At Island Conservation, we’ve long known that restoring island ecosystems has spillover benefits that revitalize entire landscapes and seascapes. A new study published in PLOS Biology confirms what we’ve seen firsthand: seabirds play a vital role in enhancing coral reef health through nutrient connectivity. 

The study, titled “Nutrient connectivity via seabirds enhances dynamic measures of coral reef ecosystem function,” reveals how seabird-derived nutrients—delivered via guano, or poop—fuel productivity in coastal ecosystems. These nutrients are recycled into the sea, boosting the growth of turf algae, which in turn supports herbivorous fish populations. This dynamic nutrient cycling is key to reef resilience. 

But why do herbivorous fish matter for the overall health of coral reefs? 

These fish, such as Parrotfish, Surgeonfish, and Damselfish, are the unsung heroes of coral reefs. Their grazing keeps fast-growing algae like turf in check, preventing it from smothering corals. The study found that for every 0.1 mm/day increase in turf algal growth (driven by seabird nutrients), herbivore productivity increased by 1.57x and fish biomass by 1.94x. This means more energy is moving up the food chain — a sign of a thriving ecosystem! 

Turf Algae’s Role in Environmental Balance

It’s easy to mistake lush turf algae for a healthy reef. But high turf cover often signals degradation. What matters more is productivity—how fast the algae grow and how efficiently herbivores graze it down. This balance between growth and grazing creates space for coral settlement, essential for reef recovery. 

And it captures carbon, too—turf algae pulls carbon out of the environment and makes it available for bigger fish to eat, moving it up through the food chain and helping rebalance our environment. 

Restoration with Real Impact!

Seabird biomass varied dramatically across study sites, depending on whether invasive rats were present. Islands free of these harmful rats had thriving seabird populations, which led to: 

• A 1.12x increase in seabird nutrient markers in coastal vegetation 

• A 1.06x increase in those markers in turf algae 

• A 32% decrease in turf cover due to increased herbivore grazing 

These findings highlight the profound impact of seabird-driven nutrient flow on reef function—and the damage caused when invasive species disrupt this connection. 

Scaling Up Around the World

At Island Conservation, one of our most impactful tools in holistic ecosystem restoration is the removal of invasive species like rats from islands.  With over 1,000 successful invasive-removal operations worldwide and a 90% success rate, we’ve seen native plants and animals return, seabird populations rebound, and marine ecosystems flourish. As this paper shows, invasive species removal is just the beginning of a cascade of benefits that scale up the trophic chain. 

Learn more about our mission and success stories—from the Galápagos to Alaska—by subscribing to our newsletter, and support us by making a donation today! Together, we can restore islands for nature and people.