Modelling association of waterfowl conglomerations and anthropogenic multi-stressor at Najafgarh Jheel, Delhi, India

Abstract

Globally the inland urban freshwater wetland biodiversity is facing threat due to anthropogenic activities. Scientist worldwide are understanding the complex linkages between ecological impacts due to human induced pollution. Wetland systems are susceptible to changes in quality and quantity of water. The paper will focus on water quality based stressors and indicative changes in biodiversity including resident and wintering avifauna density. The avifauna is an indicator towards wetland and health of its ecosystem services. The present study provides an overview of a tropical inland wetland (Najafgarh Jheel) in Delhi, India which is exposed to multiple anthropogenic stressors. The wetland is a proposed bird sanctuary and is facing acute conservation issues due to expanding urbanization and extensive agriculture. We measure the data for number of birds at nine census transect points. The census was conducted once a month for a period of one year (2017), early morning 6 am- 9 am. To each census transect we associated eleven points for water quality parameters. The wetland is organically loaded with agricultural runoff and unregulated sewage drains deteriorating quality of water. Therefore, water quality is an immediate local stressor for the resident and wintering birds. The water quality parameters were partially correlated and further modelled with yearly bird density. The generalized linear mixed models depicted that DO, BOD and TDS have higher effect on conglomeration of birds. Further, CCA plot between wintering birds and water quality from two consecutive year data was plotted. The analysis depict the interlinkages of wintering birds with specific stressor. The combination of these multiple stressors have synergistic and antagonistic effects that are decisive for management and restoration of a lake. The current hypothesis based on understanding short term freshwater research, implication towards local management policy and baseline for long term comprehensive studies with holistic approaches. The concept of understanding short-term linkages using multivariate data analysis between water quality and bird density is relatively untested in urban tropical wetlands of India.