MARINE JETTIES AS ARTIFICIAL REEFS (ARS) – A STUDY ON THE FISH ASSEMBLAGE STRUCTURE FROM PORT BLAIR, SOUTH ANDAMAN

摘要

Artificial Reefs (ARs) are those manmade structures (including marine jetties) which can support a number of native populations both moving and sessile in marine ecosystem. The present study investigated the fish assemblage structure in the marine jetties at Marina Park (MP), Panighat (PG), Chatham (CT) and Dundus Point (DP) around Port Blair, South Andaman coast. The most number of pillars in the water was found in CT (26) and MP (22) while the longest marine jetties in length were MP and PG (60m). The average temperature ranged between 32 to 35 .C while average salinity varied from 30 to 33 psu. The average pH was found to be alkaline (8.43 to 8.60), whereas the dissolved Oxygen (ml/l) varied from 4.42 - 5.78 and Biological Oxygen Demand (ml/l) was found to be highest in Dundus Point i.e. 1.07 and lowest was in Panighat (0.75). Sedentary organisms like oysters, barnacles, chiton, gastropods, algae etc. were recorded in all the stations, while soft corals were present only in Marina Park and Panighat. A total of 1971 individuals of fishes belonging to 38 species, 29 genera and 22 families were observed during the study. Lutjanids, Pomacentrids and Chaetodontids were the abundant in all the jetties. The diversity indices viz. Shannon Weaver's species diversity index, Margalef's species richness index, Simpson's species evenness index and Pielou Species evenness index have shown that Marina Park Jetty is more diverse as well as abundant in fish species (1.82, 4.27, 0.72, and 0.54 respectively) even though the anthropogenic activities like tourism were observed very high compared to other jetties, while the lowest in diversity and abundance was Dundus Point Jetty (0.71, 0.74, 0.37, and 0.44 respectively). The percentage of plastic waste was maximum in all the study sites i.e. 61.1 (MP), 15.5 (PG), 71.4 (CT) and 54.5 (DP). While the minimum percentage was found to be of fishing nets i.e. 2.7 (MP), 3.8 (PG), 1.8 (DP) and Nil in Chatham. The other waste items included glass bottles, footwear, polythene covers and clothes. The results of the present study have shown that the abundance and species diversity of fishes is related mostly to the length of the jetty as well as number of pillars in the water which can act as an artificial habitat.