reproduction. Megalonaias nervosa were collected from the Cumberland River, translocated to the Tennessee River, and held in an embayment of Kentucky Lake. After the first and second y, samples of M. nervosa were taken from the Cumberland River, an existing population in Kentucky Lake, and the translocated group. Histological examination indicated that translocated mussels had a high incidence of hermaphroditism, and like mussels originating in Kentucky Lake, had undergone an otherwise normal reproductive development. Individuals functioning successfully as females from the translocated group had mature glochidia in their marsupia. Females from the Kentucky Lake sample also had mature glochidia present. In contrast, there was no indication of reproductive activity in gonads or marsupia of individuals collected from the Cumberland River. Our results indicate that a return to a more natural temperature regime in the Cumberland River would reinstate a normal reproductive cycle. We suspect that the altered temperature regime is also disrupting the gametogenic cycle of all mussels, including at least six federally listed endangered species occurring in the Cumberland River. These relic populations will disappear unless they are translocated or the thermal regime returned to normal.
1. Vertical and horizontal movement were studied in the freshwater bivalve Elliptio complanata at a sandy site in an oligotrophic lake over 3 years. Mussel movement did not vary significantly between day and night. On average, between 2 and 8% of 527 mussels moved each month during the ice-free season and the distance travelled by moving mussels averaged 0.6 cm day–1.
2. Mussels were endobenthic during the winter, emerged from the sandy substrate in mid-May, peaked in sediment surface abundance in July, and descended into the sediments for the winter in September–October. Vertical displacement of mussels was closely correlated with water temperature although daylength may play a role. Mussels apparently move very little beneath the sediment during the winter.
3. The number of mussels moving horizontally at any given time was linearly correlated with daylength, but the distance travelled during a sampling period was related to daylength in a non-linear fashion. Greatest horizontal displacement of epibenthic mussels was found during spring and early summer, coincident with spawning in E. complanata
1. Temporal variation in the spatial aggregation of the freshwater bivalve Elliptio complanata was studied at a sandy site in an oligotrophic lake over three years.
2. Epibenthic populations varied in aggregation over the season bringing animals closer together during spawning. The complex link between movements of mussels and aggregation dynamics suggested a functional reproductive role for horizontal locomotion of unionid mussels in lentic systems.
3. The rate of locomotion did not differ systematically among males, females or hermaphrodites, and was independent of gravidity, whether compared during spawning, after spawning or throughout the ice-free season.
4. In spite of the high reproductive output of mussels and the energetic cost of locomotion, no relationship was found between the rate of movement of spawning gravid mussels and reproductive output.
Typescript (Xerox copy). Thesis (M.S.)--University of Louisville, 1968. Department of Biology. Vita. Includes bibliographical references (leaves 53-54).
http://deepblue.lib.umich.edu/bitstream/2027.42/56285/1/MP040.pdf
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A monograph of the naiades of Pennsylvania. Part 111. Systematic account of the genera and species
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1894. ~ s t u d e s sur les mollusques terrestres et fluviatiles Mission scientifique au .Mexique et duns I'Amerique Centrale
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A classification and annotated check list of the North American naiades The reproductive cycle and the glochidium of Anodonla cygnea L. from Lago Trasimeno
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The Unionida: of Lake Maxinkuckee
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Remarques sur les coquillages i coquilles, & premierement sur les moules
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