Use of Multi-Carbon Sources by Zooplankton in an Oligotrophic Lake in the Tibetan Plateau

Hu, En; He, Hongbo; Su, Yushan; Liu, Zhengwen

doi:10.3390/w8120565

Cited by 9 publications

(5 citation statements)

References 33 publications

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“…Along with degradation and transformation of allochthonous DOM, autochthonous DOM production plays a large role for the natural OM characteristics of Lake Nam Co. Microbial autochthonous DOM sources have been suggested for Lake Nam Co (Spencer et al, 2014;Maurischat et al, 2022) and other large lakes of the Himalayas . Hu et al (2016) report from a Nam Co food web study that mainly autochthonous organic carbon sources are utilised by zooplankton, further corroborating the importance of an autochthonous DOM source. The comparably low CHO index (Fig.…”

Section: Abiotic and Biotic Controls On Dom Composition Are Superimpo...mentioning

confidence: 65%

A DOM continuum from the roof of the world – Tibetan molecular dissolved organic matter characteristics track sources, land use effects, and processing along the fluvial-limnic pathway

Maurischat

Seidel²,

Dittmar³

et al. 2022

Preprint

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Abstract. The Tibetan Plateau (TP) is the world largest and highest plateau, also comprising the biggest connected alpine pasture system of the world. Like other alpine systems, it is sensitive to impacts by climate change and increasing anthropogenic pressure. Carbon cycling at the TP is complex, including sources such as primary production in lakes, glaciers, and terrestrial plants, agricultural land use but also organic matter (OM) from aeolian deposition. Dissolved organic matter (DOM) connects these carbon reservoirs in the network, following the hydrological cycle from precipitation, glaciers, and headwaters to lakes. DOM is highly complex, its molecular composition holds information from its diverse sources and transformations during transport. However, due to its complexity, DOM cycling along the headwater-fluvial-limnic pathway and how terrestrial change can impact carbon cycling in the diverse water bodies is still not well understood. Here, we study DOM molecular transformations using ultrahigh-resolution mass spectrometry (FT-ICR-MS) along the TP alpine continuum from glacial, groundwater springs, and wetland biomes including pastures and alpine steppe, to the large saline endorheic Lake Nam Co. DOM molecular composition differed with respect to allochthonous sources between endmembers, as well as between stream samples, the brackish mixing zone, and the lake. Glacial meltwater DOM contained autochthonous signatures of low-oxidised, unsaturated molecular formulae together with terrestrial-like, dust-borne DOM sources. Glacial-fed streams were characterised by fresh autochthonous, probably algal DOM, and aromatic compounds likely originating from pastoral land sources. DOM from a groundwater spring had a highly degraded, strongly oxidised signature, probably related to the shallow upper aquifer, and degraded pastoral land sources. Wetland and stream DOM were characterised by less oxidised and less degraded inputs from vascular plants and soils. At the brackish zone of the lake shore, DOM contained a mixture of lake- and terrestrial DOM inherited from the streams. At Lake Nam Co, depletion of aromatic terrestrial molecular formulae suggested photooxidation at the surface, and relative enrichment of potentially recalcitrant DOM within the lake. Additionally, a relative enrichment of more aliphatic, nitrogen-containing DOM suggests autochthonous algal and microbial DOM sources in the lake. Our study revealed that DOM composition was largely influenced by local sources and transformations in glaciers, wetlands, and groundwater springs, also incorporating molecular signatures of pasture degradation. Streams with less glacial influence had plant- and soil borne aromatic-rich DOM sources, while the endorheic Lake Nam Co had a recalcitrant DOM composition comparable to millennial-scale stable marine DOM. This suggests that there is no typical high-alpine DOM signature, but that complex processes form DOM characteristics in the fluvial-limnic continuum. Small-scale catchment properties, land degradation and aquatic domains shape the differences. Alpine DOM compositions hence appear to be closely linked to landscape properties suggesting their susceptibility to changes in water quality and OM cycling in sensitive High Asian ecosystems.

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Section: Abiotic and Biotic Controls On Dom Composition Are Superimpo...mentioning

confidence: 65%

A DOM continuum from the roof of the world – Tibetan molecular dissolved organic matter characteristics track sources, land use effects, and processing along the fluvial-limnic pathway

Maurischat

Seidel²,

Dittmar³

et al. 2022

Preprint

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show abstract

“…One of the regions experiencing rapid glacial change due to warming is the Tibetan Plateau. In this special issue, Hu et al [38] examine the extent to which organic C from glacial runoff subsidizes the plankton food web in Lake Nam Co, a typical high altitude lake in the Plateau. They did this by focusing on the zooplankton and using stable C isotope analysis and radio-carbon to determine the basal source of C in their diets.…”

Section: Related Topicsmentioning

confidence: 99%

Ecological Responses of Lakes to Climate Change

Havens

Jeppesen

2018

Water

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“…DIClake represents DIC in lake and the Δ14C of DIClake is applied as a substitute for that of phytoplankton. Data of aquatic and terrestrial plants in Lake Namtso are from Hu et al ().…”

Section: Resultsmentioning

confidence: 99%

“…The ongoing glacier mass loss and permafrost thawing have important implications for the quantity, age, and reactivity of organic carbon (OC) in proglacial freshwater (Hood and Scott ; Caraco et al ; Mann et al ; Qu et al ). By measuring natural abundance of radiocarbon ( 14 C), highly aged ( 14 C depleted) organic material has been found in some rivers and lakes, from Arctic (Schell ; Guo et al ), tropical (Mayorga et al ) to temperate rivers and lakes (Raymond et al ; Drenzek et al ; Keaveney et al a,b ; Zigah et al ), and Tibetan alpine streams and lakes (Spencer et al ; Hu et al ). A few studies have provided compelling evidence that ancient allochthonous OC may be an important food source for microbial heterotrophs (Cherrier et al ; Singer et al ; Mann et al ; Bellamy and Bauer ), invertebrates, and higher trophic consumers such as fish and waterfowl (Schell ; Hågvar and Ohlson ; Fellman et al ) and that it may be a significant resource for food webs in rivers and estuaries (McCallister et al ; Caraco et al ).…”

mentioning

confidence: 99%

Assimilation of ancient organic carbon by zooplankton in Tibetan Plateau lakes is depending on watershed characteristics

Hu²,

Liu

et al. 2018

Limnology & Oceanography

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Ancient (i.e., radiocarbon depleted) organic carbon (OC) is exported from ice sheet, glacier, and permafrost systems and may be buried, respired, or assimilated in downstream aquatic systems. Few studies have explored the potential use of this ancient OC in lake food webs. We combined natural abundance radiocarbon and stable carbon isotope data (Δ14C and δ13C) to study ancient OC utilization by zooplankton in six lakes covering a large climate gradient on the central and peripheral Tibetan Plateau. A depleted Δ14C signature of dissolved and particulate OC was found in the inflowing streams and lakes, ranging from – 49‰ to – 569‰, corresponding to radiocarbon ages between 403 yr and 6757 yr. The Δ14C values for zooplankton in the lakes ranged from – 45‰ to – 264‰, reflecting that zooplankton obtain 14C‐depleted signatures through assimilation of ancient OC and/or indirectly through consumption of phytoplankton or aquatic plant utilizing 14C‐depleted inorganic carbon. Moreover, ancient OC from inflowing streams contributed more to zooplankton diets in the temperate glacier area than in the cold glacier area. Assimilation of ancient OC by zooplankton in lakes is not only affected by drainage basin characteristics, such as the recharge coefficient of the lake, but also by the biogeochemical properties of OC. Use of ancient OC by zooplankton in high‐altitude lakes may constitute an important link between the contemporary aquatic food webs and the glaciated watersheds. Our findings have important implications for the contribution of ancient carbon to the modern lake food webs of high‐altitude and polar lakes.

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Use of Multi-Carbon Sources by Zooplankton in an Oligotrophic Lake in the Tibetan Plateau

Cited by 9 publications

References 33 publications

A DOM continuum from the roof of the world – Tibetan molecular dissolved organic matter characteristics track sources, land use effects, and processing along the fluvial-limnic pathway

A DOM continuum from the roof of the world – Tibetan molecular dissolved organic matter characteristics track sources, land use effects, and processing along the fluvial-limnic pathway

Ecological Responses of Lakes to Climate Change

Assimilation of ancient organic carbon by zooplankton in Tibetan Plateau lakes is depending on watershed characteristics

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