The coast of Pakistan is about 960 km long and borders the Arabian Sea. It extends from the border of India near Rann of Katch in the South-East, to the border of Iran near Gwader in the North-west. The territorial coastal zone of Pakistan is 23,820 sq. km, while the ‘Exclusive Economic Zone’ (EEZ) of Pakistan’s territorial marine waters is about 240,000 sq km.
Administratively, the coast of Pakistan is divided into a 745 km long strip, called the Baluchistan/Makran coast, and a 215 km long strip, called the Sindh coast. The Baluchistan coast has small towns with a population of about one million. Due to lack of industry and population, the Baluchistan coast is relatively free of pollution.
The coastal belt of Baluchistan, specially the Makran coastal belt, is one of the eight ecological zones that are the most backward and non-productive areas of Pakistan. The Sindh coast consists of the Indus River Delta and Pakistan’s largest population and industrial center namely, the Metropolitan Karachi. In contrast to the Baluchistan coast, very serious problems of environmental pollution exist along the Sindh Coast (mainly along Karachi coast and Indus Delta zone). With the exception of Karachi metropolis, most of the coastal areas of Pakistan are sparsely inhabited.
The coastal zone supports both living and non-living resources, which annually contribute to the national economy. Further, the mangrove ecosystem of the Indus deltaic region is also of significant economic as well as of scientific interest to Pakistan. The mangrove habitat supports the spawning and breeding grounds of commercially important shrimps as well as a variety of other fishes. In the absence of an alternative resource, mangroves also serve the underprivileged inhabitants of coastal communities as a valuable source of timber, charcoal and fodder for domestic animals.
There are a number of environmental issues in the coastal zone of Pakistan and, among these, the disposal of domestic wastes and industrial effluent, causing marine pollution problems along the urban centers, are the most significant. The pollution problems have arisen mainly from the indiscriminate discharge of effluent, from industrial and agricultural sources, and disposal of untreated liquid and solid wastes, generated from domestic sources, into the coastal environment. In addition, the coastal developmental activities involving man-made alterations of the coastal environment have also accelerated the impacts of pollution, leading to the deterioration of quality of coastal environmental, depletion of coastal resources, public health risks and loss of bio-diversity.
The coastal city of Karachi has an estimated population of 13 million, and is the biggest trade & economic center of Pakistan, with more than 6,000 small and large industrial units. The sewage waste generation in Karachi is some more than 300 m gal /day, out of which 40% is domestic waste and 60% is industrial waste.
This waste is dumped into the Karachi sea, via Malir river (Ghizri-Korangi Creek area), Layari river (Manora Channel/Karachi Harbour area) and small waste-drains mainly along Clifton Coast and Korangi Coast. The other coastal areas having industrial-pollution problems are Hub Coast, through Hub Industrial Estate, and Gadani Coast, through industries based in Gadani area. The heavy metals, persistent organic pollutants, air pollution and oil pollution are the more significant factors. There is very little information available on the impacts of persistent organic pollutants in the coastal areas of Pakistan although, their presence is noticeable particularly in solid-wastes disposal.
The heavy metals in the coastal waters of Karachi are being accumulated in the sediments and marine organisms, particularly those resident in the polluted areas. The accumulation of eight heavy metals (As, Cd, Co, Cr, Cu, Hg, Ni, Pb, and Zn) in the resident fauna from polluted coastal areas of Karachi has been reported. The heavy metals are being accumulated in considerably higher concentrations in marine organisms of the polluted localities. The accumulation of five heavy metals (Cu, Co, Mn, Zn, and Fe) in the resident fauna from Gharo, Bakran and Korangi Creeks in considerably higher concentrations has been reported in marine organisms comprising resident fauna of fishes including edible fishes, shrimps, some benthic organisms (bivalves and barnacles) from these areas. The concentrations of iron and zinc were found to be higher than the corresponding values for Mn, Cu and Co.
Oil pollution appears to be of some concern along the Pakistan coast. Sources of oil pollution include effluent discharges from two oil refineries, mechanized fishing boats and the cleaning of bilges and tank-washing by the large number of merchant vessels, as well as oil-tankers that pass through the EEZ of Pakistan yearly (2500 oil tankers carry 33 million tons of crude oil, ICZM report, 1994). As a consequence, tar balls (residues of weathered oil at sea) are commonly found on beaches. The recent case of oil-spill (4 June, 1998) from the ship R.V. Yashica, abandoned about 304 km south-west of Karachi (approximately 112 km south of Pasni), which was carrying 1500 tons of furnace oil.
The problem of Harmful Algal Blooms (HABs) in Pakistan is very recent. It is not that it was not occurring in the past, but we were not in fact taking notice of it, due to lack of information of its occurrence and absence of HAB alarm network.
However, in the last few years several incidences of mass-mortality of fishes have been recorded in the marine coastal environment of Pakistan. Type and origin of bloom observed at specific sites along the coast varies: it may be generated locally or may have originated at some distant location and then moved by coastal currents. Factors that trigger Harmful Algal Blooms are also yet unknown. Likewise, spatial origins of blooms are presently unknown in this area. Increasing frequency and intensity of harmful Algal blooms in the region and their concomitant adverse socioeconomic impacts pose a major problem in affected countries.
Developing countries, like Pakistan, are especially vulnerable to the effects of toxic bloom and red tide outbreaks, because of lack of information on how to cope with red tides, and insufficient scientific and managerial expertise in this field.
The toxic algal bloom appears usually once or twice in every year in this region, and cause mass mortality among fishes. Prorocentrum minimum bloom was observed in Gwadar Bay, which was the main factor for the poisoning of fish. The bloom occurred in 1987 in east Gwadar bay, a semi-enclosed shallow coastal body of highly productive water, on west coast of Pakistan. This bloom lasted for about a week that is why it was possible for the scientists to take samples and analyze them.
Over the past twenty years or so, toxic algal blooms have increased around the world in their frequency, magnitude and geographic extent, as well as in their resulting effects. It is also observed that unusual mortality of fish in the Arabian Sea has increased in last few years, which ultimately adversely affects fish marketing and fisheries industry and is of increasing public concern. Though potential “Red Tide’ forming organisms like Gonialax, Noctiluca scintillans, Phaeocystis & Peridinium have been reported by several workers, in recent incidences (Year: 1999 – 2000) of red tide in Pakistan’s coastal waters where wild fish population were hit by this phenomenon including Rough tooth & Bottle nose Dolphins, Speckled Siderial Moray, File fish and Parrot fishes, baleen whale was also found dead.
During this period, water-samples showed the bloom forming concentrations of Gymnodinium and Noctiluca species.
In order to minimize the damage to public health, aquaculture and marine ecosystem, a comprehensive monitoring system is essential.