Drivers of saltmarsh spider assemblages in a coastal lagoon: Implications for biodiversity assessment and habitat management
Drivers of saltmarsh spider assemblages in a coastal lagoon: Implications for biodiversity assessment and habitat management
Abstract
Saltmarshes provide valuable ecosystem services but face increasing degradation from land-use changes, and climate-driven sea-level rise. In Baixo Vouga Lagunar (Ria de Aveiro, Portugal), a partially constructed flood bank built in the late 1990s to prevent saline intrusion into agricultural fields created a mosaic of hydrological conditions and a unique setting to explore how environmental gradients and vegetation structure influence saltmarsh arthropod communities. Spiders have been extensively used as bioindicator species due to their rapid response to environmental changes. This study aimed to identify key ecological drivers structuring saltmarsh ground-dwelling spider assemblages across a gradient of tidal exposure, vegetation, and soil conditions. Spiders were collected using pitfall traps in spring and autumn along four transects at varying distances from the flood bank. In addition, vegetation composition, and soil parameters (pH, salinity, organic matter) were characterized at each transect. A total of 4193 spider individuals from 38 species across 15 families were identified. We used a “fourth-corner” analysis, which integrates species traits and environmental variables through the distribution of species to test whether specific traits were associated with particular environmental conditions. Spider assemblages responded more strongly to vegetation composition than directly to abiotic conditions, suggesting that environmental filtering operates indirectly through vegetation. Functional richness was lowest in areas farthest from the flood bank, where vegetation was less heterogenous. Pardosa pullata group (Araneae, Lycosidae) was the most abundant group. These findings provide baseline data before land-use change, namely potential flood bank completion and suggest spiders are effective indicators of fine-scale habitat variation in saltmarshes.
Ameixa, O., Šipoš, J., Machač, O., Lillebø, A. I., & Sousa, A. I. (2025). Drivers of saltmarsh spider assemblages in a coastal lagoon: Implications for biodiversity assessment and habitat management. Global Ecology and Conservation, 64, e03984. https://doi.org/10.1016/j.gecco.2025.e03984