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 pre-monsoon 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.
Highlights
Freshwater constitutes only 0.01% of the world’s water, yet it is host to high percentage of aquatic biodiversity (Dudgeon et al 2006)
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)
Our assessment was conducted during post-monsoon, 2014 and pre-monsoon, 2015 in Phobjikha Valley
Summary
Freshwater constitutes only 0.01% of the world’s water, yet it is host to high percentage of aquatic biodiversity (Dudgeon et al 2006). 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. 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)
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