DOI: 10.5061/dryad.3tx95x6rj
title: Data from: Flow intermittence shapes fish metacommunity variability in a Neotropical ecoregion

description: Drying River Networks (DRNs) comprise intermittent reaches that cease to
 flow or dry, and these networks are becoming more prevalent with ongoing
 climate change. However, their distribution, constituent species, and
 ecological processes remain underexplored in the Neotropics, limiting our
 ability to predict future scenarios for freshwater biodiversity. Drying is
 a strong environmental filter, leading to low α-diversity at intermittent
 reaches as taxa lacking adaptations to resist and recover from drying are
 lost. Additionally, because drying creates a complex mosaic of lotic and
 lentic habitats that change through time, β-diversity (variability in
 community composition) is high in intermittent reaches. To explore these
 dynamics, we analyzed the influence of local and regional factors on the
 spatio-temporal variability of a fish metacommunity in the Chocó
 Biodiversity hotspot in Northwestern Ecuador. Fish α-diversity was lower
 in intermittent reaches during both seasons, while temporal β-diversity
 was higher at perennial reaches. Distinct fish assemblages were indicative
 of intermittent and perennial reaches, with community composition being
 stable in intermittent reaches but more variable in perennial reaches.
 Lastly, metacommunity analysis suggests that environmental filtering was
 the primary community assembly process, with species being replaced along
 the environmental gradient of the river network. Physical distance was
 important in structuring communities but only for fish species with low
 dispersal abilities, indicating that for these species, dynamics may be
 controlled by hydrological connectivity. Our findings suggest that
 variability in fish communities results from seasonal intermittence and
 species-specific habitat preference, partially confirming previous
 hypotheses regarding the determinants of fish diversity in DRNs.
description: # Data from: Flow intermittence shapes fish metacommunity variability in a
 Neotropical ecoregion
 [https://doi.org/10.5061/dryad.3tx95x6rj](https://doi.org/10.5061/dryad.3tx95x6rj) ## Description of the data and file structure This dataset contains two separate files: one with environmental data and one containing fish abundance data from samples collected at perennial and intermittent reaches of a drying river network (DRN) in the Cube River basin, western Ecuador, across wet and dry seasons. Both files are in comma-separated values format. 1. Cube_fish_env_2021.csv refers to environmental variables collected in two sampling seasons of 2021 2. Cube_fish_spp_2021.csv refers to the species collected in two sampling seasons of 2021 The environmental dataset file (Cube_fish_env_2021.csv) is organized with sampled environmental variables as columns and samples (reach IDs) from both seasons as rows. ###### ***Variables*** * Alti = Elevation (m) * Slope = Slope * Width = Average wetted width (m) * Velo = Avg velocity macroinvertebrates (m/s) * Depth = Maximum depth (cm) * Temp = Temperature (°C) * Ph = pH * Cond = Conductivity (µS/cm) * Specific_c = Specific conductivity (µS/cm) * DO = Oxygen (mg/l) * Oxygen_Sat = (Oxygen saturation %) * Disch = Discharge (L/s) * Chla = chlorophyll *a* * AFDM = biofilm ash-free dry mass (mg/L) * Luse = Land use, 1: surrounded by forest, 0: surrounded by crops/pastures *  F⁻ = Fluoride (mg L⁻¹) * SO₄²⁻ = Sulfate: mg L⁻¹ * PO₄³⁻ = Phosphate: mg L⁻¹ *(unless reported as P; then mg P L⁻¹)* * SS = Suspended Solids (TSS) (mg L⁻¹) * TOC = Total Organic Carbon (mg L⁻¹) * Ba²⁺ = Barium (µg L⁻¹) * Ca²⁺ = Calcium (mg L⁻¹) * K⁺ – Potassium (mg L⁻¹) * Mg²⁺ = Magnesium (mg L⁻¹) * Na⁺ = Sodium (mg L⁻¹) * Pb²⁺ = Lead (µg L⁻¹) * Zn²⁺ = Zinc (µg L⁻¹) * Season = Wet or Dry * Flow = The classification of the sampled reach based on its flow regime, indicating whether it is perennial (flowing year-round) (Per) or non-perennial (temporal or intermittent, with periods of no flow) (Int). The fish abundance dataset file (Cube_fish_spp_2021.csv) is organized with species identities as columns and sampled reaches (reach IDs) from both seasons as rows; values represent species abundances, and zeros indicate that no individuals of a given species were detected at that reach. ## Code/software All R packages and functions used for data processing are specified in the associated publication.