Abundance, Distribution and Species Diversity of Invertebrates Collected By Commercial Trawler From Near Shore Coastal Areas of Karachi, Pakistan (Northern Arabian Sea).

Authors Avatar

ABUNDANCE, DISTRIBUTION AND SPECIES DIVERSITY OF INVERTEBRATES COLLECTED BY COMMERCIAL TRAWLER FROM NEAR SHORE COASTAL AREAS OF KARACHI, PAKISTAN (NORTHERN ARABIAN SEA).

RAOOF MUHAMMAD NIAZI* NAUREEN AZIZ QURESHI **AND MUZAMMIL AHMED**

*GOVERNMENT CITY COLLEGE,

F. B. AREA, KARACHI.

[email protected]

**CENTRE OF EXCELLENCE IN MARINE BIOLOGY,

UNIVERSITY OF KARACHI, KARACHI.

Total number of figures included: 5

Running Title: DIVERSITY OF INVERTEBRATES COLLECTED BY COMMERCIAL TRAWLER


ABSTRACT

The distribution and abundance of benthic macro fauna in near shore waters off Karachi is studied for over a period of one year.  For this purpose the marine benthic fauna was collected every month from otter trawl catches of “Hella” fishing trips undertaken by Karachi based commercial shrimp trawlers fishing in depths of about 12 meters.  A total of 76 species of invertebrates belonging to 38 families were studied.  The distribution and abundance varied with seasons and maximum number of invertebrate species was found during the monsoon season when salinity was low and temperature was high.  With increasing salinity and falling temperature the number of invertebrate species in the study area, seemed to decrease.  The diversity of invertebrate species collected was studied using the diversity indices and the seasonal variation in the diversity indices was also discussed.

KEY WORDS: ABUNDANCE, DISTRIBUTION, DIVERSITY INDEX, H', COMMERCIAL TRAWLER, COASTAL AREAS OF KARACHI, (NORTHERN ARABIAN SEA).


INTRODUCTION

Commercial trawlers along the cost of Karachi are conducting a lot of bottom trawling. One of the supports of the regional economy and fulfill the needs of protein source of the country. Little information is available in the literature on the bottom dwelling macro-faunas of the coast of Pakistan. There is thus a grate gap in our knowledge about our own marine fauna. The main reason for this paucity of information lies in the fact that scientific bottom trawling studies have not been frequently made, and in the occasional cases where undertaken, not much attention has been given to non-commercial or economically unimportant marine organisms. Hence subtidal fauna remains little stidied. Compared to the subtidal and benthic marine studies, investigation of the intertidal fauna, flora and their biology are many in number as shown in Ataur-Rahim, (1986). For instance, Ahmed (1977) dealt with the distribution of marine organisms on some rocky, sandy and muddyshores of Karachi region in relation to pollution. Sabsequently, Ahmed (1987) dealt with the marine fisheries resources of Indus delta (Northern Arabian Sea).

Join now!

A research has been conducted in the near shore waters off Karachi, which aims to study the near shore marine benthic fauna, documenting the diversity of the marine fauna. For this purpose the benthic faunas was collected every month for one year. A total of 76 species of invertebrates belonging to 38 families were collected. 


MATERIAL AND METHODS

The material was collected by means of an otter trawl operated from a commercial trawler during the period of one year from December 1992 to November 1993. During the study period one trip per month was undertaken. ...

This is a preview of the whole essay