SINGAPORE — A team of researchers from the Singapore–MIT Alliance for Research and Technology (SMART) go diving regularly — not for leisure, but for science.

Dr Intan Suci Nurhati, Postdoctoral Associate, and Ms Jani Tanzil, Research Engineer, dive into coral reefs in the region and use them to study past environmental changes, such as changes in the regional climate and marine chemistry. Dr Intan and Ms Jani work at the Center for Environmental Sensing and Modeling (CENSAM), one of the research groups at SMART, and their team is the first to drill and extract coral samples in Singapore waters.

Corals make fascinating subjects of study: Like the annual growth rings that appear in tree trunks, corals also display rings, which record details about the climate and ocean chemistry every year, like “nature’s own archives”, according to Dr Intan.

What we think of as coral is largely made of mineral material: Only the outermost layer is the living part of coral, and it grows outwards with time by depositing a chalk-like material. “If you drill into a coral and extract a 30cm-long cylindrical coral core, which is what we do in the field, you can see bands along the length of it,” said Dr Intan.

These bands are created by variations in the corals’ environment: Changes in the concentrations of humic acid and fulvic acid in the ocean, corresponding to changes in the amount of river runoff, are responsible for the distinct orange-brown bands along coral cores. Through chemical analysis of coral bits drilled along the length of coral cores, the amount of strontium, a chemical proxy for temperature changes, and lead, a heavy metal and a common industrial pollutant, can be tracked over time.

Said Dr Intan: “I’m a climate scientist, and Jani is a marine biologist. We work with Professor Ed Boyle, Professor of Ocean Geochemistry at the Massachusetts Institute of Technology, and it’s an interesting synergy where we work on different topics but use the same material: corals.”

Corals can provide a variety of information. “By studying the chemistry of corals, you can tell changes in temperature, which is vital if you want to study the rate of ocean warming,” said Dr Intan.

“Studying temperature is important…but as a society, what affects us more is rainfall,” said Dr Intan. “If we have flooding or droughts, that will really affect us and endanger our food security.”

The SMART team with a MIT graduate student Jong-Mi Lee also study changes in marine chemistry: They examine how the lead concentration in oceans has changed over time by analysing corals in Singapore waters, and track down where the lead is coming from.

The data from their research shows that the amount of lead found in Singapore’s corals rose until 2000, after which it dropped, according to Dr Intan, and they will move on to figure out the major source of lead in the region. And through corals obtained from the South China Sea, there seems to be an indication that the rainy season may be getting wetter in this region, though Dr Intan emphasised that that is based on preliminary data.

On the reason for using corals for scientific analysis, Dr Intan said: “If you study the environment, most of the environmental issues we face today require a longer record (for research purposes). For example, the study of global warming needs temperature measures, but we have been measuring temperature continuously via satellite for the past 30 years, at most.”

“It is crucial to extend this record, because to isolate mankind’s contribution to climate change, 30 years’ worth of data is not enough: Natural variability can take place in cycles that are 30 years or even longer, so we need (data over) at least a hundred years to study climate change.”

The use of corals offers practical benefits for research. Said Dr Intan: “Corals can grow for up to about a hundred years, so they give us a long, detailed data record. Corals also grow very fast, which means we can obtain monthly data from them, and this precision rivals instrumental measurements.”