Coral reefs could be saved by improving water quality
London: Researchers have found that an imbalance of nutrients in reef waters can increase the bleaching susceptibility of reef corals.
Corals are made up of many polyps that jointly form a layer of living tissue covering the calcareous skeletons. They depend on single-celled algae called zooxanthellae, which live within the coral polyps.
The coral animal and the associated zooxanthellae depend on each other for survival in a symbiotic relationship, where the coral supplies the algae with nutrients and a place to live. In turn, the algae offer the coral some products of their photosynthesis, providing them with an important energy source.
High water temperatures can block photosynthetic reactions in the algal cells causing a build-up of toxic oxygen compounds, which threaten the coral and can result in a loss of the zooxanthellae.
Without the algae, corals appear white, a state which is often referred to as ‘bleached’. Bleaching often leads to coral death and mass coral bleaching has had already devastating effects on coral reef ecosystems.
The study from the University of Southampton and the National Oceanography Centre, Southampton, has found that nutrient enrichment of the water can increase the probability of corals to suffer from heat-induced bleaching.
Within the coral, the growth of zooxanthellae is restricted by the limited supply of nutrients. This allows the algae to transfer a substantial amount of their photosynthetically fixed carbon to the coral, which is crucial for the symbiotic relationship.
Algal growth becomes unbalanced when the availability of a specific nutrient decreases compared to the cellular demand, a condition called nutrient starvation.
Researchers from the University of Southampton based at the Coral Reef Laboratory in the National Oceanography Centre, Southampton, found that an increased supply of dissolved nitrogen compounds in combination with a restricted availability of phosphate results in phosphate starvation of the algae.
This condition is associated with a reduction in photosynthetic efficiency and increases the susceptibility of corals to temperature and light-induced bleaching.
“Our findings suggest that the most severe impact on coral health might actually not arise from the over-enrichment with one group of nutrients, for example, nitrogen, but from the resulting relative depletion of other types such as phosphate that is caused by the increased demand of the growing zooxanthellae populations,” said Dr Jorg Wiedenmann, Senior Lecturer of Biological Oceanography at the University of Southampton and Head of the Coral Reef Laboratory, who led the study.
“Our results have strong implications for coastal management. The findings suggest that a balanced reduction of the nutrient input in coastal waters could help to mitigate the effects of increasing seawater temperatures on coral reefs.
“However, such measures will be effective only for a short period of time, so it is important to stop the warming of the oceans, which will otherwise destroy most of the reefs in their present form in the near future,” Dr Wiedenmann added.
Their findings have been published in the latest issue of the journal Nature Climate Change.
More from India
More from World
More from Sports
More from Entertaiment
- Did history fail to serve justice to Dr Shyama Prasad Mukherjee?
- Did history fail to serve justice to Dr Shyama Prasad Mukherjee? - Part II
- Did history fail to serve justice to Dr Shyama Prasad Mukherjee? - Part III
- Did history fail to serve justice to Dr Shyama Prasad Mukherjee? - Part IV
- Are central govt employees justified in demanding salary hike?
- China to feel Brexit effects, yuan to weaken against dollar: JP Morgan
- As Central India faces drought, violence and murders on the rise over water
- Baby boom! Teejay Sidhu and Karanvir Bohra to become parents for the first time
- Tripura Governor gets additional charge of Arunachal Pradesh
- Bucket list: You must try these things at least once before turning 25!