Environmental variables and diversity index as a tool for management in tropical man‐made lakes

Abstract

Fish and water samples were collected from various randomly situated sampling sites in two tropical man‐made lakes, Peechi and Pothundi reservoirs, in South India. The fish samples collected during 2014 to 2015 were taxonomically identified and the fish diversity indices of these reservoirs evaluated. The water samples collected were analysed for such environmental variables as pH, electrical conductivity, dissolved oxygen concentration, alkalinity, hardness, chlorophyll and nutrient concentrations. T‐tests indicated significant difference in both the fish diversity and environmental variables between these two reservoirs. The Pearson correlation test identified electrical conductivity as a highly correlated environmental variable to the ichthyodiversity index in Peechi and Pothundi reservoirs, with coefficients of 0.939 and 0.7012, respectively. Principal co‐ordinate analysis also was conducted on the variables to identify the best combination of variables subjective to the particular sampling site influencing the fish diversity. The analyses explained 72.8% of the total variations for Peechi reservoir, which was represented with eigenvalues of 7.53 and 3.393, respectively, for the first two dimensions. A similar analysis of Pothundi reservoir produced eigenvalues 7.05 and 3.01, respectively, for the first two dimensions, explaining 67.1% of the total inertia. The individual factor maps (IFM‐I and IFM‐II) for Peechi and Pothundi reservoirs identified a high diversity at sampling site 3 in Peechi reservoir, and a similar finding for sites 3 and 7 in Pothundi reservoir, being related to the interactions with other environmental variables, which were greatly influenced by the predominance of macrophytes. The latter is a characteristic of rainfed tropical reservoirs, with special reference to the native fish diversity and environmental variables. The findings of this study suggest management decisions for any aquatic system may be considered after prior assessment of environmental variables and the ichthyodiversity index of the indicated waterbody.

Effect of environmental drivers of fish assemblage and diversity patterns in temporal scale in Mongra Reservoir: A case study from one of the tributaries of Mahanadi Basin, Central India

“…Intake of domestic and agricultural waste might also be implicated for it. pH governs water body's productivity and biodiversity (Paul et al, 2017; Piska, 2001). While Das and Nandi (2001) in the oxbow lake of the Ichhamati river basin and Kumari et al (2019) in the Motia Lake had detected that pH levels were higher in the post‐monsoon season, these findings are similar to those of the current study.…”

“…However, the dominant changes found in five water quality indicators, such as water transparency (0.83–2.69), dissolved oxygen (4.43–6.83), total hardness (64.11–70.33), conductivity (188.25–261), phosphate (0.08–0.12) and chlorophyll‐a (2.84–4.24), were used to assess the intra‐annual comparison of environmental variables (Table 5). Total hardness, transparency, dissolved oxygen, chlorophyll‐a, phosphate and conductivity are all indicators of the state of the water and can be used to assess water quality and production (Johnson et al, 2021; Paul et al, 2017; Ramya et al, 2021; Saha et al, 2021).…”

Effectiveness of carp seed stocking in large reservoir ecosystems of India

“…Although the stocking density and size at stocking are known to positively influence fish production, increasing the stocking densities beyond carrying capacity may lead to decreased growth and survival (Lorenzen, 2001). Factors such as exploitation pattern, seed quality and composition, indigenous fish fauna and habitat quality are the important drivers of fish yield besides the stocking density (Nguen et al 2005; Paul et al, 2017; Piska & Rao, 2005; Sarkar et al, 2018; Sugunan & Katiha, 2004). The logarithmic regression relationships have shown moderate to strong relationship among stocking density and yield in each studied reservoirs.…”

Understanding the trade-offs in tropical reservoir fishery in a socio-ecological perspective

“…The diversity studies in Peechi Reservoir recorded 14 species belonging to 11 genera, 6 families and 3 orders. Paul et al (2017) recorded 18 species belonging to 15 genera, 10 families and 4 orders from this reservoir. Table 1 presents the fish species in Peechi Reservoir during the present study.…”