Marine pollutants are absorbed by corals directly from seawater and also accumulate in their food, according to a study by KAUST (King Abdullah University of Science and Technology). Scientists used the most modern spectroscopy technique. This is the first time this approach has been used to measure the accumulation of pollutants.
The hydrocarbon contaminant phenanthrene has been monitored so scientists can see how it builds up in coral tissue. Coral colonies were grown in the AIMS National Sea Simulator for two weeks before being exposed to phenanthrene, which is often used as a model for oil pollution.
Researchers have used phenanthrene in two ways. They fed it to microalgae, which were then absorbed by the corals, and also exposed the corals to phenanthrene directly in seawater. To track the absorption and accumulation of phenanthrene, they labeled it with a non-radioactive heavy isotope of carbon (13C). A spectroscopic method was then used to measure the amount of 13C in coral tissues over six days.
The analysis showed that corals accumulate the same total amount of phenanthrene both through diffusion from seawater and through absorption by their food. However, the absorption rate was higher when exposed to seawater than when fed.
Corals absorb seawater pollutants both directly and indirectly.
Understanding of the entire dynamics of this process continues. The team is planning experiments to study the release of pollutants from corals, as well as the role of other players in the food chain.