Temporal changes in bull kelp (nereocystis luetkeana) in the Salish Sea using high resolution satellite imagery
Presentation Abstract
Bull kelp (Nereocystis luetkeana) is an important feature of the nearshore environment, forming structural habitat for marine species, protection from wave energy and nutrient entrainment. In the Salish Sea, reports that kelp beds are in decline due to factors such as warming sea temperatures and deterioration of ocean conditions have raised concern amongst the scientific community. This project utilizes a long-term data set of satellite imagery to detect kelp and understand how its distribution may be changing over time. High-resolution satellite imagery acquired by QuickBird, Geoeye, SPOT and WorldView from 2004 to 2017 was analyzed to define optimal processing techniques for mapping kelp distribution in the Salish Sea. The imagery used was acquired under similar environmental conditions to optimize kelp detection: tidal height less than 1.2m, during summer months for maximum growth and sensor angles of less than 15 degrees. First, in order to improve the detection of kelp, corrections for the effects of atmosphere, sun glint and radiometry were applied followed by testing of different digital image enhancement techniques. The results show that the vegetation indices of GNDVI performed the best to separate kelp from surrounding water and other features. Furthermore, principal component analysis resulted in optimal performance. Specifically, PC1 was used for the best separation of floating kelp from other feature. Validation of the resulting kelp classifications show that the methodology for detecting kelp from current and historical satellite imagery can be an effective method for determining distribution trends.
Session Title
Kelp Distribution and Recovery Strategies in the Salish Sea: Part I
Conference Track
SSE1: Habitat Restoration and Protection
Conference Name
Salish Sea Ecosystem Conference (2018 : Seattle, Wash.)
Document Type
Event
SSEC Identifier
SSE1-637
Start Date
6-4-2018 9:00 AM
End Date
6-4-2018 9:15 AM
Type of Presentation
Oral
Genre/Form
conference proceedings; presentations (communicative events)
Contributing Repository
Digital content made available by University Archives, Heritage Resources, Western Libraries, Western Washington University.
Subjects – Topical (LCSH)
Nereocystis luetkeana--Research--Salish Sea (B.C. and Wash.); Kelp bed ecology--Salish Sea (B.C. and Wash.); Marine habitat conservation--Salish Sea (B.C. and Wash.)
Geographic Coverage
Salish Sea (B.C. and Wash.)
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
Temporal changes in bull kelp (nereocystis luetkeana) in the Salish Sea using high resolution satellite imagery
Bull kelp (Nereocystis luetkeana) is an important feature of the nearshore environment, forming structural habitat for marine species, protection from wave energy and nutrient entrainment. In the Salish Sea, reports that kelp beds are in decline due to factors such as warming sea temperatures and deterioration of ocean conditions have raised concern amongst the scientific community. This project utilizes a long-term data set of satellite imagery to detect kelp and understand how its distribution may be changing over time. High-resolution satellite imagery acquired by QuickBird, Geoeye, SPOT and WorldView from 2004 to 2017 was analyzed to define optimal processing techniques for mapping kelp distribution in the Salish Sea. The imagery used was acquired under similar environmental conditions to optimize kelp detection: tidal height less than 1.2m, during summer months for maximum growth and sensor angles of less than 15 degrees. First, in order to improve the detection of kelp, corrections for the effects of atmosphere, sun glint and radiometry were applied followed by testing of different digital image enhancement techniques. The results show that the vegetation indices of GNDVI performed the best to separate kelp from surrounding water and other features. Furthermore, principal component analysis resulted in optimal performance. Specifically, PC1 was used for the best separation of floating kelp from other feature. Validation of the resulting kelp classifications show that the methodology for detecting kelp from current and historical satellite imagery can be an effective method for determining distribution trends.
