Administrative Report Or Publication
 

Hatfield Marine Science Center Dynamic Revetment Project DSL permit # 45455-FP: Final Monitoring Report February, 2016

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https://ir.library.oregonstate.edu/concern/administrative_report_or_publications/pn89d710t

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  • Stabilization of the Yaquina Bay shoreline along the northeastern edge of the Hatfield Marine Science Center (HMSC) campus in Newport, Oregon became necessary to halt erosion that threatened both HMSC critical infrastructure (seawater storage tank) and public access to the HMSC Nature Trail. A Dynamic Revetment (gravel beach) was installed in November, 2011 on 260 feet of shoreline to mitigate erosion. Shoreline topographic and biological monitoring was initiated before and has continued after the project completion. Monitoring of beach profiles indicated that as of January 2016 the 2011 Dynamic Revetment Project (DRP) has generally successfully stabilized the shoreline in the project area. Beach profile data also indicated that a 200-ft DRP constructed in 2007 continued to be successful in stabilizing further retreat of the shoreline. In both areas, some loss of gravel at the top of the shore profile due to overtopping of the beach during highest tides was noted, and some additional placement of gravel at these locations is recommended. As a result of the rapid erosion that continued through much of 2015 in the adjacent Reference beach area, an extension of the 2011 DRP project to the south was completed during February 2015. This extension converted the Reference area used for monitoring the 2011 project into an additional gravel beach area (DRP 2015), which clearly differed from its previous characteristics. However, given the highly eroded condition of the Reference area in 2013-2014, the transition may have actually improved conditions for some monitored parameters (e.g. wrack invertebrates). Monitoring of beach wrack invertebrates, fish, and vegetation was conducted in 2015 for the fifth and last year. The Reference (DRP 2015) area had significantly higher abundance per unit dry wt versus both the DRP (2011) and DRP Reference (2007) samples. In contrast to previous years when the total amount of beach wrack was much sparser in the Reference area due to the eroded shore profile, there was little apparent difference in wrack accumulation along the shoreline. As has been a consistent pattern, fish were significantly more abundant in the Reference area compared to the DRP. However, this pattern was present in the pre-project sampling, and the Reference area may have a higher degree of physical habitat complexity. This was certainly true after the completion of the DRP 2015, where in addition to the root masses of trees that have been eroded onto the shore, six additional tree root masses were emplaced along the shoreline as an experiment. As has consistently been observed, vegetation coverage was significantly greater and presence of non-living substrata was significantly less in the Reference (DRP 2015) area as compared to the DRP. These differences are consistent with the pre-DRP 2011 project site differences, probably resulting from a low area of the shoreline which allows increased flooding and associated disturbance in the DRP back shore area. Fish and wrack invertebrates, such as beach hoppers, continue to utilize the DRP project area. Biological differences in fish and vegetation observed in the monitoring in 2015 tended to reflect differences in habitat that were present before the DRP 2011 project was implemented.
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