The relationship between sea urchins and seagrass ecosystems is fundamental to maintaining coastal ecological balance. Sea urchins, as primary herbivores in seagrass meadows, play a crucial role in regulating algal growth, which supports overall ecosystem health. However, when sea urchin populations exceed certain thresholds, their herbivory can shift from a beneficial process to one that undermines the integrity of seagrass beds. This study employs mathematical modeling to explore the population dynamics between sea urchins and seagrass, with a particular focus on overgrazing and the formation of barren ecosystems. The research highlights a significant gap in current ecological understanding—the inability to pinpoint the critical tipping point at which sea urchin populations become unsustainable for seagrass survival. By simulating the interaction between these species, this study provides valuable insights into coastal management strategies aimed at preserving healthy seagrass ecosystems. The findings could help inform policies to maintain balanced herbivory and to prevent the collapse of seagrass meadows into barren zones, ensuring long-term ecological stability.