Accounting of ecosystem services from ichthyofauna in wetlands of Uttara Kannada district, Karnataka

Sincy V. ^1,4 Jaishanker R.⁴ Asulabha K.S. ^1,4and Ramachandra T.V.^{1, 2, 3
1}Energy & Wetlands Research Group [CES TE15], Centre for Ecological Sciences, ²Centre for Sustainable Technologies (ASTRA)
³Centre for infrastructure, Sustainable Transportation and Urban Planning (CiSTUP)
⁴Indian Institute of Information Technology and Management-Kerala (IIITM-K), Thiruvananthapuram, Kerala
Indian Institute of Science, Bangalore - 560 012, India.
envis.ces@iisc.ac.in    tvr@iisc.ac.in      Phone: 080 22933099/22933503 (extn 107, 114)

Introduction

Wetlands are one of the world's most productive ecosystems. Wetlands provide habitat for diverse aquatic plants and animals and are described as "the kidneys of the landscape". Wetlands influence the microclimate, enhance the aesthetic beauty and provide recreational opportunities (Ramachandra et al., 2016a). Wetlands sequester carbon efficiently and help in regulating climate (Turpie et al., 2010). Ecosystem services refer to the benefits that humans derive from ecosystems, which include provisioning services, regulating services, and cultural services (de Groot et al., 2020; Ramachandra et al., 2019). Provisioning services refer to the provision of water, food, and raw materials. Regulating services are processes such as water purification, flood control, groundwater recharge, sediment retention, and carbon sequestration. Cultural services refer to ecosystem attributes such as spiritual, educational, cultural, and recreational use (MEA, 2003; Haines-Young and Potschin, 2018). The market value was used for the valuation of provisioning services, whereas non-market values are used for regulating and cultural services (Aulia et al., 2020). The total economic value of the lake and marsh wetlands in China was estimated as 8.1841 × 10¹⁰ USD (Yiran et al., 2014); 674000 USD/yr for Ghodaghodi wetland (Aryal et al., 2021); and 20843.31 USD/yr for Songore wetland (Mahlatini et al., 2020). The economic value of wetlands in India ranged from 3.1 million USD per year (Nagaland) to 7896.5 million USD per year (Karnataka) (Pandey et al., 2004). There are few studies focused on the economic valuation of wetlands in India (Ramachandra et al., 2011; Jala and Nandagiri, 2015; Mukherjee, 2008; Ramachandra et al., 2005). The worth of Rachenahalli lake in Bengaluru, Karnataka, with an area of 42.09 ha was 10435 Rs/ha/day (Ramachandra et al., 2005), while the worth of polluted Varthur Lake, Bengaluru is Rs 220ha/yr (Ramachandra et al., 2011). The valuation of wetland services helps to identify the contribution of wetland ecosystems in the regional economy and also understand the causes of environmental degradation and biodiversity loss, which promote wise use of wetland resources, effective decision-making, and to raise incentive and financial support for conservation activities. Wetlands are being degraded rapidly due to unplanned urbanization, and consequent population pressure, habitat conversion, unsustainable harvesting of resources, lack of environmental consideration and natural causes (Quagraine et al., 2021; Ramachandra et al., 2020a; Al-Mahfadi and Dakki 2016). The degradation of wetlands and loss of ecosystem functions and services will result in the decline of social and economic costs.

Wetlands provide vital habitat, breeding, and feeding areas for fish. Thus, wetlands need to be protected from pollution. Fish provide nutritious food and support the livelihoods of individuals through income generation (Sincy et al., 2022; Mahlatini et al., 2020). Microalgae and macrophytes in wetlands serve as a source of feed for omnivorous/herbivorous fish (Slembrouck et al., 2018; Hasan and Rina, 2009). Fishes regulate the plankton population in lake water and convert the nutrients in the water into readily consumable biomass (Mukherjee and Bardhan, 2019). Fish is a rich source of easily digestible protein, polyunsaturated fatty acids, vitamins, and minerals for human nutrition (Elaigwu et al., 2019; Hua et al., 2019). Total fish used as food was estimated to be ~58000 t in Karnataka, ~6000 t in Kerala and ~1000 t in Tamil Nadu. The fish oil production was estimated to be 30500 t, 3000 t, and 500 t in Karnataka, Kerala, and Tamil Nadu, respectively (Ponnusamy et al., 2012).

The nutritional composition of fish varies seasonally, depending on their life cycle stages, food availability, and environmental conditions (Bogard et al., 2015). Fish are important biotic components of an aquatic ecosystem as they serve as keystone species and bioindicators of water quality as well as wetland health (Nath et al., 2015). The changing habitat conditions may influence the survival, growth, and breeding of fishes. Aquatic life is extremely influenced by the physicochemical properties of the aquatic ecosystem (Oikonomou and Stefanidis, 2020). Inland fishery production is impacted by overfishing, habitat alteration, the introduction of exotic species and water pollution (Perivolioti, 2020). Invasive exotic species like Clarias gariepinus, Oreochromis mossambicus, Oreochromis niloticus, Cyprinus carpio var. communis, and Gambusia affinis in wetlands have led to the decline of native species (Sincy et al., 2018) affecting theavailability of diverse food and medicine. Water pollution, increased sedimentation, water abstraction, reduction in water volume, and illegal fishing practices cause a decline in the diversity of ichthyofauna (Mruthyunjaya et al., 2016). Water pollution as well as heavy metal contamination through industrial discharges affect the growth rate and reproduction of aquatic organisms, resulting in changes in the community structure and trophic levels, ultimately leading to the deterioration of the ecosystem (Ramachandra et al., 2020b; Kumar et al., 2015). Fish kills occur due to changes in temperatures, hypoxia, algal blooms, ammonia toxicity, hydrogen sulphide toxicity, water pollution, and accidental spills (Mishra et al., 2017). Fish become stressed during a low dissolved oxygen period, overcrowding, and high ammonia levels in lake water and become more susceptible to viral or bacterial infections (Njiru, 2015; Khatun et al., 2011). Fish usually require a minimum of 5 mg/L of dissolved oxygen (DO) for optimum health. The sudden fall in dissolved oxygen levels due to the sustained inflow of domestic sewage resulted in fish kills due to asphyxiation in Sankey tank (Benjamin et al., 1996) and Ulsoor lake in Bangalore (Ramachandra et al., 2016b). Thus, water quality assessment is required to evade further pollution of waterbodies to ensure the growth and survival of aquatic ichthyofauna.

Valuation of ecosystem services involves assigning quantitative and monetary values to ecosystem services provided by ichthyofauna (fish) in wetlands. The main objectives of the current study include: (a) understanding various provisioning, regulating and cultural services from ichthyofauna in wetland ecosystems; (b) computation of total ecosystem supply value (TESV) and (c) computation of net present value (NPV) of freshwater wetlands in the Uttara Kannada district of Karnataka.