KARACHI - An International study titled; Degradation of Indus Delta Mangroves in Pakistan; authored by Amjad A Shah, I Kasawani and J. Kamaruzaman, talks at length about the major threats being posed to mangroves plantations in Pakistan. Mangroves are ever green forests between land and sea, found essentially in the inter-tidal zone and occupying large tracts along the shallow coasts, estuaries and in the deltas where they are influenced by tides, widely differing conditions of saline and rainfall regimes. The coastline of Pakistan is 1,050 km long and 40-50 km wide shared by the provinces of Sindh (350 km) and Balochistan (700 km). In the Sindh province, mangroves are found in the Indus Delta, which occupy approximately 600,000 ha extending from Korangi Creek in the north to Sir Creek in the South. Indus Delta comprises 17 major creeks, numerous minor creeks and extensive mudflats and constitutes 97% of total mangrove forests found in Pakistan. The Indus Delta Mangroves are unique as being the largest arid climate mangroves in the world. The survival of these forests is largely associated with perennial fresh water supplies from the River Indus, which flows through the delta before reaching the Arabian Sea. An area of 3,44,845 ha of the Indus delta has been declared as protected forests and is under the control of Sindh Forest Department. The Indus Delta is nearly 95% of the mangroves comprise the species Avicenia marina. Very small patches of Ceriops tagal and Aegiceras corniculatum are found near the mouth of the Indus at Keti Bunder. Rizophora mucronata has been introduced in the Indus delta through replanting work. In Balochistan province, the mangroves occur at three sites, Miani Hor, Kalmat Khor and Gwatar bay. Total area under mangrove cover in all three sites has been estimated to be 7,340 ha. This area is equal to 3% of total mangroves found in Pakistan. Miani Hor is the only area in Pakistan where three species of mangrove Avicennia marina, Rhizophora mucronata and Ceriops tagal occur naturally. Some of the roles/functions of mangroves are as under. Firstly, they support diverse forms of plants and animal life, provide food, shelter and breeding ground to prawns, shrimp, several fish, crabs and other marine life, having annual export earning is of US$4 billions. Reduce wave action and help stabilize coastlines. Assimilate sewage water wastes and heavy metals from industrial plants. They even protect seaports from cyclones; they reduce the intensity of cyclones. The report highlights that in the coastal region, there is a general scarcity of sweet water. All the creeks are full of seawater and are subjected to tidal action. The main source of sweet water is the River Indus that has been changing its course frequently within historical times. The existing mangrove vegetation depends upon its water supply from sea. It has adopted itself to the high salt contents of seawater, so much so that every part of tree is salty in taste. Most important cause of degradation of Indus delta mangrove ecosystem is reduction in the quantum of fresh water discharge from Indus due to diversion of water for agriculture, hydro-electricity and other uses in the upper reaches. Estimated total water available from the Indus catchments is 150 MAF. Over the period of past sixty years, the quantity of sweet water flow has been reduced to about 35 MAF (43 billion m3) that mainly occur during 3 months. The total silt load is estimated as 400 million tons/year and the actual quantities discharged are estimated at 100 m/tons/year. Geophysical factors affecting the mangrove ecosystem include existing problems and the threat of global warming. The general phenomenon of sea level rise is attributed to global warming. It is reported that over the last 100 years, the sea level near Karachi has been rising at a rate of 1.1 mm. per year and this may increase with global warning. Pakistan has been included in the list of ten countries most vulnerable to the impacts of rising sea levels. A continuation of the present trend will cause more stunted growth of mangroves and the biodiversity of mangrove areas will be eroded. Given the inelastic supply of land in Karachi, future economic growth will require reclamation of land from the sea at the cost of removal of mangroves. Unless this cost is correctly valued to capture long-term effects on the sustenance of coastal areas, the trend is likely to continue and biodiversity will suffer irreversible losses.