Asheesh Shivam Mishra

Longitudinal Distribution of Benthic Macroinvertebrate Assemblages in a Central Highlands River, The Tons (Central India)

The median density of benthic macroinvertebrate assemblage declined longitudinally from headwater to mouth (except increase at T3) in the river Tons. Arthropoda was largest component followed by Mollusca and Annelida. The abundance of assemblages forming taxa Brachycentridae, Helidae and Leptophlebiidae declined at T2 and was replaced by Neoephemeridae and Glossocolecidae. Similarly, abundance of Baetidae and Caenidae decreased at T4 and was replaced by Chironomidae and Nephthydae at T4. The assemblages varied from the T1 to T4 but were dominated by Thiaridae at all stations except Neoephemeridae at T3. Principal component analysis revealed that Glossosomatidae, Glossocolecidae, Thiaridae and Neoephemeridae were the characteristic taxa at T1, T2–T4 and T3, respectively. Canonical correspondence analysis indicated that the substratum was an important factor for T1, T2 and T3, while water temperature for Chironomidae at T4. Rhyacophilidae, Neoephemeridae, Caenidae were associated with landuse and substratum, while current velocity was responsible for the abundance of Thiaridae. Thus, landuse, slope and substratum were the effective variables responsible for assemblage in the river Tons.

The health of benthic diatom assemblages in lower stretch of a lesser Himalayan glacier-fed river, Mandakini

This study examines the ecological state of epilithic diatom assemblages along the lower stretch of Mandakini, a glacier-fed Himalayan river. The diatoms were sampled at four stations during winter and summer, only once in each season. Valve counts were obtained from Naphrax mounts prepared from each sample. Assemblages were recorded for each location. The software OMNIDIA Ver. 5.3 was used for computing the ecological values from the sample counts. Normally Achnanthidium spp. dominated the assemblages, except Nitzschia fonticola (Grunow) at S1 (Kund) and Encyonema minutum (Hilse in Rabh) at S4 (Rudraprayag), only during summer. The ecological values revealed that the assemblages were in β-mesosaprobic and mésotraphentic states. However, at S4, trophic state was observed to be eutraphentic. Louis Leclercq index indicated that organic pollution was nonexistent, while the anthropogenic eutrophication was low except at S2 (Tilwara) and S3 (Medanpur) in summer and was moderate at S4 in winter characterized by a lean flow. The most abundant indicator taxa for anthropogenic eutrophication are varied; Cymbella tumida (Brebisson-Van Heurck) at S1, Encyonema minutum at S2, S4 while Surirella aungusta (Kutzing) at S3. Ordination showed that the taxa indicating degradation and anthropogenic eutrophication figured as characteristic taxa at respective locations.

Ecosystem health indicators in the Ganga Basin (Uttarakhand, India): Biodiversity, spatial patterns in structure and distribution of benthic diatoms, macro-invertebrates and ichthyofauna

This is the pioneering attempt to study the spatial patterns in structure of lotic ecosystems that form the Ganga River system in the Himalaya. The diversity of source (glacier-fed [GF], snow-fed [SN] and spring-fed [SF]) and stream-size (both interrelated) across the altitudinal panorama, create numerous habitats that contribute to structural diversity. The spatial patterns in richness, density and taxonomic composition and distribution of benthic diatoms are less affected by source compared with macro-invertebrates but shows strong influence on the distribution of fish fauna that are poikiliotherms, because a glacier-fed river carries ice-cold water (usually <20°C) in contrast to normal waters in spring-fed system (22°C near snowline, 32°C in foothills). The abundance patterns of biota of lower organisation grade (diatoms, macro-invertebrates) do not differ sharply even across distant river basins as they are more influenced by proximate factors; thus the sub-basins of the Alaknanda resemble more by virtue of one basin and there is notable resemblance between distant SF Bemunda (lower Ganga basin) and SF Gomti (East Rāmgangā basin) and even the farthest Yamuna and Rāmgangā. Fish are more sensitive to temperature and current velocities that are related to altitude and hence longitudinal rather than the spatial gradients in the mountains. The lotic ecosystem of Doon Valley harbour rich and diverse diatom flora, macroinvertebrate fauna and ichthyofauna. The examination of trophic, saprobic and ecological status shows that organic pollution, degradation and anthropogenic eutrophication are non-existent in the Lesser Himalayan rivers and streams, but the fragile Doon Valley is under severe anthropogenic stress. This and habitats fragmented by hydropower projects in the major rivers has threatened the iconic game fish Himalayan mahseer in the Ganga.

River ecosystems of the Central Highland ecoregion: Spatial distribution of benthic flora and fauna in the Plateau rivers (tributaries of the Yamuna and Ganga) in Central India

This study reveals the relationship of biotic assemblages to their environments in the Central Highland Ecoregion rivers (Ken, Paisuni and Tons). Such knowledge will enhance our predictive abilities in the ecological studies and resource management in the concerned region. Rivers of an ecoregion are expected to harbour similar flora, fauna, and communities. This hypothesis was examined by tracking the spatial variation in richness, density, and taxonomic composition of benthic diatom and macroinvertebrate assemblages in three Plateau rivers whose course lay within 3°N latitude. Taxonomic richness and density decreased with the reduction of substrate size from the headwaters to the lowlands. Cluster and ordination analyses indicate prevalence of intrabasin rather than interbasin gradients of abundance. In both assemblages, the most abundant taxon is rarely similar longitudinally or across the river sections in the ecoregion. Hence, proximate factors govern the assemblages rather than ecoregional properties (latitude, altitude). This, and the high richness of diatom flora, points to diverse assemblages from the headwater to the lowland section in each river and among the rivers of the ecoregion.

Spatial Distribution of Benthic Macroinvertebrate Fauna in Mountain Streams of Uttarakhand, India

The large-scale (regional) distribution pattern for the benthic macroinvertebrate fauna has been investigated for the first time in the west Himalayan streams. The macroinvertebrate fauna in the river basins of Uttarakhand region consists of Trichoptera, Ephemeroptera, Diptera, Coleoptera and Plecoptera. The faunal composition varied from the western (Yamuna) to eastern part (the Ramganga) of the Himalaya as the share of Trichoptera and Ephemeroptera is relatively low in the Yamuna river basin but dominates from Bhagirathi to Ramganga basin. The marginal increase of Diptera, Coleoptera and Mollusca in the Yamuna basin accounted for the decline of Trichoptera and Ephemeroptera in this basin. Leptoceridae and Glossosomatidae are the dominant taxa in the river Alaknanda and Mandakini, respectively, while Glossosomatidae and Philopotamidae are simultaneously dominant in the Bhagirathi, all trichopterans. Heptageniidae is dominant in the Ramganga and Yamuna, while Heptageniidae and Glossosomatidae are simultaneously dominant in the Pindar. The taxonomic composition is similar in the basins; Bhagirathi (Mandakini and Alaknanda), Yamuna and Ramganga, Pindar. The characteristic taxa varied among the forest type. No taxa are characteristic to Deodar forest. The characteristic taxa varied from oak in the west to pine forest type in the east. The scrapers (Blephariceridae, Limnephilidae, Planorbidae, Lymnaeidae), predators (Dixidae, Perlidae) and gatherers (Ephemerellidae, Baetidae, Hydropsychidae) characterised the pine forest. Similarly, the shredders (Leptoceridae) and filterers (Simuliidae) characterised the oak forest, while the scrappers (Elmidae, Dryopidae) and predators (Rhyacophilidae, Agrionidae) the pine–oak forest. Trichoptera is abundant in the forest as well as forest–agriculture land use. They functioned as shredders, collectors and gatherers in the former, whereas collectors, gatherers, filterers in the forest–agriculture land use. Scrapers (mainly Ephemeroptera) occurred in very low percentage in the forest–agriculture land use. Slope is observed to be an important environmental variable influencing taxonomic composition and distribution of caddisfly with case (Limnephilidae, Leptoceridae, Philopotamidae) along with mayfly (Leptophlebiidae, Baetidae) and stonefly (Perlodidae). As slope is a manifestation of altitude, it indirectly indicates the role of altitude and hence the forest.

Distribution of Major Floral and Faunal Diversity in the Mountain and Upper Gangetic Plains Zone of the Ganga: Diatoms, Macroinvertebrates and Fish

Present study examines the distribution of biodiversity elements (diatom, macroinvertebrate and fish) in respect of their taxonomic richness, density, composition in the high gradient mountain zone (MZ) and low gradient plains zone (PZ) consisting PZ I (Hardwar to Allahabad) and PZ II (Allahabad to Varanasi). The richness of benthic diatom and algal flora declines with loss of substrate heterogeneity from MZ to PZ, but that of plankton, macroinvertebrate and fish, increases gradually. Diatom predominate the benthic flora in MZ but richness declines mildly in PZ. The plankton community of PZ is mildly richer in diatom flora, as share of green algae is substantial. The macroinvertebrate fauna is predominated by insects in the MZ and a combination of insects and molluscs in the PZ. Low Jaccard’s similarity and high distances among MZ and PZ I, illustrate unique flora in these zones. Since, PZ II shows greater distance from both MZ and PZ I, this zone has different biodiversity in respect of these communities. In contrast the fauna is unique in MZ, while PZ I and PZ II have relatively more similarity, less in case of macroinvertebrate but high in fish.