Miss Katherine Cavanaugh1, Dr. Kyle Cavanaugh1, Dr. Laura Rogers-Bennett2,3,4
1University of California, Los Angeles, Los Angeles, USA, 2University of California, Davis – Bodega Marine Laboratory, Bodega Bay, USA, 3California Department Fish and Wildlife, Bodega Bay, USA, 4Karen C. Drayer Wildlife Health Center, Bodega Bay, USA
Kelp forests in northern California suffered significant declines in 2014 after multiple disturbances triggered a large-scale ecosystem shift to urchin barrens. While populations across 350 km of coastline remained at historically low levels through 2020, small subpopulations were able to persist in refuge areas where conditions were decoupled from the unsuitable, surrounding environment. The potential for regional recovery depends on the interchange of spores from these populations in refugia to extirpated locations, allowing for and accelerating recolonization of the landscape. However, if refugia are separated by distances larger than those required for effective spore dispersal, some areas may be slow to recover, even after conditions improve. We used a combination of high resolution occupied aircraft data (2 m) and satellite imagery (3 m) to map kelp canopy in northern California for the seven year period following initial declines (2014-2022) and to determine the influence of connectivity on kelp forest persistence and recovery. We calculated the colonization probability of empty habitat using metrics that incorporated distance to the nearest refugia population. There were signs of kelp recovery in 2021, with populations recolonizing about 4.5 sq. km of empty habitat between 2020 and 2021. This recovery was strongly and positively predicted by refugia proximity, even when the nearest patch was relatively small and sparse. However, we also observed highly connected habitat that has yet to recover, which appeared to be driven by a combination of physical factors (e.g., necessary environmental conditions for successful recruitment) and spatial variability in grazing pressure. Our results provide insight into the role of kelp refugia in supporting population persistence throughout disturbance events, as well as successful reestablishment when environmental conditions become favorable. These populations and their pathways of connectivity may be critical for effective conservation and restoration in northern California
Presentation Slides – Katherine Cavanaugh
Biography:
Katherine Cavanaugh is a PhD student at UCLA studying the population dynamics of coastal California kelp communities. Her research involves leveraging remote sensing technologies (i.e., satellite, UAV, and ROV) for understanding the drivers and consequences of climate-driven changes.
