<b>Stream macro-invertebrate diversity of the Phobjikha Valley, Bhutan</b>

Abstract

Macro-invertebrates form an integral part of aquatic systems, and assessment of macro-invertebrate communities is one of the best ways to monitor the health of a stream. Despite this, stream monitoring of macro-invertebrates has been extremely limited in Bhutan. A study was conducted to generate baseline information on macro-invertebrate diversity in the Phobjikha valley, covering community composition and seasonal variation in diversity during post and pre-monsoon seasons. From a total of 244 units sampled in streams, 50 families from 13 orders were recorded. The dominant order overall was Ephemeroptera (31%), which also dominated the premonsoon assessment (33%), while Trichoptera (39%) dominated the post-monsoon assessment. The pre-monsoon assessment recorded two additional orders, Caenogastropoda and Veneroida. There was no significant difference in diversity between the post-monsoon and pre-monsoon assessments (p˃0.3), but a significant difference in species diversity between seasons was observed in pools and riffles. Physicochemical parameters indicated that pH, electrical conductivity and salinity were within favorable ranges for macro-invertebrates. Further studies of other habitats in different seasons will produce a more comprehensive understanding of macro-invertebrate diversity.Keywords: Environmental variables, macro-invertebrate diversity, pools, post-monsoon, pre-monsoon, riffles, wetland.Journal of Threatened Taxa | www.threatenedtaxa.org | 26 January 2018 | 10(1): 11126-11146 11127 INTRODUCTIONFreshwater constitutes only 0.01% of the world's water, yet it is host to high percentage of aquatic biodiversity . Macro-invertebrates are vitally important to freshwater ecosystems, converting plant matter and detritus into major food resources for higher trophic levels in aquatic and terrestrial communities (Wallace & Webster 1996;Covich et al. 1999). Their role in decomposition of organic detritus, nutrient cycling, and water purification are crucial for the existence of stream organisms. Aquatic macro-invertebrates also constitute valuable natural resources for economic, cultural, aesthetic, ecological, scientific and educational purposes . Across the globe, about 126,000 freshwater species are reported, and experts have projected the number of species to surpass one million as aquatic biodiversity assessment continues (Darwall 2010). Specifically, over 6,500 species of Odonata (Trueman & Rowe 2008), over 3,141 species of Ephemeroptera (Truffer et al. 2003), over 3,400 species of Plecoptera (Yang & Yang 2006), and 12,627 species of Trichoptera (Moor & Ivanov 2008) are known. From a total of 70,000 known species of Mollusca (Haszprunar 2001) 5,000 are freshwater species, of which 4,000 are Gastropoda and 1,000 are Bivalvia (Balian et al. 2008).Bhutan is in the early stages of documenting freshwater biodiversity Dorji 2014;Gurung & Thoni 2015). Since 2004 documentation of freshwater biodiversity, particularly macroinvertebrates, was initiated by the National Environment Commission (NEC) in coll...

Seagrass Ecosystems of India as Bioindicators of Trace Elements

“…For example, small seagrass species like Halophila beccarii, Halophila ovalis are found in the muddy or sandy-muddy habitat of the intertidal region (Parthasarathy et al, 1991), whereas other seagrass species like Thalassia hemprichii and H. beccarii are found associated with mangroves (Jagtap et al, 2003;Mishra and Apte, 2020;Mishra and Mohanraju, 2018). Consequently, bigger seagrass plants like Enhalus acoroides are found at increased depths ( Patankar et al, 2018). However, this distribution of seagrass plants is dependent upon various limiting factors such as turbidity, light penetration, nutrient availability (Arumugam et al, 2013) that affect seagrass photo-physiology and reproductive processes (Patankar et al, 2018;Mishra and Apte, 2020b).…”

“…Consequently, bigger seagrass plants like Enhalus acoroides are found at increased depths ( Patankar et al, 2018). However, this distribution of seagrass plants is dependent upon various limiting factors such as turbidity, light penetration, nutrient availability (Arumugam et al, 2013) that affect seagrass photo-physiology and reproductive processes (Patankar et al, 2018;Mishra and Apte, 2020b). Secondly, this distribution of seagrass species is also influenced by presence of other seagrasses or mangroves or coral reefs that determines distribution patterns and ecological connectivity with sourrounding ecosystems (Apte et al, 2016;Mishra and Apte, 2020).…”

The Benthic Macro-Invertebrate Fauna of Owalla Reservoir, Osun State, Southwest, Nigeria

“…The benthic species diversity is controlled by productivity, habitat heterogeneity and biotic interactions; in general, invertebrates have a clumped distribution, which is assumed to be related with the mosaic of interchanging conditions in the substratum, flow conditions/velocities, depth and the type of substrate (Moretti and Callisto, 2005;Stamou et al, 2018). Some physical and chemical features directly affect taxonomic composition and community structure; substratum particle size, substratum stability, substratum organic matter contents (Wangchuk and Dorji, 2018), habitat spatial heterogeneity and sediment characteristics such as; grain size, predator exposure and food availability are important factors regulating macro-invertebrates abundance, distribution and richness, and hence, habitat characterization is of prime importance to the knowledge of macroinvertebrate distribution (Moretti and Callisto, 2005;Olapoju and Edokpayi, 2018). The relatively high number of individuals (benthic macroinvertebrates) from Owalla Reservoir could be attributed to probably the high nutrients and organic matter levels in the sediments (organic matter content: range = 0.69 -14.10 %; Mean±S.E.…”

Ecological Conditions of Luetshokha Lake and its Recharge Potential using Rooftop Rainwater Harvesting, Samtengang, Wangdue Bhutan

“…Unidentified organisms were preserved in 70% alcohol and labeled accordingly to be identified later. Macroinvertebrates were identified up to family level by referring "Field guide to freshwater invertebrates" (Thorp and Rogers, 2010) and available literatures from Bhutan (Wangchuk and Eby, 2013;Wangchuk and Kuenzang, 2018). The physico-chemical variables such as temperature, pH, conductivity, Total dissolved solids (TDS) and salinity were measured insitu using water samples collected from all the 35 sampling quadrants using PCSTestr 35.…”