Supplementary material

Figure S1: Multiple sequence alignment for Acanthocephala parasitizing the isopod Asellus aquaticus. This figure was generated in Geneious (Biomatters).

Figure S2: Multiple sequence alignment for Microsporidia parasitizing the isopod Asellus aquaticus. This figure was generated in Geneious (Biomatters).

Figure S3: Pleotelson widths according to a) sampling month, and b) infection status.

Figure S4: Means and standard deviations of δ13C and δ15N values of isopods and cystacanths (Acanthocephalus spp.). Isopods were further differentiated according to their infection status. Microsporidian single findings are included here. While acanthocephalan-infected isopods were measured individually, acanthocephalans were pooled in September and November 2023. In addition, one acanthocephalan in November 2023 did not yield enough dry mass for SIA.

Table S1: Water parameters and number of collected isopods for each sampling.

Table S2: Overview of host individuals, acanthocephalans, and microsporidians.

Table S3: Minimum (min), maximum (max), mean and standard deviation (sd) of pleotelson widths of A. aquaticus, as well as the number of measured individuals (n), according to sampling month and infection status. Values rounded to two decimals. Note that the total number of measured isopods is 535, as three pleotelson widths were not taken.

Table S4: Pairwise comparisons of the pleotelson width of A. aquaticus between different infection statuses, according to sampling time. P-values and corresponding significance levels are indicated as follows: p < 0.05 = *, p < 0.010 = **, p < 0.001 = ***, ns = not significant.

Table S5: Measured δ¹⁵N and δ¹³C values in isopods and acanthocephalans. “Mean” columns include the mean values of replicates as well as individual measurements if no replicates were available. “SD” columns include the corresponding standard deviation if samples had replicates.

© A. Doliwa et al., published by EDP Sciences, 2025