Abstract

Coastal Bays are productive habitats used by a variety of fishes and other benthic organisms but little information is available on the ecology and population dynamics of benthic fishes of coastal bays in the tropical zones. This paper deals with the biodiversity, faunal assemblages, seasonal variations in the benthic fish population of a shallow tropical Bay named Nizampatnam Bay, located in southern province of Bay of Bengal, East coast of India. The standing stock of benthic fishes and associated environmental factors of the study area were also reported in this paper. Sampling was done in two successive post monsoons and pre monsoons during 2006 to 2008. Water and sediment samples were collected from 20 stations covering 10, 20 and 30 m zones. Altogether, 128 biological samples were collected with a Naturalist’s dredge. Thirty benthic fish species belonging to 21 genera, 12 families, 6 orders and 1 class were recorded in this study dominated by Cociella crocodilus and Pisodonophis boro. The mean of Shannon Wiener diversity index H’ was recorded 1.3±0.4 during post-monsoon and 1.2±0.2 at pre monsoon suggesting that the benthic fish diversity of this Bay was poor. Multivariate (Bray-Curtis similarity) analyses typified two large groups of stations representing respectively the post monsoon and pre monsoon periods. The two faunal associations recognized off the Nizampatnam Bay were, Cociella crocodilus, Cynoglossus lida, Cynoglossus punticeps and Astroscopus zephyreus (Group I) representing post monsoon and Pisodonophis boro, Trichonotus arabicus, Acentrogobius cyanosmos and Pseudorhombus elevatus (Group II) representing pre monsoon. Canonical correspondence analysis (CCA) showed that salinity, temperature, dissolved oxygen, % sand and sediment mean particle diameter influenced seasonal variability in the distribution of benthic fish population. This study will provide the baseline information on the biodiversity, ecology and seasonal variations in benthic fish associations of this area and will contribute to the Pisces list of Indian seas.

Keywords: Species diversity; Seasonal variations; Benthic fishes; PRIMER; Canoco; Physicochemical properties; Nizampatnam bay; Bay of Bengal