As the Chitra turns saline, mangroves appear

Kamran Reza Chowdhury

Salinisation of freshwater near Sundarbans  leading to mangrove forests and spelling the end of an ecosystem that was heavy with sweet water vegetation and fish

Environmentalists have consistently warned that climate change would adversely affect the world’s largest mangrove forest and World Heritage Site, the Sundarbans, with the reduction in flow of fresh water, and increase in salinity.

In reality, salinisation of the freshwater river Chitra – adjacent to the Sundarbans – started a couple of decades ago. Now, new mangrove forests are springing up, replacing other vegetation and spelling the end of an ecosystem that was heavy with sweet water vegetation and fish.

The newly emerged mangrove forest stretches across three and half kilometres, in the villages of Goalbari, Putia and Gurguria in Begerhat district.

“The Chitra has always been a freshwater river [but] since our youth, we have seen Sundari, Keora, Golpata, Ura and other trees spreading along two sides of the river,” Tauhidul Islam, a former chairman of Mulghor, told thethirdpole.net, adding that the trees grow in the saline waters of the Sundarbans.

“You will not see non-saline species in the area,” said slam, a fish trader. The increased salinity has pushed mango, coconut, and other species out from Mulghor. “The coconut trees have been getting thinner day by day and dying.”

Kalipada Biswas, a councillor in Mulghor, told thethirdpole.net that about 30 years ago, the poor people from that area used to go to the Sundarbans for fishing.

“The forest department barred the fishermen from taking the seeds of the species out of the Sundarbans. Many were caught and faced imprisonment and fines. But some of them managed to bring a few seeds to Mughor,” he said. “They planted the seeds in the shoal areas on the Chitra, which also carried seeds from the Sundarbans. Thus, the forest has expanded.”

Mohammed Rafiq, a local farmer, told thethirdpole.net that the expansion of the mangrove forest made them scared. “Many of us cut the trees,” he said. “People say the government would acquire the land and stop us entering the forest, if the forest expands quickly.

Mahmood Hossain, who teaches forestry and wood technology at Khulna University told thethirdpole.net that the mangrove forest along the Chitra river developed around 20 years ago.

“I have detected at least 12 commonly seen Sundarbans species along the Chitra river. Sundari, Gewa, Golpata, and Chaylia are commonly seen. I have also seen some of the Sundarbans creepers such as Kalialata, Hargozapata, and the tiger fern,” he said. “About 20 to 25 years ago, there was no mangrove forest … this means that salinity has increased in the Chitra river.”

Hussain said the Chitra river had been carrying the seeds of the Sundarbans species, but mangrove trees could not flourish due to the low salinity in the Chitra river.

“It is not true that mangrove species only grow in saline condition. When you plant seeds of a mangrove species in zero saline soil, it will grow. But it cannot survive competing with the non-saline species. But when salinity increases in the same soil, the non-saline species cannot survive while the mangrove species survive,” he said.

The mangrove forest along the Chitra has been expanding due to increased salinity, especially in the dry season when the flow of freshwater declines.

As a proof of increased salinity level in the Chitra, Tauhidul Islam said the pattern of fish production had changed over the years.

“For around 20 years, the production of brackish Bagda shrimp has increased while the sweet water species Golda shrimp, as well as freshwater fish like the Ruhi and Catla, has gone down,” he said.

The Bangladesh water development board, which looks after the salinity and morphology of rivers, seems clueless about the mangrove forest on the Chitra in Mulghor.

“We do not have any salinity monitoring station in Fakirhat. So I cannot give you the salinity level in the Chitra in the place where mangrove species developed,” Mohammed Delwar Hossain Akhand, the superintendent engineer of the Hydrology wing of the board told thethirdpole.net. “Without research, we should not say anything about it.”