Systematics and Ecology of Polychaete Worms of the Pakistan Coastal Waters

Abstract

Polychaete worms are segmented worms and belong to phylum Annelida. They are mostly found in marine habitat but some species are estuarine. Their size ranges from a few centimetre to over one metre. They play a significant role in the ecosystem of the ocean. Some of them are primary and intermediate consumers and some convert organic debris into protoplasm. They are prayed upon by a variety of marine animals including fishes, crabs and shrimps. There are several species of polychaete which are considered as pollution indicator. These species have been the subject of studies involving chemical effects of industrial and domestic effluents on the populace. Marine biofoulers also include species of polychaete worms, although they are less harmful then others biofoulers such as branacles. Some polychaete worms of the family spionidae are pest on oyster, an edible shell – fish, and cause ‘mud – blister’ disease. The diseased oyster have low survival rate and fetch low price in market. There are other polychaetes worms like eunicid and nereid worms which are used as fish – bait and also as life food in aqua culture industry. Nereistoxin is a toxic substance restricted from polychaetes form and is used as insecticide. Despite their importance and abundance, polychaete worms of the Pakistan coast received very little attention. Consequently the polychaete fauna of Pakistan is poorly known. This lack of knowledge is one of the major hurdle in undertaking studies involving various aspects of biology and ecology of marine worms of our coast. The present project was therefore initiated to fill the existing gap and to help overcome the problem which is hindring progress in this important field of marine biology. Present report is based on polychaete collected during the period of June, 1996 to may 1997 from various localities of the Karachi coast. The report describe and illustrate 71 species of these, 32 species, 20 genera and 4 families are new records for Pakistan. This goes to show that there exist an urgent need to continue work on the subject. So that complete picture of polychaete fauna can be obtained and there importance can be understood. This report also contains an identification key to families of polychaete worms of Pakistan and where necessary keys for the genera and the species are also included. A set of worms described here has been deposited in the Pakistan museum of Natural history Islamabad . All the polychaete worms which are known to occur in the coastal waters of Pakistan (including this report) have been collected from Karachi or its immediate vicinity. No attempt has ever been made to study the polychaete fauna of the Balochistan coast where a number of species might await discovery. This is a reasonable expectation for more then 200 species of polychaete have been reported from the adjacent coast of Iran. It is therefore suggested that in the future Balochistan coast should be included in sub study so that a comprehensive account of the polychaete fauna of Pakistan could be made available.