The effects of single and multiple pathogen and parasite infections on juvenile chinook and coho salmon during early marine residency Public Deposited

http://ir.library.oregonstate.edu/concern/graduate_thesis_or_dissertations/k3569686h

Descriptions

Attribute NameValues
Creator
Abstract or Summary
  • Nearly 3000 juvenile Chinook (Oncorhynchus tshawytscha) and coho (O. kisutch) salmon captured in nearshore waters off the coasts of Washington and Oregon from 1999-2004 were tested for infection by Renibacterium salmoninarum, Nanophyetus salmincola, and skin metacercariae. First, three quantitative PCR primer/probe sets were compared for detection of R. salmoninarum; amplification of the single copy abc gene was best at detecting medium-high levels of infection and was used in subsequent studies. Parasite infections were detected visually. Infection by N. salmincola was the most common single infection among all juvenile salmon (55.2%), followed by R. salmoninarum (27.5%) and skin metacercariae (16.5%). Infection by R. salmoninarum was highest in 2000, with 54.8% of all juvenile salmon infected, and was much lower in 2004 (<10%). Subyearling (but not yearling) Chinook salmon infected by N. salmincola had significantly reduced growth; skin metacercarial infection was associated with significantly reduced growth only for coho salmon. Infection by R. salmoninarum was associated with significantly reduced growth in yearling Chinook salmon and coho salmon. Multiple infections did not have significantly more severe effects on growth than single infections, although the prevalence of triple infections was very low. The prevalence of R. salmoninarum was significantly and positively correlated with increased survival for both yearling Chinook and coho salmon. To better understand the apparent paradox that higher prevalences correlate with increased survival, we examined the effects of ocean conditions using the summer Pacific Decadal Oscillation (PDO) index as an indicator of good (cold) or bad (warm) ocean condition years. The years 1999-2002 were cold ocean years, and 2003-2004 were warm ocean years. The prevalence of R. salmoninarum was significantly higher in cold years, when ocean conditions were favorable, and more salmon with severe infections were captured; there was no effect of infection on growth. In the summers of warm years, infected yearling Chinook and coho salmon had significantly reduced growth, and the prevalence and severity of R. salmoninarum infections declined. These data indicate that the infection is less detrimental in years with favorable ocean conditions, and suggest that R. salmoninarum infection may be a mechanism linking ocean indices to salmon survival.
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
Keyword
Subject
Rights Statement
Language
Replaces
Additional Information
  • description.provenance : Approved for entry into archive by Julie Kurtz(julie.kurtz@oregonstate.edu) on 2010-06-30T20:26:00Z (GMT) No. of bitstreams: 1 SandellToddA2010.pdf: 1498841 bytes, checksum: 90fb19a1b141cf3c3cadd2954aa58dde (MD5)
  • description.provenance : Submitted by Todd Sandell (sandellt@onid.orst.edu) on 2010-06-29T02:25:39Z No. of bitstreams: 1 SandellToddA2010.pdf: 1498841 bytes, checksum: 90fb19a1b141cf3c3cadd2954aa58dde (MD5)
  • description.provenance : Made available in DSpace on 2010-06-30T21:20:46Z (GMT). No. of bitstreams: 1 SandellToddA2010.pdf: 1498841 bytes, checksum: 90fb19a1b141cf3c3cadd2954aa58dde (MD5)
  • description.provenance : Approved for entry into archive by Laura Wilson(laura.wilson@oregonstate.edu) on 2010-06-30T21:20:46Z (GMT) No. of bitstreams: 1 SandellToddA2010.pdf: 1498841 bytes, checksum: 90fb19a1b141cf3c3cadd2954aa58dde (MD5)

Relationships

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

Downloadable Content

Download PDF
Citations:

EndNote | Zotero | Mendeley

Items