Seasonal influence of water quality on the assemblage and diversity of phytoplankton along Dubai Creek, Arabian Gulf

Abstract

The research aims to find out the seasonal variation in phytoplankton diversity, composition and their abundance in response to various environment parameters. Seasonal variation in the phytoplankton community associated with various biological and water quality parameters (Temperature, Salinity, Dissolved Oxygen (DO), Nitrate (NO3-N), Phosphate (PO4-P), Chlorophyll-a, Phaeophytin and Carotenoids) were studied along 10 sampling stations of the Dubai Creek during January–December 2018. One-way ANOVA (p< 0.005) and correlation coefficient between the phytoplankton abundance and the physico-chemical parameters revealed positive trends of phytoplankton composition. The phytoplankton species diversity varied from 55 (Sanctuary) to 95 (Creek mouth). A total of 110 species of phytoplankton were recorded in Dubai Creek, comprising of 76, 29, 3, 1 and 1 species of Bacillariophyceae, Dinophyceae, Cyanophyceae, Euglenophyceae and Ciliophora respectively. The annual mean variation in phytoplankton population were recorded between 744 (Hyatt Regency) to 31906 cells × 103 L−1 (STP outfall). Due to the morphology, hydrodynamic regime and polluted nature in the upper Creek presented an unique phenomenon where the phytoplankton species and density divided Dubai Creek into two (2) sections. The first section (downstream of the Dubai Creek) include the stretch from the Creek mouth to the Floating bridge stations with low population and high species diversity, whereas the other section (upstream of the Dubai Creek) cover stations from Al Gharhoud bridge up to the Sanctuary with dense population and low species diversity. The diversity index showed highest along downstream of Dubai Creek. A ‘k’ dominance plots for phytoplankton abundance between samples showed lower and higher steep curves along downstream (Creek mouth, Abra and Hyatt Regency) and upstream regions (Al Jaddaf, Sanctuary and STP outfall) of Dubai Creek. This could probably de due to the polluted and unpolluted conditions of the Creek. Bray–Curtis cluster analysis showed strong similarity (>60%) among upstream stations of Dubai Creek associated with polluted conditions, whereas an overlap of Creek mouth, Abra and Hyatt Regency on remaining stations showed unpolluted and healthy conditions of the phytoplankton in downstream stations. Canonical Correspondence Analysis revealed that Bacillariophyceae have a positive strong relationship with different environment variables between stations Abra, Hyatt Regency and Creek mouth, indicating influence of high flushing of the coastal waters on phytoplankton species and diversity. The study presents an outline of the seasonal dynamic relationship between phytoplankton structure and environmental conditions in the Dubai Creek.