Impact of sample collection on prokaryotic and eukaryotic diversity of niche environments of the oil-sand mining impacted Athabasca River.

Microbial communities are an important aspect of overall riverine ecology; however, appreciation of the effects of anthropogenic activities on unique riverine microbial niches, and how the collection of these samples affects the observed diversity and community profile is lacking. We analyzed prokaryotic and eukaryotic communities from surface water, biofilms, and suspended load niches along a gradient of oil sands-related contamination in the Athabasca River (Alberta, Canada), with suspended load or particle-associated communities collected either via Kenney Sampler or centrifugation manifold. At the phylum level, different niche communities were highly similar to each other and across locations. However, there were significant differences in the abundance of specific genera among the different niches and across sampling locations. A generalized linear model revealed that use of the Kenney Sampler resulted in more diverse bacterial and eukaryotic suspended load community than centrifugal collection, though suspended load communities collected by any means remained stably diverse across locations. Although there was an influence of water quality parameters on community composition, all sampled sites support diverse bacterial and eukaryotic communities regardless of the degree of contamination, highlighting the need to look beyond ecological diversity as a means of assessing ecological perturbations, and consider collecting samples from multiple niche environments.

River space: A hydro-bio-geomorphic framework for sustainable river-floodplain management.

The lateral dimension of an alluvial river - floodplains - provides a plethora of goods and services for human needs. Also, it supports the richest and diverse riverine ecosystems on Earth. But over-utilization of floodplain resources had impacted functions of river system adversely. So, the present study attempts to formulate a hydro-bio-geomorphological framework to assess the lateral dimension of a river system for sustainable management of river-floodplains and termed as river space in this paper. The study illustrates river space at seven hydro-meteorological sites situated on the main stem of the Ganga river in the ~750 km stretch that lies between Haridwar and Prayagraj cities. For hydrological aspect, the flood frequency analysis is used to identify flood inundation widths for floods of different return periods with the help of the rating curve and derived cross-section from satellite imagery. Bio-geomorphological aspects are taken into consideration for corroborating the hydrologically assessed river widths (lateral dimension). The present study suggests that the minimum river space should be equal to the lateral width corresponding to the 1-year return period flood. In the present hydro-meteorological sites in the middle Ganga plains, it ranges from 2 to 21 km. Overall, the present study gives an insight of a simple and logical approach that could be beneficial for the biomic restoration of rivers and their floodplains.