Tuna is an Indicator of Climate Change

TheIndonesia.id - The Indonesian oceans are rich in biodiversities. One of them is tuna fish which is considered the best food dish from the archipelago.

Behind the delicious blessing of tuna, it turns out to have other benefits, a natural indicator for climate change. Oceanography expert at the National Research and Innovation Agency (BRIN) of Indonesia, Dr. Martiwi Diah Setiawati, said tuna has the best sensor in providing indicators of rising sea temperatures.

"Actually, in Indonesia, the sea temperature consistently rises every year, therefore the movement of tuna will be directly equivalent to the graph of temperature changes map in the Indonesian sea," said Tiwi, Dr. Martiwi Diah Setiawati's nickname, as quoted by Antara news agency.

Tuna is always moving, depending on the surrounding conditions. Certain types of tuna will tend to move according to the preferred temperature. Tuna is looking for a comfortable condition, waters that tend to be cold. Through remote sensing, the movement of tuna can provide an overview of which areas are experiencing an increase in temperature. Because waters that experience an increase in temperature will result in fewer varieties of tuna living in them. In general, all tuna species avoid temperatures above 29 degrees Celsius. Oceans close to urban areas have higher heat than other areas due to the urban heat island effect.

In terms of quality, Tiwi explained that remote sensing can map sea conditions and detect such as temperature, chlorophyll, salinity, or saltwater density. Those data were mapped using remote sensing, integrated with mapping of the migration path of tuna, can be used to conclude the results of temperature changes in the sea which finally determine the level of climate change.

Although there are many varieties of tuna, mostly tuna always migrate from warm temperatures to cooler temperatures. So the relationship between the movement of tuna in the ocean and the graphic of climate change which is indicated by the ocean temperature is very closely related.

However, prevention efforts should be done. The problem is, tuna is not a type of fish that is cultivated, so their growth and reproduction are natural in the ecosystem. In an effort to prevent an increase in ocean temperature, it can be seen from a biogeochemical perspective. Without policy changes, expansion of the highest heat stress level (very strong pressure level), then the worst condition of global warming will be an increase, at least more than double by 2030, with land change and climate change scenarios. In fact, during extreme conditions, the heat stress level will increase one more level above it (extreme heat pressure).

Associate researcher in the field of Marine Biogeochemistry, Dr. A'an Johan Wahyudi, gave an answer that is, carbon circulating in the sea must be regulated in order to reduce global warming that comes from the sea. "My field of research is marine biogeochemistry, which is an interdisciplinary branch of science that studies the process of continuous exchange or change between abiotic and biotic components," he said.

In particular, biogeochemistry studies the transfer of material elements (eg carbon, nitrogen, oxygen, water, etc.) between environmental compartments.

The carbon cycle in the ocean has a strong factor in increasing temperatures. The carbon cycle of coastal and pelagic marine ecosystems takes place dynamically, where the processes and variations influence each other with physical factors (current, temperature, salinity), as well as chemical and biological factors (nutrients, heavy metals, primary productivity, and others).

Indonesian marine waters, especially in the Sunda Shelf area, receive massive land inputs. For example, it is estimated that 0.5 Pg of organic carbon enters from land to coast each year via rivers. The extensive input from land, especially the islands of Sumatra, Kalimantan, and Java, has made the Southeast Asia region a major hot spot for carbon fluxes, nutrients, and heavy metals. For example, land-to-sea organic carbon fluxes in this area account for 10 percent of the total global dissolved carbon inputs. This condition also affects the response of coastal and marine waters physically, biologically, and physically.