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. 2025 Nov 15;197(12):1342.
doi: 10.1007/s10661-025-14770-4.

Biogeochemistry and trophic state assessment of a tropical estuary during contrasting seasons and associated management challenges

Cindrella Joy Joseph  1 , Rose Santhosh  1 , Digila Rani M  1 , Ihjas K  1 , Naveena K  1 , Renjith K R  2
Affiliations

Biogeochemistry and trophic state assessment of a tropical estuary during contrasting seasons and associated management challenges

Cindrella Joy Joseph et al. Environ Monit Assess. .

Abstract

This study employs an integrated biogeochemical approach to assess labile and refractory carbon fractions in surface sediments of the Beypore Estuary, Southwest India, across contrasting seasons to comprehend the organic matter quality and trophic status. Biochemical analysis revealed the conspicuous dominance of carbohydrates (79.3%) in the labile organic matter pool, over proteins and lipids (9.4% and 11.3%, respectively). Stable carbon isotope signatures (δ13C values, - 28.023 to - 19.857‰) confirmed substantial terrestrial organic matter inputs, particularly during the wet periods. The benthic environment exhibited a meso-oligotrophic state, while the water column parameters indicated a delicate balance near the meso-eutrophic threshold, reflecting increased nutrient enrichment during the wet season. This study demonstrates the complex seasonal interplay between hydrological variability, terrestrial organic matter loading, and biogeochemical processes on the estuarine productivity, making it indispensable to develop a sustainable management strategy.

Keywords: Biochemical composition; Biogeochemistry; Biopolymeric carbon; Trophic status; Tropical estuary.

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Conflict of interest statement

Declarations. Competing interests: The authors declare no competing interests.

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