The Role of Macroalgal-Epifaunal Communities in Ocean-Based Food Systems: Long-Term Environmental and Ecological Drivers in Rocky Reef Ecosystems

Macroalgae are foundational to rocky reef ecosystems, creating complex habitat that supports diverse species assemblages and provides vital ecosystem services such as coastal food production and carbon dioxide sequestration. Within rocky reefs, macroalgae host dense communities of epifaunal invertebrates, which play a key role in energy transfer and nutrient cycling within marine food webs. However, these ecosystems face compounding environmental stressors, including ocean warming, increased storm disturbance, and nutrient limitation. Additionally, the limited temporal resolution of existing datasets has hindered our understanding of long-term fluctuations in macroalgal-epifaunal communities. This research examines the drivers of macroalgal-epifaunal community structure in California’s Santa Barbara Channel, focusing on long-term environmental impacts at Santa Cruz Island to inform sustainable, multi-trophic aquaculture systems. Using 16 years of ecological community data alongside records of sea surface temperature, wave height, and nutrient availability, we assess how regional and reef-scale drivers shape community dynamics over time. Our findings reveal a positive relationship between macroalgal species density and epifaunal richness, suggesting that reefs with greater macroalgal species density enhance energy flow through epifauna, supporting fish and invertebrate populations critical to local fisheries. Further analysis will investigate how climate-related factors influence reef resilience and productivity, offering critical insights for sustainable, climate-resilient ocean-based food systems that support both biodiversity and fisheries. These findings contribute to the development of biodiversity-supporting aquaculture practices that can strengthen ocean-based food systems in a changing climate.