Soil ciliates of the Indian Delhi Region: Their community characteristics with emphasis on their ecological implications as sensitive bio-indicators for soil quality

Abstract

The present investigation aims to study the diversity of ciliates from different habitats in and around Delhi, India, and the correlation of this diversity with soil quality {agricultural lands (site 1 and 2), dump yards (site 3 and 4), sewage treatment plant (site 5), residential land (site 6), landfill (site 7) and barren land (site 8)}. Various physicochemical parameters of the different soil samples were studied and analysed for soil texture, interstitial water, pH, conductivity, total organic carbon, total organic matter, total nitrogen and phosphorous content, using standard protocols. Seventeen ciliate taxa belonging to four classes, seven orders, ten families, and 17 genera were recorded, with the maximum number of species (eleven) belonging to the class Spirotrichea. Ciliate diversity was highest at sites 5 and 6 and lowest at sites 1 and 2. Spathidium sp. was the dominant species in the conditioned land (site 8), while the ciliate Colpoda sp. was present in all the sites examined, showing the highest population density in the sewage treatment plant site (site 5). Statistical analysis showed that ciliate diversity was positively correlated to physicochemical parameters such as interstitial water, total organic matter and organic carbon, total nitrogen and total phosphorous content. Analyses of spirotrichs/colpodids (S/C) ratio and diversity indices implied that the habitat conditions of sites 1, 2, 3 and 8 are relatively unfavourable for soil ciliates to flourish; while sites 4, 5, 6 and 7 provided more favourable conditions. The ubiquity of ciliate distribution suggests their important role in the soil food webs and nutrient cycling, and their community structure and specific characteristics appear to be of major importance for soil formation. A full understanding of soil ciliate diversity and physicochemical parameters helps to inform best practice for improving soil quality as well as conservation practices for sustainable development and management of farms and cultivated lands. In conclusion, ciliate diversity serves as an important and sensitive bio-indicator for soil quality.

A Study on Spatio-Temporal Variations in Physicochemical Parameters and Ciliate Community Structure of Three Freshwater Bodies from Delhi, India.

“…In SL, the diversity was lowest in January (winter) with a pH of 7.7 ± 0.04 and in RJ, the lowest diversity was noticed in July (monsoon season) with pH of 8 ± 0.06. Thus, this indicates that increase in pH (from neutral to slightly alkaline) decreased the ciliate diversity since it has been reported that increase in pH or alkalinity decreases the growth of ciliate species (Abraham et al 2019 In all the sites and all the months, the threshold value of dissolved oxygen was higher than the classic de nitions of hypoxia (< 2.0 mg/L), suggesting favourable conditions for microbial growth (Spietz et al 2015). The previous report on the DO levels of OBS suggests a low level of DO (average value of 1.6 ± 0.84 mg/L) in the year 2009-2010 (Manral and Khudsar 2013).…”

“…Increase in pH indicates an increase of CO 2 uptake by phytoplanktons leading to algal blooms(Thirunavukkarasu et al 2014;Vajravelu et al 2018). This gradually depletes the nutrient contents in the ecosystem thereby affecting the species diversity at higher pH(Abraham et al 2019).…”

“…OBS, having high ciliate diversity, showed the lowest EC mean value (600.90 ± 60.70 µS/cm) followed by SL (793.93 ± 135.86 µS/cm) and highest was in RJ (1361.70 ± 281.25 µS/cm). It has been reported that high EC indicates the hypersaline condition of the water which inhibits ciliate diversity(Abraham et al 2019). EC is considered to be an important factor for characterizing water quality(Esteves 1988).…”

Use of ciliate communities for monitoring ecological restoration of grain for the green in north-western China

“…They are sensitive to farming systems and contribute significantly to mineralization processes and key ecosystem functions in soil (Heger et al, 2012;Domonell et al, 2013). Changes in soil ciliate community structure have also been suggested as bioindicators of environmental stress, improvements in soil quality, CO 2 flux increments in soil, and peat-bog restoration (Lüftenegger et al,1985;Yeates et al, 1991;Foissner, 1999;Mayzlish and Steiberger, 2004;Mieczan et al, 2017;Gabilondo et al, 2018;Abraham et al, 2019). Several previous studies on the diversity of soil ciliate communities at GFG sites in north-western China have been carried out by Ning et al (2011bNing et al ( , 2016Ning et al ( , 2017aNing et al ( , 2018Ning et al ( , 2019.…”

Application of DNA barcoding for identifying potential biotechnological candidate organisms from the River Nile, Egypt.

“…Even there are some recent studies that assessed the role of their pheromones and secondary metabolites as potential anticancer derivatives (Catalani et al, 2016). They have been elucidated as biomarkers for improved environmental quality, such as in the soil (Abraham et al, 2019). Moreover, some species actively reduce bacterial flocs and increase ammonia removal from activated sludge, leading to a long-term enhancement of sewage-treatment through activated sludge (Walczyńska et al, 2018).…”