Moss-inhabiting diatoms as ecological indicators in Neora Valley National Park (Eastern Himalaya), India

Abstract

Terrestrial mosses which retain moisture provide a suitable ambience for diatoms colonization and suitable experimental platforms for observing climate change impact. The distribution and diversity patterns of such epibryic diatom communities are governed by various biotic and abiotic factors of moss habitats. The present study is first of ever attempt to investigate the moss-inhabiting diatoms in relation to various abiotic environmental variables from the Indian Himalayan Region (IHR). Samples were collected from 23 different sites in the Neora Valley National Park in Eastern Himalayas and analyzed through standard methods. Two-way indicator species analysis (TWINSPAN) and cluster analysis (CA) performed to classify the samples and habitats while direct canonical correspondence analysis (CCA) was used to determine the linkage between moss-inhabiting diatom species from various sample and abiotic environmental gradients. A total of 27 diatoms found colonizing on terrestrial moss patches from 23 sites of the park. CCA ordination plots showed that pH, conductivity and relative humidity were the primary factors influencing the diatom diversity and distribution, but altitude and temperature had no influence on the species distribution. But, correlation study on the average valve length of the most abundant and frequent taxa of Neora Valley National Park, i.e. Eunotia paludosa, E. bigibba and Hantzschia amphioxys, in relation to the environmental variables like, altitude, moisture content, relative humidity and temperature revealed a significant inference. The average valve length of these three diatoms decreases in warmer and drier climatic conditions at lower altitudes. Thus, these can be considered as potential indicator species to observe any climate change.