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2025
2025
Project 1: Microplastics, Freshwater Ecology and Aquatic Assessments in the Streams and Rivers of Thimphu, Bhutan: Plastic Free Rivers and Seas for South Asia
In the heart of Bhutan’s capital, the streams and rivers of Thimphu tell a complex story of resilience and vulnerability. As part of the "Plastic Free Rivers and Seas for South Asia (PLEASE)" initiative, our latest research dives deep into the pulse of these waterways—assessing biodiversity, water quality, and the creeping menace of microplastic pollution. Spanning 12 streams across shifting seasons, our findings reveal a striking contrast: vibrant pre-monsoon ecosystems teeming with macroinvertebrates give way to a post-monsoon landscape of decline, shaped by flash floods and pollution. The discovery of plastic-laden sites hosting pollution-tolerant species underscores an urgent call for action—a future where science, policy, and community unite to safeguard Bhutan’s freshwater lifelines.
Project 2: Aquatic Biodiversity Study for the Integrated Multipurpose Hydropower Project in Pachhu
The study assesses aquatic biodiversity and distribution patterns in Tsento Gewog, Paro Dzongkhag. The region features high-altitude ecosystems with rugged terrain, fast-flowing rivers, and significant elevation changes. The study evaluates the potential impacts of hydropower development on aquatic life, focusing on fish and macroinvertebrate populations, and provides recommendations to minimize ecological disruption.
Methodology
Data collection was conducted during both wet (July 26-31, 2024) and dry (December 12-18, 2024) seasons using systematic random sampling techniques. Key equipment included:
AVFM 6.1 Area Velocity Flow Meter: Measured water velocity and depth.
YSI ProDSS Multiparameter Water Quality Meter: Analyzed pH, dissolved oxygen, turbidity, and temperature.
Fish and macroinvertebrate specimens were collected using cast nets, electro-shockers, and D-frame aquatic dip nets. Samples were photographed, preserved, and identified.
Key Findings
1.Fish Species:
Only one species, Salmo trutta (Brown Trout), was recorded across all sampling sites in both seasons.
2.Macroinvertebrates:
Dry Season: Higher species richness (SR = 5.16), diversity (H = 2.28), and evenness (EH = 0.86).
Wet Season: Dominated by Baetis (RA = 59.23%), with lower diversity (H’ = 1.38) and evenness (EH = 0.60).
Seasonal hydrological changes significantly influence macroinvertebrate distribution, highlighting the need for adaptive management strategies.
Project 3: Gelephu Mindfulness City- Aquatic Biodiversity and its habitat preferences
The aquatic biodiversity baseline survey for the Gelephu Mindfulness City pre-feasibility study assessed fish and macroinvertebrate populations in lowland riverine ecosystems along the proposed Gelephu-Taraythang road and bridge in southern Bhutan. The study recorded 35 fish species from 14 families, with 282 fish (32 species) observed during the monsoon season and 849 fish (28 species) in the post-monsoon season. Dominant species included Garra birostris (18.79% of monsoon samples) and Garra annandalei (27.21% of post-monsoon samples). Additionally, 14 macroinvertebrate species from seven orders and 14 families were documented, with the Baetidae family (genus Baetis) being the most abundant at 39.63% of total samples. The post-monsoon season showed a slight increase in diversity (H' = 1.90) and species richness (SR = 4.82), indicating ecosystem recovery.
The survey found no critically endangered or endangered species according to the IUCN Red List, suggesting the area’s biodiversity, while rich, is not at immediate risk of extinction. The dominance of Cyprinidae (fish) and Baetidae (macroinvertebrates) families underscores their ecological importance. These findings provide critical baseline data to guide conservation and mitigation strategies, ensuring minimal environmental impact from the Gelephu Mindfulness City project and preserving biodiversity for future generations.
Project 4: Aquatic ecology of Fishes, Macroinvertebrates, Microinvertebrates and Water Quality in Sankosh
Our team is currently working as Aquatic Consultant for Druk Green Power Corporation, providing aquatic expert services for the 12th hydropower project we have collaborated on. This study focuses on the ecological health of the Sankosh River, assessing fish populations, macro- and microinvertebrates, microbial communities, and plankton, alongside 28 key water quality parameters. As we support the development of the Sankosh Hydropower Project, our dedicated and hardworking team is committed to delivering precise and comprehensive ecological insights. With one round of data collection completed and three more to go in the coming months, this rigorous assessment will span the entire 2025 research year, ensuring informed decision-making for sustainable hydropower development.
The Enigmatic Bagarius
During our aquatic survey, we discovered the skull of Bagarius, a giant catfish species, collected by a local Forestry official. Though we have yet to encounter a live specimen, its presence sparks curiosity—this species is considered mythical by local communities, often likened to a river mermaid--Tshomen. This remarkable find suggests that the Sankosh River sustains large fish populations, including Golden Mahseer, Copper Mahseer, and Labeo species, reinforcing the river’s ecological richness and the need for its conservation.
In the southern regions of Bhutan, particularly near bigger rivers like Sankosh, the Lhotshampa community, such as the Subba people, hold a fascinating belief—Bagarius, the giant catfish, is considered like a sacred grandmother figure. This deep-rooted reverence means they neither touch, catch, nor consume the species. In my opinion--interestingly, the fish’s barbels, mouth structure, and head shape bear an uncanny resemblance to a woman’s face when viewed from a distance, possibly fueling this mystical association. Whether myth or ecological wonder, Bagarius remains an enigma, weaving culture and nature into one fascinating tale.
Field and Laboratory Experts collecting the specimens
Sampling experts collecting specimens from different habitats
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