Data and code from: Spatiotemporal environmental gradients shape early life stage fish densities, assemblage structure, and growth in river-reservoir ecosystems

Early life stage fishes are susceptible to variation in environmental gradients, which dictate growth and survival, ultimately shaping adult assemblages. Creation of river-reservoir ecosystems (RRE) by impounding rivers results in longitudinal zonation within the reservoir (i.e., riverine, transition, and lacustrine zones) and gradients owing to changes in temperature, flow, turbidity, food availability, and physical structure. We quantified relationships among density, assemblage structure, size structure and daily growth rates of early life stage (ELS) fishes and environmental conditions across zones of eight RRE in central Ohio. We observed significantly higher densities in upstream zones of RRE, correlated with increases in littoral and floodplain habitat (p < 0.001). Fish assemblage structure was similar across zones from river inflows to the dam, but more variable temporally due to seasonal differences in water temperature (p < 0.001), and spawning periodicity. Fish size inc..., , # Data and code from: Spatiotemporal environmental gradients shape early life stage fish densities, assemblage structure, and growth in river-reservoir ecosystems

Dataset DOI: [10.5061/dryad.9cnp5hr0f](https://doi.org/10.5061/dryad.9cnp5hr0f)

## Description of the data and file structure

The description of data collected for the manuscript titled \"Spatiotemporal environmental gradients shape early life stage fish densities, assemblage structure, and growth in river-reservoir ecosystems\" is provided.

### Files and variables

#### Folder: RRE_27FEB2026.zip

**Description:** Within this folder contains an r project \"RRE_2.Rproj\", .an \"R_Code\" folder containing .R code required to run analysis, and a \"Data\" folder containing .csv files needed to run .R scripts. Each folder is described in detail below. 

#### Folder: R_Code

This folder contains .R code required to analyze data. Each .R file within the folder is described below.

**File: Density Analysis_30JAN2026.R**

Description: This..., ,