Biodiversity and Abundance of Phytoplankton from Auranga Estuary, Valsad District, Gujarat, India

Abstract

This study describes phytoplankton abundance and diversity from site 1 (downstream) and site 2 (upstream) of Auranga Estuary (20˚63’ N and 72˚82’ E). A Total of 44 species of phytoplankton were recorded, 35 species from downstream and 24 species from upstream. The assessed abundance was 129 cells/mL and 86 cells/mL from the downstream and upstream, respectively. Bacillariophyceae (19) was the dominant group followed by Chlorophyceae (10), Cyanobacteria (07), Dinophyceae (07), and Chrysophyceae (01). Nitzschia, Coscinodiscus and Ceratium were abundant genera at site 1 and Spirogyra, Microcystis, Chlorella and Oscillatoria were abundant at site 2. Nitzschiaceae and Zygnemataceae had highest family contribution at the downstream and upstream, respectively. Members of Bacillariophyceae and Cyanobacteria were present in high numbers throughout the year. The abundance of Chlorophyceae did not fluctuate greatly. Chrysophyceae (Chromulina pascheri) was observed during the summer period. Spatially, downstream had higher species diversity and abundance than upstream whereas winter season was favorable for plankton growth compared to summer and monsoon. Species dominance (Site 1: 0.238; Site 2: 0.257) richness (Site 1: 1.13; Site 2: 1.36), evenness (Site 1: 0.88; Site 2: 0.79) and diversity were assessed using alpha biodiversity indices. The Shannon diversity index was 1.417 and 1.268 for downstream and upstream, respectively. It indicates less diversity level in this estuary

Keywords

• phytoplankton
• diversity
• distribution
• seasonal variations
• diversity indices