Geomorphic and Climatic Controls on Water Temperature and Streambed Scour, Copper River Delta, Alaska : Implications for Understanding Climate Change Impacts to the Pacific Salmon Egg Incubation Environment Public Deposited

http://ir.library.oregonstate.edu/concern/graduate_thesis_or_dissertations/4j03d234z

Descriptions

Attribute NameValues
Creator
Abstract or Summary
  • Pacific salmon (Oncorhynchus spp.) face numerous challenges associated with climate change. Most research has emphasized the potential effects of elevated summer water temperatures; however, climatic changes are also projected to significantly alter incubation and rearing habitats during the late autumn, winter, and spring months ("the incubation period"). Along the southern coast of Alaska, projected climatic changes include increases in the frequency of above freezing winter temperatures and reductions in low elevation snowpack. These changes are expected to impact the hydrology of salmon streams by increasing both water temperatures and the magnitude and frequency of winter floods. Projected increases in water temperature may accelerate embryo development, impacting juvenile viability. More powerful and more frequent winter floods could reduce the survival of salmon eggs by increasing streambed scour. Here, I investigate climatic and geomorphic controls of water temperature and potential scour depth at salmon spawning and rearing sites on the Copper River Delta, a large coastal foreland in Southcentral Alaska. In chapter 2, I utilized surface water temperature data collected at 18 sites to test the abilities of regression models to project year-round water temperature metrics based on catchment characteristics (elevation, slope, area, percent lake area) and air-water temperature correlations. Considerable variability in water temperature was observed on spatial and temporal scales. Both temperature maxima and the frequency of freezing conditions were positively correlated with percent lake area and negatively correlated with catchment elevation and slope. Sites with upwelling groundwater and sites with high-relief, high elevation catchments exhibited lower thermal sensitivity and water temperatures are anticipated to be less impacted by projected climatic changes. In chapter 3, I utilized surface and streambed water temperature data collected at 8 spawning sites to compare water temperatures during incubation periods under climatological mean ("severe winter") and anomalously warm ("mild winter") conditions. I also collected stream stage and channel geometry data at a subset of 3 sites and calculated streambed scour at bankfull discharge. The magnitude and seasonality of accumulated thermal units (°C/day) (ATU) within spawning gravels varied significantly between severe and mild winters at shallow flowpath sites, but not at upwelling groundwater sites. When seasonal snow and ice was absent, increases in spring ATU at shallow flowpath sites were particularly significant. Modelled mean scour depths varied from 3 to 72 cm, suggesting the impacts of scour on egg mortality will be variable across the landscape. I conclude that the impacts of projected climatic changes are likely to vary in magnitude across the Copper River Delta, even at small spatial scales, due to heterogeneity in climatic and geomorphic controls.
Resource Type
Date Available
Date Copyright
Date Issued
Degree Level
Degree Name
Degree Field
Degree Grantor
Commencement Year
Advisor
Committee Member
Non-Academic Affiliation
Keyword
Subject
Rights Statement
Peer Reviewed
Language
Replaces
Additional Information
  • description.provenance : Approved for entry into archive by Laura Wilson(laura.wilson@oregonstate.edu) on 2016-05-05T20:38:25Z (GMT) No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: bb87e2fb4674c76d0d2e9ed07fbb9c86 (MD5) AdelfioLucaA2016.pdf: 7209776 bytes, checksum: f85f81aaa7759b05c79d571c0917cf64 (MD5)
  • description.provenance : Made available in DSpace on 2016-05-05T20:38:26Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: bb87e2fb4674c76d0d2e9ed07fbb9c86 (MD5) AdelfioLucaA2016.pdf: 7209776 bytes, checksum: f85f81aaa7759b05c79d571c0917cf64 (MD5) Previous issue date: 2016-04-21
  • description.provenance : Approved for entry into archive by Julie Kurtz(julie.kurtz@oregonstate.edu) on 2016-05-05T18:42:13Z (GMT) No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: bb87e2fb4674c76d0d2e9ed07fbb9c86 (MD5) AdelfioLucaA2016.pdf: 7209776 bytes, checksum: f85f81aaa7759b05c79d571c0917cf64 (MD5)
  • description.provenance : Submitted by Luca Adelfio (adelfiol@oregonstate.edu) on 2016-05-03T01:48:04Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: bb87e2fb4674c76d0d2e9ed07fbb9c86 (MD5) AdelfioLucaA2016.pdf: 7209776 bytes, checksum: f85f81aaa7759b05c79d571c0917cf64 (MD5)

Relationships

In Administrative Set:
Last modified: 08/14/2017

Downloadable Content

Download PDF
Citations:

EndNote | Zotero | Mendeley

Items