Survival, Growth and Condition of Freshwater Mussels: Effects of Municipal Wastewater Effluent

Abstract

Freshwater mussels (Family Unionidae) are among the most imperiled group of organisms in the world, with nearly 65% of North American species considered endangered. Anthropogenic disturbances, including altered flow regimes, habitat alteration, and pollution, are the major driver of this group's decline. We investigated the effects of tertiary treated municipal wastewater effluent on survivorship, growth, and condition of freshwater mussels in experimental cages in a small Central Texas stream. We tested the effluent effects by measuring basic physical parameters of native three ridge mussels (Amblema plicata) and of non-native Asian clams (Corbicula fluminea), before and after 72-day exposure at four sites above and below a municipal wastewater treatment plant outfall. Survivorship and growth of the non-native Asian clams and growth and condition indices of the native three ridge mussels were significantly higher at the reference site above the outfall than in downstream sites. We attribute this reduction in fitness below the outfall to elevated nutrient and heavy metal concentrations, and the potential presence of other untested-for compounds commonly found in municipal effluent. These results, along with an absence of native mussels below the discharge, indicate a significant negative impact of wastewater effluent on both native and non-native mussels in the stream.

Reassessing Enigmatic Mussel Declines in the United States

“…These approaches represent two opposite ends of the research spectrum, and both are essential, but the link between these approaches is underrepresented in our knowledge base. The link is measuring specific responses (e.g., survival, growth, physiological condition) of individual mussels to ambient conditions in the wild (e.g., Bartsch et al 2003;Gagné et al 2004;Nobles and Zhang 2015;Haag et al 2019). This approach also may be correlative, but it provides a realtime assessment of mussel responses to current conditions (whether or not wild mussel populations exist), it is repeatable and replicable to a much greater extent than assemblage-or population-focused approaches, and it allows evaluation of toxicological results in a natural context.…”

Silent invasion: Sinanodonta woodiana successfully reproduces and possibly endangers native mussels in the north of its invasive range in Europe

“…As Anodonta anatina and Anodonta cygnea can live 20 years or more (Aldridge, ), mussels up to 4‐year‐old represent recent recruiters and we refer to them a “young”; this does not reflect their reproductive status. Condition factor (CF) of live mussels was calculated as the individual wet mass divided by the product of linear dimensions of the shells where WM is the wet mass, L is the length, H is the height, and W is the width of the shell (Abraszewska‐Kowalczyk, ; Gillis, ; Nobles & Zhang, ). We compared the values of CF in this study with CF values calculated for mussel populations living in favorable conditions: A. anatina and A. cygnea reported in Ożgo and Abraszewska () and S. woodiana collected in 2015 from the heated Konin lake system (Urbańska, unpublished data).…”

“…where WM is the wet mass, L is the length, H is the height, and W is the width of the shell (Abraszewska-Kowalczyk, 2002; Gillis, 2012;Nobles & Zhang, 2015). We compared the values of CF in this study with CF values calculated for mussel populations living in favorable conditions: A. anatina and A. cygnea reported in Ożgo and Abraszewska (2009) and S. woodiana collected in 2015 from the heated Konin lake system (Urbańska, unpublished data).…”

Exposure to Elevated Concentrations of Major Ions Decreases Condition Index of Freshwater Mussels: Comparison of Metrics

“…After testing three commonly used formulas, they recommended a standardized method, calculated as CI ¼ dry soft tissue weight (g) 3 1000/internal shell cavity capacity (g). However, review of recent literature for freshwater bivalves still shows wide variation in the methodology used to calculate CI, with soft tissue weight (wet or dry) divided by either shell length (Blaise et al 2017), shell length^3 (Spooner and Vaughn 2009), shell weight (Payton et al 2016;Bertucci et al 2017;Zhao et al 2017), shell cavity volume (Nobles and Zhang 2015;Otter et al 2015), total dry weight (Ganser et al 2015), or total wet weight (Michel et al 2013), with or without the use of scaling factors (310, 3100, etc. ).…”