Using environmental DNA metabarcoding to determine endangered Redside Dace occurrence and associated community composition in urban streams

Redside Dace, an endangered fish native to the Greater Toronto Area (GTA), faces significant threats from urbanization, which has degraded its habitat and water quality. Understanding its current distribution is essential for guiding conservation efforts, identifying critical habitats for protection, and targeting degraded areas for restoration. We collected water samples from streams previously inhabited by Redside Dace in the GTA and used eDNA metabarcoding to determine its contemporary distribution and the associated fish communities. As expected, Redside Dace was less frequently detected in heavily urbanized streams, highlighting the negative impact of urbanization. Co-occurrence analysis identified nine positive associations with other fish species, many of which inhabit cool water streams and build nests, suggesting possible shared habitat preferences or reliance on these species as nest hosts. This study emphasizes the value of eDNA metabarcoding in assessing urbanization’s effec..., , # Using environmental DNA metabarcoding to determine endangered Redside Dace occurrence and associated community composition in urban streams

Dataset DOI: [10.5061/dryad.9p8cz8wvr](10.5061/dryad.9p8cz8wvr)

## Description of the data and file structure

The data were collected as part of an environmental DNA (eDNA) monitoring study aimed at assessing the distribution and community structure of the endangered Redside Dace (*Clinostomus elongatus*) in urban streams. Field sampling involved the collection of water samples from multiple sites across the Greater Toronto Area, followed by metabarcoding analyses to detect Redside Dace presence and characterize associated fish communities.

### Files and variables

#### File: R_script_for_processing_blast_results.R

* R script created to process blast results and create tables to analyze the data

#### File: RSD_habitat_eDNA_2020.xlsx

* File created to assign standardized site codes to water bodies for consistent reference throughout the stud...,