Event Title

Initial characterization and comparison of beach sediment throughout Puget Sound

Presentation Abstract

An understanding of the sediment grain size distribution of a beach provides important information about its physical properties and ecological functions. Forage fish are a diverse assemblage of species that serve as an essential component to the marine food web. The ability of forage fish to produce viable spawn is dependent on the grain size present. Surf smelt Hypomesus pretiosus and Pacific sand lance Ammodytes hexapterus utilize sediment within a unique grain size range as a spawning substrate. Pacific herring Clupea pallasii are known to utilize native eelgrass Zostera marina as a spawning substrate, which grows in fine sediment-supported nearshore environments. Sediment grain size data can also provide information related to shoreline armoring impacts, feeder bluff activity, and the sediment budget of a littoral drift cell, which can help to inform land-use and resource management decisions. The Washington Department of Ecology Coastal Monitoring & Analysis Program employed a photogrammetric method to characterize sediment grain size along 10 drift cells throughout Puget Sound that have active feeder bluffs and are rich in high-value natural resources. Previously, grain size distributions were obtained using a laborious and time consuming sieve analysis technique, which requires the collection of sediment samples for lab analysis. The sieve technique cannot incorporate coarse gravel and cobbles, which are a significant constituent of Puget Sound beaches. By employing Daniel Buscombe’s digital grain-size analysis algorithm on photos taken using a “Cobble Cam” technique, we were able to perform in-situ grain size characterization of sediments. Photos of sediment were taken along cross-shore beach profiles to enable both cross-shore and longshore comparisons of grain size distributions. At each profile, sediment grain size was obtained at increments of 0.5m elevation, extending from the backshore to the shoreline, with the locations of samples recorded using real-time kinematic GPS equipment.

Session Title

General Habitat Topics

Conference Track

Habitat

Conference Name

Salish Sea Ecosystem Conference (2016 : Vancouver, B.C.)

Document Type

Event

Location

2016SSEC

Type of Presentation

Poster

Contributing Repository

Digital content made available by University Archives, Heritage Resources, Western Libraries, Western Washington University.

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Type

Text

Language

English

Format

application/pdf

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Initial characterization and comparison of beach sediment throughout Puget Sound

2016SSEC

An understanding of the sediment grain size distribution of a beach provides important information about its physical properties and ecological functions. Forage fish are a diverse assemblage of species that serve as an essential component to the marine food web. The ability of forage fish to produce viable spawn is dependent on the grain size present. Surf smelt Hypomesus pretiosus and Pacific sand lance Ammodytes hexapterus utilize sediment within a unique grain size range as a spawning substrate. Pacific herring Clupea pallasii are known to utilize native eelgrass Zostera marina as a spawning substrate, which grows in fine sediment-supported nearshore environments. Sediment grain size data can also provide information related to shoreline armoring impacts, feeder bluff activity, and the sediment budget of a littoral drift cell, which can help to inform land-use and resource management decisions. The Washington Department of Ecology Coastal Monitoring & Analysis Program employed a photogrammetric method to characterize sediment grain size along 10 drift cells throughout Puget Sound that have active feeder bluffs and are rich in high-value natural resources. Previously, grain size distributions were obtained using a laborious and time consuming sieve analysis technique, which requires the collection of sediment samples for lab analysis. The sieve technique cannot incorporate coarse gravel and cobbles, which are a significant constituent of Puget Sound beaches. By employing Daniel Buscombe’s digital grain-size analysis algorithm on photos taken using a “Cobble Cam” technique, we were able to perform in-situ grain size characterization of sediments. Photos of sediment were taken along cross-shore beach profiles to enable both cross-shore and longshore comparisons of grain size distributions. At each profile, sediment grain size was obtained at increments of 0.5m elevation, extending from the backshore to the shoreline, with the locations of samples recorded using real-time kinematic GPS equipment.