WILLEMSTAD – Scientists conducting research on Curaçao have demonstrated that short-lived spikes in nutrient levels can significantly extend the lifespan of Caribbean macroalgae, accelerating the shift of coral reefs from coral-dominated to algae-dominated ecosystems.
The findings were published recently in the Journal of Aquatic Plants and are based on a study carried out by researchers from Carmabi, IHE Delft, and the Nederlands Instituut voor Onderzoek der Zee (NIOZ).
The researchers examined two common species of macroalgae found on Caribbean reefs. Rather than focusing on constant nutrient pollution, the study concentrated on temporary increases in nutrients, known as “nutrient pulses,” which can occur after heavy rainfall, sewage overflows, or coastal runoff.
According to the study, these brief nutrient pulses do not necessarily cause algae to grow faster. Instead, they allow algae to survive for longer periods. This extended lifespan increases the likelihood that macroalgae will occupy space on coral reefs, limiting opportunities for corals to recover and re-establish themselves.
As corals struggle to regain lost ground, reefs become increasingly dominated by algae, leading to long-term changes in ecosystem structure and resilience. The researchers warn that this process can undermine the health and biodiversity of coral reefs, which are already under pressure from climate change, rising sea temperatures, and human activity.
The study concludes that reef managers and policymakers should not rely solely on average nutrient levels when assessing water quality. Temporary nutrient spikes, the researchers argue, can have substantial long-term ecological consequences and should be factored into strategies aimed at protecting and restoring Caribbean coral reefs.