Thesis
Ichthyoplankton dynamics in relation to prey availability and environmental variables in a northeast Pacific estuary (Willapa Bay, WA, USA)
Washington State University
Master of Science (MS), Washington State University
2012
Handle:
https://hdl.handle.net/2376/102430
Abstract
The relative importance of prey resources versus abiotic environmental variables in structuring larval fish communities is a matter of much interest and debate. We therefore conducted a 13-month (July 2008-July 2009) field study in Willapa Bay, Washington, in which we sampled ichthyoplankton, potential prey of larval fish, and other environmental variables including temperature, dissolved oxygen, riverflows, and upwelling. Cluster analysis showed the ichthyoplankton community and environmental conditions were characterized by two distinct seasons (summer and winter). Arrow Goby larvae dominated in the summer season, while five other larval fish taxa were found during the winter season: Surf Smelt, Pacific Staghorn Sculpin, Eulachon, High Cockscomb, and Prickly Sculpin. Non-metric multidimensional scaling showed temperature, dissolved oxygen, river flow, and magnitude of upwelling or downwelling to have the strongest influence on ichthyoplankton communities, while various zooplankton prey taxa and sizes were found to be much less important. The only larval fish species found to occur in peak abundance coincident with peak zooplankton abundance (38-100 µm width) was the Arrow Goby. The winter ichthyoplankton abundance and community composition was not associated with any taxon or size of zooplankton prey. This apparent trophic decoupling between larval fish and metazoan prey could be explained by several factors, such as the under-appreciated role of protozoan microprey, an 'extended critical period' for late larval or juvenile fish, and/or sampling bias. Nevertheless, our results point to physical-chemical factors and processes as strong drivers of ichthyoplankton community dynamics.
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Details
- Title
- Ichthyoplankton dynamics in relation to prey availability and environmental variables in a northeast Pacific estuary (Willapa Bay, WA, USA)
- Creators
- Carl. J. Wepking
- 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
- 99900525019101842
- Language
- English
- Resource Type
- Thesis