Type of Presentation

Oral

Session Title

Challenges and opportunities related to habitat enhancement, restoration, and ecosystem productivity in the Salish Sea

Description

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.

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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.