TEMPORARY PONDS - A NEGLECTED ECOSYSTEM

Temporary ponds are usually rain fed water bodies found in different geographical locations. They are examples of Inland Wetland ecosystem. A few of them are slowly diminishing due to natural ecological succession. But most of them disappear due to human interference at various levels and reclamation of the prime lands.

The productivity and the variety of the temporary pond habitat foster a wonderful abundance and diversity of wildlife including birds, fishes, crabs, worms, insects, reptiles and amphibians. These ponds act as habitats to live, feed and to reproduce. They provide ideal spots for migratory birds to rest during their journey. These are linked to one another and an assortment of plants and microorganisms through complex food webs and other interactions. The pond provides an abiotic frame, arena, made up of all the physical and chemical characteristics of that specific pond, such as morphology, sediment conditions, nutrient concentrations, light availability, pH, and temperature. This abiotic frame will differ spatially among and even within the ponds as well as temporarily within a specific pond (Southwood, 1988; Moss et al 1994). The niche provided is unique to each pond and diversity of life may also be unique to the system. The transitional development stages of various animals are dependent on these water bodies. Aestivation and hibernation principles adapted by the smaller groups are examples of these cases. Many amphibian communities are solely dependent on this micro habitat (Brownmark C and Hansson L., 1998).

Apart from their ecological significance they also serve the local community. Among the benefits, these ponds are sites of recreation, scientific knowledge, education and aesthetic values. About 30 - 50 years ago, villagers in many parts of Dakshina Kannada district used to raise agricultural crop using water from these ecosystems. Among the agrarian land there were scattered rain fed as well as a few ground water fed water bodies from which the farmers used to lift water manually and by mechanical means. These water bodies supplied sufficient water for agricultural activities. As the withdrawal was manual, the recharging capability used to replenish the water bodies by next morning. The water were collected either by small wood scoops or kaidambe or Yatha.

Boating, fishing, swimming and bird watching are a few of the numerous recreational activities people enjoy in these systems. Temporary ponds are valuable laboratories for scientists and students, providing complex lessons in biology, geology, history and social issues, bringing in the ecosystem concept. They also provide a great deal of aesthetic enjoyment for the people who live, work or recreate in and around them.

Community ponds and lakes were common in villages, used for agriculture, domestic animals, drinking, washing, community bathing and fishing, aesthetic values and swimming. The sediments rich in organic material were excavated once in two years and used as nutrient for paddy fields and coconut gardens. The banks of these water bodies used to harbor certain plants especially those thriving on the banks (Pandanus sp.) which were used to make special mats. With the community pressure, these water bodies have almost disappeared.

Unfortunately the increase in the population upsets the natural balance of these habitats and threatens their integrity. The water is polluted and the boundaries are reconstructed to accommodate housing, transportation and agricultural needs. Many a time, the stress is also caused by overuse of resources and unchecked land use practices, which have resulted in unsafe drinking water, eutrophication, algal blooms, loss of habitat, fish kills and a host of other human health and natural resource problems. The values attributed to these wetlands vary from human use to wildlife and others. These ponds may be drained and used for agriculture or developed for housing and other land uses. They have been used as waste discharging sites.

A couple of decades back there were many temporary ponds around Mangalore, which included rain fed temporary, stagnant water bodies and temple tanks. The temple authorities are taking care of the latter. Many of the ponds now have been reduced to small water bodies and a few of them have disappeared completely. There are still others which dry during summer. Many old ponds have shrunken to small water bodies because of improper management practices. A few of the important ponds of Mangalore city are:

Yemmekere - was found in the heart of the city (Near Jeppu, Mangalore). It harboured a large number of fishes, and was a site for the study of Ichthyology by the students of Department of Bioscience, Mangalore University during 1980-90. Now it is completely a land filled area.

Gujrikere - is a completely weed choked pond. An initial neglect caused this crunch to the pond ecosystem.

Kavoorkere - (Fig.1) was originally occupying an area of 12 km2, but now covers approximately 5-6 km2 area of water. It supports varied vegetation along the banks. During heavy rains a large amount of silt and soil as well as other solids accumulate on the banks year by year reducing the area of water (ecological succession precedes transformation into a terrestrial ecosystem). The Government of Karnataka has taken an initiative to retrieve this pond under Small Scale Irrigation Project. Many migratory birds visit this pond for feeding and resting purposes.

Padil Tank - (Fig.2) is another important perennial pond, on the outskirts of the city. It supports many families for household and irrigation needs. Many birds rest and feed on fishes. The water is present throughout the year. However, there is a threat of shrinking due to the organic loading as aquatic weeds and feeding and floating macrophytes (Pistia sp. and Hydrilla sp.) occupy this pond.

Temple tanks - are generally maintained by the temple authorities. Many temples preserve these water bodies as sacred tanks. The functions of these water bodies should be stressed and eutrophication process retarded.

Temporary ponds along National Highways 48 and 17 are generally full during rainy season and recede during summer months. They harbour a variety of weeds, rushes, grasses and birds. The coloured flowers of Nymphia add to the scenic beauty of the water body. The rate of transformation of these water bodies into land is rapid for commercial purposes.

Wetland conservation is an important program of ecological importance. Temporary ponds, which are being neglected, should be given importance. Even though many of them were in the revenue land, now no local government takes interest in protecting them earnestly. Although there is a small-scale irrigation program, a sincere attempt involving local people, panchayath and authorities concerned should be made to retrieve these ecosystems and restore them. Many of the management plans are either in print or in words, but it is not always enough, as these ecosystems will be destroyed any minute. Community education will enhance the involvement and participation of people in restoring this threatened ecosystem.

Brownmark, C. and Hansson, L., 1998. The biology of lakes and ponds. Oxford University Press, Oxford. 216.

Moss, B., Jones, P. and Phillips, G., 1994. August Thienemann and Loch Lomond - An approach to the design of a system for monitoring the state of North temperate standing waters. Hydrobiologia 290, 1-12.

Southwood, T.R.E., 1988. Tactics, strategies and templates. Oikos, 52. 3-18.

1.) Department of Biosciences,
Mangalore University,
Mangalagangothri 574 199,
India