Transplanting Orange Sea Pens: Challenges and Opportunities
Presentation Abstract
Orange sea pens (Ptilosarcus gurneyi; OSP) are a colonial octocoral known for aggregating at high densities; one such aggregation exists at Roberts Bank near Delta, British Columbia. OSP are considered key biogenic habitat by Fisheries and Oceans Canada, providing structure in soft sediments where there is otherwise little habitat complexity. A portion of the aggregation at Roberts Bank overlaps with the footprint of a proposed development Project and, therefore, implementation of appropriate mitigation measures is required to address adverse effects; however, the current state of biological knowledge on OSP is limited, and there is no precedent for mitigating effects to this species, presenting a unique set of challenges and opportunities. The proponent initiated a pilot study to explore the feasibility and effectiveness of transplanting OSP to suitable locations outside the Project footprint. A species distribution model (SDM) was used to identify possible transplant locations based on environmental predictor variables and a method was developed to safely harvest, move, and re-plant individuals. Overall, 1,200 OSP were moved from the existing aggregation to three nearby transplant sites at two density treatments that mimic those observed naturally (four and six individuals per square metre). Densities were monitored over the course of one year to estimate survivorship and to determine differences in success between the two treatments. Results show high survivorship at two of the three transplant sites (80% and 86%, respectively) and low survivorship at the third (16%), largely attributed to nudibranch predation. No significant difference between density treatments was observed, implying there may be some flexibility in planting densities without loss of effectiveness. Overall, this pilot program is considered a success: the SDM was able to accurately predict suitable transplant locations and monitoring results suggest that transplantation can be a feasible and viable mitigation method.
Session Title
Challenges and opportunities related to habitat enhancement, restoration, and ecosystem productivity in the Salish Sea
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)
Sea pens--Salish Sea (B.C. and Wash.)--Geographical distribution
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
Transplanting Orange Sea Pens: Challenges and Opportunities
2016SSEC
Orange sea pens (Ptilosarcus gurneyi; OSP) are a colonial octocoral known for aggregating at high densities; one such aggregation exists at Roberts Bank near Delta, British Columbia. OSP are considered key biogenic habitat by Fisheries and Oceans Canada, providing structure in soft sediments where there is otherwise little habitat complexity. A portion of the aggregation at Roberts Bank overlaps with the footprint of a proposed development Project and, therefore, implementation of appropriate mitigation measures is required to address adverse effects; however, the current state of biological knowledge on OSP is limited, and there is no precedent for mitigating effects to this species, presenting a unique set of challenges and opportunities. The proponent initiated a pilot study to explore the feasibility and effectiveness of transplanting OSP to suitable locations outside the Project footprint. A species distribution model (SDM) was used to identify possible transplant locations based on environmental predictor variables and a method was developed to safely harvest, move, and re-plant individuals. Overall, 1,200 OSP were moved from the existing aggregation to three nearby transplant sites at two density treatments that mimic those observed naturally (four and six individuals per square metre). Densities were monitored over the course of one year to estimate survivorship and to determine differences in success between the two treatments. Results show high survivorship at two of the three transplant sites (80% and 86%, respectively) and low survivorship at the third (16%), largely attributed to nudibranch predation. No significant difference between density treatments was observed, implying there may be some flexibility in planting densities without loss of effectiveness. Overall, this pilot program is considered a success: the SDM was able to accurately predict suitable transplant locations and monitoring results suggest that transplantation can be a feasible and viable mitigation method.
