Thesis
Ichthyoplankton of the Lower Columbia River Estuary in relation to environmental variables
Washington State University
Master of Science (MS), Washington State University
2008
Handle:
https://hdl.handle.net/2376/102317
Abstract
The Lower Columbia River Estuary (LCRE) is thought to be an important nursery ground for young fish, but this issue has not been studied comprehensively in 25 years. Thus, we examined the community of larval fish in the LCRE, USA, in relation to environmental variables over a full annual cycle (January - December 2006). Larval fish collections occurred monthly from Tongue Pt., OR to the mouth of the river using 0.6 m diameter bongo nets of 335 [mu]m and 500 [mu]m mesh size. Thirty taxa were captured;, Eulachon (Thaleichthys pacificus) was the most abundant species, followed by Prickly Sculpin (Cottus asper), Butter Sole (Isopsetta isolepis) and English Sole (Parophrys vetulus), which together accounted for 94.6% of the total abundance. Peak larval fish abundance occurred in spring, between the months of March and June. Larval fish in the LCRE were absent or in low abundance during summer and fall, which coincide with warmer temperatures and higher salinities as freshwater outflow is reduced in the estuary. Larval fish of oceanic origin (e.g. pleuronectids) were distributed within estuary reaches nearer to the mouth in more saline waters, while estuarine dependant fish (e.g. cottids) were located upriver in brackish waters. Salinity, season and temperature were the environmental variables that best explained the variation seen in the LCRE larval fish assemblage and appear to structure the larval fish community in terms of their abundance, distribution and composition. Our findings, when compared with other studies, indicate that the LCRE assemblage has changed over the past 25 years and is substantially different from other larval fish assemblages in Northeast Pacific estuaries.
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Details
- Title
- Ichthyoplankton of the Lower Columbia River Estuary in relation to environmental variables
- Creators
- Lisa Marie Marko
- Contributors
- Stephen M. Bollens (Degree Supervisor)
- Awarding Institution
- Washington State University
- Academic Unit
- Environment, School of the (CAHNRS)
- Theses and Dissertations
- Master of Science (MS), Washington State University
- Publisher
- Washington State University; [Pullman, Washington] :
- Identifiers
- 99900525151101842
- Language
- English
- Resource Type
- Thesis