Graduate Thesis Or Dissertation

 

Effects of acute stress and exercise on subsequent seawater adaptation and cortisol dynamics in juvenile steelhead trout (Oncorhynchus mykiss) Público Deposited

Contenido Descargable

Descargar PDF
https://ir.library.oregonstate.edu/concern/graduate_thesis_or_dissertations/qz20sw39d

Descriptions

Attribute NameValues
Creator
Abstract
  • The present study investigated the effects of stress and exercise on seawater (SW) adaptation and cortisol dynamics in juvenile steelhead (Oncorhynchus mykiss). To examine the effects of stress, fish acclimated to freshwater (FW) were subjected for 3 hours to confinement stress in FW, and subsequently SW (25 ppt) was introduced to all tanks. Fish were sampled immediately after the stress treatment, and 1, 7, and 14 days after introduction of SW. Electrolytes, cortisol, glucose and lactate followed the typical pattern that we expected after stress treatment in FW. Fish regained osmotic balance within 24 hours. Glucose concentrations were increasing throughout the experiment and lactate levels stayed elevated during the time spent in SW. IGF-1 did not show an immediate response to stress but after transfer to SW we detected significantly higher concentrations for control fish at days 1 and 14. The differences in IGF-1 levels between stressed and control fish are not reflected in SW adaptability but positive correlations between IGF-1 and electrolyte levels in control fish may indicate its role for osmoregulation. Confinement stress did not impair feed intake subsequently in SW, but our results suggest that feed intake was suppressed by the change of the media from FW to SW. The second study investigated the effects of exercise treatment in FW on SW adaptation and cortisol dynamics in juvenile steelhead. Plasma cortisol and in vitro cortisol secretion by interrenal cells after a 24 hr SW challenge test were neither affected by moderate exercise nor by water temperature (13°C, 21°C), however, plasma osmolality was lower in exercised fish compared to unexercised fish. Half-life (T[subscript 1/2]) of ³H-cortisol was shorter in fish exposed to exercise whereas metabolic clearance rate (MCR) did not respond to exercise treatment. Uptake and retention of corticosteroids in liver and gall bladder were enhanced in exercised fish, and retention of corticosteroids in muscle tissue was longer in unexercised fish. Our findings suggest that exercise likely decreases stress levels in fish and improves the adaptation to seawater (SW) in juvenile steelhead.
Resource Type
Fecha Disponible
Fecha de Emisión
Degree Level
Degree Name
Degree Field
Degree Grantor
Commencement Year
Advisor
Committee Member
Academic Affiliation
Non-Academic Affiliation
Subject
Declaración de derechos
Publisher
Peer Reviewed
Language
Digitization Specifications
  • File scanned at 300 ppi (Monochrome) using ScandAll PRO 1.8.1 on a Fi-6670 in PDF format. CVista PdfCompressor 4.0 was used for pdf compression and textual OCR.
Replaces

Relaciones

Parents:

This work has no parents.

En Collection:

Elementos