Roundup: Mercury in Meltwater, Fish in Himalayas, and Black Flies in Colombia

Mercury Deposited as Snowfall Incorporated into Meltwater

From the Journal of Environmental Sciences: “The Tibetan Plateau (TP) is recognized as the ‘Water Tower of Asia.’ Yet our understanding of mechanisms influencing incorporation of mercury (Hg) into freshwater in mountain glaciers on the TP remains quite limited. Extensive sampling of environmental matrices (e.g., snow/ice) were conducted on the East Rongbuk glacier on Mt. Everest and Zhadang glacier on Mt. Nyainqentanglha for Hg speciation analysis. Speciated Hg behaved quite different during snowmelt: a preferential early release of DHg (dissolved Hg) was observed at the onset of snowmelt, whereas PHg (particulate-bound Hg) and THg (total Hg) become relatively enriched in snow and released later.”

Map of sampling locations.
Map showing the study’s sample sites and glacier locations (Source: Sun et al.).


Fish Diversity in Himalayan Streams Varies in Glacial and Rain-fed Streams

From Environmental Biology of Fishes: “Assessment of headwater biodiversity is essential for maintaining upstream downstream ecosystem services of rivers. Fish biodiversity assessment was conducted in the headwater tributaries of the glacial-fed Tamor River and rain-fed Kamala River in eastern Nepal. A total of eight sites were sampled… A total of 8940 fishes belonging to four orders, 10 families, 26 genera and 34 species were enumerated. Significant variation in Shannon-Weiner Diversity Index (p = 0.015) and Species Richness (p = 0.005) between the glacial fed and rain fed streams with higher values of these indices in the rain fed tributaries… These findings indicate that fish assemblages reflect the different ecological regimes of the glacial-fed and rain-fed headwaters.”

Map of study area
Map of study area (Source: Jha et al.).


Glacial Areas in Colombia Have Fewer Black Flies

From Acta Tropica: “Vector ecology is a key factor in understanding the transmission of disease agents, with each species having an optimal range of environmental requirements. Scarce data, however, are available for how interactions of local and broad-scale climate phenomena, such as seasonality and the El Niño Southern Oscillation (ENSO), affect simuliids. We, therefore, conducted an exploratory study to examine distribution patterns of species of Simuliidae along an elevational gradient of the Otún River in the Colombian Andes, encompassing four ecoregions… Species richness and occurrence in each ecoregion were influenced by elevation, seasonality, and primarily the warm El Niño and cool La Niña phases of the ENSO.”

Photo of Fly species examined by the study
Fly species examined by the study (Source: Mantilla et al.)


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