27 September 2012, by Tom Marshall
Too many nutrients can put corals at risk, a new study shows. Excessive nitrogen in the water affects their ability to cope with rising water temperatures and other environmental pressures, making them vulnerable to harmful bleaching.
That is, an excessive supply of nutrients can paradoxically lead to nutrient starvation. It does this by over-fertilizing the symbiotic algae on which corals depend, making them grow more quickly than the more limited supply of phosphorus can support. This unbalanced growth makes them more susceptible to stress.
The discovery may point towards ways we can help protect coral reefs, safeguarding these uniquely rich habitats as well as the livelihoods of the millions of people who depend on them. It’s the latest in a long list of reasons to control nitrogen pollution, which has also catastrophic effects on river ecosystems and causes harmful algal blooms in coastal waters.