# Effects of topographic complexity on space-use by a key intertidal grazer in artificial environments

## TL;DR

This study explores how the physical complexity of intertidal environments affects the movement of a key species, the common limpet, and how these effects scale up to landscape levels.

## Contribution

This is the first experimental study to assess the direct effects of eco-engineered topographic complexity on the movement of intertidal gastropods.

## Key findings

- Limpets moved greater distances on surfaces with intermediate topographic complexity.
- At landscape scales, random configurations of intermediate complexity panels induced the longest simulated movement paths.
- Lower complexity surfaces resulted in more frequent but shorter movements.

## Abstract

The movement of animals in intertidal environments underpins community structure and is influenced by both abiotic and biotic factors within the environment. Whilst the effects of body size, tidal regime and temperature on the timing and ability of movement have been well-explored, physical features of the environment that generate complexity have received comparatively less attention. Given alterations to the topographic complexity of intertidal habitats associated with climate change and anthropogenic activities, understanding the effects of varying levels of topographic complexity on the movement of intertidal animals is critical to our understanding of biodiversity and ecosystem functioning in these habitats going forward.

We experimentally manipulated topographic complexity using bespoke concrete panels at two scales, the individual panel and configuration of panels in a modelled 2 × 4 m area, to explore the effects of topographic complexity on the movement of a key intertidal gastropod and ecosystem engineer, the common limpet Patella vulgata. Using a combination of time-lapse photography and correlated random-walk modelling, we ‘scaled-up’ these experimental results to model the effects of topographic complexity on movement and space-use at landscape scales.

Results revealed a significant effect of topographic complexity on limpet movement, with greater distances travelled on ‘intermediate’ topographic complexity surfaces (surface areas = 0.08 m2 and 0.09 m2), but more frequent, shorter movements on lowest topographic complexity (surface area = 0.06 m2). At landscape scales, panels with intermediate topographic complexity placed in random configurations at highest spatial cover induced the greatest path lengths of simulated limpets.

This study and its results represent the first experimental assessment of the direct effects of eco-engineered topographic complexity on the small-scale movements of intertidal gastropods and outline a first step towards the mechanistic extrapolation of results to heterogenous landscapes to explore the space-use of gastropods across larger spatial scales. With ongoing changes to intertidal environments resulting from climate change and anthropogenic activities, understanding how the movement of animals is impacted by variation in topographic complexity is essential to predicting future impacts on metapopulation dynamics and ecosystem functioning.

The online version contains supplementary material available at 10.1186/s40462-026-00629-x.