A baseline study on diversity of birds in Sani Bheri River Valley, Nepal

Rivers and lakes are important habitats for both resident and migratory wetland-dependent birds. This paper presents the study of birds’ seasonal diversity in Sani Bheri River Valley, outside the protected areas of Nepal. The study was carried out from 8-17 March 2019 (Spring) and 12-21 October (Autumn) 2019 covering a 52 km river stretch from Naighat (upstream area where Pelma River and Uttarganga River mix and flow as Sani Bheri river) to Remnaghat (downstream towards the confluence with Thuli Bheri) using the Mackinnon Listing method. The present study recorded 851 occurrences belonging to 11 Orders, 33 Families, and 71 bird species. Order Passeriformes (52 species) and family Muscicapidae (13 species) were dominant. Plumbeous Water-redstart (Phoenicurus fuliginosus) had the highest relative abundance (7.64%). Shannon-Weiner diversity index (H’= 3.61) and Evenness index (e= 0.85) indicate the diverse assemblage of avian fauna in the study area. This study showed that Sani Bheri River Valley provides the habitat for one globally threatened, four nationally threatened, and eight species listed in Appendix-II of CITES. The results provide the baseline information on avian species, which can provide a good database and can be incorporated in conservation implications.

Metal Contaminants Occurrence and Microbial Diversity From the Perspectives of Dual Tolerance by the Bacterial Isolates Along Altitudinal Zonation of River Teesta – a Pristine River System in Eastern Himalayas

The present study was conducted along River Teesta in Eastern Himalaya. Water and sediment samples were collected from six sampling points during the monsoon and winter seasons along the course of the river. The background information was collected by analysing physico-chemical parameters and the heavy metal concentrations. Culturable bacterial diversity using culture-based and molecular based 16S rRNA approaches characterized bacterial isolates to 5 major phyla, majority belonging Proteobacteria, Actinobacteria and Firmicutes followed by Bacteroidetes, Alpha-Proteobacteria, Beta-Proteobacteria, Gamma-Proteobacteria, Actinobacteria, Bacilli, Flavobacteriia, Deinococci, Sphingobacteriia and Cytophagia. The total of 245 characterized isolates belonged to 69 genera. Diversity indices were calculated for each site. There were variations in the community structure of culturable bacteria along the river stretch with some common and unique groups. Heavy metal tolerance and antibiotic resistance profiles showed some isolates to be tolerant to high levels of heavy metals and multiple antibiotic indicating a major concern. The antibiotic resistance diversified along the human impacted downstream sites. The present report on bacterial diversity and the associated metal and antibiotics tolerance is the first of its kind on Teesta river, the only major river system flowing through the state of Sikkim and parts of North Bengal.

Legacy and Emerging Pollutants in an Urban River Stretch and Effects on the Bacterioplankton Community

River contamination is due to a chemical mixture of point and diffuse pollution, which can compromise water quality. Polycyclic Aromatic Hydrocarbons (PAHs) and emerging compounds such as pharmaceuticals and antibiotics are frequently found in rivers flowing through big cities. This work evaluated the presence of fifteen priority PAHs, eight pharmaceuticals including the antibiotics ciprofloxacin (CIP) and sulfamethoxazole (SMX), together with their main antibiotic resistant genes (ARGs) and the structure of the natural bacterioplankton community, in an urbanized stretch of the river Danube. SMX and diclofenac were the most abundant chemicals found (up to 20 ng/L). ARGs were also found to be detected as ubiquitous contaminants. A principal component analysis of the overall microbiological and chemical data revealed which contaminants were correlated with the presence of certain bacterial groups. The highest concentrations of naphthalene were associated with Deltaproteobacteria and intI1 gene. Overall, the most contaminated site was inside the city and located immediately downstream of a wastewater treatment plant. However, both the sampling points before the river reached the city and in its southern suburban area were still affected by emerging and legacy contamination. The diffuse presence of antibiotics and ARGs causes particular concern because the river water is used for drinking purposes.

Predominance of clonal propagation conceals extinction risks of the highly endangered floodplain herb Cnidium dubium

Habitat loss and degradation due to human-induced landscape alterations are considered to be a major threat to biodiversity. The decline of biodiversity may occur with a time delay leading to a so called extinction debt. Therefore, determining extinction risks and conservation status is not always straightforward. Several life history traits might play a role for the accumulation of an extinction debt. Thus, perennial plant species capable of vegetative propagation might be able to persist temporarily in degraded habitats even though sexual and evolutionary processes are effectively halted. We studied Cnidium dubium, which occurs in scattered patches along river corridors in Central Europe and is critically endangered in Germany. It is a perennial species which is able to propagate clonally. Our aims were to reconstruct demographic processes regarding clonal propagation and gene flow along 400 km of river stretch and with respect to the position in the flooplain, i.e. before or behind dykes. We also wanted to determine whether there is evidence for an extinction debt in C. dubium and to use our insights for conservation recommendations. For this, we used nuclear microsatellites and maternally inherited chloroplast DNA markers and applied a systematic grid based sampling strategy for small scale geographic structures. We observed a high level of clonal propagation. In 935 analysed plants we observed only 121 different genotypes and of 50 studied patches of C. dubium the majority (31 patches) consisted of one single genotype each. Patch size and position were correlated with clonal diversity. Large patches and patches behind dykes exhibited higher clonal diversity. There was no evidence for a large scale genetic substructuring of the study area and no differences in overall genetic diversity between upstream and downstream patches as well as between patches before and behind the dykes. High levels of heterozygosity and a high number of 18 chloroplast DNA haplotypes togetherwith a slightly elevated inbreeding coefficient (Fis) point toward a high level of ancestral polymorphism in an out of equilibrium population due to high levels of clonal propagation and low levels of gene flow and recombination. Therefore, we assume that an extinction debt is present in C. dubium. As a management strategy, we propose to transplant ramets between multiple patches to increase the number of mating partners and therefore restore sexual reproduction.

Drinking water quality assessment of river Ganga in West Bengal, India through integrated statistical and GIS techniques

An attempt has been made to assess the water quality status of the lower stretch of river Ganga flowing through West Bengal for drinking using integrated techniques. For this study, 11 parameters at 10 locations from Beharampur to Diamond Harbour over nine years (2011–2019) were considered. The eastern stretch of Ganga showed a variation of WQI from 55 to 416 and SPI from 0.59 to 3.68 in nine years. The result was endorsed through a fair correlation between WQI and SPI (r2 > 0.95). The map interpolated through GIS revealed that the entire river stretch in the year 2011, 2012, and 2019 and location near to ocean during the entire period of nine years were severely polluted (WQI > 100 or SPI > 1). Turbidity and boron concentration mainly contribute to the high scores of indices. Further, the origin of these ions was estimated through multivariate statistical techniques. It was affirmed that the origin of boron is mainly attributed to seawater influx, that of fluoride to anthropogenic sources and other parameters originated through geogenic as well as human activities. Based on the research, few possible water treatment mechanisms are suggested to render the water fit for drinking.

Deep Pools: Ecological Sanctuaries for Steindachneridion melanodermatum, a Large Endemic and Endangered Pimelodid of the Iguaçu River

Steindachneridion melanodermatum, an endemic and endangered species, is the largest catfish in the Lower Iguaçu River basin. Currently, the wild population of this species no longer exists in most of this basin, probably due to the loss of habitat by successive hydroelectric dams. This study evaluated the spatial distribution and abundance of S. melanodermatum in the last free-flowing river stretch of approximately 190 km downstream from the Salto Caxias Dam, upstream of the Iguaçu Falls, as well as some tributaries. Hydroacoustic and fishing campaigns were performed between September 2010 to December 2016 to characterize the preferred habitat. A total of 180 specimens was sampled with higher abundances in a protected area near Iguaçu Falls in the Iguaçu National Park. Twenty-four deep pools were identified with maximum depths ranging from 5 to 25 m: 21 pools were along the main channel of the Iguaçu River, and three pools were in tributaries. Deep pools are preferential habitats for this species, especially the deep pool called Poço Preto (P23) and its surroundings. Conservation strategies are required to protect these habitats and prevent S. melanodermatum from becoming extinct, such as establishing deep pools as ecological sanctuaries, intensifying the inspection of illegal fishing, and maintaining dam-free tributaries.

Ichthyofauna in the last free-flowing river of the Lower Iguaçu basin: the importance of tributaries for conservation of endemic species

The fish fauna from the Lower Iguaçu River and tributaries upstream of the Iguaçu Falls, the last free-flowing river stretch, were investigated. Twenty five sites in tributaries and the main channel were sampled between 2010 and 2016 using several kinds of fishing gear. The species were categorized according to their size, origin, and conservation status. Species richness and abundance in the main channel and tributaries were compared. In total, 87,702 specimens were recorded, comprising 76 species, 25 families, 53 genera, and eight orders. Characiformes and Siluriformes were the richest orders, representing 92% of the total specimens; Characidae, Cichlidae, Pimelodidae, and Loricariidae were the richest families. The fish fauna was composed of small and medium-sized species and included endemic (42%), autochthonous (24%), allochthonous (21%), and exotic (9%) species, as well as hybrids (4%). Significant differences in the relative numerical abundance of species were found among sites. Ancistrus mullerae and Rhamdia branneri (endemic) were indicator species for tributaries inside of Iguaçu National Park (INP), while Phalloceros harpagos (autochthonous) and Ictalurus punctatus (exotic) for tributaries outside of INP and Odontesthes bonariensis (allochthonous) for the main channel. The last dam-free stretch of the Lower Iguaçu River and tributaries upstream the Iguaçu Falls exhibits a rich endemic fish fauna, including some rare, endangered species (Steindachneridion melanodermatum, Gymnogeophagus taroba, and Psalidodon gymnogenys). These findings are essential to predict and understand the effects caused by the new Baixo Iguaçu Hydroelectric Power Plant and highlight the importance of tributaries and Iguaçu National Park for conservation of endemic species.