Bioaccumulation and elimination of Hg in the fireworm Eurythoe complanata (Annelida: Polychaeta) from Mazatlan, Mexico

Effects of mercury on growth, emergence, and behavior of Chironomus riparius Meigen (Diptera: Chironomidae)

Mercury is a pervasive toxicant that can be found in the environment due to anthropogenic activity as well as natural sources. The majority of studies in freshwater environments focus mainly on bioaccumulation, population dynamics, and biomagnification. Here, we study the effects of mercuric chloride on Chironomus riparius Meigen, simulating a mercury discharge on a freshwater ecosystem. Growth, emergence, development time, and behavior were the end points assessed. Growth was measured after 8 days of exposure and behavior was recorded on days 4 and 10 of the experimental period. The behavioral responses of C. riparius to different mercury treatments were recorded with an online biomonitor, which allows a more objective and precise behavioral understanding than visual observation. Mercury exposure resulted in reductions in growth and emergence, a delayed development time, and a decrease in locomotor activity of the larvae. Our results demonstrate that mercury exposure can impair life-history responses of chironomids.

Mortality and abnormalities observed after experimental Hg exposure in the polychaete Eurythoe complanata (Pallas) from Mazatlan, Mexico

Lethal effects of Hg on Eurythoe complanata held under laboratory conditions were evaluated (LC50 and LT50). Worms were exposed to 0-900 microg/L of Hg for 10 days. Mortality occurred in all the treatments, being faster at 200-900 microg/L, which was confirmed by a Friedman ANOVA non-parametric test. The 4-day LC50 = 197.15 microg/L (200 microg/L LT50 = 3.4 days) was similar to that reported for other Hg tolerant annelids. Abnormalities were observed in worms exposed to all the treatments, becoming more severe as Hg concentrations increased: body darkening, rough, white and opaque skin, everted and swollen proboscis and gut evisceration.