ASSESSING MICROALGAL COMMUNITY STRUCTURE IN FIVE TEMPLE PONDS OF TIRUCHIRAPPALLI, TAMIL NADU

Abstract

Microalgae and cyanobacteria are key primary producers and rapid bioindicators of aquatic ecosystem health. This study systematically documented microalgal diversity across five temple ponds in Tiruchirappalli, Tamil Nadu (Panchavarna Samy, Nachiyar, Uyyakondan Thirumalai, Vayalur Murugan, and Periya Nachi Amman Temples). Sampling in the pre-monsoon (March) revealed 93 phytoplankton species (51 genera): 42 cyanobacteria, 34 green algae, and 17 diatoms. Physicochemical analyses showed strong gradients among ponds; for example, Pond-1 had high chloride and inorganic phosphorus, whereas Pond-5 had higher pH and sulfate. Correlation analyses indicated algal abundance was positively related to nitrate, sulfate, pH, and nitrite, but negatively related to chloride, ammonia, inorganic phosphorus, calcium, and magnesium. These patterns suggest nutrient availability and organic loading shape community composition. Many recorded taxa (e.g., Oscillatoria, Phormidium, Navicula, Synedra) are known pollution-tolerant genera, consistent with moderate nutrient enrichment. Biodiversity indices (Shannon’s H′, Simpson’s D) confirmed high diversity (Shannon H′ ≈ 2.8–3.4). We also performed multivariate analyses (PCA and hierarchical clustering) to explore community patterns, which showed ponds grouping by similar water chemistry. Although restricted to a single season, our study highlights the rich algal assemblages in temple ponds. These algae represent potential bioresources; many green algae have high lipid/carbohydrate content for biofuel and can bioremediate wastewater nutrients and metals. These findings provide a baseline inventory of temple-pond microalgae and insights into their ecological relationships and biotechnological potential.