title: Time course of the acute response of the North Pacific spiny dogfish shark (Squalus suckleyi) to low salinity.
abstract: Dogfish are considered stenohaline sharks but are known to briefly enter estuaries. The acute response of North Pacific spiny dogfish (Squalus suckleyi) to lowered salinity was tested by exposing sharks to 21‰ salinity for 48 h. Temporal trends in blood pH, plasma osmolality, CO2, HCO3(-), Na(+), Cl(-), K(+), and urea concentrations, and in the rates of urea efflux and O2 consumption, were quantified. The rate of O2 consumption exhibited cyclic variation and was significantly depressed by lowered salinity. After 9 h, plasma [Cl(-)] stabilized at 9% below initial levels, while plasma [Na(+)] decreased by more than 20% within the first 12 h. Plasma [urea] dropped by 15% between 4 and 6 h, and continued to decrease. The rate of urea efflux increased over time, peaking after 36 h at 72% above the initial rate. Free-swimming sharks subjected to the same salinity challenge survived over 96 h and differed from cannulated sharks with respect to patterns of Na(+) and urea homeostasis. This high-resolution study reveals that dogfish exposed to 21‰ salinity can maintain homeostasis of Cl(-) and pH, but Na(+) and urea continue to be lost, likely accounting for the inability of the dogfish to fully acclimate to reduced salinity.
authors: Department of Biological Sciences, CW405 Biological Sciences Bldg, University of Alberta, Edmonton, AB T6G 2E9, Canada; Bamfield Marine Sciences Centre, 100 Pachena Road, Bamfield, BC V0R 1B0, Canada. Electronic address: guffey@ualberta.ca.
authors: Samuel C
authors: SC
authors: Guffey
authors: Department of Biological Sciences, CW405 Biological Sciences Bldg, University of Alberta, Edmonton, AB T6G 2E9, Canada; Bamfield Marine Sciences Centre, 100 Pachena Road, Bamfield, BC V0R 1B0, Canada. Electronic address: ggoss@ualberta.ca.
authors: Greg G
authors: GG
authors: Goss
mesh_terms: D000818:Animals; D001158:Arteries / Q000378:metabolism; D002245:Carbon Dioxide / Q000097:blood; D002712:Chlorides / Q000097:blood; D006863:Hydrogen-Ion Concentration; D009994:Osmolar Concentration; D010101:Oxygen Consumption; D010140:Pacific Ocean; D011188:Potassium / Q000097:blood; D054712:Salinity; D012964:Sodium / Q000097:blood; D048250:Squalus / Q000097:blood / Q000502:physiology*; D013997:Time Factors; D014508:Urea / Q000097:blood
chemical_list: D002712:Chlorides; D002245:Carbon Dioxide; D014508:Urea; D012964:Sodium; D011188:Potassium
keywords: Acclimation; Chloride; Elasmobranch; Euryhaline; Homeostasis; Sodium; Tolerance; Urea