Spatial and depth distribution of understory kelp and other marine vegetation in Central Puget Sound.
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
Genre/Form
conference proceedings; presentations (communicative events)
Subjects – Topical (LCSH)
Understory plants--Salish Sea (B.C. and Wash.); Kelps--Monitoring--Salish Sea (B.C. and Wash.); Kelp bed ecology--Salish Sea (B.C. and Wash.)
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.
Type
Text
Language
English
Format
application/pdf
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.
