Ecological and anthropogenic covariates ... - GANGAPEDIA

Discussion
Humans have preferentially settled in close proximity of freshwater resources and
subsequently, freshwater ecosystems and species have suffered from multiple
historical and on-going stresses from use by humans (Revenga et al 2005). These
stresses are often interrelated and endangered species, like the gharial (Gavialis
gangeticus), are highly susceptible to these combined pressures (Malmqvist & Rundle
2002). The gharial, a charismatic flagship species of freshwater ecosystems, is
increasingly threatened due to human induced disturbances. Land-use changes,
reduction in water flow due to dams, modification of river morphology, loss of
nesting sites, mortality in fishing nets and egg-collection for consumption (Whitaker,
2007; Hussain, 2009) are some of the factors affecting gharial populations. The
gharial is especially at risk from change in factors like water flow because it prefers
fast-flowing river habitats, which are prime sites for dams (Dudgeon, 2000).
Information on the effects of habitat attributes (availability and profile of basking and
nesting sites; water flow and quality; channel depth and width, etc.); biotic factors
(prey density and diversity, co-predators, etc) and human disturbances (impact of
dams, barrages, canals, pollution, excessive water extraction, fishing, sand-mining,
riverbed cultivation, livestock presence, etc.) on gharial distribution and abundance
are either scant or completely lacking, and thus are an impediment to effectively
understand the conservation needs of the species.
My study describes gharial habitat use in terms of river depth -channel width profile
and basking site characteristics. Previous studies, using a non-mapping technique, on
basking site selection and water depth preferences of the gharial have reported
preference for sandy basking sites, and size-related preference for different water
depths (Hussain, 2009). My study also showed a similar pattern of habitat use by
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