Pedobiologia 47, 842–845, 2003 © Urban & Fischer Verlag http://www.urbanfischer.de/journals/pedo 0031-4056/03/47/05–06–842 $15.00/0 *E-mail corresponding author: momin@s6.coopenet.com.ar The 7th international symposium on earthworm ecology · Cardiff · Wales · 2002 Effect of UV radiation on Eisenia fetida populations Ariadna Hamman, Fernando Roberto Momo*,Andrés Duhour, Liliana Falco, Maria Cecilia Sagario and Maria Eugenia Cuadrado Laboratorio de Ecología, Universidad Nacional de Luján, CC 221, B6700ZAB Luján, Argentina Submitted September 6, 2002 · Accepted May 20, 2003 Summary The objective of this work was to evaluate the effect of different UV radiation doses on the population dynamics of Eisenia fetida. The experiment was performed under laboratory conditions (20 °C, 12 hours light period) in 5 L boxes with soil and cattle manure with five earthworms per box. Three treatments were established: 1) without UV radia- tion, 2) with a normal dose of UV radiation (45 ± 5 Watts/m 2 ) and 3) with an increased UV dose (60 ± 5 Watts/m 2 ). Four replicates of each treatment were established. Adult earthworms, juveniles and cocoons were counted weekly over a period of 2 months. Cocoons were removed and incubated and the percentage of fertile cocoons was recorded. Populations under the three treatments showed a positive rate of increase. However, UV radiation caused a diminution in E. fetida fecundity from 6.4 ± 0.5 cocoons per individual per week in the treatment (1) to 4.7 ± 0.5 cocoons per individual per week in the treatment (3). UV radiation also caused a decrease in the cocoons’ fertility of around 70 %. The intrinsic rate of increase (r) of the population varied from 0.19 to 0.07 month -1 following the UV radiation increment. These results indicate that earthworm populations can be seriously affected by the enhancement of the UV radiation due to the ozone depletion. Key words: Eisenia fetida, UV radiation, populations, ozone depletion The anthropogenic release of volatile compounds such as chlorofluorocarbons and bromine halons has led to a steady decline in the concentration of stratospheric ozone (Anderson et al. 1991; World Meteorological Organization 1994; Rozema et al. 1997; Björn et al. 1998). This ozone loss is a major factor in the in- creased amount of UV radiation that reaches the bios- phere. The enhancement of UV radiation incidence is an environmental problem that affects all latitudes and regions in the world and can produce ecological effects at individual, population, community or whole ecosys- tem level (Mitchell & Karentz 1993; Piacentini & Her- mann 1996; Piancentini & Cede 1997; Rozema et al. 1999; Vernet 2000). Earthworms play an essential role in organic matter recycling and dynamics. Despite the fact that earth- worms are little exposed to solar radiation, some of them are epigeic, living and depositing cocoons on the soil surface. In some of these species, lethal effects of UV radiation have been proven (Sicken et al. 1999). Introduction