# Land use drives trematode dynamics in a restored stream system

## TL;DR

This study shows that land use, especially agriculture, strongly influences trematode infections in snails in restored urban streams.

## Contribution

The study reveals that land use, not restoration history, is the main driver of trematode dynamics in urban freshwater systems.

## Key findings

- Agricultural areas had higher trematode species richness and prevalence compared to forested or urban areas.
- Trematode communities in snails recovered quickly in restored habitats, regardless of restoration history.
- Ampullaceana balthica snails were the primary hosts for most trematode species and showed the highest infection rates.

## Abstract

Urban freshwater ecosystems are subjected to multiple anthropogenic and natural stressors, emphasizing the need to evaluate and restore their ecological status amid ongoing biodiversity loss. While successional dynamics of free-living taxa are commonly assessed, the environmental drivers shaping parasite-host interactions in degraded and restored systems remain poorly understood. Here, we examined trematode species richness, overall prevalence, and community composition in first intermediate snail hosts across an urban stream system with a history of severe degradation and gradual restoration. Over two years of monthly sampling, we assessed differences in trematode dynamics across restoration stages and adjacent land-use types. We examined 6300 snails of 13 different species and identified 25 trematode species with an overall prevalence of 19.1%. Adjacent land use emerged as a consistent predictor of trematode dynamics, with agricultural sites supporting higher species richness and prevalence than forested or urban sites. In contrast, trematode community composition showed limited spatial turnover and did not differ substantially with restoration history or land use. Restoration history was not associated with trematode richness, overall prevalence, or community composition, suggesting quick recovery of trematode-host assemblages in recently restored habitats. The most abundant snail, Ampullaceana balthica, was identified as a key host species, harboring the majority of trematode taxa and the highest infection prevalence. Overall, our results highlight land use as a dominant landscape-level driver of trematode dynamics in urban freshwater ecosystems and support the potential of trematodes as complementary bioindicators for assessing ecological conditions in restored habitats.

Image 1

•Two-year study of snail-trematode dynamics in a restored urban freshwater system.•Agricultural land use increases trematode richness and prevalence.•Trematode communities establish rapidly, independent of restoration history.•Ampullaceana balthica as a key host with the highest trematode diversity and prevalence.

Two-year study of snail-trematode dynamics in a restored urban freshwater system.

Agricultural land use increases trematode richness and prevalence.

Trematode communities establish rapidly, independent of restoration history.

Ampullaceana balthica as a key host with the highest trematode diversity and prevalence.