Multi‐stage disruption of freshwater mussel reproduction by high suspended solids in short‐ and long‐term brooders

Abstract

Summary Suspended solids are one of the most widespread pollutants in streams, but little is known about their effects on freshwater mussels. In a previous study, we showed that increasing concentrations of total suspended solids (TSS) resulted in a decreased proportion of gravid female mussels; however, the generality of this effect and the specific stage at which reproduction was inhibited remain unknown. In this study, we examined stage‐specific disruption of reproduction in a short‐term brooding mussel species (Reginaia ebenus) and a long‐term brooding species (Ligumia subrostrata). High TSS concentrations disrupted reproduction in both the short‐ and long‐term brooding species, but the mechanism appeared to differ between species. A high proportion of female Reginaia ebenus (range = 0.33–0.93) were fertilised across the entire TSS gradient (11–92 mg L−1), but few glochidia developed at TSS >20 mg L−1. In contrast, only a low proportion (0–0.28) of female Ligumia subrostrata were fertilised at high TSS concentrations, but all gravid females eventually produced fully developed glochidia. Excessive inputs of sediments and/or nutrients probably disrupt early reproductive stages of freshwater mussels via elevation of inorganic or organic TSS concentrations and may be important drivers of freshwater mussel declines.

Influence of surrounding land-use on mussel growth and glycogen levels in the St. Croix and Minnesota River Basins

“…Measured declines in mussel populations over the past century in many rivers across the U.S. have been attributed to a variety of causes, including increases in water velocity, shear stress and suspended sediment loads. These factors have been hypothesized to interfere with filtration, fertilization, recruitment and establishment of juvenile mussels in several studies (Reid et al, 2012;Gascho Landis et al, 2013;French & Ackerman, 2014;Gascho Landis & Stoeckel, 2016;Hansen et al, 2016;Stoeckel & Geist, 2016;Hornbach et al, 2019). However, our results suggest highsuspended sediment loads may not affect mussel glycogen content or growth in a negative way.…”

“…Second, at high levels of suspended solids there could be negative impacts on the availability of sperm for reproduction leading to reduced reproduction. Gascho Landis & Stoeckel (2016) found that even when the organic matter content of suspended material was high there were negative impacts on reproduction in mussels. Thus, high food availability, which would support higher growth, coupled with high-suspended solids could still result in lower population sizes due to reproductive failure.…”

“…They also found that there was an important feedback between mussel populations and suspended sediment loads, with larger populations of mussels moderating the amount of suspended solids in the water column. High concentrations of suspended solids, especially the inorganic fraction of TSS, promote lower mussel abundance through reduced recruitment (Ö sterling et al, 2010;Gascho Landis et al, 2013;Ö sterling, 2015;Gascho Landis & Stoeckel, 2016), inducing physiological stress (Aldridge et al, 1987;Payne et al, 1999) and reducing feeding/clearance rates (Moore, 1977;Hornbach et al, 1984;Vaughn & Hakenkamp, 2001;Gascho Landis et al, 2013). Biological mechanisms through which TSS affected gravidity were hypothesized to be either that highinorganic TSS-lowered female-sperm encounter rates, or triggered an increase in pseudofeces, which could bind sperm in mucus and lead to egestion before fertilization or to juvenile recruitment failure (Ö sterling et al, 2010;Gascho Landis et al, 2013;Gascho Landis & Stoeckel, 2016).…”

Does size matter? Particle size vs. quality in bivalve suspension feeding

“…Specifically, decreases in water clarity impede photosynthetic organisms (Madsen, Chambers, James, Koch, & Westlake, ), and make food acquisition challenging for visual predators (Barkalow & Bonar, ; Swanbrow Becker, Brooks, & Gabor, ). Increased TSS has likely contributed to the decline of unionid mussels through reductions in feeding and reproductive efficiencies (Aldridge, Payne, & Miller, ; Gascho Landis & Stoeckel, ; Tuttle‐Raycraft et al., ) and disruption of unionid–host fish relationships (McNichols, Mackie, & Ackerman, ). Consequently, approximately 44% of unionid species globally, and more than 70% in North America, have conservation concerns (Hansen et al., ; Lopes‐Lima et al., ).…”

Living the high turbidity life: The effects of total suspended solids, flow, and gill morphology on mussel feeding

“…Contributing factors to the decline in unionid populations include overexploitation (Lopes-Lima et al 2017), invasive species (Lucy et al 2014), loss of fish hosts (McNichols et al 2011), loss of habitat, and habitat alteration (Poole and Downing 2004) including the negative impacts of increased total suspended solids (TSS; e.g., Gascho Landis et al 2013;Tuttle-Raycraft et al 2017) due largely to erosion (Brim Box and Mossa 1999;Santos et al 2015). Whereas certain mussel species are tolerant of turbid conditions and silt accumulation (Ellis 1936), large and diverse populations of other species are found in turbid rivers, where they are predicted to have lower feeding and reproductive efficiency (Gascho Landis and Stoeckel 2016;Tuttle-Raycraft et al 2017). Specifically, elevated TSS in turbid rivers should result in lower clearance rates (CR; volume of water cleared of particles per unit time; Widdows et al 1979) as TSS concentrations exceed 8-20 mg L −1 (Gascho Landis et al 2013;Tuttle-Raycraft et al 2017) because bivalves spend more time cleaning their gills (i.e., producing pseudofeces; Foster-Smith 1975).…”