Vegetation affects photoprotective pigments and copepod distribution in the Himalayan lakes: Implication for climate...

Lakes in the Himalayas host unique biota and biological communities which are highly sensitive to climate change. High penetration of solar UV radiation in clear shallow lake affects the distribution and abundance of the zooplankton communities. Survival of copepods in such habitats often relies on available photoprotective compounds. We estimated species diversity and distribution patterns of copepods with detectable carotenoids in 7 lakes of the central Himalayas along the altitudinal gradients. To determine the factors influencing the accumulation of high-level photoprotective compounds, we analyzed the physicochemical parameters of water and the concentration of Lignin like Compounds (LLCs), Aromaticity (ARO), Humic Compounds (HCs), Degree of Humification (DoH) and percent Total Organic Matter (TOM) in littoral sediments. In the shallow lakes, copepod abundance and diversity correlate with water transparency. Humic compounds (HCs) derived from ligninaceous plants stimulate the accumulation of photoprotective compounds that allow for the domination of diaptomidae. Copepods receive photoprotective compounds from the humic-bounded sediment substrate. The amount of photoprotectants in the aquatic food chain of the central Himalayas is largely influenced by ligninaceous compounds derived from catchment vegetation. In copepods of shallow clear lakes, the remnant of dead trees in the littoral zones helps to minimize hazards caused by exposure effect and climatic stress. The reduction of vegetative covers in the shorelines may alter the community structure of zooplankton, particularly in the upland ecosystem.