A multi-metric fish index to measure the ecological quality of tropical predominantly open estuaries along the western coast of India

Sreekanth Giri Bhavan; Sajiya Mujawar; Shivakumar Haragi; Jagannath Rathod; Baban Ingole; Trivesh Mayekar; Dhanya Mohan Lal; Sri Hari Murugesan; Kiranya Bella; Bijukumar Appukuttannair; Pramila Sahadevan; Ranjeet Kutty; Parveen Kumar

doi:10.1007/s10661-023-11013-2

A multi-metric fish index to measure the ecological quality of tropical predominantly open estuaries along the western coast of India

Environ Monit Assess. 2023 Feb 22;195(3):421. doi: 10.1007/s10661-023-11013-2.

Affiliations

¹ ICAR Central Coastal Agricultural Research Institute, Old Goa, Goa, 403402, India. gbsree@gmail.com.
² ICAR Central Coastal Agricultural Research Institute, Old Goa, Goa, 403402, India.
³ Department of Studies in Marine Biology, Karnatak University, Karwar, Karnataka, 581303, India.
⁴ National Centre for Polar and Ocean Research, Headland Sada, Vasco da Gama, Goa, 403802, India.
⁵ ICAR-Central Institute of Fisheries Education, Mumbai, Maharashtra, 400061, India.
⁶ School of Fisheries, Centurion University of Technology and Management, Paralakhemundi, Gajapati, Odisha, 761211, India.
⁷ Kerala University of Fisheries and Ocean Studies, Kochi, Kerala, 682506, India.
⁸ Department of Aquatic Biology and Fisheries, University of Kerala, Thiruvananthapuram, Kerala, 695581, India.

PMID: 36811708
DOI: 10.1007/s10661-023-11013-2

Abstract

Defining the ecological quality of estuaries is challenging because of the inadequacy of available methods and indices to characterise the ecosystem. In Indian estuaries, there are no scientific attempts to establish multi-metric fish index to determine the ecological status. A multi-metric fish index (EMFI) was customised for twelve predominantly open estuaries on India's western coast. The index was established at the individual estuary level to ensure uniformity and contrast from sixteen metrics that designate the fish community and diversity, composition and abundance, estuarine use and trophic integrity from 2016 to 2019. A sensitivity study was followed to measure the responses of the EMFI under different metric varying scenarios. There were seven metrics identified as the most prominent for the EMFI in metric alteration scenarios. We also deduced a composite pressure index (CPI) based on the anthropogenic pressures described for the estuaries. The ecological quality ratios (EQR) defined based on EMFI (EQR_E) and the CPI (EQR_P) for all the estuaries were positively correlated. The EQR_E values calculated based on the regression relationship (EQR_E on EQR_P) showed the divisions from 0.43 (bad) to 0.71 (high) for the Indian west coast estuaries. Similarly, the standardised CPI (EQR_P) values for different estuaries indicated that the values range from 0.37 to 0.61. Our results based on the EMFI suggest four estuarine systems (33%) as 'good', seven (58%) as 'moderate' and one (9%) as 'poor'. Generalised Linear Mixed Model for EQR_E showed that EQR_P and estuary influenced EQR_E; however, the effect of year was not significant. This comprehensive study based on the EMFI is the first record for predominantly open estuaries along the Indian coast. Therefore, the EMFI established in this study could be reliably advocated as a sound, effective and composite tool of ecological quality for tropical open transitional waters.

Keywords: Composite pressure index; Ecological integrity; Ecological quality ratio; India’s western coast; Multi-metric fish index; Tropical estuary.

MeSH terms

Animals
Ecosystem*
Environmental Monitoring / methods
Estuaries*
Fishes
India