A review of the effects of heavy metals on freshwater mussels

Abstract

: The widespread recent decline in the species diversity and population density of freshwater mussels in North America may be partly related to chronic, low-level exposure to toxic metals. As benthic filter-feeding organisms, freshwater mussels are exposed to metals that are dissolved in water, associated with suspended particles and deposited in bottom sediments. Thus, freshwater mussels can bioaccumulate certain metals to concentrations that greatly exceed those dissolved in water. In adult mussels, the most common site of metal uptake is the gill, followed by the mantle and the kidney. The toxic effects of metals on freshwater mussels have been examined in a few acute toxicity tests, but the sublethal effects of long-term exposure to low environmental concentrations are little understood. Sublethal exposure to metals can alter growth, filtration efficiency, enzyme activity and behaviour. Sublethal effects are frequently observed at concentrations that are only half the lethal concentrations. However, few toxicity tests have used environmentally realistic exposure concentrations. Total concentrations of Cd, Cu, Hg and Zn in many oxic surface waters are in the ngl(-1) range, yet many toxicity studies have exposed mussels to concentrations in the μgl(-1) or even the mgl(-1) range. An understanding of the processes by which metals affect freshwater mussels would provide insights on the ecotoxicological significance of metal contamination to natural mussel populations and aid in the development of water-quality criteria that adequately protect mussels.

When and how? Freshwater mussel recolonization in Lake Orta

“…Even after the improvement of Lake Orta conditions and the neutralization of pH values accomplished by liming (1989)(1990), studies documenting the progressive recovery of both pelagic and benthic populations (Baudo et al, 2001a;Bielli and Tesauro, 2001;Nocentini et al, 2001) failed to reveal the presence of mussels or any other molluscs. Since mussels are highly sensitive to acidification (Økland and Økland, 1986;Taskinen et al, 2011), ammonia (Augspurger et al, 2003;Wang et al, 2008) and heavy metals (Naimo, 1995;Keller et al, 2006), particularly at the earlier life stages (Wang et al, 2007a(Wang et al, , 2007bCope et al, 2008;Cleawater et al, 2014), the high sediment toxicity, that did not improved but was rather worsened by liming, likely hindered recolonization. Furthermore, once extirpated from a water body, mussels are not able to recolonize easily, particularly if they lack access to restocking populations (Strayer et al, 2004), due to constraints related to their complex life cycle.…”

Biomonitoring of Pb and Cd in two impacted watersheds in Southeast Brazil, using the freshwater mussel Anodontites trapesialis (Lamarck, 1819) (Bivalvia : Mycetopodidae) as a biological monitor

“…They are somewhat sedentary, regionally abundant, long lived and have adequate tissue mass for analysis. They readily accumulate many metals and their body burden seems to reflect mean exposure levels over time (Naimo, 1995). Consequently, such organisms have been largely used in programmes of biological monitoring in either salt water (Farrington, 1983;De Gregori et al, 1994;McConnell and Harrel, 1995;Avelar et al, 2000) or in freshwater (Manly and George, 1977;Foster and Bates, 1978;Millington and Walker, 1983; ) Abaychi and Mustafa, 1988;Hameed and Raj, 1990;Kraak et al, 1991;Camusso et al, 1994;Valdovinos et al, 1998;Villar et al, 1999;Rutzke et al, 2000).…”

Heavy Metal Contamination in Brazilian Agricultural Soils due to Application of Fertilizers

“…However, areas distant from the industrial centers in many cases also show metals contamination, due to the atmospheric transportation of these comEnvironmental Risk Assessment of Soil Contaminationpounds [48] and in the case of agricultural soils, due to the use of fertilizes contaminated with these metals [6].…”