Event Title

Spatial and depth distribution of understory kelp and other marine vegetation in Central Puget Sound.

Streaming Media

Presentation Abstract

Despite their importance, there is limited information on the spatial and depth distribution of understory kelp in Puget Sound. This is a critical gap in our knowledge of nearshore habitat given the vulnerability of kelp species to changes in temperature and water quality. Here, we report on a pilot project to fill this information gap for understory kelp and other nearshore algae by expanding the methods of the WA Department of Natural Resources eelgrass monitoring program. In 2018 and 2019, DNR comprehensively surveyed the shoreline of King County, Vashon Island, and the Colvos Passage in collaboration with King County and the Suquamish Tribe. We collected towed underwater videography along 1912 stratified random transects that were oriented perpendicular to shore, and spanned a depth range from the intertidal to approximately 15m below MLLW (the depth range for the majority of macrophytes in this area). At a subset of these transects, we classified video frames at 5 second intervals to determine the percent cover for several broad classes of marine vegetation, including seagrass, prostrate kelp, stalked kelp, sargassum, other brown/red algae, and green algae. Each frame includes associated geospatial and depth information, which was used to calculate depth distribution and site area estimates. Preliminary results indicate that understory kelp is widespread throughout the study area. There are clear patterns in spatial and depth distribution of both understory kelp, and other marine vegetation types. These patterns are partly determined by gradients in environmental covariates. These results suggest that we can leverage footage from the existing eelgrass monitoring project to assess the distribution of other marine vegetation, with minor changes to the sampling and analysis protocols. Data from the pilot project form a baseline for assessing future change of marine vegetation in response to anthropogenic stressors such as water quality degradation and climate change.

Session Title

Session 2.1A: Kelp: Stressors, Trends, and Value (Part I)

Conference Track

Kelp & Seagrass

Conference Name

Salish Sea Ecosystem Conference (2020 : Online)

Document Type

Event

SSEC Identifier

2020_abstractID_4066

Start Date

22-4-2020 10:30 AM

End Date

22-4-2020 12:00 PM

Geographic Coverage

Salish Sea (B.C. and Wash.)

Rights

Copying of this document in whole or in part is allowable only for scholarly purposes. It is understood, however, that any copying or publication of this document for commercial purposes, or for financial gain, shall not be allowed without the author's written permission.

Language

English

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Apr 22nd, 10:30 AM Apr 22nd, 12:00 PM

Spatial and depth distribution of understory kelp and other marine vegetation in Central Puget Sound.

Despite their importance, there is limited information on the spatial and depth distribution of understory kelp in Puget Sound. This is a critical gap in our knowledge of nearshore habitat given the vulnerability of kelp species to changes in temperature and water quality. Here, we report on a pilot project to fill this information gap for understory kelp and other nearshore algae by expanding the methods of the WA Department of Natural Resources eelgrass monitoring program. In 2018 and 2019, DNR comprehensively surveyed the shoreline of King County, Vashon Island, and the Colvos Passage in collaboration with King County and the Suquamish Tribe. We collected towed underwater videography along 1912 stratified random transects that were oriented perpendicular to shore, and spanned a depth range from the intertidal to approximately 15m below MLLW (the depth range for the majority of macrophytes in this area). At a subset of these transects, we classified video frames at 5 second intervals to determine the percent cover for several broad classes of marine vegetation, including seagrass, prostrate kelp, stalked kelp, sargassum, other brown/red algae, and green algae. Each frame includes associated geospatial and depth information, which was used to calculate depth distribution and site area estimates. Preliminary results indicate that understory kelp is widespread throughout the study area. There are clear patterns in spatial and depth distribution of both understory kelp, and other marine vegetation types. These patterns are partly determined by gradients in environmental covariates. These results suggest that we can leverage footage from the existing eelgrass monitoring project to assess the distribution of other marine vegetation, with minor changes to the sampling and analysis protocols. Data from the pilot project form a baseline for assessing future change of marine vegetation in response to anthropogenic stressors such as water quality degradation and climate change.