The evaluation of individual production and scope for growth in aquatic sow bugs (Asellus aquaticus)

Abstract

The possibility to assess the instantaneous production of benthic invertebrates in the field avoiding direct measurements of somatic and generative growth is discussed. The scope for growth (SfG) (assimilation minus respiration) and instantaneous individual production (mass increment during growth) for Asellus aquaticus were determined and compared. Results of this study have confirmed the assumption that the difference between SfG and individual production of isopods P is approximately equal to reproductive investment. In juveniles and males these differences should be compensated, in large degree, for the exuviae. As confirmed by the closely identified values of P after summing it with eggs production, excess of SfG in comparison with P may be attributed to the part of energy which is allocated to generative products. So, the predicted coincidence of SfG with P coupled with egg production allows to expect that SfG may be implicated in evaluation of instantaneous population production. To verify this assumption, the data on population production of A. aquaticus previously reported in the literature were drawn. The results have shown a close conformity of compared data, and led to the conclusion that this method should be of more general use, and not limited to the populations exposed to stress, as it is currently treated.