DRAFT REPORT
SIUSLA W DREDGED MATERIALDISPOSAL SITE Benthic InfaunaAnd Demersal Fish Evaluation ContractNumber: W9127N-08-P-0259 Prepared For: u.S. Army Corps ofEngineers Portland District Portland, Oregon

Prepared By: Marine Taxonomic Services, Ltd.

5125 NW Crescent Valley Dr.

Corvallis, OR 97330-9721 January, 2009Table 1 Table 2 Table3A &B Table4 Tables 5A&B Table 6 Table7A &B LIST OF TABLES

Station Locations for the Siuslaw ODMDS Study Sediment Grain Sizes and Total Organic Carbon StatisticalData SummaryTables Relative Densities ofMajorTaxa DominantFiveFaunafrom Each Station DensityData

- Eight MostDominant Species Each Cruise Trawl Data

iii1 2 3 4 5 6 7 8 9 10 11 Appendix Appendix Appendix Appendix Appendix Appendix Appendix Appendix Appendix Appendix Appendix LIST OF APPENDICES

Station Locations List ofEquations UsedinAnalysis ofInvertebrate Data PlotofInvertebrate Diversity (R') Plot ofShannonDiversity Value (SDV) Plot ofEvenness Value (1') Plot ofSpeciesRichness (SR) Relative Densities

- Major TaxaGroups FiveMost Dominant Species From Each Station EightMost Dominant Species FromEach Cruise Trawl Data Species DataByStation



### v

### METHODS AND MATERIALS
The purpose of this study is to supplement the earlier benthic data and provide information about the fish and epibenthic species present in the study area (see map, Figure 1and Table 1, Appendix 1for station locations).
This study consisted oftwo separate tasks. The benthic infaunal study (Task 1) used a modified Gray-O'Hara box core to take five biological cores and one geological core at each ofthe ten predetermined sampling sites.
The demersal fish and epibenthic study (Task 2) used a 12 foot semi-balloon otter trawl with a**~** 

### inch mesh liner to take twenty minute (bottom time) trawls at each ofthe six predetermined trawl tracks. Both studies were undertaken in early August and again in September of 2008.
The geological samples were placed in a pre-labeled zip-lock style bag, cooled, and shipped to Columbia Analytical Services Laboratory in Kelso, Washington for grain size and sediment chemistry analysis. Geological samples were only taken during the early August cruise. Biological samples for both cruises were sieved through a 0.5 mm screen and the retained material was placed in a container and fixed with a 10% solution ofbuffered formalin and seawater for a minimum of72 hours. The samples were then rewashed through a 0.25mm screen to remove the formalin solution and transferred to appropriately sized containers. These containers were filled with a mixture of70% isopropyl alcohol and Rose Bengal stain. Rose Bengal is a protein stain added to facilitate sorting the animals from anyretained detritus. Each samplewas sorted under a dissecting microscope and all animals were removed and placed in major groups, i.e. Polychaeta, Mollusca, Crustacea, Echinodermata and miscellaneous groups. Taxonomists then identified all organisms to the lowestpractical taxa.

3TABLE 2 Sediment Grain Size and Total Organic CarbonData

StationNumber % Sand 1 98.3 2 98.7 3 99.2 4 98.4 5 97.2 6 97.3 7 98.6 8 97.8 9 88.0 10 99.0 % Total Organic Carbon 0.07 0.06 0.07 0.07 0.14 0.08 0.05 0.08 0.40 0.05

Total organic carbon was also performed on the geological sediment samples. Low organic carbon numbers were present at all stations. The data ranged from 0.40-0.05 percent ofthe total volume.
The invertebrate fauna found in the box core samples were typical ofthe nearshore high energy environment found along the Oregon coast. The infaunal data were computer analyzed and the following components ofcommunity structure were calculated: a) H', the Shannon-Weaver diversity index (Shiumon-Weaver, 1963); b) SDV, the Simpson Diversity Value (Simpson, 1949); c) SR, species richness, defined by Margalef(1958) as the number of species in a sample; and d) 

### J', evenness, defined as the distribution of individuals among species (Lloyd and Ghelardi, 1964) (see equations, Appendix 2).

5These data also show several commercially and recreationally important species present in the study area. Most of the specimens are juvenile or sub-legal individuals. Commercially and recreationally important species include the following: Cancermagister (Dungeness crab) Citharichthys sp. (Sand dab) Isopsetta isolepis (Butter sole) Psettichthys melanostictus (Sand sole) Ophiodon elongates (Ling Cod) Parophrys vetulus (English Sole)

7Many ofthe benthic species in this study are able to survive in this dynamic environment being eitherverymobile orbeing able to reactbothto natural orman made perturbations. Theyreadilyrecolonize in disturbed areas such as dredging scars ordisposal site events.

Task II The trawl samples denote this near shore area as a nursery ground with an abundant food source. Most ofthe species encountered in the trawl samples were benthic feeders that tend to utilize the shallower areas both because of the abundant food and because of fewer predators. The majority ofthe fish and crabs captured in the trawls werejuveniles and young ofthe year. However, larger crabs and fish have the ability to avoid the trawl net.

CONCLUSIONS
The variability noted throughout this study appears to be consistent with other areas of the Oregon Coast and does not necessarily indicate a manmade impact on the studyarea. The variation seen could be related to several factors but was most likely an artifact of spatial and temporal sampling. The data includes many animals newly recruited into the system as juveniles which were either lost through natural mortality, or moved to "better" feeding sites. Those that are not mobile tend to stabilize disturbed sites with their tube or burrow structures thus allowing more colonization by more long lived species. Spiophanes species are known to produce sediment stabilizing tube structures. (J.A. Blake, ENSR, Pers Comm).

13BIBLIOGRAPHY Blake, J.A. 2002. Pers. Comm. Byrne, J. V. and D. A. Panshin. 1977. Continental ShelfSediments OffOregon. Oregon State University Extension Service. SG-8. Emmett, R. L. 2001. Pers. Comm. Hancock, D. R., P. O. Nelson, C. K. Sollitt, K. J. Williamson. 1981. Coos BayOffshore Disposal Site Investigation Interim Report Phase I, February 1979

- March 1980. Report to U.S. Corps ofEngineers, Portland District, Oregon for ContractNo. DACW 57-79-C-0040. Oregon State University, Corvallis, Oregon. Hancock, D. R. 1989. Pers. Comm. Jones, K. K. 2002. Pers. Comm. Lloyd, M. and R. J. Ghelardi. 1964. A table for calculatingthe "equitability: component ofspecies diversity. J. Anim. Ecol. 33: 217-225. Margalef, R. 1958. Informationtheoryin ecology. Gen. Syst. 3: 36-71. MarineTaxonomic Services, Ltd. 2000. Yaquina BayOcean DredgedMaterial Disposal SiteBenthic InfaunaEvaluation. A Comparative Study 1984-1999 Part A. USACE Portland District for Contract No. DACW-57-99-M-0742. MarineTaxonomic Services, Ltd. 2001. Yaquina Bay OceanDredge Material Disposal SiteBenthic Infaunal Evaluation. A Comparative Study 1999

- 2000. USACE Portland District for ContractNumberDACW-57-00-0-0398. MarineTaxonomic Services, Ltd. 2002. YaquinaBayOcean Dredged Material Disposal Site Benthic Infaunal Evaluation A Comparative Study. 1999-2002 Part C. Prepared for USACE PortlandDistrict. ContractNumberDACW 57-02-Q-00ll. Pacific Fisheries Environmental Group. 2001,2003,2007. Upwellingindices http://www.pfeg.noaa.gov/ Pearcy, W.G. 2005. Final WhitePaper Distribution and Abundance ofMarineFishes. Prepared for the Institute for Natural Resources. Oregon StateUniversity, Shannon, C. E. and W. Weaver, 1963. Themathematical theoryofcommunication. Univ. Illinois Press, Urbana 117p. Simpson, E. H. 1949. Measurement ofdiversity. Nature 163:688

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