Primary production is a fundamental ecosystem process that influences nutrient and carbon cycling, and trophic structure in streams. The magnitude and timing of gross primary production (GPP) are typically controlled by hydrology, light, nutrient availability and grazers. Estimates of GPP and its drivers in high-mountain streams remain elusive at present. 2) We estimated GPP in streams typical for high-mountain catchments, namely a glacier-fed, groundwater-fed (krenal) and a snowmelt-fed (nival) stream. Using high-resolution sensor data over 2 years in combination with numerical simulations of stream hydraulics, we studied the periods of GPP characteristic for these streams, as well as their major drivers. 3) Favourable windows for GPP were constrained to periods at the onset of the snowmelt and its recession, when photosynthetic active radiation at the streambed and streambed stability facilitated GPP. 4) During these windows of opportunity, GPP was higher in the nival stream (3.7 ± 3.4 g O2 m−2 day−1), followed by the glacier-fed (1.5 ± 1.6 g O2 m−2 day−1) and the krenal streams (0.6 ± 0.6 g O2 m−2 day−1). GPP was largely controlled by photosynthetic active radiation at the stream bottom, however, we were not able to establish an unequivocal relationship between flow-induced bed movement and GPP. 5) Our results highlight the capacity of primary producers to exploit the discrete and relatively predictable windows of opportunities in high-mountain streams. We propose that climate-driven change in snow and glacier melt reduction may ameliorate stream environmental conditions, thereby enhancing the potential autochthonous organic matter supply within the catchment.
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A stream is a continuous body of surface water flowing within the bed and banks of a channel. Depending on its location or certain characteristics, a stream may be referred to by a variety of local or regional names. Long, large streams are usually called rivers, while smaller, less voluminous and more intermittent streams are known as streamlets, brooks or creeks. The flow of a stream is controlled by three inputs – surface runoff (from precipitation or meltwater), daylighted subterranean water, and surfaced groundwater (spring water).
In ecology, primary production is the synthesis of organic compounds from atmospheric or aqueous carbon dioxide. It principally occurs through the process of photosynthesis, which uses light as its source of energy, but it also occurs through chemosynthesis, which uses the oxidation or reduction of inorganic chemical compounds as its source of energy. Almost all life on Earth relies directly or indirectly on primary production. The organisms responsible for primary production are known as primary producers or autotrophs, and form the base of the food chain.
Groundwater is the water present beneath Earth's surface in rock and soil pore spaces and in the fractures of rock formations. About 30 percent of all readily available freshwater in the world is groundwater. A unit of rock or an unconsolidated deposit is called an aquifer when it can yield a usable quantity of water. The depth at which soil pore spaces or fractures and voids in rock become completely saturated with water is called the water table.
High‐resolution time series of dissolved oxygen (DO) have revealed different ecosystem energetics regimes across various stream types. Ecosystem energetic regimes are relevant to better understand the
2020
High-altitude catchments have a major role in the transport of organic matter to streams due to the storage of dissolved organic carbon (DOC) in soils and glacier ice and the subsequent mobilization d
Stream ecosystem metabolism integrates production and respiration of organic matter and plays a fundamental role in the global carbon (C) cycle. Several studies have identified distal and proximal