Event Title

Subtidal riprap in Puget Sound: Its ecological structure and function, and its impact on adjacent soft sediment environments

Presentation Abstract

In the past decade, several studies have examined the effects of coastal defense structures, such as riprap, in the intertidal zone in Puget Sound. However, these structures commonly extend well below the intertidal. In subtidal environments, very little is known about the ecological structure, function, and processes on riprap. We conducted photo surveys in the Seattle area to characterize the community composition on subtidal riprap installations. Subtidal riprap was dominated by a wide variety of red algae species and sessile invertebrate fauna. The community on subtidal riprap was not typical of that that observed on natural rocky substrates in the region. We also conducted sediment surveys, which revealed that biogenic materials from subtidal riprap installations were readily incorporated into sediments immediately adjacent to riprap. Two types of biogenic material were particularly common: (1) shell hash from Balanus sp., Pododesmus machrochisma, and other rocky sessile invertebrates, and (2) small pieces of red algae. The density of these materials decreased significantly with increasing distance from subtidal riprap, and may influence the community composition of infauna in surrounding sediments. While previous studies in the intertidal have emphasized the importance of intertidal riprap in altering erosive forces in surrounding habitats, subtidal riprap may serve as growing medium for biogenic materials and resources that subsidize adjacent soft sediment communities.

Session Title

Session S-01G: New Strategies for Shorelines

Conference Track

Shorelines

Conference Name

Salish Sea Ecosystem Conference (2014 : Seattle, Wash.)

Document Type

Event

Start Date

1-5-2014 5:00 PM

End Date

1-5-2014 6:30 PM

Location

Room 6C

Contributing Repository

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

Rights

This resource is displayed for educational purposes only and may be subject to U.S. and international copyright laws. For more information about rights or obtaining copies of this resource, please contact University Archives, Heritage Resources, Western Libraries, Western Washington University, Bellingham, WA 98225-9103, USA (360-650-7534; heritage.resources@wwu.edu) and refer to the collection name and identifier. Any materials cited must be attributed to the Salish Sea Ecosystem Conference Records, University Archives, Heritage Resources, Western Libraries, Western Washington University.

Type

Text

Language

English

Format

application/pdf

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May 1st, 5:00 PM May 1st, 6:30 PM

Subtidal riprap in Puget Sound: Its ecological structure and function, and its impact on adjacent soft sediment environments

Room 6C

In the past decade, several studies have examined the effects of coastal defense structures, such as riprap, in the intertidal zone in Puget Sound. However, these structures commonly extend well below the intertidal. In subtidal environments, very little is known about the ecological structure, function, and processes on riprap. We conducted photo surveys in the Seattle area to characterize the community composition on subtidal riprap installations. Subtidal riprap was dominated by a wide variety of red algae species and sessile invertebrate fauna. The community on subtidal riprap was not typical of that that observed on natural rocky substrates in the region. We also conducted sediment surveys, which revealed that biogenic materials from subtidal riprap installations were readily incorporated into sediments immediately adjacent to riprap. Two types of biogenic material were particularly common: (1) shell hash from Balanus sp., Pododesmus machrochisma, and other rocky sessile invertebrates, and (2) small pieces of red algae. The density of these materials decreased significantly with increasing distance from subtidal riprap, and may influence the community composition of infauna in surrounding sediments. While previous studies in the intertidal have emphasized the importance of intertidal riprap in altering erosive forces in surrounding habitats, subtidal riprap may serve as growing medium for biogenic materials and resources that subsidize adjacent soft sediment communities.