I would need a reference for the relation of earthworm fresh mass vs. dry mass or in other words the water content of earthworm tissue. I suppose dry mass is about 15 % of the fresh mass?
I know there is always the problem of gut content (yes / no) and of weight loss by fixation. In our case its earthworms with gut content fixed in formalin, but I would also be happy with references dealing with other conditions.
Dear Anneke,
Prof Zicsi in the early 70's carried out some (never published) experiments, and r5ecogniset that tzhe dry weight (104 C) / living weight ratio is species specific rangig between 4.57-6.49 (living weight to 1 unite dry-weight) being the smallest at F. pl. depressa and largest at L. rubellus.
Dear Anneke, please find the information in ISO 23611-1 "Hand-sorting and extraction of earthworms chapter 6.3 and in Petersen, H. and Laxton, M. 1982 Oikos 39 287-388.
A comparative analysis of soil fauna populations and their role in decompostion processes. B.-Michael
I did this research years ago with r= 0.91
Reynolds, J.W. 1972. The relationship of earthworm (Oligochaeta: Acanthodrilidae and Lumbricidae) distribution and biomass in six heterogeneous woodlot sites in Tippecanoe County, Indiana. J. Tenn. Acad. Sci. 47(2): 63-67.
This full paper is available in Researchgate.
15-18% can be a correct estimattion. Zicsi's data show the same (21.8% - 15.4%)
Thanks to all of you! I agree that measuring dry weight enables more reliable comparisons as fresh weight depends on the condition of the animals.
Dear Anneke,
The lost of biomass strongly depends on earthworm species, adult/juvenile stage as well as the method of conservation (formol versus alcohol). I think the previous paper could help you, I add those of G. Cuendet (1985).
Regards,
Claire