Species composition of shoreline wolf spider communities vary with salinity, but their diets vary with wrack inflow

Abstract

Shorelines and other riparian habitats are often described as hotspots for arthropod predators, and spiders in particular seem to thrive in these habitats (Batzer & Wu, 2020;Mellbrand & Hambäck, 2010;Polis & Hurd, 1995). There are several reasons underlying these high spider densities, but an important factor seems to be the high prey density in these near-water habitats (Polis & Hurd, 1995;Sanchez-Ruiz et al., 2018), which also reduces intraguild predation (Wise, 2006). Prey densities are high in these sites both because of a direct inflow of insects from the aquatic environment, such as midges with aquatic larvae and terrestrial adults, and because large inflows of organic material are deposited on shorelines providing food for detritivores and fertilizing plants (Baxter et al., 2005;Colombini & Chelazzi, 2003;Hyndes et al., 2022). At the same time, most shorelines are harsh environments due to flooding and wave disturbance, and on marine shorelines due to a high salinity and a high turnover of organic material (Barboza & Defeo, 2015;