Beach wrack communities within a commercially harvested coastline of the Salish Sea
Presentation Abstract
Accumulations of beach-cast seaweeds and other matter, collectively known as wrack, are a common and ecologically important occurrence along coastal regions worldwide. Between the unincorporated communities of Deep Bay and Bowser, on the east coast of Vancouver Island, beach wrack is primarily composed of an introduced species of red algae called Mazzaella japonica, which became the target of a commercial beach-cast harvest in 2007. Little is known, however, about the ecological role of M. japonica in this recipient system. Furthermore, literature on the effects of harvesting beach-cast seaweed is limited. The goal of this research was therefore threefold: 1) To quantify the contribution of M. japonica to wrack inputs within the harvest region; 2) to explore how wrack characteristics influence macrofauna communities; and 3) to determine if the commercial removal of beach-cast seaweeds has a detectable effect on wrack characteristics and macrofauna community structure. To answer these questions we monitored a series of permanent transects at six sites across the harvest region, from November 2014 until March 2015. We recorded as much as 853 kg (±99.8 SE) of wrack per meter of shoreline, 63 % to 82% of which was identified as M. japonica across sites. Despite the removal of 674.5 tonnes of beach-cast seaweeds, we found that the trends in wrack biomass were similar between both harvested and unharvested locations. Macrofauna communities differed significantly between study sites, as well as with the age class, depth, and total biomass of the wrack from which they were sampled.
Session Title
General Marine Habitat
Conference Track
Habitat
Conference Name
Salish Sea Ecosystem Conference (2016 : Vancouver, B.C.)
Document Type
Event
Start Date
2016 12:00 AM
End Date
2016 12:00 AM
Location
2016SSEC
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)
Marine algae--British Columbia--Vancouver Island; Marine algae--Harvesting--British Columbia--Vancouver Island
Geographic Coverage
Salish Sea (B.C. and Wash.); Vancouver Island (B.C.)
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
Beach wrack communities within a commercially harvested coastline of the Salish Sea
2016SSEC
Accumulations of beach-cast seaweeds and other matter, collectively known as wrack, are a common and ecologically important occurrence along coastal regions worldwide. Between the unincorporated communities of Deep Bay and Bowser, on the east coast of Vancouver Island, beach wrack is primarily composed of an introduced species of red algae called Mazzaella japonica, which became the target of a commercial beach-cast harvest in 2007. Little is known, however, about the ecological role of M. japonica in this recipient system. Furthermore, literature on the effects of harvesting beach-cast seaweed is limited. The goal of this research was therefore threefold: 1) To quantify the contribution of M. japonica to wrack inputs within the harvest region; 2) to explore how wrack characteristics influence macrofauna communities; and 3) to determine if the commercial removal of beach-cast seaweeds has a detectable effect on wrack characteristics and macrofauna community structure. To answer these questions we monitored a series of permanent transects at six sites across the harvest region, from November 2014 until March 2015. We recorded as much as 853 kg (±99.8 SE) of wrack per meter of shoreline, 63 % to 82% of which was identified as M. japonica across sites. Despite the removal of 674.5 tonnes of beach-cast seaweeds, we found that the trends in wrack biomass were similar between both harvested and unharvested locations. Macrofauna communities differed significantly between study sites, as well as with the age class, depth, and total biomass of the wrack from which they were sampled.
