Distribution of Zostera japonica 2004 to 2013 in Padilla Bay, Washington
Presentation Abstract
In Padilla Bay, Washington, Zostera japonica, an introduced eelgrass species grows both intermixed with the native Zostera marina and in homogeneous patches of the upper intertidal. Competition mechanisms between Z. japonica and Z. marina are not well understood. In light of the recent declaration of Z. japonica as a Class C noxious weed by the Washington State Noxious Weed Control Board we took the opportunity to update the status of Z. japonica in Padilla Bay by revisiting nearshore groundtruth sites that had been recorded in 2004 for a mapping project (the extensive eelgrass beds of Padilla Bay were mapped in 2004 from aerial photos interpreted using more than 1300 ground truth sites). The groundtruth data consisted of GPS site locations where species type, estimates of species composition, and visual estimate of percent cover were recorded for a 10m2 area. During the summer of 2013 we revisited nearly 500 of the sites where Z. japonica would be likely to occur (mid to upper intertidal) to determine if there were changes in species distribution. Preliminary results show 296 of all the sites had Z. Japonica present in 2004 and/or in 2013. At these sites Z. japonica was lost at 49% of the sites and Z. japonica gained at 51% of the sites. There were a of total of 263 sites where Z. japonica changed to or from Z. marina, at 53% of the sites Z. japonica was lost to Z. marina and at 47% of the sites Z. japonica gained at the expense of Z. marina. This data would support the accepted paradigm that while there is great annual variability at a given site, the eelgrass populations of Padilla Bay as a whole are reasonably stable.
Session Title
Session S-07E: Aquatic Vegetation
Conference Track
Habitat
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
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)
Dwarf eelgrass--Washington (State)--Padilla Bay--Mathematical models; Invasive plants--Washington (State)--Padilla Bay--Mathematical models; Plant competition--Washington (State)--Padilla Bay
Geographic Coverage
Salish Sea (B.C. and Wash.); Padilla Bay (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
Distribution of Zostera japonica 2004 to 2013 in Padilla Bay, Washington
Room 6C
In Padilla Bay, Washington, Zostera japonica, an introduced eelgrass species grows both intermixed with the native Zostera marina and in homogeneous patches of the upper intertidal. Competition mechanisms between Z. japonica and Z. marina are not well understood. In light of the recent declaration of Z. japonica as a Class C noxious weed by the Washington State Noxious Weed Control Board we took the opportunity to update the status of Z. japonica in Padilla Bay by revisiting nearshore groundtruth sites that had been recorded in 2004 for a mapping project (the extensive eelgrass beds of Padilla Bay were mapped in 2004 from aerial photos interpreted using more than 1300 ground truth sites). The groundtruth data consisted of GPS site locations where species type, estimates of species composition, and visual estimate of percent cover were recorded for a 10m2 area. During the summer of 2013 we revisited nearly 500 of the sites where Z. japonica would be likely to occur (mid to upper intertidal) to determine if there were changes in species distribution. Preliminary results show 296 of all the sites had Z. Japonica present in 2004 and/or in 2013. At these sites Z. japonica was lost at 49% of the sites and Z. japonica gained at 51% of the sites. There were a of total of 263 sites where Z. japonica changed to or from Z. marina, at 53% of the sites Z. japonica was lost to Z. marina and at 47% of the sites Z. japonica gained at the expense of Z. marina. This data would support the accepted paradigm that while there is great annual variability at a given site, the eelgrass populations of Padilla Bay as a whole are reasonably stable.
