Porites corals are found in many tropical seas, including Indonesia. It is sometimes called hump coral or finger coral because it generally resembles a hump or dome and has branching fingers, like deer antlers but small.
The preservation of porites is very important for humanity, especially related to the climate crisis. This is because these corals keep records of climate change hundreds to thousands of years ago, with differences in identification times of up to a month. That way, humanity can predict future climate change as well as mitigate global warming.
“The bigger the size of the coral, the more information is learned from the skeletons [chalk skeleton] so that information on climate change can be known. Its large size is useful as a barrier [protection] for the beach from the threat of abrasion,” said Muhammad Rizza Mufitiadi, lecturer and researcher from the Aquatic Resources Management Study Program, Faculty of Agriculture, Fisheries and Biology, University of Bangka Belitung.
As an archipelagic country , Indonesia has 18 percent of the world’s coral reefs. However, the UNEP report also states that Indonesia is the world’s largest exporter of live coral, around 70 percent. In addition to economic opportunities, this is also a threat to the preservation of coral reefs in Indonesia, if not done wisely.
Porite corals are found in Indonesia, scattered in Raja Ampat, Komodo Island, Wakatobi, Bunaken, Pulisan, Derawan, also Ujung Kulon . Besides that, there are also Togean, Banggai, Bali, Bunaken, Tombariri, Luwuk, to Pulau Weh. On Kacasa Island, 31 kilometers from Bangka Island, porites are also found there.
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Under X-rays, experts can read records of changes in the environment from the dark to light of pieces of porites coral . Environmental impacts on coral growth can be analyzed, both regionally and globally. The physical and chemical data of the marine environment are buried and printed in the porites strokes . The strokes are like tree rings which are used to estimate their age.
Sri Yudawati Cahyarini , a BRIN researcher explained in an article that Indonesia has past climate data available in various forms. Among them are stored in coral, marine sediments, lake sediments, speleotherms , tree rings, as well as the Puncak Jaya ice core, Papua.
Studies of past climates or paleoclimate using various mediums have their respective advantages. So, it would be better to combine the data obtained to be able to complement one another.
For example, marine sediment climate data is known to be able to provide climate information for millions of years, but with data resolution of tens to hundreds of years. Meanwhile, coral climate data can provide data for hundreds to thousands of years, but with a resolution of up to months.
“In the climate archive, there are chemical elements that can be used to reconstruct sea surface temperature, salinity, rainfall, etc., known as geochemical proxy data,” he wrote.
For example, the content of strontium [Sr] and calcium [Ca] in porites corals can record sea surface temperature data. Meanwhile, the oxygen isotope content in coral can provide information on salinity levels.
“Coral growth is one centimeter per year. [If] we have three meters of [long] coral, it means we can extract data 300 years back from now,” he said, quoted from Tempo .
Indonesian researchers together with researchers from Australia, America, Taiwan and China using porites coral managed to reveal the positive IOD [Indian Ocean Dipole] phenomenon which rarely occurred in the past. A positive IOD means sea surface temperatures and precipitation are increasing in the western Indian Ocean region.
As a result , there is drought in Southeast Asia and Australia due to low rainfall in the eastern Indian Ocean. It is estimated that today’s positive IOD is more common and is predicted to get worse if humans do not seek to reduce greenhouse gas emissions.
BRIN utilizes dead porites coral taken from coral reef waters in the Sunda Strait, Lampung Bay, which represents past climatic conditions. From this dead coral, researchers were able to uncover medieval warm climate data, namely the period from 1100 to 1140. Meanwhile, live coral porites taken from the Enggano Islands represented climate data from 1968 to 2008.
So there are more and more reasons why we should preserve coral reefs. Corals with various shapes and colors are the habitat for marine biota which fishermen depend on for their livelihood. Strong and healthy coral can protect against the crashing waves that erode the land.
Corals are also known to store carbon which reduces the impact of global warming. In addition, we can enjoy its beauty by diving or snorkeling .