Those who rear fishes in aquariums know that the fishes produce ammonia as waste. The bacteria present in the tank convert ammonia into nitrate and other bacteria convert nitrite into nitrate. Ammonia, nitrite and nitrate are forms of nitrogen and are food for plants. Thus the aquarists grow plants in their aquaria to keep them free from excess ammonia and prevent premature death of fishes. In a nutshell, these plants are like kidneys of aquariums that cleanse the water.

But kidneys of the landscape, sounds funny! Yes, the wetlands are sometimes called as the kidneys of the landscape. Strictly speaking a wetland is an interface between truly terrestrial and aquatic systems, says the Wikipedia.

Wetland is a collective term used for marshes, swamps, bogs etc. Wetlands occupy nearly 6.4 percent of the earth’s land surface. These perform enormous functions such as recycling nutrients, purifying water, attenuating floods by taking in the excess water, maintaining stream flow in case of non-snow-fed rivers, recharging groundwater, providing drinking water, and often buffer shoreline erosion.

It is needless to repeat that the wetlands are of great significance and need to be conserved. It may also be mentioned here that in urban areas many of them have been usurped by the land mafia and even in far flung areas like Sunderbans in West Bengal efforts are lacking to save them.

Wetlands draw the scientists and naturalists to them. In one such project aimed at working out the proportion of macro and microphytes in an around Deepor Beel (lake) near Guwahati, Assam, S.K. Bera and S.K. Basumatary of Birbal Sahni Institute of Palaeobotany (BSIP), Lucknow and R. Gogoi of Botanical Survey Of India carried out extensive surveys. Their findings were significant for the society and have been published in the recently held Diamond Jubilee International Conference of the BSIP.

Like the plants in an aquarium wetlands have aquatic plants that grow in or near them. They not only provide cover for the fishes and aquatic fauna but also produce oxygen. Lack of macrophyte in a wetland affects the biota. Macrophytes are excellent indicators of watershed health. Similarly microphytes are the microscopic algae, often seen as green algal bloom on the ocean surface too. It is estimated that these tiny plant organisms produce about 70 to 80 percent oxygen of our planet.

Deepor Beel has a holding area of 10 sq km but during floods it enlarges to 40 sq km, says the report. Two rivers Pojora stream from Meghalaya and Basistha Bahini from south contribute to the Beel. It has outflow channels too. Climate of the area is humid and tropical with prolonged monsoon.

Despite a congenial climate the study by Bera and his associates found that the pollen and spore percentage is poor compared to the macrophyte content. Less production of pollen means reduction in growth of vegetation. This is not a healthy sign. If the floral content of the Beel is on wane, it will affect the fauna too. As in an aquarium a wetland has to have a balance between growth of plants and biota.

The authors attribute the reduction of aquatic growth to extensive fishing. Less fish means less ammonia and naturally reduced plant growth. Paddy cultivation in the surrounding area, felling of trees and shrubs on the shores, construction activity on the shores, etc have also contributed.

It is time we recognise the importance of the kidneys of the landscape.