Exploring the ecosystem health of a tropical Indian estuary using mass-balanced ecosystem model

• Published in: Aquatic sciences 2022-07, Vol.84 (3), Article 46
• Main Authors: Bhavan, Sreekanth Giri, Ingole, Baban, Rakshit, Nabyendu, Giriyan, Asha, D’souza, Fraddry, Dourado, Shalita, Mayekar, Trivesh, Rivonkar, Purva, VishnuRadhan, Renjith, Bhanudasrao, Chakurkar Eakanath
• Format: Article
• Language: English
• Subjects: Anthropogenic factors; Aquatic animals; Aquatic biota; Biomass; Biomedical and Life Sciences; Biota; Brackishwater environment; Detritus; Dolphins; Ecological function; Ecology; Ecosystem assessment; Ecosystem models; Ecosystems; Environmental Management; Estuaries; Estuarine dynamics; Estuarine ecosystems; Exergy; Fishers; Food chains; Food webs; Foods; Freshwater & Marine Ecology; Functional groups; Indicators; Life Sciences; Life support systems; Marine & Freshwater Sciences; Marine mammals; Oceanography; Perturbation; Primary production; Research Article; Sustainability; Trophic levels; Tropical climate
• ISSN: 1015-1621; 1420-9055
• DOI: 10.1007/s00027-022-00880-5

Estuaries provide life support to aquatic biota and livelihood support to fishermen and local inhabitants. However, the ecosystem function of estuaries is impaired due to anthropogenic stressors and hence, the assessment of ecosystem health using ecological indicators will deliver the status of stability, maturity, and integrity of an estuary. In this paper, we compiled comprehensive ecological data into an Ecopath model from 2018 to 2019 for a tropical Indian estuary, Mandovi (ME) located along the western coast of India. The functional groups (22) identified in the food web ranged from primary producers (trophic level (TL) = 1) to dolphins (TL 4.4). The indices: biomass/total system throughput (0.01), primary production/respiration (11.04), and primary production/ biomass (35.7) showed that the estuary is a developing ecosystem far from maturity. The ME food web is an immature, complex and organized trophic network with a medium rate of recycling (Finn’s Cycling Index = 9.75%), high total system throughput (17,132.33 tons km −2  year −1 ), low ascendency (19,610 tons km −2  year −1 ), high relative ascendency (47.8%), moderate connectance (0.36), and omnivory indices (0.26). The health indices: eco-exergy index (21,471.33 gm detritus equivalent m −2 ) and system robustness (0.153) showed that the ecosystem is immature but resilient to unexpected perturbations in the ecosystem. The ecological indicators were compared with other global estuaries, and the environmental indices were developed for the ME. Based on the ecological indices, the estuarine system is immature, moderately developed, and not well organized in terms of its ecological components. The study also indicates that an ecological approach would be more appropriate and essential in analyzing tropical transitional waters' health and sustainability.