Elucidation of the Phytoplankton Distribution at an Egyptian Ramsar Site (Burullus Lake, Egypt) using Alpha Diversity Indices Supported with RS and GIS Maps

This study was conducted to detect the effect of nutrients on the microscopic count of phytoplankton and chlorophyll-a concentration. Water samples were collected from nine selected stations in Lake Burullus, Egypt in October 2020. Integration of remote sensing (RS) data was assessed to estimate and determine the distribution of the phytoplankton groups in the lake during two different periods. Results showed high levels of nutrients and chlorophyll (indication to trophic levels), especially behind the drains’ outlets according to the count of phytoplankton species. Changes in nitrates (NO₃) and phosphates (PO₄) were the most effective on the phytoplankton count and chlorophyll-a concentration in the lake. On the other hand, the concentrations of chlorophyll a, nitrate and phosphate are marked gradients with high values recorded near the drains and originated from the inputs released into the lake. In general, nitrates and phosphates were limiting factors as well as silicate (SiO₄) which correlated with the blooming of diatoms. GIS maps of alpha diversity indices revealed that the Shannon index value was high near El-Shaklouba area (indication to pollution). The regression model for the estimation of the groups of phytoplankton species indicates interrelation of Euglenophyceae group, with band ratios of red and infrared (R²=0.7). In addition, a predicted distribution map was made for the Euglenophyceae group in the year 2021 in the summer season according to the correlation between the retrieved phytoplankton group of Euglenophyceae with the same bands of Landsat image of 2021 (R²=0.98).