## 3 Results and Discussion
### Enchytraeus cryptic  
Enchytraeid Reproduction Test (ERT)  
FOS induced no effects in terms of survival and reproduction of _E. cryptic_ after 28 d of exposure (\(p>0.05\), Figure 5A). However, a decrease in the population number after 56 d was found at 1250 mg/kg FOS (\(p<0.05\), Figure 5B). The toxicity of FOS to _E. cryptic_ seems to have increased with the increase of the exposure period. This corroborates the idea that, for some endpoints (in this case reproduction), FOS seems to have a toxicological action analogous to the organophosphates, since it only caused toxic effects after a longer-term exposure [18, 49, 53, 54]. In addition, all the tested concentrations of FOS (except for 500 mg/kg) enhanced the size (length) of adults after 28 d (\(p<0.05\), Figure 3C). No study was found about the effects of FOS to _E. cryptic_. However, for a _Folsonia candidia_ chronic exposure with FOS water-dispersible granule containing 800 g/kg (WG80) (Bayer CropScience) an EC\({}_{20}\) of 958.8 mg/kg for reproduction was calculated [10]. In soil, FOS can be rapidly transformed to their metabolites, phosphonic acid and ethanol (DT\({}_{50}\) = 0.1 d). Phosphonic acid is an important degradation product of FOS due to its persistence with a DT\({}_{50}\) of 28 to 130 d in soil [10]. Hence, we cannot discard the hypothesis that the  
Figure 4: Effects of 96 h pf exposure to fosetyl-Al on zebrafish larvae for cholinesterase (ChE) (**A**); glutathione _S_-transferase (GST) (**B**); catalase (CAT) (**C**) activities; and total glutathione (TG) content (**D**). Data are expressed as average value (AV) \(\pm\) standard error (SE). * Significant differences to control (\(p<0.05\)).  
observed effects in the present study may be due to FOS metabolite, phosphonic acid. A value of LC\({}_{50}\) > 615 mg/kg was estimated for earthworms after acute exposure (14 d) to phosphonic acid [38]. Based on the current data gap, a phosphonic acid risk assessment for soil invertebrates is needed (this is also in line with the Terrestrial Guidance Document from the European Commission) [38].  
For _E. crypticus_, a recent work with various fungicides showed that 21 d exposure of prosaro did not also affect reproduction and survival of the organisms [16]. On contrary, another fungicide, amistar, had a toxic effect to _E. crypticus_, with the reproduction being the most sensitive endpoint [16]. Another study reported that _E. crypticus_ were not affected by the pesticide toxaphene even at the highest tested concentration (1000 mg/kg) [15]. Dimethoate increased the survival and mancozeb decreased the survival and reproduction of enchydraeids [17]. The size of the adults was significantly affected by dimethoate, increasing the dimethoate concentration limited growth [17]. This is an opposite effect considering the one detected in our study: FOS increased the organisms' sizes. Growth is a very relevant ecological endpoint [56]. Effects of the contaminants on the organisms' sizes may induce harmful consequences in terms of organisms' performances, e.g., change in age structure and, hence, population dynamics [57]. The detected increase of size may be a trade-off, i.e., an investment of the organisms in terms of optimal size for their survival, after the exposure to FOS. Indeed, no significant alterations were found on survival of _E. crypticus_ after 28 d of exposure. It is of interest to note that the increase of adults' sizes in the first generation (as mentioned, probably an investment for survival) did not prevent the impact on reproduction at 56 d, which was significantly reduced when parents were largest (Figure 5B,C).