A resilient native seagrass species could help reshape coastal restoration

A resilient native seagrass species could help reshape coastal restoration efforts, according to new findings from researchers at Florida Atlantic University’s Harbor Branch Oceanographic Institute. The study highlights the potential of Ruppia maritima, a less common seagrass found in Florida’s Indian River Lagoon, to play a crucial role in restoring degraded coastal ecosystems. This discovery comes amid ongoing concerns over the decline of seagrass habitats, which are essential for maintaining biodiversity, stabilizing sediments, and improving water quality. The research, published in Regional Studies in Marine Science, focuses on the life cycle and ecological adaptability of Ruppia maritima. In the Indian River Lagoon, seagrass loss has been exacerbated by harmful algal blooms, leaving many areas with minimal natural recovery. However, Ruppia maritima has shown remarkable persistence in some of the lagoon’s most disturbed zones, such as mosquito impoundments, man-made wetlands isolated from the main body of the lagoon by dikes and water-control structures. These systems experience fluctuating water levels and varying water quality due to rotational management practices, creating harsh conditions for most seagrass species. Yet, Ruppia maritima continues to thrive under these circumstances, making it a subject of scientific interest. To better understand the plant’s resilience, researchers tracked naturally occurring populations at two locations within Bee Gum Point Nature Preserve over a period of three years. During this time, they observed seasonal variations in seagrass coverage, biomass, and environmental factors. Additionally, they analyzed the sediment seed bank and conducted controlled lab experiments to identify the triggers for seed germination. Their findings reveal that Ruppia maritima undergoes a distinct annual cycle, growing predominantly from late winter through spring, blooming, and then dying back during the summer months. Despite facing periodic flooding and poor water quality, the species consistently recovers each year. One of the most striking discoveries was the presence of a persistent seed bank in the sediment. Even when the plants appeared to vanish above ground, the population endured underground, ready to regrow once conditions improved. Laboratory tests confirmed that lower salinity, especially exposure to freshwater, significantly accelerated germination. This characteristic allows Ruppia maritima to survive periods of environmental stress and rebound quickly when favorable conditions return. Further testing took place at the FAU Harbor Branch Seagrass Nursery, where plants collected from the preserve were transplanted into aquaculture tanks. There, they exhibited a growth pattern mirroring that of wild populations and produced viable seeds. Notably, the cultivated population has maintained itself independently since its introduction in 2021, demonstrating its viability for large-scale restoration projects. Rachel Brewton, Ph.D., the lead researcher and an assistant research professor at FAU Harbor Branch, emphasized the significance of these findings. “Ruppia maritima has a remarkable ability to persist through disturbance,” she stated. “Even when the plants disappear above ground, the population can persist as a seed bank in the sediment, waiting for conditions to become favorable.” Her comments underscore the practical implications of the research for coastal restoration initiatives. With its capacity to regenerate from a seed bank and its success in controlled cultivation, Ruppia maritima presents a promising candidate for restoring damaged seagrass habitats. As scientists continue to explore its potential, the species may offer a new strategy for combating the ongoing degradation of coastal ecosystems.