Physiological responses to hypersalinity correspond to nursery ground usage in two inshore shark species (Mustelus antarcticus & Galeorhinus galeus)

• DOI: 10.1242/jeb.139964
• Publication Date: 2016-05-10T01:03:14Z
• Authors: Louise Tunnah; Sara R. C. Mackellar; David A. Barnett; Tyson J. Maccormack; Kilian M. Stehfest; Andrea J. Morash; Jayson M. Semmens; Suzanne Currie
• Keywords: Osmolyte; Chondrichthyes

Shark nurseries are susceptible to environmental fluctuations in salinity because of their shallow, coastal nature; however, the physiological impacts on resident elasmobranchs largely unknown. Gummy sharks (Mustelus antarcticus) and school (Galeorhinus galeus) use same Tasmanian estuary as a nursery ground; each species has distinct distribution patterns that coincident with changes local conditions, such increases salinity. We hypothesized these differences were directly related differential tolerances high To test this hypothesis, we exposed wild, juvenile gummy an environmentally relevant hypersaline (120% SW) event for 48 h. Metabolic rate decreased 20-35% both species, gill Na(+)/K(+)-ATPase activity was maintained but 37% sharks. measured plasma ions (Na(+), K(+), Cl(-)) osmolytes [urea trimethylamine oxide (TMAO)], observed 33% increase Na(+) hyperosmotic exposure, while displayed typical ureosmotic urea (∼20%). With elevated salinity, TMAO concentration increased by 42% 30% Indicators cellular stress (heat shock proteins HSP70, 90 110, ubiquitin) significantly white muscle species- tissue-specific manner. Overall, exhibited greater osmotic perturbation ionic dysregulation larger response compared Our findings provide correlates movement shark critical grounds.