Toxicity of sediments from lead–zinc mining areas to juvenile freshwater mussels (Lampsilis siliquoidea) compared to standard test organisms

Abstract

Sediment toxicity tests compared chronic effects on survival, growth, and biomass of juvenile freshwater mussels (28-d exposures with Lampsilis siliquoidea) to the responses of standard test organisms-amphipods (28-d exposures with Hyalella azteca) and midges (10-d exposures with Chironomus dilutus)-in sediments from 2 lead-zinc mining areas: the Tri-State Mining District and Southeast Missouri Mining District. Mussel tests were conducted in sediments sieved to <0.25 mm to facilitate recovery of juvenile mussels (2-4 mo old). Sediments were contaminated primarily with lead, zinc, and cadmium, with greater zinc and cadmium concentrations in Tri-State sediments and greater lead concentrations in southeast Missouri sediments. The frequency of highly toxic responses (reduced 10% or more relative to reference sites) in Tri-State sediments was greatest for amphipod survival (25% of samples), midge biomass (20%), and mussel survival (14%). In southeast Missouri sediments, the frequency of highly toxic samples was greatest for mussel biomass (25%) and amphipod biomass (13%). Thresholds for metal toxicity to mussels, expressed as hazard quotients based on probable effect concentrations, were lower for southeast Missouri sediments than for Tri-State sediments. Southeast Missouri sites with toxic sediments had 2 or fewer live mussel taxa in a concurrent mussel population survey, compared with 7 to 26 taxa at reference sites. These results demonstrate that sediment toxicity tests with juvenile mussels can be conducted reliably by modifying existing standard methods; that the sensitivity of mussels to metals can be similar to or greater than standard test organisms; and that responses of mussels in laboratory toxicity tests are consistent with effects on wild mussel populations.

Relative sensitivity of an amphipod Hyalella azteca, a midge Chironomus dilutus, and a unionid mussel Lampsilis siliquoidea to a toxic sediment

“…The sediments in the exposure beakers were held for approximately 7 d under static conditions to allow the sediment samples to better equilibrate before the start of the exposures [15][16][17].…”

“…Surviving L. siliquoidea in each replicate were preserved in 8% formalin for subsequent dry weight measurement. The biomass of surviving H. azteca from each replicate was estimated as the sum of individual amphipod weights calculated from the empirical relationship [16,17,26] weightðmgÞ ¼ ð 0:177 Â length mm ð Þ ½ À 0:0292Þ 3 Dry weight of surviving L. siliquoidea in each replicate was determined after the mussels were dried for 24 h at 60 8C. The dry weight was measured to the nearest 0.001 mg with a microbalance (Model MX5, Mettler Toledo).…”

“…Additional studies and evaluations are needed to determine which endpoints provide the most useful indicators of the chronic toxicity of contaminants to midges; the utility of indicators may vary by chemical class or mode of chemical action. Measuring reproductive endpoints of C. dilutus beyond emergence requires testing of numerous replicates (e.g., 16 replicates/treatment [1,2]), compared with only 8 replicates tested in the present study to determine larval biomass and adult emergence. Weight and biomass of H. azteca in the 28-d exposures were 2-fold to 3-fold more sensitive relative to the 10-d exposures in the Grand Calumet River sediment diluted with West Bearskin Lake sediment (based on EC20s in Table 2 and Figure 1B).…”

“…Moreover, juvenile mussels are in direct contact with sediment, often burrowing into the upper 1-cm to 2-cm layer of sediment [14]. Water-only toxicity methods for mussels [7] have been adapted to conduct 28-d whole-sediment toxicity tests with freshwater mussels [15][16][17]. However, additional data are needed comparing the response of mussels with other commonly tested species in whole-sediment toxicity tests.…”

Evaluation of chronic toxicity of sodium chloride or potassium chloride to a unionid mussel (Lampsilis siliquoidea) in water exposures using standard and refined toxicity testing methods

“…The survival of control mussels in previous chronic tests (e.g., Wang et al 2007aWang et al , 2010Wang et al , 2011Wang et al , 2016Besser et al 2013;Kunz et al 2017) exceeds the test acceptability criterion of !80% survival for chronic water-only exposures with juvenile mussels (ASTM International 2017); however, the growth of mussels in controls of these studies has been inconsistent among chronic toxicity tests . Because mussel growth is often a more sensitive endpoint than survival (e.g., Wang et al 2007aWang et al , 2010Wang et al , 2011Wang et al , 2013Wang et al , 2016Besser et al 2015;Ingersoll et al 2015), consistency in growth across studies is important to better assess mussel responses to contaminants. Further studies were necessary to optimize feeding and other test conditions for assessing the mussel growth endpoint (Wang et al 2011;Ingersoll et al 2015).…”