Ms Lianna Gendall1, Dr Margot Hessing-Lewis2, Dr Maycira Costa1
1Spectral Remote Sensing Lab, University Of Victoria, Victoria, Canada, 2The Hakai Institute, Quadra Island, Canada
Canopy kelps are dominant habitat-forming organisms in nearshore temperate ecosystems that provide shelter and food for many ecologically important species, supporting cultural practices and fisheries. High-resolution satellite imagery can quantify the distribution of kelp forests over large areas like the Haida Gwaii coastline and establish datasets necessary to detect change over time. Kelp monitoring for the Pacific Coast of Canada is at its inception and the drivers of change remain poorly understood. Our goal is to use satellite imagery alongside historic and environmental driver data to quantify and understand patterns of change in an important kelp forest region of Haida Gwaii, British Columbia, Canada by: 1) assessing changes in kelp forest canopy area using high to medium resolution satellite imagery (1973-2021) and historic data from British nautical charts (1856-1958), and 2) assessing regional climate indices and local drivers to understand the spatio-temporal trends in kelp forest canopy area. Overall, patterns of kelp forest change varied across the study region with some areas showing huge losses while others showed long term resilience. The dramatic loss of kelp forests occurred in the North of the region where approximately 60% of the total maximum kelp forest area previously documented disappeared. This disappearance correlates with a shift in the late 1970s from a cool to warm period in the Pacific Decadal Oscillation and El Nino Southern Oscillation coupled with a strong local sea surface temperature gradient that exist across the region. In contrast, more sheltered and cooler subregions showed high variability and resilience where kelp forests have persisted over a century. These spatial and temporal scale-dependent results highlight how local environmental gradients can cause unexpected losses in areas well within species range limits and highlight the need for long-term datasets to capture trends in highly variable kelp forest areas through time.
Presentation Slides – Lianna Gendall
Biography:
Lianna Gendall is a Master’s candidate with interests in kelp forest ecology, ecosystem-based management, traditional ecological knowledge and the use of remote sensing to answer important ecological questions in a time of rapid global change. She recieved a BSc at the Unviersity of Alberta before moving to the temperate west coast of Canada. Lianna’s research focuses on creating time series of kelp forest canopy change along the coast of Haida Gwaii and exploring environmental drivers of change. This project is part of the BC Kelp Resilience Program of the SPECTRAL remote sensing laboratory at the University of Victoria.
