A qualitative network model for the management and conservation of bull kelp (Nereocystis luetkeana) in Puget Sound

Abstract

Significant declines in the extent and density of the canopy-forming kelp Nereocystis luetkeana (bull kelp) have been documented within the inland waters of the Salish Sea, most notably the Puget Sound. Expert focus groups in combination with a global literature review have been used to identify the primary stressors most likely driving kelp decline in the Salish Sea in the absence of quantitative data. Qualitative network models require only a qualitative understanding of the interactions between the components of an ecological system, and can be useful management tools in data-limited situations. The goal of this project was to develop a qualitative network model to evaluate the impacts of identified stressors on bull kelp in Puget Sound, following the development of a conceptual model by Hollarsmith et al. (2022). Simulations of the model system highlight the indirect impacts of human activities on bull kelp canopy cover, the threats climate change poses to bull kelp in Puget Sound, and explore management interventions to protect and restore bull kelp.