DOI: 10.5061/dryad.q2bvq83zx
title: Micro-refuges or ecological traps: context-dependent effects of rock pools on intertidal biodiversity across latitudes

description: Biodiversity is unevenly distributed across the Earth. At very large
 spatial scales, the decline in species richness from the tropics to the
 poles, the Latitudinal Diversity Gradient (LDG), remains one of the most
 widely recognized patterns in ecology. We investigated how
 local-scale environmental heterogeneity influences biodiversity patterns
 across broad biogeographic gradients, using intertidal
 microhabitats (rock pools and adjacent emergent rock) as a model
 system within one of the most environmentally stressful ecosystems on
 Earth. This Dryad dataset compiles standardized biodiversity and
 microclimate observations from rocky intertidal habitats at 26 locations
 in 21 countries across six continents, spanning 38°S to 60°N
 (2019–2022). Across the survey, 675 taxonomic entities were
 recorded (505 identified to species level), with rock pools containing 618
 taxa (274 unique) and emergent rock 401 taxa (57 unique). Data show that
 microhabitat differences can strongly modify latitudinal biodiversity
 patterns, with pools generally supporting higher taxonomic and functional
 diversity than emergent rock, but with context-dependent outcomes under
 extreme conditions. By mediating exposure to environmental
 stress, intertidal microhabitats provide insight into how fine-scale
 variability interacts with latitudinal stress gradients to shape
 biodiversity distributions. Incorporating microhabitat variability into
 biogeographic frameworks is important for understanding global
 biodiversity patterns and predicting ecological responses to climate
 change.
description: This Dryad dataset compiles standardized biodiversity and
 microclimate observations from rocky intertidal habitats at 26 locations
 in 21 countries across six continents, spanning 38°S to 60°N (2019–2022).
 At each location, two rocky shore sites (≥500 m apart) were sampled during
 locally defined “milder” and “harsher” periods. During each sampling
 event, 20 quadrats (10 × 10 cm) were placed at mid-shore height in (i)
 shallow rock pools (&lt;12 cm; avoiding sediment) and (ii) adjacent
 emergent rock (~20 cm away). Sessile taxa were recorded as percent cover
 (nearest 5%) and mobile/solitary taxa as counts, identified to the lowest
 possible taxonomic level. The dataset also includes functional-group
 assignments and in situ substrate temperature measurements (°C) where
 available (temperature data were collected for 17 of 26 locations),
 alongside R scripts used in the associated analyses.
description: # Micro-refuges or ecological traps: context-dependent effects of rock
 pools on intertidal biodiversity across latitudes Dataset DOI:
 [10.5061/dryad.q2bvq83zx](https://doi.org/10.5061/dryad.q2bvq83zx) ##
 Description of the data and file structure This global dataset contains
 the datasets and R scripts used for analysis in the associated manuscript.
 Data include taxa abundance and richness, functional grouping information
 and environmental temperature records (from direct measurements) from
 intertidal microhabitats in tidepools and emergent rock across sites
 spawning six continents and three oceans. The dataset contains the
 following files: two R scripts with General Aditive Models routine (R and
 Rmd files, see further methodological details in the main manuscript) and
 six CSV files used in these analyses: CODE FILES: *
 **Firth_etal_2026_Richness.R**: R script to reproduce richness-based
 analyses and figures (GAM framework as described in the manuscript
 methods). * **Firth_etal_2026_Functional.Rmd**: R Markdown workflow to
 reproduce functional richness analyses, plots, and model outputs DATA
 TABLES: * **rockpools_dataset.csv**: quadrat-level taxa abundance *
 **rock_pools_tot.csv**: total abundance per sample / summary table *
 **Singletons.csv**: unique taxa counts by treatment/microhabitat (pool vs.
 emergent rock) * **full_dataset_richness.csv**: richness and functional
 richness per sample * **Temp_Data.csv**: in situ microhabitat temperature
 * **rockpools_functions.csv**: functional group assignment for taxa in
 *rockpools_dataset* and *rock_pools_tot* SOFTWARE: Analyses were conducted
 in R using GAMs (e.g., mgcv) and post hoc / plotting tools (e.g., emmeans,
 sjPlot) as described in the manuscript. ### DATA TABLES BREAKDOWN Note:
 The exact column names are given in the header row of each CSV.
 Definitions below describe the intended meaning of the key fields.
 **rockpools_dataset.csv** — Sample-level raw biotic data Description:
 Quadrat-by-quadrat taxon abundance observations across habitats, sites,
 and sampling periods. Key variables: * Province: Country/Location
 identifier (one of 26 global locations across 21 countries) * Location:
 sampled sites (two per province, ≥500 m separation) * Sample: Unique
 identifier per quadrat within site × period × habitat * Treatment:
 MicroHabitat: pool or rock (adjacent emergent rock) * Latitude /
 Longitude: Coordinates for the location or site (see manuscript Table S1
 for details) * Season: milder or harsher and wet or dry * Anthropization:
 level of coastal habitat modification/land based on satellite image
 observation (subjective) * Date: sampling date (day-month) * Benthic cover
 variables (percent cover) * TOT_cov: Total biological and substrate cover
 recorded in the quadrat. * Bare_space: Percentage of uncovered substrate *
 Sediment: Percentage covered by loose or settled sediment *
 Bleached/Burnt_algae: Percentage of algae that are bleached, stressed, or
 dead * Dead_Saccostrea-Mytilus_shells; Percentage of cover made up of dead
 shells * Filamentous_algae: Percentage covered by thin, hair-like algae,
 often fast-growing and disturbance-tolerant. * Biofilm_Periphyton:
 Percentage covered by microbial films * Non-calcareous_crusts: Crusting
 organisms without calcium carbonate skeletons * Crusts: Percentage covered
 by calcareous crusts * Taxa names: Lowest possible morpho-taxonomic
 identification. Numbers indicate abundance: Percent cover for sessile taxa
 (0–100), and counts for mobile taxa **rock_pools_tot.csv** — Sample-level
 totals / summaries Description: Same as *rockpools_dataset.csv* but with
 aggregated biotic summaries per sampling unit (total cover per quadrat).
 Key variables (described above): Province, Location, atitude, Longitude,
 Treatment, Season, Anthropization * Bare_space: percent cover of
 uncolonized (exposed) rock **Singletons.csv** — Unique taxa per
 microhabitat Description: Counts of taxa that occur exclusively in rock
 pools or exclusively on emergent rock within a defined grouping level
 (season x site). This corresponds to the “unique taxa” metric described in
 the manuscript. Key variables (described above): Province, Location,
 Treatment, Season * Pool: number of taxa found only in pools * Rock:
 number of taxa found only on emergent rock **full_dataset_richness.csv** —
 Richness and functional richness table Description: The analysis-ready
 dataset used for functional richness models (number of functions per
 quadrat). Key variables (described above): Province, Location, atitude,
 Longitude, Treatment, Season, Anthropization rich: mean number of
 functions per quadrat (alpha diversity) **rockpools_functions.csv** —
 Functional group assignments Description: Lookup table mapping each taxon
 to a functional group category. Key variables: * Taxonomical variables:
 Phyllum.Division, Class, Order, Family, Genus and Sample (name given by
 samplers = lowest available identification)     Functional grouping
 variables:  * Heterotrophs (Metazoans): herbivores (H.Veg), omnivores
 (H.Omn), carnivores (H.Car), detritivores (H.Det), scavengers (H.Scav) *
 Autotrophs: morpho-functional groups: encrusting (A.Enc), turf (A.Turf),
 sub-canopy (A.SubC), canopy (A.Canop), with calcification subgroups:
 Crustose Coralline Algae (A.CrusC) and Articulated Coralline Algae
 (A.ArtC) **Temp_Data.csv** — In situ microhabitat and temperature data
 Description: Point measurements of substratum temperature (° C) collected
 using temperature loggers or thermocouples during sampling, for both pools
 and emergent rock. Due to limited access to this equipment by some
 researchers, temperature data for both habitats and sampling periods were
 collected for 17 out of the 26 locations (two sites at each location);
 there was no latitudinal bias in this subset. Key variables (described
 above): Province, Location, Treatment, Season, Date * Pool_depth: average
 pool depth from pool's water surface to bottom during low tide *
 major_diameter: larger diameter measurement for the pool during low tide *
 minor_diameter: shorter diameter measurement for the pool during low tide
 * Temp: Temperature (º C) collected during sampling * direction:
 temperature difference between pool and emergent rock: hotter = pool
 measurement was higher than that for its nearby emergent rock
 (pool&gt;rock º C); cooler = pool measurement was lower than that for its
 nearby emergent rock (pool