Toxicity and Bioaccumulation of a Mixture of Heavy Metals in Chironomus Tentans (Diptera: Chironomidae) in Synthetic Sediment

Abstract

Abstract-This research investigated toxicity and bioaccumulation of a mixture of Cd, Cu, Pb, and Zn in Chironomus tentans in synthetic sediment, and compared predicted to measured steady-state bioaccumulation factors (BAFs). In a toxicity test, C. tentans were exposed to various dilutions of a base concentration (1.0 ϫ) of a mixture of the four metals (5 g/g Cd, 10 g/g Cu, 70 g/g Pb, and 300 g/g Zn) in synthetic sediment. Mortality ranged from 17 to 100%. To measure bioaccumulation of the metals, C. tentans were exposed to 0.35 ϫ the base concentration for a period of up to 14 d in two uptake tests. Bioaccumulation of all four metals increased over the 14-d uptake phases. Concentrations of metals in chironomids were significantly correlated with exposure time in the uptake phases. Only concentrations of copper approached background levels after 7 d depuration. Uptake rate coefficients and elimination rate constants were determined for each metal. Bioaccumulation factors were highest for Cd and lowest for Pb. With the exception of Pb, steady-state BAFs were within a factor of about two of those calculated using the first-order kinetic model. The high BAFs calculated may indicate greater bioavailability in synthetic sediment. Studies comparing toxicity and bioaccumulation of natural and synthetic sediments are necessary before the use of synthetic sediments is widely adopted.

The midgut epithelium of aquatic arthropods: a critical target organ in environmental toxicology.

“…For C. tentans larvae exposed for 6 days, the LD 50 for copper and cadmium are 2.5 and 5 ppm, respectively (11). In contrast, as little as 0.1 ppm cadmium or copper induces CTTUB1 in a 1-day exposure.…”

“…Theoretically, organisms such as aquatic arthropods that experience long-term exposure to the mixtures would be most impacted by such heavy-metal pollution. Interspecific differences in aquatic arthropod populations, including reduced diversity and shifts in benthic community composition at sites located downstream from mining sites, occur in response to heavy-metal pollution (1,4,11). In addition, we previously demonstrated that the population genetic structure of Baetis tricaudatus was also perturbed in the Arkansas River in Colorado, presumably in response to impediments to gene flow in the population caused by mortality arising from exposure to pollution from heavymetal mixtures from mining sites (2).…”

“…Insects exposed to heavy metals at sublethal doses exhibit pathological effects on many biological activities (1)(2)(3)5,7,11,17). Concentrations and toxic effects of metals depend on the bioavailability of the metal and the size, age, sex, and developmental stage of the arthropod (2,6,8,10,11,18).…”

“…Concentrations and toxic effects of metals depend on the bioavailability of the metal and the size, age, sex, and developmental stage of the arthropod (2,6,8,10,11,18). Resistance to heavy metals varies with different genotypes and strains within a species (2,5-7).…”

Tests of chronic and acute toxicity of crude oil on larvae of Chironomus kiiensis Tokunaga (Diptera: Chironomidae)

“…Larvae of species in the family Chironomidae (Diptera) represent one of the most abundant aquatic insects in most ecosystems, and they have demonstrated their importance as test organisms for studies on risk assessment of substances such as pesticides (Taenzler et al, 2007), heavy metals (Watts and Pascoe, 1996;Harrahy and Clements, 1997;Bechard et al, 2008) and oil (Rosenberg and Wiens, 1976;Cushman, 1984;Crunkilton and Duchrow, 1990;Hatch and Burton Junior, 1999). However, toxicity studies using petroleum-derived products on animals have only been conducted for Amazonian fish (Veintemilla, 2006;Duarte et al, 2010), there being no studies assessing effects on aquatic insects.…”