Climatic control of ultraviolet radiation effects on lakes

Leavitt, Peter R.; Cumming, Brian F.; Smol, John P.; Reasoner, Mel A.; Pienitz, Reinhard; Hodgson, Dominic A.

doi:10.4319/lo.2003.48.5.2062

Cited by 70 publications

(40 citation statements)

References 26 publications

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“…In Lake 5, the absorptivity was measured with and without filtration to account for the scattering of glacier flour. Though this procedure is not entirely correct, it gives probably a better estimate of the absorption/scattering in a glacier turbid lake (Leavitt et al, 2003).…”

Section: Uv Transparency and Cdom Absorptivitymentioning

confidence: 99%

Preferential accumulation of carotenoids rather than of mycosporine-like amino acids in copepods from high altitude Himalayan lakes

Sommaruga

2010

Hydrobiologia

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Zooplankton species have evolved several adaptive strategies to minimize damage caused by exposure to solar ultraviolet radiation, but the environmental conditions favoring one strategy or another are not yet fully understood. Here, I quantified the concentration of photoprotective compounds (carotenoids and mycosporine-like amino acids or MAAs) and assessed the photorepair activity (photolyase assay) in populations of the calanoid copepod, Arctodiaptomus jurisowitchi and the cladocerans, Daphnia himalaya and D. longispina, from five high altitude lakes located in the Himalayan Region (Khumbu Valley, Nepal) between 4890 and 5440 m above sea level. The concentration and diversity of MAAs were low in copepods, as well as in seston samples. Significant differences in the concentration of MAAs among the five copepod populations were largely explained (96%) by the lake depth refuge (i.e., the fraction of the water column to which 1% of the surface UVR at 320 nm penetrates). Concentrations of carotenoids (mostly free astaxanthin) in copepods were among the highest reported in the literature. Similar to MAAs, the carotenoid concentration was inversely related to the lake depth refuge. The lowest concentration of photoprotective compounds in copepods was observed in a turbid glacier lake, whereas the highest was found in a shallow water body dominated by a benthic mat of filamentous green algae. Except for the presence of melanin in D. himalaya, no other photoprotective compounds were found in cladocerans. The assay of photolyase activity in A. jurisowitchi and D. himalaya suggested the absence of a photorepair mechanism. The results of this study indicate that the copepod populations from this relatively pristine alpine region rely mainly on the accumulation of carotenoids to minimize damage by UV radiation, a pattern that strongly contrasts with what is known for copepods from other alpine lakes, for instance, in the Alps. I hypothesize that this difference is attributed to nitrogen limitation of the MAA synthesis in phytoplankton from remote Himalayan lakes.

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Section: Uv Transparency and Cdom Absorptivitymentioning

confidence: 99%

Preferential accumulation of carotenoids rather than of mycosporine-like amino acids in copepods from high altitude Himalayan lakes

Sommaruga

2010

Hydrobiologia

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“…A combination of altitude and low concentration of UV-absorbing substances favours the penetration of harmful UV radiation in the water column (Laurion et al, 2000). Despite the development of several adaptations by aquatic organisms (Sommaruga, 2010), alpine lakes are a potentially vulnerable environment to climate change because of the possible increase of UV doses connected to variations in organic matter inputs and, most notably, to decreases in ice cover (Neale et al, 2001; Leavitt et al, 2003;Rogora et al, 2003).…”

Section: Introductionmentioning

confidence: 99%

Photochemical production of organic matter triplet states in water samples from mountain lakes, located below or above the tree line

Laurentiis¹,

Minella²,

Maurino³

et al. 2012

Chemosphere

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davide.vione@unito.it (D.V.). AbstractThe production of triplet states (T*) of chromophoric dissolved organic matter (CDOM), reacting with the probe molecule 2,4,6-trimethylphenol (TMP) was measured upon irradiation of water samples, taken from lakes located in a mountain area (NW Italy) between 1450 and 2750 m above sea level. The lakes are located below or above the tree line and surrounded by different vegetation types (trees, alpine meadows or exposed rocks). The most photoactive samples belonged to lakes below the tree line and their fluorescence spectra and CDOM optical features suggested the presence of a relatively elevated amount of humic (allochthonous) material. The lowest (negligible) photoactivity was found for a lake surrounded by exposed rocks. Its CDOM showed an important autochthonous contribution (due to in-lake productivity) and considerably higher spectral slope compared to the other samples, suggesting low CDOM molecular weight and/or aromaticity.Among the samples, CDOM photoactivity (measured as the rate of TMP-reactive T* photoproduction) decreased with changing vegetation type in the order: trees, meadows, rocks. It 3 could be connected with decreasing contribution from catchment runoff and increasing contribution from autochthonous processes and possibly precipitation.

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“…chlorophyll a) are a reliable proxy of modern algal biomass. As a result of the number of biological, physical and chemical factors that influence their deposition and abundance (Leavitt, 1993), pigments have been successfully used as indices of present and past trophic conditions (Gorham et al, 1974;Sanger, 1988;, lake acidification (Guilizzoni et al, 2006) and climate change (Smol et al, 1991;Leavitt et al, 2003). Plant pigments are relatively susceptible to early oxidative decomposition.…”

Section: Introductionmentioning

confidence: 99%

Sedimentary evidence for recent increases in production in Tibetan plateau lakes

et al. 2010

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The Tibetan Plateau is a vast, elevated plateau in Central Asia with an average elevation of over 4,500 m and contains the world's third largest store of ice. It occupies a climatic transition zone between the Asian monsoons and westerly airflow. As a result of this location, the region is sensitive to changes in climate on timescales of decades to millennia and longer. Long-term data are needed to evaluate climatic changes and their impact on ecosystems, but in areas as remote as the Tibetan Plateau, long-term instrumental records of environmental change are geographically sparse and monitoring has only been undertaken in recent times. Paleolimnological approach might be then one of the few means by which environmental variability can be ascertained at scales that allow comparison with contemporary monitoring data and future model projections. Therefore, a paleolimnological study was undertaken in eight different lakes sampled along a North-South transect across the Tibetan Plateau analysing geochemistry and algal pigment in order to assess longer term variability in the trophic condition of these systems and their potential to reconstruct changes in relation to recent climate evolution and possible human impacts. Chronologies for the last century were based on radiometric techniques ( 210 Pb, 241 Am and 137 Cs). Results show that inorganic sediment dominates the composition of the cores used in this study. Organic carbon constitutes less than 5% d.w. in all the lake cores, except for Kemen Co core where concentrations up to 14% d.w., are observed. Corg:N ratios are generally in the order of 5-10, indicating that autochthonous algal production is the principal biological source of organic matter. Pigment preservation is generally good throughout the cores from all lakes as shown by the 430:410 nm ratio that is generally around 1.0 or higher. Six out of eight lakes show an increase in primary production in recent times. High pre-1800 AD pigment concentrations were detected only in Qinghai Lake. Since most of the lakes show a similar behaviour in the most recent section of the core, we interpret this as a response to climate and land-use changes that have increased autochthonous production throughout the Tibetan Plateau.

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Climatic control of ultraviolet radiation effects on lakes

Cited by 70 publications

References 26 publications

Preferential accumulation of carotenoids rather than of mycosporine-like amino acids in copepods from high altitude Himalayan lakes

Preferential accumulation of carotenoids rather than of mycosporine-like amino acids in copepods from high altitude Himalayan lakes

Photochemical production of organic matter triplet states in water samples from mountain lakes, located below or above the tree line

Sedimentary evidence for recent increases in production in Tibetan plateau lakes

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