Stress, osmoregulation, and the hormone cortisol in yearling coho salmon, Oncorhynchus kisutch Public Deposited

http://ir.library.oregonstate.edu/concern/graduate_thesis_or_dissertations/tm70mx50p

Descriptions

Attribute NameValues
Creator
Abstract or Summary
  • Freshwater (FW) and seawater (SW) acclimated yearling coho salmon, Oncorhynchus kisutch, were subjected to severe confinement stress in FW, SW, or a medium (1/3 SW) that was approximately isosmotic to the fish's blood. Chronic stress caused osmotic imbalances in FW and SW, but not in 1/3 SW. In SW, blood osmolarity and electrolyte concentrations increased, while in FW they generally decreased. Acclimation conditions (FW or SW) before stress influenced the severity and duration of the osmotic imbalance. Confinement stress greatly amplified the osmotic imbalance following transfer from FW to SW compared to that in unconfined fish whose water supply was switched from FW to SW. Plasma cortisol levels during stress were also affected by acclimation conditions and ambient salinity. Plasma cortisol levels increased during acclimation to SW. Maxmimal concentrations of approximately 220 ng/ml occurred within 1.5 h after the water source was switched from FW to SW. After 21 d in SW, cortisol levels were still slightly elevated (23 ng/ml) compared to those in FW control fish (4 ng/ml). Chronic treatment with cortisol lowered gill Na+-K+-ATPase levels in FW fish but did not affect plasma osmolarity, Na, K, Ca, or Mg levels in fish in FW or during acclimation to SW. Thyroxine (T) and triiodothyronine (T3) levels in plasma increased significantly after ambient water was switched from FW to SW. Maximal levels of T3 (8.0 ng/ml) occurred within 12 h after the initial exposure to SW, followed by a return to FW basal levels (4.0 ng/mi) within 24 h. Plasma T levels were higher than FW control levels (4.2 ng/ml) for at least 120 h after exposure to SW; peak levels (14.3 ng/ml) occurred at 12 and 72 h. Chronic treatment with cortisol significantly lowered plasma T3 levels in FW and during acclimation to SW; but it had no significant effect on T concentrations. The metabolic clearance rate of corticosteroids determined after a single injection of 3H-cortisol was higher in SW- than in FW-acclimated fish. Uptake and retention of corticosteroids in liver, gill filaments, and gall bladder bile was greater in SW than in FW fish. The stress of long-term (5 d), but not short-term (12 h), continuous confinement apparently increased the clearance rate of corticosteroids in both FW and SW fish. Chronic, but not acute, administration of exogenous cortisol at physiological levels appeared to increase the clearance rate of corticosteroids in FW fish.
Resource Type
Date Available
Date Copyright
Date Issued
Degree Level
Degree Name
Degree Field
Degree Grantor
Commencement Year
Advisor
Committee Member
Academic Affiliation
Non-Academic Affiliation
Subject
Rights Statement
Peer Reviewed
Language
Digitization Specifications
  • File scanned at 300 ppi (Monochrome) using Capture Perfect 3.0.82 on a Canon DR-9080C in PDF format. CVista PdfCompressor 4.0 was used for pdf compression and textual OCR.
Replaces
Additional Information
  • description.provenance : Made available in DSpace on 2011-08-10T19:01:33Z (GMT). No. of bitstreams: 1 ReddingJosephMichael1983.pdf: 1092754 bytes, checksum: 83058af858f0183eb639ee827c62c6f1 (MD5) Previous issue date: 1982-12-12
  • description.provenance : Approved for entry into archive by Anna Opoien(anna.opoien@oregonstate.edu) on 2011-08-09T23:52:04Z (GMT) No. of bitstreams: 1 ReddingJosephMichael1983.pdf: 1092754 bytes, checksum: 83058af858f0183eb639ee827c62c6f1 (MD5)
  • description.provenance : Submitted by Eric Vanderwall (ewscanner@gmail.com) on 2011-08-02T17:25:07Z No. of bitstreams: 1 ReddingJosephMichael1983.pdf: 4498505 bytes, checksum: 69f045c0400fd9599d8b30a29686d44b (MD5)
  • description.provenance : Approved for entry into archive by Anna Opoien(anna.opoien@oregonstate.edu) on 2011-08-10T19:01:33Z (GMT) No. of bitstreams: 1 ReddingJosephMichael1983.pdf: 1092754 bytes, checksum: 83058af858f0183eb639ee827c62c6f1 (MD5)
  • description.provenance : Rejected by Deborah Campbell(deborah.campbell@oregonstate.edu), reason: Not ocr'ed. on 2011-08-03T22:23:29Z (GMT)
  • description.provenance : Submitted by Eric Vanderwall (ewscanner@gmail.com) on 2011-08-04T17:02:55Z No. of bitstreams: 1 ReddingJosephMichael1983.pdf: 1092754 bytes, checksum: 83058af858f0183eb639ee827c62c6f1 (MD5)

Relationships

In Administrative Set:
Last modified: 08/02/2017

Downloadable Content

Download PDF
Citations:

EndNote | Zotero | Mendeley

Items