Soil salinity and the salinity of trophic resources may alter the osmoregulatory processes
of arthropod, challenging the smooth regulation of body water, and, ultimately, survival.
The intra and extracellular build-up of osmolytes represent a common strategy to attenuate
acute hyperosmotic stress in several arthropod species. In the present study, we aimed
to determine the impact of substrate and trophic resource salinities on salt tolerance
in the female wolf spider, Arctosa fulvolineata, which is considered a specialist
salt marsh species. We evaluated adult female survival and egg laying, and quantified
the osmo-induced accumulation of compatible solutes (GC-MS). Three concentrations
of substrate salinity were tested (0‰, 35‰ and 70‰) under three trophic conditions
(starved spiders, spiders fed with salt prey [intertidal amphipods] and spiders fed
with unsalted prey [freshwater amphipods]). We found no support for diet preferences
in female A. fulvolineata, which exhibited similar predation rates on freshwater and
marine amphipods. Survival and egg-laying were significantly impaired when female
A. fulvolineata were exposed to hypersaline conditions for 12 days. Our results showed
an increase in the level of several compatible solutes when spiders were exposed for
12 days to saline conditions. For instance, α-alanine, β-alanine, arginine, asparagine,
aspartate, homoserine, glutamine, glycine, proline and serine levels were 4-10 times
higher under hypersaline conditions. The osmo-induced accumulation of amino acids
may increase the osmolality of body fluids, thus enhancing the smooth regulation of
body fluids and survival ability of wolf spider under extreme saline conditions.