Effect of Sediment Type, Feeding Level, and Larval Density on Growth and Development of a Midge (Chironomus Riparius)

Fullerenes(nC60) affect the growth and development of the sediment-dwelling invertebrate Chironomus riparius larvae

“…Time to first emergence were observed at the day 17 in all other treatments and control besides the treatment 0.5 mg/kg of fullerenes where it was at the day 19. In many ecotoxicological studies the emergence rate of C. riparius has been observed to increase when organisms are subjected to stress by exposing them to chemicals, increasing the effort put in reproduction (Ristola et al, 1999). This occurred in the fullerene concentrations of 10, 40 and 80 mg/kg used in this study.…”

“…dw, particle size <0.5 mm) was added during each treatment just before starting the experiment. The amount of Urtica was chosen to correspond to our previous study; the food level was high enough to be sufficient for this bioassay (Ristola et al, 1999), but did not mark out the potential effect of the fullerenes (Waissi-Leinonen et al, 2012). The dry mass to wet mass ratio of the sediment was determined to be 0.56 to 0.62 and the total organic carbon content (TOC) was 4.51 ± 0.12 g/kg (Multi N/C 2100 Analytic Jena AG Germany).…”

“…In both experimental sets some concentrations and controls were duplicated to ensure the results being repeatable. Exposure was conducted individually to exclude the possible effects of higher larval density on growth and mortality (Ristola et al, 1999). The results of the growth experiments were utilized in selecting the concentration ranges for the emergence experiments.…”

“…Whiskers indicate standard deviation, asterisks point out significant differences from untreated sediments (Dunn's Multiple Comparison test, **p < 0.01, ***p < 0.001) (n ¼ 400). 0.12 mg/larva/day (Ristola et al, 1999) for midge bioassays. Larvae were fed three times a week by stopping aerations and adding the TetraMin-suspension gently to the sediment surface.…”

“…This factor, the densitydependence, is expected to have an impact on larval survival and growth due to competition. When studying larval growth it is essential to expose them in an individual chambers (Ristola et al, 1999). Nevertheless, when studying the effect at the population level exposures in groups should be preferred.…”