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
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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...
