Saline stress tolerance partly matches with habitat preference in ground‐living wolf spiders

Abstract

Salinity interacts with many physiological functions and therefore probably influences the distribution of terrestrial fauna in tidal flooded salt marshes. The present study tests the hypothesis that the physiological tolerance of stenotopic wolf spiders for saline conditions at least partially determines their occurrence throughout salt‐marsh and nonsaline habitats. The duration of survival of three stenotopic wolf spider species (Araneae: Lycosidae) with different habitat preferences is compared in a controlled laboratory experiment. The forest‐dwellingPardosa saltans, the salt‐marsh residentPardosa purbeckensisand its sister species the inland‐livingPardosa agrestisare exposed to experimental conditions with different levels of salinity. Individuals (45 males and 20–45 females per treatment) are placed in individual air‐tight boxes filled with water‐saturated sand. Three levels of salinity are tested: nonsaline (0‰), medium saline (33–35‰) and highly saline (66–70‰). Contents of carbon, hydrogen and nitrogen and the molar ration carbon/nitrogen remain constant over time and do not differ among salinity treatments, indicating that starvation effects on survival, if any, are similar for all treatments. Conversely, body water significantly decreases over time and differs among salinity treatments, in accordance with patterns of survival. Conforming to their habitat preference, the survival ofP. saltansandP. agrestisdecreases quickly under highly saline conditions.Pardosa purbeckensis, however, has a high survival under both saline and nonsaline conditions. The duration of survival of females is significantly lower than that of males ofP. saltansandP. purbeckensis. Durations of survival of ground‐living wolf spiders exposed to salinity partly match their habitat distribution but do not explain the restriction of salt‐marsh species to saline habitats.