Fish Physiology and Biochemistry

, Volume 42, Issue 1, pp 219–232

Physiological effects of salinity on Delta Smelt, Hypomesus transpacificus

  • Brittany D. Kammerer
  • Tien-Chieh Hung
  • Randall D. Baxter
  • Swee J. Teh

DOI: 10.1007/s10695-015-0131-0

Cite this article as:
Kammerer, B.D., Hung, TC., Baxter, R.D. et al. Fish Physiol Biochem (2016) 42: 219. doi:10.1007/s10695-015-0131-0


Abiotic factors like salinity are relevant to survival of pelagic fishes of the San Francisco Bay Estuary. We tested the effects of 4 parts per thousand (ppt) salinity increases on Delta Smelt (DS) in a laboratory experiment simulating salinity increases that might occur around the low-salinity zone (LSZ) (<6 ppt). Adult DS, fed 2 % body mass per day, starting at 0.5 ppt [freshwater (FW)], were exposed to weekly step-increases of 4 ppt to a maximum of 10 ppt saltwater (SW) over 19 days, and compared to FW controls. DS (n = 12/treatment per sampling) were sampled at 24, 72, and 96 h (1, 3, and 4 days) post-salinity increase for analyses of hematocrit, plasma osmolality, muscle water content, gill chloride cell (CC) Na+/K+-ATPase (NKA) and apoptosis after being weighed and measured (n = 3 tanks per treatment). No apparent increase in length or weight occurred nor did a difference in survival. Following step-increases in SW, hematocrit increased over time. Other fish responses generally showed a pattern; specifically plasma osmolality became elevated at 1 day and diminished over 4 days in SW. Percent muscle water content (%) did not show significant changes. CCs showed increased NKA, cell size and apoptosis over time in SW, indicating that CCs turnover in DS. The cell renewal process takes days, at least over 19 days. In summary, DS are affected by salinities of the LSZ and ≤10 ppt, though they employ physiological strategies to acclimate.


Delta Smelt Fluorescent confocal microscopy Salinity Na+/K+-ATPase Apoptosis Chloride cells Physiology Low-salinity zone 

Funding information

Funder NameGrant NumberFunding Note
California Sea Grant, University of California
  • 2053

Copyright information

© Springer Science+Business Media Dordrecht 2015

Authors and Affiliations

  • Brittany D. Kammerer
    • 1
  • Tien-Chieh Hung
    • 2
  • Randall D. Baxter
    • 3
  • Swee J. Teh
    • 1
  1. 1.Department of Veterinary Medicine: Anatomy, Physiology, and Cell BiologyUniversity of CaliforniaDavisUSA
  2. 2.Department of Biological and Agricultural EngineeringUniversity of CaliforniaDavisUSA
  3. 3.California Department of Fish and Wildlife, Bay-Delta Region 3StocktonUSA

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