Applicability of Diatom Indices and Phytoplankton Functional Groups to Assessment of Water Quality in the Coastal Egyptian Mediterranean Estuary

Authors

• Fatma A. Zaghloul, National Institute of Oceanography and Fisheries, NIOF, Egypt.Follow
• Soha H. Shabaka, National Institute of Oceanography and Fisheries, NIOF, Egypt.

Article Type

Research Article

Subject Area

Hydrobiology

Corresponding Author

dr.zaghloul89@gmail.com

Abstract

This study provides the first application of diatom-based water quality and eutrophication assessments in Egypt, focusing on the El Mex Bay situated along the Mediterranean Coast of Egypt, providing a comprehensive evaluation of how diatom assemblages can serve as reliable bioindicators for ecological monitoring in this heavily impacted coastal system. It analyzes two distinct periods: monthly from 2003-2004 and seasonally from 2020-2021. Diatom community composition shifted significantly between the two decades. The earlier period hosted 109 diatom species, which declined to 69 species in the later period. Concurrently, overall abundance decreased from 1,071 x 10³ to 728 x 10³ cells/L. This decline in biodiversity coincided with a marked deterioration in water quality. The estuary transitioned from a mesotrophic-eutrophic state in 2003-2004 to a uniformly eutrophic-hypertrophic state by 2020-2021. The research employed a functional group classification based on Reynolds' theory, identifying thirteen and fourteen distinct groups in the first and second periods, respectively. The results confirm that fluctuations in phytoplankton populations reliably reflect changing water conditions, successfully validating the functional group approach in an Egyptian aquatic environment for the first time. Multiple analytical tools, including biodiversity indices, diatom indices {Trophic diatom index (TDI), Diatom index (DI), Generic diatom index (GDI), Trophic State Index (TSI), and Diatom Water Quality (DQI)}, the Palmer Index, Principal Component Analysis (PCA), and a modified Water Quality Index (WQI), were used to interpret the data. This study establishes a critical baseline and represents an initial step toward calibrating biomonitoring indices specifically for the El Mex Region, paving the way for developing a robust, locally-tailored tool for environmental assessment.

Full Text of Submission

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Recommended Citation

Zaghloul, Fatma A. and Shabaka, Soha H. (2026) "Applicability of Diatom Indices and Phytoplankton Functional Groups to Assessment of Water Quality in the Coastal Egyptian Mediterranean Estuary," Blue Economy: Vol. 4 : Iss. 1 , Article 5.
Available at: https://doi.org/10.57241/2805-2994.1052

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This work is licensed under a Creative Commons Attribution-NonCommercial-No Derivative Works 4.0 International License.