Abstract
The present study attempted to investigate the changes in temperature conducive to fish habitability during the summer months in a hydrologically modified wetland following damming over a river. Satellite image-driven temperature and depth data calibrated with field data were used to analyse fish habitability and the presence of thermally optimum habitable zones in some fishes, such as labeo rohita, cirrhinus mrigala, tilapia fish, small shrimp, and catfish. The study was conducted both at the water's surface and at the optimum depth of survival. It is very obvious from the analysis that a larger part of the wetland has become an area that destroyed aquatic habitat during the post-dam period, and existing wetlands have suffered significant shallowing of water depth. This has resulted in a shrinking of the thermally optimum area of fish survival in relation to surface water temperature (from 100.09 to 74.24 km2 before the dam to 93.97 to 0 km2 after the dam) and an improvement in the optimum habitable condition in the comfortable depth niche of survival. In the post-dam period, it increased from 75.49 to 99.76%. Since the damming effect causes a 30.53 to 100% depletion of the optimum depth niche, improving the thermal environment has no effect on fish habitability. More water must be released from dams for restoration. Image-driven depth and temperature data calibrated with field information has been successfully applied in data sparse conditions, and it is further recommended in future work.
Highlights
Water temperature is regarded as an important indicator of its physical habitability (Zhang et al.2020; Gleeson et al 2020; Quan et al 2020)
Wetland area is primarily concentrated alongside the main river within a 4-kilometer buffer zone, and density is highest near the stream's confluence segment
More than 70% of wetland area has been converted to land, and existing wetlands have undergone into hydrological inconsistency, diminishing water depth, unpredictable water supply, and rising temperatures and all of these are detrimental to the aquatic environment in general and fish habitat in particular (Whitney et al 2020; Pandey et al 2021; Thaman 2021)
Summary
Water temperature is regarded as an important indicator of its physical habitability (Zhang et al.2020; Gleeson et al 2020; Quan et al 2020) It directly and indirectly influences and controls a wide range of aquatic ecological processes (Zhang et al 2020; Yang et al 2020). There are numerous rivers, streams, estuaries, backwaters, impoundments, mangroves, flood plain wetlands, man-made reservoirs, dams, tanks, and ponds throughout India. This country has a diverse fish population with high genetic diversity (2,200 species) and ranks ninth in terms of freshwater mega biodiversity (Sarkar et al 2008). Seasonal wet and dry spells of rainfall, as well as hot and cold spells of temperature, are very noticeable in this country dominated by a subtropical monsoon climate
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