Dissertation
DISTRIBUTION OF DEEP-WATER CORAL AND SPONGE HABITATS OFF WASHINGTON AND OREGON AND THEIR FUNCTIONAL LINKS AS FISH HABITAT
Doctor of Philosophy (PhD), Washington State University
01/2016
Handle:
https://hdl.handle.net/2376/117704
Abstract
Emerging evidence suggests that deep-sea sponges and corals (DSCS) are important sources of structurally complex habitat for some demersal fishes. The functional role of these habitats; however, is still being elucidated, particularly their value as essential fish habitat (EFH) for groundfish along the US West Coast.
In the first chapter of this dissertation, the distribution of DSCS habitats and diel association patterns by demersal fishes were examined on Heceta Bank, located off central Oregon. The second chapter compares inter-site patterns in DSCS distributions and fish associations at Heceta Bank and the Olympic Coast National Marine Sanctuary (OCNMS), located off Washington State. While DSCS distributions at both sites appeared to be influenced by several similar environmental factors, including substrate type and water depth, DSCS densities were significantly higher at OCNMS than at Heceta Bank. The findings highlight that several fish taxa were associated with DSCS habitats. Overall, however, only a small proportion of the total fish community (<7%) at either site were associated with DSCS. Over 90% of these associations were with rockfishes (Sebastes spp.). Associations mostly occurred at the broadest spatial scale examined (≤1 m) with few displaying actual physical contact. At night fishes were more likely to be associated with DSCS, and were more sedentary and to associate with DSCS over smaller spatial scales. Overall, there was a high degree of variability in associations amongst taxa.
Finally, the third chapter examines a series of habitat suitability models developed for five sponges and one coral taxa on Heceta Bank. The models used a range of physical and environmental variables thought to influence DSCS distributions. The fair to excellent model fits obtained for most DSCS taxa strongly support the use of species distribution models for predicting the distributions of both deep-sea coral and sponge habitats. Models predicted that the majority of high suitability deep-sea coral and sponge habitat occur outside of current EFH closure.
Discerning how and under what conditions DSCS habitats are utilized by demersal fishes as EFH is fundamental to improving our understanding the ecological role of these habitats and for developing effective strategies for their management.
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Details
- Title
- DISTRIBUTION OF DEEP-WATER CORAL AND SPONGE HABITATS OFF WASHINGTON AND OREGON AND THEIR FUNCTIONAL LINKS AS FISH HABITAT
- Creators
- Sean Charles Rooney
- Contributors
- Brian Tissot (Advisor)Alexander Dimitrov (Committee Member)Elizabeth M Clarke (Committee Member)Christopher Rooper (Committee Member)Stephen Bollens (Committee Member)
- Awarding Institution
- Washington State University
- Academic Unit
- Environment, School of the (CAHNRS)
- Theses and Dissertations
- Doctor of Philosophy (PhD), Washington State University
- Number of pages
- 200
- Identifiers
- 99900581631301842
- Language
- English
- Resource Type
- Dissertation