PARENT SESSION
Poster Session 23: Soil Ecology
Wednesday, August 10, 5:00 PM - 6:30 PM, Exhibit Hall 220 A-E, Level 2, Palais des congrès de Montréal
Marking earthworms with rubidium for release-recapture studies.
Whalen, Joann*,1, Kulhanek, Ales1, 2, Lacombe, Simon1, 1 Macdonald Campus, McGill University, Ste-Anne-de-Bellevue, QC, Canada2 National Institute of Public Health, Prague, Czech Republic
ABSTRACT- A classic method of assessing animal population dynamics is to mark a population, release them into the wild, and make measurements on individuals that are captured after a period of time. There are many techniques for marking or identifying animals such as mammals, birds and fish. However, techniques for marking soil invertebrates have not been studied extensively, possibly because it is difficult to devise efficient and cost-effective methods for these small, cryptic animals. The objective of this study was to determine whether earthworms can assimilate and retain sufficient rubidium (Rb) in their tissues that introduced earthworms could be differentiated from an indigenous population in the field. Adults and juveniles of the endogeic earthworm Aporrectodea caliginosa were placed in soil containing 500 mg Rb kg -1 for one week. Then, some earthworms were transferred to clean soil and Rb elimination from their tissues was determined during a 39 day period. Earthworms assimilated Rb readily from the soil, and the concentration of Rb in earthworm tissue was 100-fold greater than background levels after one week. When earthworms were transferred to clean soil, they eliminated 46 to 50% of the Rb in their tissues within 3 days. The Rb concentration declined exponentially during the elimination period, but stabilized at 90 to 95 mg Rb kg-1 tissue around day 25. The Rb concentration in unmarked earthworms (about 8 mg Rb kg-1 tissue) is about 10 times lower than in Rb-marked earthworms. These results indicate that marking earthworms with Rb may be an effective way to track individuals and differentiate introduced earthworms from indigenous populations in release-recapture studies.
Key words: earthworm population dynamics, labeling technique, release-recapture study