## 3 Results and Discussion
### Changes in E. fetida Populations  
The development of earthworm populations in vermiculture, by an increase in number and biomass is vital for the effectiveness and rate of utilization of organic waste [47]. In the current experiment, earthworm populations were relatively stable--a volume of 150 g of waste was enough for a population of _E. fetida_ for the period of approximately 70 days (Figures 3 and 4). After this period, in vermieactors processing _T. latifolia_ (between day 140 and day 175 of the experiment) a significant decrease in the number of mature _E. fetida_ specimens (by 56.9%; \(p<0.05\)), young specimens (by 60.4%; \(p<0.05\)) and cocoons (by 59.1%; \(p<0.05\)) was observed (Table 3). Different results were presented by [PERSON] and [PERSON] [48], who noted an increase in the number and biomass of _E. fetida_ during their studies on vermicomposting of various macrophyte species. Dissimilar observations may be evoked by physico-chemical differences between the utilized macrophytes as well as by the differences in vermicomposting technology [49]. In the present study, a slight decrease in the number of mature species was noted in every population and it amounted, on average, to 6% (\(p>0.05\)) (Figure 3a). A significant reduction concerned the biomass at that time. On day 70 of the experiment, the most pronounced loss (49%, \(p<0.05\)) was observed utilizing _T. latifolia_ (T) (Figure 4a). In the other groups, a decrease in biomass was significant as well, but slightly minor: Earthworms utilizing _I. pseudacorus_ (I) and _C. demersum_ (C); decreased by 40% and 30%, respectively (\(p<0.05\)) (Figure 4a). This tendency was also reflected by the average biomass of the individuals (Figure 4d). Such a situation may be explained by the limited access to food [35; 50] and can be completely referred to (I) and (C), in which the earthworms utilized 100% of plant waste after 70 days of the experiment. Unfavorable changes in the (T) population did not result from lack of food--in this study group the experiment was discontinued on day 210 because all of the earthworms died (Table 3, Figure 1), whereas incompletely utilized waste was still present (Figure 2).  
During the process of utilization of littoral plant waste, the earthworms produced cocoons in all the study groups (Figure 3c). The highest mean number and the sum of biomass of cocoons was observed on day 70 of the experiment in (C), where these values were greater by 32% and 38%, respectively (\(p<0.05\)) compared to the other groups (Figures 3c and 4c). Differences in the mean individual cocoon biomass were not significant (Figure 4f; \(p>0.05\)). As reported by [PERSON] [49], nitrogen content in the substrate has a strong effect on cocoon production. This fact is reflected in the present study, as a similar number of cocoons on day 70 of the experiment in (T) and (I) (\(76.25\pm 17.73\) and \(74.50\pm 17.09\)) is correlated with a similar nitrogen content in biomass of _T. latifolia_ and _I. pseudacorus_ (\(1334.2\pm 23.1\) and \(1344.7\pm 13.7\) mg kg\({}^{-1}\)).  
As a result of cocoon production by _E. fetida_, young earthworms appeared (Figures 3b and 4b,e). The highest number of specimens, sum of biomass and biomass of young individuals were observed in (I), whereas the smallest values of the above-mentioned characteristics were noted in (T). Significant differences were demonstrated in relation to the mean number of young individuals 58% (\(p<0.05\)) (Figure 3b), mean sum of biomass of young individuals 69% (\(p<0.05\)) (Figure 4b) and mean biomass of an individual 25% (\(p<0.05\)) (Figure 4e).  
Figure 3: Dynamics of the mean number of adult specimens (**a**), young specimens (**b**) and cocoons (**c**) of _E. fetida_ in the process of vermicomposting of littoral plant biomass.  
Figure 4: Dynamics of the mean sum of biomass and the mean biomass of adult specimens (**a**) and (**d**), young specimens (**b**,**e**) and cocoons (**c**,**f**) of _E. fetida_ in the process of vermicomposting of littoral plant biomass.