Lack of change in swimming capacity (Ucrit) following acute salinity exposure in juvenile shortnose sturgeon (Acipenser brevirostrum)
The Saint John River (SJR) is home to the only Canadian population of shortnose sturgeon, Acipenser brevirostrum. Adult shortnose sturgeon routinely enter saltwater to forage, yet less is known about how juveniles cope with the associated osmoregulatory pressures. Recently, it has been shown that short-term (24 h) exposure to saltwater causes significant changes to ion and water levels in juvenile shortnose. In some species of fish, notably salmonids, it has been shown that shifts in fluid and ion levels following saltwater challenges reduce the swimming capacity. The relationship between ion concentration and swimming capacity is not well understood for sturgeon species. Our research aimed to determine whether short-term salt exposure affects swimming ability in juvenile shortnose sturgeon. Juvenile, SJR, hatchery-raised shortnose sturgeon (< 1 year old) were exposed to salinities of 0 (control), 16, or 24‰ for 24 h and then subjected to a critical swimming speed test (Ucrit) to quantify swimming ability. Following the test, the fish were weighed and blood samples were drawn to be analyzed for plasma ion and cortisol levels. While ion levels and weight loss were significantly higher in salt exposed fish, there were no significant differences in critical swimming speed or cortisol concentrations. This is in contrast to what has been observed in salmonids and Adriatic sturgeon. This suggests the hydromineral imbalance caused by moderate salt exposure is not sufficient to affect the swimming performance of shortnose sturgeon. Shortnose sturgeon are not thought to enter the saline stretches of the SJR until roughly 8 years of age, yet this research shows that much younger juveniles withstand moderate salinity for short periods, with little whole-animal ramifications.
KeywordsSturgeon Osmoregulation Critical swimming speed Cortisol
Funding for this research was provided by a Natural Science and Engineering Council Grant of Canada (NSERC) discovery grant to J.D.K. Support was also provided by the MADSAM fish group, and the Marguerite and Murray Vaughan Graduate Fellowship in Marine Science (to F.M.P.). All procedures followed the guidelines of animal use set out by the Canadian Council of Animal Care and were approved by the institution’s Animal Care Committee.
Compliance with ethical standards
All experimental design used in this paper was review and approved by the University of New Brunswick Saint John’s Animal Care Committee, protocol number 2010-4C-01.
- Bell W, Terhune L (1970) Water tunnel design for fisheries research. Fisheries Research Board of Canada, Biological StationGoogle Scholar
- Doroshov SI (1982) The biology and culture of sturgeon. In: Muir JF (ed) Recent Adv Aquac, vol 2. Croon Helm, London, pp 251–274Google Scholar
- Jenkins W, Smith T, Heyward L, Knott D (1993) Tolerance of shortnose sturgeon, Acipenser brevirostrum, juveniles to different salinity and dissolved oxygen concentrations. Proc Annu Conf Southeast Assoc Fish and Wildlife Agencies 47:476–484Google Scholar
- Kieffer JD, Wakefield AM, Litvak MK (2001) Juvenile sturgeon exhibit reduced physiological responses to exercise. J Exp Biol 204:4281–4289Google Scholar
- R Core Team (2015) R: a language and environment for statistical computing. R Foundation for Statistical Computing, ViennaGoogle Scholar