Incorporating giant kelp connectivity into management strategies in the southeast Pacific

Abstract

Intensive harvesting and climate change affect the delivery of multiple ecosystem services provided by giant kelp, Macrocystis pyrifera, in the Southeast Pacific region. Amid these threats, dispersal and connectivity are crucial processes that support the replenishment and recovery of giant kelp, yet they remain poorly understood. Here, we assess the connectivity of giant kelp in the Southeast Pacific to inform its conservation and management. To achieve this, we use the outputs of a biophysical model and network analysis to identify critical source and sink areas and key connectivity corridors at multiple spatial and temporal scales. We also assess the influence of seasonal and El Niño Southern Oscillation (ENSO) variability on connectivity in the region. We found that the southern population (36–43°S) is the highest priority for management (e.g. no-take zone) as it serves as a crucial source-sink area, playing a fundamental role in propagule dissemination, local retention and non-local retention. We also identified changes in the connectivity within the central population (28-35°S), influenced by both ENSO events and seasonal variability. Adaptive management strategies, including temporal harvest closures, are recommended to address both inter and intra-annual fluctuations in connectivity. Additionally, through the delineation of management units based on population connectivity, we identify key source areas within each unit that warrant protection. The outputs of our study underscore the importance of integrating connectivity and regional environmental dynamics into conservation frameworks to enhance the resilience of kelp forests in the Southeast Pacific and elsewhere.