Seagrass meadows, vital underwater ecosystems that support marine life and protect coastlines, are facing mounting threats from climate change. However, new research led by marine ecologist Fee Smulders from Wageningen University & Research reveals that tropical seagrasses may be more resilient than previously believed.
Why Seagrass Ecosystems Matter
Seagrass beds are crucial for marine biodiversity, offering food and shelter to sea turtles, fish, and invertebrates. They also play a key role in carbon sequestration, absorbing CO₂ from the atmosphere, and in coastal protection, helping prevent erosion. Yet, rising sea temperatures, overgrazing, and nutrient pollution are increasingly putting these ecosystems at risk.
A Comprehensive Study Along the Western Atlantic Coast
An international team of over 30 researchers conducted a large-scale, year-long study across 10 locations stretching from the Caribbean to the southeastern United States. The goal was to understand how seagrass responds to three main stressors:
- Warming ocean temperatures
- Grazing pressure from herbivores like sea turtles and fish
- Nutrient overload from agricultural runoff and pollution
At each study site, scientists created small gaps in the seagrass meadows and monitored recovery both above and below ground. Half of these test plots were exposed to excess nutrients to evaluate how pollution influences recovery rates.
Surprising Results: Moderate Warming Aids Recovery
One of the key findings is that moderate ocean warming can actually enhance seagrass regrowth in some areas. “Unlike coral reefs, which bleach under heat stress, seagrass appears to thrive in slightly warmer waters,” said Fee Smulders. However, she warns that extreme heatwaves can still lead to the complete loss of seagrass beds.
The Double Threat of Grazing and Pollution
Climate change is pushing herbivores like sea turtles and fish into new, more northern regions, where they feed heavily on seagrass. When this grazing is combined with high nutrient levels—often from fertilizers or untreated sewage—it severely impacts the resilience of seagrass.
“Too many nutrients promote algal blooms that smother the seagrass, preventing sunlight from reaching the plants,” Smulders explained. The research revealed that the combination of heavy grazing and nutrient pollution is especially damaging.
Water Quality: Key to Seagrass Survival
Co-author Marjolijn Christianen, also from Wageningen University, emphasized the critical importance of maintaining good water quality to ensure the survival of these ecosystems.
“Seagrass meadows are incredibly valuable—not just for marine life but for coastal communities and climate mitigation. If we want to protect them in the face of climate change, we must reduce additional human-induced stressors,” she said.
Published Research and Further Reading
The full study, titled “Temperature Drives Seagrass Recovery Across the Western North Atlantic,” is available in the journal Global Change Biology.
Citation:
Smulders, F.O.H. et al. (2025). Global Change Biology. DOI: 10.1111/gcb.70172
Source: Wageningen University & Research