Reef Fish Biodiversity and Complexity in the North Bay Reef of Andaman and Nicobar Islands, India

Abstract

Under water visual census using traditional belt transect method (30m x 5m) was conducted to survey the community structure of reef fish assemblages in the North Bay reef of A & N Islands over a period of 3 months on May, June and July of 2008. The Bay is a 1 km² fringing reef area lies between 11⁰42’12.1˝N latitude and 92⁰45’11.0˝E longitude in the vicinity of the East Coast of main city Port Blair. Five sampling areas were used for this study and the depth ranged from 2.2 m to 5.7 m. The total abundance (TA) was 4130 individuals, with 159 species from 31 families. The average TA of the different sampling stations from North to South in entire reef was 826 ± 118.00, diversity index (H’) 1.57, evenness index (J’) 0.3097 and species richness index (d) 18.98. H’ indicated less heterogeneity of species and individuals were unevenly distributed. J’ indicated variation on communities between the species. The coral fish diversity index (CFDI) for the reef was 69 and the appropriate regression formula (4.234 X 69-114.446) predicted an appropriate total of 178 species, indicating that at least 19 more species could be expected. Monthly mean of TA increased from 593.5 in May to 869 in June to 1039 in July, indicated progressive addition of new species with rainy season due to influx of nutrient rich run-off from surrounding hill areas. Pomacentridae dominated the entire reef with a TA of 1677 (40.61%) individuals followed by Phempheridae, 369 (8.94 %) individuals. Species richness of Pomacentridae was highest with 28 species followed by Serranidae with 17 species. Highest single species abundance in the Bay was 448 (10.85%) individuals by Chromis nigrura (Pomacentridae) followed by Phempheris vanicolensis (Phempheridae) with 369 (8.94%) individuals, indicated settlement of these species from nearby mangrove and sea bed areas where bigger sized predatory fishes seldom visit because of shallower depth and anthropogenic disturbances mainly tourist activities as the site is open-access to them. Spatial and temporal variations are less prominent in the reef.